Agenda Item - 2022-11-16
Natural Areas Habitat
Management Plan
City of Lake Oswego
November 2022
Lake Oswego Natural Areas Habitat Management Plan
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Prepared for:
Lake Oswego Parks & Recreation
PO Box 369
Lake Oswego, OR 97035
Prepared by:
888 SW 5th Avenue
Suite 600
Portland, OR 97204
aecom.com
and
2100 S River Pkwy
Suite 100
Portland, OR 97201
Acknowledgements:
This plan benefited from stakeholder input, including members of the City’s Parks staff, Parks, Recreation
& Natural Resource Advisory Board, watershed councils, Friends groups, the Clackamas Soil and Water
Conservation District, citizen volunteers, and the City’s contractors that have been actively restoring the
City’s natural areas for several years. The authors wish to extend special gratitude to the staff at Mosaic
Ecology and Ash Creek Forest Management, whose detailed input on park conditions and past
restoration efforts has greatly benefited this plan.
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Executive Summary
This Natural Areas Habitat Management Plan (Plan) focuses on improved ecological resiliency for 27 of
the City of Lake Oswego’s (City) natural areas. It also provides a framework for the management of other
natural lands in the City. This Plan seeks to achieve an overarching management goal for Lake Oswego’s
natural areas:
Enhance and restore Lake Oswego’s natural areas to provide safe and healthy ecosystems.
For the purposes of this plan, “healthy” natural area ecosystems are defined as:
Natural areas that can support a wide diversity of native plants and animals and can adapt to
change to maintain functionality amidst increased recreation, encroachment by invasive species,
changes to natural water flows, and threats posed by wildfire and climate change.
This Plan summarizes the management of the City’s natural areas to date by Lake Oswego Parks and
Recreation (LOPR), which collaborates with restoration contractors to enhance park properties. To date,
LOPR has focused on the treatment and removal of ivy (Hedera helix, H. hibernica) and other prioritized
invasive species, and the installation of native plants in disturbed habitat areas. This Plan also
summarizes the City’s partnerships with local volunteer groups and watershed councils, which are
instrumental to the continued care of the City’s natural areas.
This Plan was developed by mapping and classifying seven general habitat types that are commonly
observed within each of the City’s natural areas. The seven habitat types include: mixed-conifer
deciduous forest, deciduous forest, Oregon white oak woodland, conifer forest, shrubland, upland
grassland, and wetland. Habitats were classified based on a unique condition ranking system for
purposes of managing lands based on their ecological status (degraded, moderate, or good quality). The
Plan then lists eight Management Objectives to support the overarching management goal:
Objective 1. Enhance Natural Area Health and Resilience by Supporting Natural Ecological Processes
Objective 2. Noxious Weed Control
Objective 3. Minimize Habitat Fragmentation
Objective 4. Improve Climate Resilience
Objective 5. Reduce Wildlife Hazards
Objective 6. Enhance Hydrologic Function and Resource Protection Districts
Objective 7. Selective Tree Removal to Improve Safe and Healthy Ecosystems
Objective 8. Adaptively Manage Ongoing Public Engagement Opportunities that Benefit Habitat
Protection and Enhancement
These objectives were developed based on habitat conditions and observed factors that constrain healthy
ecosystems (e.g., invasive species, dispersed, informal trails, and increased drought stress from
increasing summer temperatures). Success criteria were developed for each objective to provide a means
of determining whether objectives are achieved and to inform an adaptive management approach.
This Plan includes management prescriptions, or strategies, that can be applied to help achieve these
eight objectives. The prescriptions have been grouped into three categories: General (apply to all parks
and habitat types), Habitat-specific (apply to specific habitat types across all parks based on existing
condition), and Park-specific (apply to individual parks). The Plan is intended to be a living document that
is periodically updated. To that end, it concludes with recommendations for adaptive management, a
systematic approach for improving natural resource management based on periodic monitoring and a
review of trends to inform ongoing management approaches. Data review and resulting plan updates are
recommended every 6 years (every three biennial planning cycles).
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Table of Contents
Executive Summary ...................................................................................................................................... iv
Acronyms and Abbreviations ....................................................................................................................... vii
1. Introduction ........................................................................................................................................ 1
2. Background ........................................................................................................................................ 1
2.1 Overview of Lake Oswego Natural Areas ................................................................................................. 2
2.2 Summary of Natural Areas Management Efforts to Date .......................................................................... 5
2.3 Related Plans ........................................................................................................................................... 5
2.4 Available Data ........................................................................................................................................... 6
3. Generalized Plant Communities in Lake Oswego Natural Areas ...................................................... 6
3.1 Plant Community Summaries ................................................................................................................... 7
3.1.1 Mixed Conifer-Deciduous Forest ................................................................................................ 7
3.1.2 Deciduous Forest ....................................................................................................................... 7
3.1.3 Oregon White Oak Woodland ..................................................................................................... 8
3.1.4 Conifer Forest ............................................................................................................................. 8
3.1.5 Shrubland ................................................................................................................................... 8
3.1.6 Upland Grassland ....................................................................................................................... 9
3.1.7 Wetland ...................................................................................................................................... 9
3.2 Limiting Factors ........................................................................................................................................ 9
3.2.1 Invasive Species ...................................................................................................................... 10
3.2.2 Off-Leash Dogs ........................................................................................................................ 10
3.2.3 Informal Trails ........................................................................................................................... 10
3.2.4 Forest Pests ............................................................................................................................. 10
3.2.5 Encroachment .......................................................................................................................... 10
3.3 Conditions Ranking ................................................................................................................................. 10
4. Management Goal, Objectives, and Prescriptions .......................................................................... 12
4.1 Management Goal and Objectives.......................................................................................................... 12
4.1.1 Objective 1. Enhance Natural Area Health and Resilience by Supporting Natural Ecological
Processes ............................................................................................................................................... 12
4.1.2 Objective 2 Noxious Weed Control ........................................................................................... 12
4.1.3 Objective 3. Minimize Habitat Fragmentation and Protect Sensitive Areas .............................. 13
4.1.4 Objective 4. Improve Climate Resilience .................................................................................. 14
4.1.5 Objective 5. Reduce Wildfire Hazards ...................................................................................... 14
4.1.6 Objective 6. Enhance Hydrologic Function and RP Districts .................................................... 15
4.1.7 Objective 7. Selective Tree Removal to Improve Safe and Healthy Ecosystems ..................... 15
4.1.8 Objective 8. Adaptively Manage Ongoing Public Engagement Opportunities that Benefit
Habitat Protection and Enhancement ..................................................................................................... 16
4.2 Management Prescriptions ..................................................................................................................... 16
4.2.1 General Prescriptions ............................................................................................................... 17
4.2.2 Habitat-Specific Prescriptions ................................................................................................... 19
4.2.3 Natural Area-Specific Prescriptions .......................................................................................... 21
5. Coordination with Urban Forestry Planning Policies ....................................................................... 23
6. Monitoring and Adaptive Management ............................................................................................ 24
7. References ...................................................................................................................................... 25
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Tables
Table 1. Lake Oswego Natural Areas Assessed by this Plan ....................................................................... 3
Table 2. Data Sources Used to Help Identify Plant Community Boundaries ................................................ 6
Table 3. Summary of General Management Strategies by Objectives ....................................................... 17
Table 4. Summary of Management Strategies by Habitat Type .................................................................. 19
Table 5. Summary of Priority Management Strategies by Natural Area ..................................................... 21
Figures
Figure 1. Lake Oswego Natural Area Study Sites Considered in this Plan .................................................. 4
Appendices
Appendix A - Park Summary
Appendix B - Habitat Inventory and Classification Map Set
Appendix C - Target Native Plants by Habitat Type
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Acronyms and Abbreviations
City City of Lake Oswego
CSRT Climate Smart Restoration Tool
dbh diameter at breast height
HEP Habitat Enhancement Program
LDC Lake Oswego Community Development Code
LO Lake Oswego
LOC Lake Oswego Code
LOPR Lake Oswego Parks and Recreation
ODA Oregon Department of Agriculture
ODFW Oregon Department of Fish and Wildlife
OPWG Oak Prairie Work Group
Plan Natural Areas Habitat Management Plan
RC Resource Conservation (District)
RP Resource Protection (District)
RLIS Regional Land Information System
SWCD Soil and Water Conservation District
USDA US Department of Agriculture
USFWS US Fish and Wildlife Service
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1. Introduction
The purpose of this Natural Areas Habitat Management Plan (Plan) is to provide a framework for
consistent management of natural areas parklands by the City of Lake Oswego (City). This Plan is
focused on developing habitat- and area-specific natural area management objectives and strategies
tailored to the existing habitat conditions observed within the City’s various natural areas.
The City’s Parks and Recreation Department (Lake Oswego Parks and Recreation [LOPR]) manages
over 460 acres of land to maintain and enhance the natural character and beauty of Lake Oswego. As
stated in its mission, LOPR provides excellence in building community, enriching lives, and caring for our
urban and natural environment. Protecting and conserving natural area parks is an important aspect of
this mission due to their role in providing important habitat for plants and animals, watershed and
stormwater management, and spaces for the community to connect with nature. While restoration
practices are meant to return urban parks to their natural state, ongoing maintenance is acknowledged
and expected in all of these habitats.
This Plan was developed with an overarching management goal for Lake Oswego’s natural areas:
Enhance and restore Lake Oswego’s natural areas to provide safe and healthy ecosystems.
For the purposes of this plan, “healthy” natural area ecosystems are defined as:
Natural areas that can support a wide diversity of native plants and animals and can adapt to
change to maintain functionality amidst increased recreation, encroachment by invasive species,
changes to natural water flows, and threats posed by wildfire and climate change
This Plan focuses on ecological restoration, enhancement, and improved ecological resiliency for 27 of
the City’s natural areas and sets the framework for other natural lands in the City. Improved ecological
resiliency can be achieved via a suite of actions aimed at improving climate resiliency, supporting native
vegetation (generally), supporting Oregon Conservation Strategy species and habitats, improving native
species diversity, and reducing fire hazard. This Plan was developed by identifying and mapping habitat
types within each of the City’s natural areas, ranking the condition of habitats within each natural area,
creating management objectives based on habitat conditions, addressing specific threats (e.g., invasive
species, climate change), and recommending management actions accordingly. The Plan is adaptable
and will be updated every 6 years, as necessary, based on monitoring data and recommendations for
adaptive management.
Anticipated benefits of the Plan include:
Developing healthy ecosystems;
Providing the City with a framework for planning and prioritizing restoration activities ;
Providing a framework that can be applied to other smaller or future natural area sites ;
Ensuring transparency in how natural areas are managed;
Providing background information to help support land use approvals for necessary enhancement
activities, particularly for natural resources identified by the City’s Sensitive Lands Map; and
Streamlining project development for habitat enhancement grant applications.
2. Background
The City encompasses 11.2 square miles in Clackamas (primarily) and Multnomah Counties and is
located about 8 miles south of the City of Portland. Current management of the City’s natural areas is
conducted by LOPR, which performs tasks such as noxious weed removal, native plant establishment,
trash removal, and maintenance of physical structures (i.e., fences, signs, restrooms, trails, picnic
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facilities, and interpretive features). Responsibilities of LOPR natural areas staff include natural areas
management and maintenance, oversight of enhancement and restoration efforts, and management of
contractors hired to conduct ecological enhancement activities. Staff also manage trail maintenance,
outreach and education with the public, and coordination with volunteers. LOPR works in coordination
with the Planning, Fire, and Engineering Departments on specific aspects of this restoration work as well.
The City partners with local volunteer groups for maintenance of natural areas:
Friends of Hallinan Heights Woods, Friends of Iron Mountain Park, Friends of Lily Bay Natural
Area, Friends of Luscher Farms, Friends of the Walugas, Friends of Southwood Park, Friends of
Springbrook Park, Friends of Woodmont
Parks, Recreation and Natural Resource Advisory Board, as well as the Natural Areas Work
Group (a sub-committee)
Clackamas Soil & Water Conservation District
Backyard Habitat Certification Program (Portland Audubon and Columbia Land Trust)
SOLVE and many other local service groups
Oswego Lake Watershed Council, Tualatin River Watershed Council, Tryon Creek Watershed
Council (non-city land)
The recommendations of this Plan are consistent with the City Charter (Chapter X. Section 43. Limitations
of Development) which states that “the City of Lake Oswego shall be allowed to maintain (or allow any
person to maintain) a Native Preserve for the purposes of ecological restoration that provides a safe and
healthy natural area that is accessible for public enjoyment, provides a healthy habitat for wildlife,
eliminates invasive species, restores native species, and mitigates fire hazards.”
2.1 Overview of Lake Oswego Natural Areas
Lake Oswego’s natural areas are located within Oregon’s “Interior (Willamette) Valley” vegetation zone,
described as a mosaic of oak woodlands, coniferous forests, grasslands, shrub communities, and riparian
forests, which are enclosed by the Cascade Range to the east and the Coastal Ranges to the west
(Franklin and Dyrness 1988). The locations of natural area parks range from hill tops (such as Cook’s
Butte) to low-lying shoreline areas along Oswego Lake or the Tualatin River (Lily Bay and River Run,
respectively). Most of the natural area lands are forested or in the process of becoming forested; very few
areas remain in a maintained grassland state (e.g., Stevens Meadows). General habitat types observed
within the natural areas are consistent throughout the City, with characteristics generally associated with
elevation, topography, and water presence. Natural areas on slopes tend to consist of primarily conifer or
mixed conifer and deciduous forest. Natural areas along streams or rivers contain deciduous, riparian
forest habitat. Natural areas located on low-gradient (relatively flat) terraces generally contain deciduous
upland or wetland habitats. Further detail is provided in Appendix A. Table 1 lists the 27 Lake Oswego
natural areas evaluated for this Plan and Figure 1 provides their locations within the City.
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Table 1. Lake Oswego Natural Areas Assessed by this Plan
Name Size
(acres)
Bryant Woods Park 19.7
Canal Acres 27.3
Cooks Butte City Park 43
Cornell Natural Area 3.2
East Waluga Park* 53
Freepons Park* 5.9
George Rogers Park* 26
Glenmorrie Park* 2.3
Glenmorrie Greenway 3.9
Hallinan Woods 3.8
Iron Mountain* 51
Kelly Creek 3.7
Lamont Springs Natural Area 0.5
Lily Bay 1.8
Luscher Farm Natural Areas 19
Pennington 2.4
Rassekh** 2.1
River Run 10.8
Roehr Natural Area* 7.9
Sierra Vista 1.3
South Shore Natural Area 9.2
Southwood Park 2.5
Springbrook Park 52
Stevens Meadows 27.8
Sunny Slope 12
West Waluga Park* 22.8
Woodmont Natural Park 6.8
TOTAL 421.5***
Notes:
*Hybrid park
**Hybrid park In planning stage (only stream corridor is managed as a natural area)
***These are the acres assessed by this plan; not the total acres of areas managed by the City as Natural Areas Parks
(approximately 460 acres)
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Figure 1. Lake Oswego Natural Area Study Sites Considered in this Plan
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2.2 Summary of Natural Areas Management Efforts to Date
Healthy ecosystems support the health, wellness, and safety of Lake Oswego residents. The City has
recognized this and has a long history of protecting and planning for projects that enhance parks and
natural areas. In 2011, the City Council directed LOPR to prioritize ivy (Hedera helix, H. hibernica)
removal from natural area parks. LOPR was asked to redirect $70,000 of general funding to support ivy
removal annually, which became the Invasive Removal Program. This funding was used to hire
restoration contractors to treat and remove ivy and other prioritized invasive species. While developing
the LOPR 2025 Master Plan, the City’s natural areas were evaluated and ranked on the basis of condition
and resource values. The Master Plan established the initial framework to guide City staff, contractors,
and volunteer restoration priorities.
In 2014 the City developed an updated Sensitive Lands Ordinance in coordination with Metro. Sensitive
Lands regulated by the City include wetlands, streams, riparian areas, and upland forest stands. Updates
to the Sensitive Lands Ordinance reduced regulations on private landowners with the promise that the
City would increase restoration efforts and protections on City-owned land. The City Council directed
$250,000 in annual funding to support and expand ongoing restoration efforts. This funding created the
Habitat Enhancement Program (HEP). The HEP continued invasive removal efforts, added native species
planting projects, and provided for ongoing maintenance. Currently, HEP funds are used in the following
ways:
City restoration
Grant funding for local watershed councils to support restoration work on private land
Use as matching funds for restoration grant applications (leveraged to gain grant funding)
Purchase of plants for volunteer work parties.
To date, Invasive Removal Program and HEP funds have been used to enhance 31 public natural areas,
including more than 370 of the 460 acres of natural area parks managed by the City. Funding has also
supported all three local watershed councils with annual support for various watershed restoration
projects on private lands. It should be noted that natural areas management efforts are iterative and often
require multiple site visits over several years to control noxious weeds and establish native plant
communities.
LOPR has also been instrumental in developing master plans and restoration/maintenance plans for
several of the natural area park properties (e.g., Iron Mountain Park Master Plan [2017]; George Rogers
Park Master Plan [2002]; Cooks Butte Park Management Plan [2008]; and Woodmont Natural Park
Master Plan [2017]).
In 2021, Lake Oswego voters passed Citizen’s Initiative 3-568 to amend the City Charter to include
additional protections of natural areas within the City. This initiative was a grassroots effort to protect
natural areas.
2.3 Related Plans
Some of the related plans that have been reviewed are listed below. Applicable elements of these plans
have been incorporated into this Plan.
Lake Oswego Sensitive Lands regulations
Lake Oswego Open Space Plan (City of Lake Oswego 2001)
Lake Oswego Urban & Community Forestry Plan (City of Lake Oswego 2007)
Lake Oswego’s State of the Urban Forest Report (City of Lake Oswego 2009)
City of Lake Oswego Comprehensive Plan 2013, Healthy Ecosystems Chapter (2015) (Ordinance
2687)
City of Lake Oswego Parks Plan 2025 (City of Lake Oswego 2012a)
Mountain Park Homeowners Association Natural Areas Assessment (Pacific Habitat Services
2012)
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City of Lake Oswego Addendum to the Clackamas County Multi-Jurisdictional Hazard Mitigation
Plan (University of Oregon 2019)
Sustainability and Climate Action Plan for Lake Oswego (City of Lake Oswego 2020a)
City of Lake Oswego Stormwater Management Manual (City of Lake Oswego 2020b)
Integrated Pest Management Practices (City of Lake Oswego 2022)
2.4 Available Data
Plant communities were classified and their boundaries were delineated using a combination of brief field
visits, input from the City’s restoration contractors, input from City staff, high-resolution aerial imagery,
high-resolution topographic imagery, and a variety of spatial data (mapping data that can be visualized
and queried). Available spatial data that was particularly helpful in the remote delineation of plant
communities is summarized in Table 2.
Table 2. Data Sources Used to Help Identify Plant Community Boundaries
Plant Community Layer (Source)
Oregon White Oak Woodland OakPoints (OPWG)
Upland Conifer Forest
Deciduous Forest
Mixed Conifer-Deciduous Forest
condec (Conifer-Deciduous; RLIS),
aerial imagery (Google Earth, ArcGIS Online)
LO_RP_3_2019 (City of LO, Resource Protection [RP] Districts)
Upland Grassland
Shrubland
condec (gaps in this layer do not have a forest canopy; RLIS)
Land_Cover (Regional Conservation Strategy, RCS)
aerial imagery (Google Earth, ArcGIS Online)
Wetland LO_RP_3_2019 (City of LOLO)
Land_Cover (RCS)
Hydric Soils (USDA/RLIS)
stream_route (RLIS)
National Wetland Inventory (USFWS)
Draft Local Wetland Inventory (Fishman 1992)
Notes: City and Contractor expertise were used to verify and refine GIS layers listed above. For Iron Mountain Park, an existing
habitat assessment (ESA 2017) was also referenced.
Acronyms: LO = Lake Oswego; OPWG = Oak Prairie Work Group (a project of The Intertwine Alliance); RCS = Regional
Conservation Strategy; RLIS = Regional Land Information System (Metro); RP = Resource Protection; USDA = US Department of
Agriculture; USFWS = US Fish and Wildlife Service.
3. Generalized Plant Communities in Lake Oswego
Natural Areas
This Plan addresses management of seven generalized plant communities that characterize the variety of
unique habitats within the City’s natural areas: mixed conifer-deciduous forest, deciduous forest, Oregon
white oak woodland, upland conifer forest, shrubland, upland grassland, and wetland. It should be noted
that riparian habitat occurs within many of the plant communities described below, particularly deciduous
forest. However, because riparian areas require specific delineation methods described in Lake Oswego
Community Development Code (LDC) section 50.05.010, they were not field delineated for purposes of
this Plan. Although these habitats are not separately inventoried, they are generally indicated on the
habitat maps (Attachment B) by the City’s Resource Protection (RP) overlay zones. Due to their
ecological importance, several management strategies for riparian areas are described in this Plan.
The RP Overlay Zone includes an estimated stream or wetland and associated riparian buffer area, which
can have a variable width dependent on slope gradient. Most park forest stands that are not zoned RP
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are zoned as Resource Conservation (RC) zones. Forest management policies within RP and RC districts
are unique and must comply with the standards described in LDC 50.05.010 (Sensitive Lands Overlay
Districts).
Approximate plant community boundaries and habitat condition rankings were determined using a
combination of available geospatial data review (per Section 2.4 above), limited site visits, input from the
City’s restoration contractors, input by LOPR staff, and literature review. Field assessment was conducted
at a limited number of the larger natural areas to field test the initial habitat boundary delineations and to
determine the dominant canopy and understory species present, collect notes on vegetation age and
structure, and assess noxious weed cover. Initial inventory and ranking were improved upon by
incorporating input provided by the City’s natural area restoration contractors, who are very familiar with
existing conditions and past restoration efforts. The resulting habitat inventory and classification is
included as Appendix B to this plan. While the inventory and ranking provide an important context for
planning and future management of the City’s natural area parks, it should be noted that the inventory
was largely delineated remotely and is, therefore, imprecise; none of the habitat polygon boundaries were
field surveyed.
The following documents were used as references for the habitat types that were mapped in the City and
are described below:
Portland Plant List (City of Portland 2016)
Classification of Native Vegetation of Oregon (Kagan et al. 2004)
Native Freshwater Wetland Plant Associations of Northwestern Oregon (Christy 2004)
City of Lake Oswego Native and Invasive Plants (City of Lake Oswego 2012b)
Oregon Conservation Strategy
3.1 Plant Community Summaries
The following subsections provide an overview of each general plant community that commonly occurs
throughout the City’s natural area parks. More detail on each plant community and a list of key native
plant species associated with each community is provided in Appendix C.
3.1.1 Mixed Conifer-Deciduous Forest
This forest community is a common cover type within multiple natural areas and dominates several of the
City’s larger natural areas. Total area within Lake Oswego’s natural areas is 112.4 acres. The dominant
species in the canopy include Douglas-fir (Pseudotsuga menziesii) and bigleaf maple (Acer
macrophyllum). Additional common canopy species include western red cedar (Thuja plicata), red alder
(Alnus rubra), and Pacific madrone (Arbutus menziesii). Most of the overstory trees are young to mature,
with diameters ranging from 8 inches to a maximum of 24 inches diameter at breast height (dbh). Canopy
cover typically ranges from 80 to 100 percent, with variable canopy heights. This community is often
found within many of the areas mapped as RP overlay zones. Common native understory trees and
shrubs include Scouler’s willow (Salix scouleriana), vine maple (Acer circinatum), Indian plum (Oemleria
cerasiformis), Oregon grape (Mahonia aquifolium), salal (Gaultheria shallon), beaked hazelnut (Corylus
cornuta var. californica), red elderberry (Sambucus racemosa ssp. pubens), trailing blackberry (Rubus
ursinus), and snowberry (Symphoricarpos albus). Common native herbaceous species include sword fern
(Polystichum munitum), fringecup (Tellima grandiflora), and large-leaved avens (Geum macrophyllum).
3.1.2 Deciduous Forest
In Lake Oswego, deciduous forests are the second most common habitat type, totaling 82.2 acres within
the City’s natural areas. In deciduous forest stands, very few mature conifers are present in the overstory.
Bigleaf maple is typically the dominant species, with red alder occasionally abundant, particularly along
draws and ravines. Black cottonwood (Populus trichocarpa) is also seen within this habitat type. Some
stands contain conifer saplings (e.g., western red cedar), indicating that they will become mixed conifer-
deciduous forest over time. The shrub layer is typically dominated by red-osier dogwood (Cornus
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sericea), beaked hazelnut, Indian plum, and Pacific ninebark (Physocarpus capitatus). This plant
association is often found in riparian areas along streams and rivers.
3.1.3 Oregon White Oak Woodland
This habitat is dominated by Oregon white oak (Quercus garryana) and is generally less common than
the coniferous forested habitat types in Lake Oswego. According to the Oregon Conservation Strategy,
oak woodland habitat is characterized by a tree canopy that obscures 30 to 70 percent of the sky and an
understory that is relatively open with shrubs, grasses, and wildflowers. Areas mapped as Oregon Oak
Woodland in Appendix B include areas that contain relatively dense oak trees but do not necessary meet
the definition of oak woodland habitat per the Conservation Strategy. For example, the understory may be
crowded rather than open. However, they identify areas with the potential to become oak woodland with
ongoing management.
Historically, oak woodlands were most common on flat to moderately rolling terrain, usually in drier
landscapes. Although historically a common element of the Willamette Valley, today less than 5 percent of
oak woodland habitat remains.1 In Lake Oswego, this habitat type occurs on approximately 17.5 acres of
natural areas; however, many of these oak stands are overcrowded by large conifers and other species
and do not currently have an open understory as is characteristic of this habitat type. Because of its
uniqueness and regional loss, this habitat type is an important component of the City’s biodiversity and
would benefit from specific management actions. Oak woodlands are an Oregon Department of Fish and
Wildlife (ODFW) Conservation Strategy Habitat and support species that have a high degree of fidelity to
oak trees. Shrub species associated with this habitat include western serviceberry (Amelanchier alnifolia),
Oregon grape, and buckbrush (Ceanothus cuneatus). Herbaceous plants include grasses (Bromus
carinatus, Elymus spp., Festuca spp.) and sedges (Carex spp.). Historical burning by indigenous
communities was a major factor in maintaining oak woodlands in this area, as frequent low-intensity fires
hinder conifers such as Douglas-fir. Within the City, it is common for oak woodlands to contain Oregon
ash (Fraxinus latifolia) as a subdominant species.
Modern fire suppression practices have resulted in this habitat type being overrun by native conifers and
invasive species. Loss of oaks, particularly large-diameter, open-structured trees valuable to wildlife, is of
particular concern because oak trees have a slow growth rate, which slows restoration success. In
addition, reproduction and recruitment of younger trees are poor in many areas.
3.1.4 Conifer Forest
In Lake Oswego’s natural areas, conifer forest stands encompass approximately 52.3 acres and contain
Douglas-fir as dominant and western hemlock (Tsuga heterophylla) as a subdominant species emerging
below the forest canopy. In more mature forests, this habitat may include additional conifer species,
including grand fir (Abies grandis) and western red cedar. Occasional bigleaf maple and/or red alder may
be present as minor understory stand components, but these species are typically not included in the
forest canopy. The shrub understory varies in diversity, with native areas dominated by sparse-to
moderate-density native shrubs (similar to those found in the mixed conifer-deciduous forest habitat).
3.1.5 Shrubland
In Lake Oswego, the upland shrubland habitat type occurs primarily in former agricultural land such as old
orchards. This habitat type represents a relatively small portion of Lake Oswego’s natural areas, with 8.6
acres mapped within the natural areas. Wetland shrubland habitat often occurs in areas that have
experienced frequent or recent disturbance (such as regular flooding or recent fire) that would preclude
tall overstory tree species. Native shrub species often include willows, red-osier dogwood, hardhack
(Spirea douglasii spp. douglasii), and/or Pacific ninebark. Shrubland habitat is considered transitional,
meaning that over time and without repeated or continued disturbance, it will convert to a tree-dominated
habitat type. For this reason, young tree saplings can also be present within this habitat type.
1 https://oregonconservationstrategy.org/strategy-habitat/oak-woodlands/
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3.1.6 Upland Grassland
Historically, the Willamette Valley contained upland grassland habitat, also known as prairies, which often
occurred near oak woodlands where fire was also used to maintain the open character of that habitat
type. Grasslands were historically dominated by native perennial bunchgrass species such as Lemmon’s
and California needlegrass (Acnatherum lemmonii and A. occidentalis ssp. californica), California brome
(Bromus carinatus), blue wildrye (Elymus glaucus ssp. glaucus), and fescues (Festuca spp.) (City of
Portland 2016). Forbs are also present, including many wildflowers such as camas (Camassia quamash),
yarrow (Achillea millefolium), clovers (Trifolium spp.) and clarkias (Clarkia amoena and C. rhomboidei)
(City of Portland 2016). Camas is a native tuberous lily that was a staple in the diet of local indigenous
communities. As such, it is widely regarded as a culturally important native plant and is often associated
with relic or restored wet prairie habitats. Several native plant species became adapted to growing only in
(endemic to) these prairie habitats. As prairies have largely been converted to agriculture or development,
these endemic species are becoming imperiled, and many have been placed on the Oregon Endangered
Species list (e.g., White Rock larkspur [Delphinium leucophaeum], peacock larkspur [Delphinium
pavonaeceum], Nelson’s checker-mallow [Sidalcea nelsoniana], Kincaid’s lupine [Lupinus oreganus] and
Willamette daisy [Erigeron decumbens]).2
The City’s grasslands (approximately 38.0 acres) can be managed to encourage the development of
native prairie habitat. This opportunity could be considered if regional partnerships or grant funding
opportunities supporting native prairie habitat restoration are available. The largest areas of upland
grassland habitat can be found at Luscher Farm and Stevens Meadow natural areas. Other options for
habitat improvements include transitioning upland grassland habitat that consists of fallow lawn areas to
native shrub or forest habitat through restoration.
3.1.7 Wetland
Wetlands are characterized by plants that have adapted to growing in areas that, under normal
circumstances, are seasonally inundated or saturated within a foot of the soil surface for at least two
consecutive weeks during the growing season. Probable wetlands (not officially “delineated” but likely
based on data review) are the dominant cover type in some of Lake Oswego’s natural area parks,
including West Waluga and Canal Acres. A variety of wetland forms exist within the City’s natural areas:
forested wetlands, shrub wetlands, and herbaceous marsh totaling approximately 58.6 acres. Although
these different wetland forms are structurally different, they are all managed under similar federal, state,
and local regulatory protections, face similar threats, and would be managed in a similar manner ; thus, all
wetland forms are grouped for purposes of this management plan. Wetland prairies, if present now or in
the future, would be managed differently from these wetland forms (i.e., more like grasslands), with
threats and recommendations that are very similar to those for upland grassland prairies.
Forested wetlands in Lake Oswego are generally dominated by Oregon ash in the overstory, with a
variety of shrubs common in the understory. In some areas, black cottonwood and red alder co-dominate
the forest canopy, particularly near surface waters. Shrub-dominated wetlands and shrub understory
species within forested wetlands typically include red-osier dogwood, hardhack, Pacific ninebark, and
willows. Common native wetland herbs and forbs include slough sedge (Carex obnupta), small-fruited
bulrush (Scirpus microcarpus), rushes (Juncus spp.), water parsley (Oenanthe sarmentosa), and large-
leaved avens. Wetlands are often correlated with areas mapped as RP zones in the City’s Sensitive
Lands Atlas.
3.2 Limiting Factors
Each of the natural area habitats in the City have unique attributes, including specific ecological factors
that limit the habitats from becoming fully healthy native ecosystems (such as reed canarygrass [Phalaris
arundinacea] in wetlands). However, there are some common limiting factors that are ubiquitous
throughout all of Lake Oswego’s natural areas. These are described in the sections that follow. Limiting
factors inform the objectives of this plan, as described in Section 4 of this report.
2 https://agsci-labs.oregonstate.edu/willamettevalleyprairies/threatened-and-endangered-plants-of-willamette-valley-prairies/
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3.2.1 Invasive Species
According to the Lake Oswego Master Plant List (Lake Oswego Code [LOC] Section 50.11.004), invasive
plants “tend to dominate plant communities, crowding out other native plants. They generally have low
value to wildlife, and some are considered harmful to humans.” Target species for removal, listed in the
Clackamas Soil and Water Conservation District (SWCD) WeedWise program (CSWCD 2021), represent
a culmination of expertise on current site conditions, and consider local and regional invasive species
lists, such as those prepared by the Oregon Department of Agriculture (ODA).
3.2.2 Off-Leash Dogs
Off-leash dogs are a threat to the City’s natural areas (LOC 34.12.620) and are allowed only in areas
specifically designated as off-leash dog parks (at Hazelia Field, Pilkington Park, West Waluga Park, and
McNary Park). Pets can spread invasive species, cause physical damage to native plants, and aggravate
wildlife.
3.2.3 Informal Trails
The City plans for trails to be located and maintained in specific areas that balance human access and
recreation with habitat protection objectives. Park users often stray from main trails to find shortcuts or
explore interior areas of parks. These informal trails attract followers, which can exacerbate habitat
degradation by introducing humans, pets, litter, soil erosion, and noxious weeds into sensitive areas that
are intended to be managed for conservation. When used heavily, these trails break up otherwise
cohesive blocks of habitat that are used by wildlife for forage and cover—a process known as habitat
fragmentation.
3.2.4 Forest Pests
The presence of forest pests such as invasive or harmful insect and fungi species are monitored and
effectively managed if necessary. Of recent concern is the introduction of the emerald ash borer beetle
(Agrilus planipennis) because of the significant management costs and ecological harm this pest poses.
This beetle is a wood-boring pest of ash trees (Fraxinus spp.) and is considered the most destructive
forest pest in North America (Oregon Department of Forestry 2021). It presents a significant concern for
Lake Oswego where Oregon ash is abundant such as within forested wetland habitats and within Oregon
white oak woodland. This beetle is native to parts of Asia but was first detected in North America in 2002
near Detroit, Michigan and Windsor, Ontario (Oregon Department of Forestry 2021). In June 2022, the
emerald ash borer was detected in Oregon which is the first confirmation of this invasive pest on the West
Coast. The Oregon Department of Forestry and ODA have prepared an Emerald Ash Borer Readiness
and Response Plan for Oregon (Oregon Department of Forestry and ODA 2021) to be used as a guide for
response to this species.
3.2.5 Encroachment
The City is undergoing restoration and fuel reduction work along park borders and encountering years’
worth of encroachment from private lands owners. Dumping of debris, building of fire pits and permanent
structures, and ornamental landscaping on encroached land creates fire hazards and stalls restoration
efforts. The City is working with these private landowners to display survey markers and reestablish
borders for current and future tenants.
3.3 Conditions Ranking
Forest habitats were ranked based on a schema that evaluates three ecological attributes that are
relatively simple to measure: stand age, diversity of native species, and noxious weed cover.3 This
ranking system borrows from the Clean Water Services system for ranking vegetated corridors (vegetated
buffers of water quality sensitive areas) but was adapted to natural areas based on AECOM’s experience
in evaluating habitats throughout the City as part of on-call Sensitive Lands reviews conducted between
3 “Noxious” weeds include those listed in Clackamas SWCD WeedWise
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2016 and 2022. These base attributes are intended to be representative of conditions that infer overall
habitat quality for wildlife and ecological resiliency against factors such as climate change, noxious weed
infestation, and increased recreational use. These are not a strict grading criteria for plant populations
with characteristically slow growth rates (e.g., Oregon white oak).
Ecological condition was ranked “High” where a plant community meets the following metrics:
Age (Forested): Majority of trees ≥50 years old or average tree dbh ≥20 inches for Douglas-fir or
bigleaf maple or >12 inches for Oregon ash trees within the stand.
Diversity (Forest): ≥4 native tree species (in forested areas), ≥6 native shrub species, and ≥2
native groundcovers (e.g., ferns)
Diversity (Shrub): ≥6 native shrub species, and ≥4 native groundcovers (graminoid or forb)
Diversity (Herbaceous): ≥8 native groundcovers (e.g., graminoids, ferns, wildflowers) with total
cover of >50% and with each of the 8 species having at least 2% cover
Noxious Weed Cover: <25%
Each species counted toward the diversity goal should provide a minimum of 2% of total cover within the
habitat polygon being assessed.
Ecological condition was ranked “Moderate” where a plant community meets the following metrics:
Age (Forested): Majority of trees ≥~25 years old and <~50 years old; average tree dbh 10-20
inches
Diversity (Forest/Shrub): ≥2 native tree species (in forested areas), ≥4 native shrub species,
and ≥2 native groundcovers (e.g., ferns)
Diversity (Herbaceous): ≥4 native groundcovers (e.g., graminoids, ferns, wildflowers) with total
cover of >25% and with each of the 4 species having at least 2% cover
Noxious Weed Cover: <40%
Ecological condition was ranked “Low” where a plant community meets the following metrics:
Age (Forested): Majority of trees <~25 years old; average tree dbh <10 inches
Diversity (Forest/Shrub): ≤2 native tree species (in forested areas; to be considered a tree, dbh
must be ≥6 inches), <4 native shrub species, and <2 native groundcovers (e.g., ferns)
Diversity (Herbaceous): <4 native groundcovers (e.g., graminoids, ferns, wildflowers)
Noxious Weed Cover: >40%
For each attribute assessed, a habitat is given a score of 1 for low, 2 for moderate, and 3 for high. Based
on these scoring criteria, forest habitats would receive one condition score that is based on the average
of their age, diversity, and noxious weed cover scores. For example:
Forest habitat X: Age (2), Diversity (3), Noxious Weed Cover (1) = condition score of 2 ((2+3+1)/3).
Because herbaceous and shrub habitats are not ranked for age, their scores are based on the average of
their diversity and noxious weed cover scores. The resulting condition rank is based on the following
average scores:
0 to 1.4 — Low
1.5 to 2.2— Moderate
2.3 to 3 — High
As such, the condition rank for “forest habitat X” in the example above would be moderate, based on the
combination of moderate age, high diversity, and abundant noxious weed cover.
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4. Management Goal, Objectives, and Prescriptions
Diverse and healthy ecosystems provide many benefits to the City, including improved air and water
quality, habitat for wildlife, shade/temperature regulation, soil health, nutrient cycling, pest management,
recreation, and mental health benefits for City residents.
The following sections describe the City’s overall management goal and eight objectives developed to
achieve that goal. This section also summarizes management prescriptions recommended to achieve the
goal and objectives.
4.1 Management Goal and Objectives
The following objectives are designed to achieve one overarching goal for this plan:
This Plan was developed with an overarching management goal for Lake Oswego’s natural areas:
Enhance and restore Lake Oswego’s natural areas to provide safe and healthy ecosystems.
For the purposes of this plan, “healthy” natural area ecosystems are defined as: Natural areas
that can support a wide diversity of native plants and animals and adapt to change to maintain
functionality amidst the increase of recreation, encroachment by invasive species, changes to
natural water flows, and threats posed by wildfire and climate change.
4.1.1 Objective 1. Enhance Natural Area Health and Resilience by Supporting
Natural Ecological Processes
To protect the long-term health of Lake Oswego’s natural areas and improve their resilience to land use
pressures such as recreation, stormwater management, climate change, and recreational uses, the City
should employ a variety of management actions that minimize habitat degradation, mitigate prior
disturbance, and fortify against future ecological threats. The City has 12 years of experience conducting
restoration activities. This experience will inform future projects in conjunction with adjustments made for
changing conditions, new techniques or methodologies, and new collaborations and partnerships.
Success Criteria: Within 10 years, at least 25% of plant associations (by area) noted as being in low or
moderate rank will be elevated to moderate or high rank, respectively. Photo monitoring will be conducted
on a yearly basis to visually demonstrate changes to habitats in restoration.
4.1.2 Objective 2 Noxious Weed Control
Invasive species (many of which are also considered noxious weeds) threaten natural resources through
competition, habitat degradation, reduction of genetic diversity, and introduction of diseases. The ODA
(2020) definition of a noxious weed is “a terrestrial, aquatic, or marine plant designated by the Oregon
State Weed Board under Oregon Revised Statute 569.615 as among those representing the greatest
public menace and as a top priority for action by weed control programs.” As mentioned in Section 2.2 of
this report, the City has dramatically reduced noxious weed cover in several of the City’s natural areas
since 2011. Recommended actions in this Plan focus on continuing efforts that target invasive species
identified by the Clackamas SWCD WeedWise program (CSWCD 2021). This target list was developed to
focus efforts on species with the greatest potential to adversely affect the health, resiliency, and
functionality of native ecosystems. Removal of weeds follows the integrated pest management guidelines
outlined within the department’s IPM policies.
Following the removal of target noxious weeds, native plant species will be planted to reoccupy the open
soil. Continued removal of noxious weeds will allow for the native plants to grow and become the
dominant plant species within the supported habitat. Native plants will be chosen to fit the habitat being
restored, and planned succession will be taken into consideration. By reducing the noxious weed load
and reintroducing and supporting native plant species, target noxious weed cover can be reduced in an
ecologically resilient manner.
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Target invasive species presence in each of the natural areas can change over time, particularly after
removal efforts have begun and when new species are introduced, so this objective must be closely
monitored and linked to the restoration practices described in Objectives 1 and 6.
Success Criteria: A sample of parks having target invasive species (Clackamas SWCD WeedWise
Program) will be monitored every 5 years and shown to have decreasing target invasive cover of at least
5% (e.g., from 20% to 15% cover). Monitoring locations should be randomly selected and should include
all the plant associations described in Section 3 above. For natural area parks with <10% cover by target
invasive species, ongoing treatment should be considered at the discretion of LOPR staff. If stable and
not expanding, further treatment may be unnecessary, but monitoring should continue to detect increases
in target invasive plant populations. As most natural areas with robust target invasive plant infestations
have already received intensive, preliminary herbicide treatments, this standard assumes gradual
ongoing reductions of target weeds over time and intentionally avoids further dramatic reductions that
would require substantial amounts of herbicide use (although such intensive herbicide applications may
still be warranted at sites where needed to reduce robust infestation). For ease of management, a portion
of applicable natural areas should be monitored each year, rather than once every five years.
4.1.3 Objective 3. Minimize Habitat Fragmentation and Protect Sensitive Areas
Lake Oswego’s natural areas provide valuable habitat refuges for wildlife while at the same time offering
recreation and public access opportunities, which provide many physical and mental health benefits to
City residents. Balancing recreation and resource protection goals can be challenging, particularly in
smaller natural area parks where there is inadequate space to provide buffers for sensitive habitats. This
Plan recommends actions that identify and prioritize highly sensitive habitat areas and develop habitat
protection strategies to minimize habitat fragmentation and recreational use conflicts in the City’s more
sensitive habitat areas.
Lake Oswego’s natural areas are already fragmented by decades of development. Fragmented habitats
are less likely to support sensitive species and are more susceptible to ecological degradation such as
the spread of invasive species along informal trails. However, within the existing natural areas there are
opportunities to restore cohesive habitat blocks via native plant establishment and by addressing issues
of invasive species and erosion. There are also opportunities to minimize future habitat fragmentation by
limiting the potential for new informal or social trails through patches of sensitive habitat. Efforts by LOPR
in support of this objective are already underway, including providing signage to identify areas where
public access and recreation are approved. However, specific efforts to create natural barriers around
highly sensitive habitat areas can help further this objective by reducing unwanted social trail
establishment. For example, plantings of native shrubs with thorns or natural woody debris barriers may
aid in directing pedestrian traffic around highly sensitive habitat areas.
This Plan defines a highly sensitive habitat area as one that is in relatively good condition and meets any
of the following criteria:
Contains unique habitat communities such as wetland or camas prairie (see “Other Unique
Features” noted in Appendix A);
Has been recently restored (thus more susceptible to damage while plants establish); and/or
Contains sensitive plant or wildlife species per the Rare, Threatened, and Endangered Species of
Oregon4 (ORBIC 2019).
Efforts to minimize habitat fragmentation can create cohesive blocks of habitat that enhance wildlife
habitat conditions within natural areas. Protection of these habitat areas may also support efforts to
enhance wildlife corridors (existing or planned) between natural area parks. These efforts should be
4 At this time, Iron Mountain is the only of the City’s natural areas are known to contain rare species (White Rock larkspur) and is
actively managed for this species; however, should additional rare species become identified, a management plan should be
developed to identify appropriate protective buffers around populations of these species, which would be managed as highly
sensitive habitat areas.
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consistent with regional plans for connectivity, such as Metro’s Title 13 Resource Inventory (Metro 2005),
and in collaboration with adjoining property owners and conservation partners such as local watershed
councils. HEP funding, which is administered to conservation partners by LOPR, is often used to for this
purpose. Additionally, as funding for future conservation opportunities becomes available, those that
enhance wildlife corridors should receive priority over similar opportunities that do not.
Success Criteria: Using the habitat classification mapping developed for this plan, priority sensitive
areas will be identified by LOPR and flagged for restricted access within 2 years. Within 5 years, sensitive
areas that are under threat of fragmentation due to uncontrolled access will have access restrictions put
in place, including possible trail closures, signage, and/or barriers made of natural materials.
4.1.4 Objective 4. Improve Climate Resilience
According to the Fourth National Climate Assessment, the Northwest has warmed 2˚F since 1900 and is
projected to continue to warm during all seasons under all future climate scenarios (May et al. 2018).
Warmer winters result in reduced snowpack, which correlates to drought, water scarcity, and large
wildfires (May et al. 2018; Barbero et. al. 2015).
Climate change impacts, including increases in temperature and changes in normal precipitation patterns,
have the potential to exacerbate existing threats on natural ecosystems. Lake Oswego’s natural areas
may experience increased tree mortality from heat, drought, and invasive species infestations. Natural
parks may no longer be able to support certain native plant and animal species, as thermal thresholds for
some species are expected to be surpassed. Changes in climate would also affect shifts in the timing of
migration, life cycles, and flowering, which are important for ecological processes such as reproduction
and nutrient cycling.
Climate change presents unprecedented challenges for natural resource managers but taking proactive
steps to ensure that Lake Oswego’s natural areas are more resilient to the impacts of climate change will
make the challenges more manageable. This will require management that prepares the natural areas for
a changing climate rather than relying on historical norms and practices. Some examples of this type of
management, also termed “climate-smart restoration” are increasing the diversity of native tree species in
forested areas and ensuring mixed ages and different structures within a given forested area. These
practices protect the overall ecological function of a natural area by avoiding a complete loss of forest
canopy during a heat event or drought that may result in die-off of certain species or age class.
Additionally, plant species selection (e.g., selecting more heat and drought tolerant native species), seed
sourcing (e.g., selecting native seeds from local populations in areas where the climate is hotter and
drier), and assisted migration (e.g., purposefully selecting species whose range occurs outside the area
but is anticipated to be suitable for future climate conditions and whose addition to the ecosystem would
be either neutral or beneficial to overall functioning) can help a restoration project be successful given
projected future climate conditions. Guidance resources specific to climate-smart restoration in Oregon
are in development.5 Climate-smart restoration practices should be adaptive and consistently reevaluated
as new research and developments are introduced.
Success Criteria: All new restoration projects will incorporate a review of climate-smart
forestry/restoration practices (Oregon Department of Forestry 2021; CSRT, in development) and
incorporate these practices into design and construction. A summary of these efforts will be included in
the Natural Areas Management Plan Effectiveness Monitoring Report (see Section 6).
4.1.5 Objective 5. Reduce Wildfire Hazards
The natural areas that make Lake Oswego a beautiful and desirable place to live and work inherently
come with the risk of wildfire by supplying a potential fuel source. Fire hazards are present when there is
fuel (e.g., wood) combined with conditions related to local topography and seasonal weather, particularly
relative humidity, heat, and wind. The City will continue efforts to remove ladder fuels and other woody
weed species that pose a threat to canopy fires. Lake Oswego’s Fire Department website provides
5 Climate Smart Restoration Tool (CSRT), in development, US Forest Service, Conservation Biology Institute, and Oregon State
University https://consbio.org/projects/climate-smart-restoration-tool/
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instructions for maintaining defensible space and fire-resistant plants along the interface between human
developments and forested areas. The City’s Addendum to its Multi-Jurisdictional Hazard Mitigation Plan
(University of Oregon 2019) lists wildfire hazards for neighborhoods bordering specific natural areas,
including Iron Mountain Bluff, Springbrook Park, and [East] Waluga Park. In general, this objective is met
by existing policies related to reducing fuels along the periphery of natural areas, in coordination with the
Fire Department, where they are adjacent to human developments and removal of hazard trees. The City
refers to the Clackamas Community Wildfire Protection Plan (Clackamas County 2017) for coordination
and fire hazard reduction management strategy.
Success Criteria: The City will coordinate with regional partners to remove fire hazards observed within
park boundaries and reduce woody debris piles within natural area peripheries. This may include thinning
fuels in natural areas containing dense undergrowth, especially where such density slows natural forest
development or where it would benefit oak release. Fire hazard reduction efforts will be documented in a
Natural Areas Management Plan Effectiveness Monitoring Report once every 6 years.
4.1.6 Objective 6. Enhance Hydrologic Function and RP Districts
Lake Oswego’s rivers, streams, and wetlands provide many ecological functions valued by society for
their ability to sustain fish and wildlife, improve water quality, and control flows for both flood hazard
reduction and summer base flow support. Waters and associated riparian areas are ODFW Conservation
Strategy Habitats, as they are ecologically important and sensitive to degradation from human land use
pressures. For example, increased runoff from surrounding development introduces sediments and
pollutants that contribute to water quality issues. When water flow is impeded by barriers such as roads
and culverts, channelization (detachment from natural floodplain) occurs. This restricts the natural ability
of streams to meander over time. Changes in runoff patterns resulting from impervious developments and
invasive plant species have altered the frequency and duration of flows into and through streams, often
resulting in erosion, channelization, and/or blockage of flow.
A variety of stream enhancement measures may be implemented based on the hydrologic conditions of
each stream. As such, LOPR should look for grant opportunities or partners to fund stream assessments,
particularly in areas with known flooding concerns and/or known fish passage barriers, such as those
mapped by the ODFW on Tryon Creek and Oswego Creek (ODFW 2022a). With grant funding, streams
should be assessed by a professional stream ecologist and/or water resource engineer to determine the
stream mechanics and conditions resulting in poor performance. Then the specialist can recommend a
suite of management measures to enhance stream form, flows, and water quality (e.g., temperature and
dissolved oxygen) where impaired. Common enhancement strategies include grade controls, fish
passage barrier removal, streamside plantings, bank stabilization measures, control of noxious weeds,
and treatment/storage of incoming surface flows. In headwater locations, enhancement efforts typically
focus on hydrologic cycling for water retention, improving water quality, and slowing water flow. This
objective also supports Objective 4 (climate resilience). The role of LOPR in this objective should be
limited to grant development, support, and coordination with ongoing natural areas management activities
(e.g., riparian planting and target invasive species control).
Success Criteria: The City will seek grant funding to hire contractors to plan and implement river, stream,
riparian, and/or wetland restoration projects each biennium. Priority will be for perennial streams, large
wetlands, and fish passage barrier removal opportunities. Fish passage projects should focus on streams
the drain directly to the Willamette or Tualatin Rivers. Grant efforts will be documented and summarized in
a Natural Areas Management Plan Effectiveness Monitoring Report once every 6 years.
4.1.7 Objective 7. Selective Tree Removal to Improve Safe and Healthy
Ecosystems
Forest stand health can be weakened by disease, drought, infestation, or overcrowding of saplings.
Furthermore, trees along public trails and roadways have the potential to become hazard trees if they are
weakened and prone to falling. Several habitats in Lake Oswego are weakened by competition with non-
native trees, including English hawthorn (Crataegus monogyna), English holly (Ilex aquifolium), English
Laurel (Prunus laurocerasus), and eastern cherry tree (Prunus spp.) species. To promote healthy growth
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of native trees, areas containing overcrowding or hazard trees should be identified and treated or
removed/thinned. This will support oak release projects, keep tree-falling hazards minimal along formal
trails and roads, and prevent the spread of pests, such as emerald ash borer. Removal of trees should
focus on locations where such removal would benefit the overall health of the forest habitat or remove a
falling hazard adjacent to public trails, neighboring developments, or roadways. Some trees should be left
as snags to improve habitat conditions if they are free from disease or pests.
Success Criteria: During the development of management plans or restoration project proposals, LOPR
will review natural areas to determine whether selective tree removal should be incorporated into the
plans for improved forest health and safety. In addition, LOPR will review publicly available hazard tree
inventory data, including ongoing citizen-led tree inventory data, and plan for selective removals in natural
areas where such actions would improve forest health and/or pedestrian safety. These efforts should be
documented in a Natural Areas Management Plan Effectiveness Monitoring Report once every 6 years.
4.1.8 Objective 8. Adaptively Manage Ongoing Public Engagement
Opportunities that Benefit Habitat Protection and Enhancement
Lake Oswego is actively engaged with a volunteer community encompassing many different groups and
organizations. Volunteer work parties have focused on removal of target invasive species, native planting
projects, demonstration gardens, and citizen science monitoring projects (via the Watershed councils).
Continued public involvement in stewardship activities is crucial for maintaining and enhancing Lake
Oswego’s natural areas. As participating volunteers come and go, the City is routinely engaged in trying
to maintain current levels of volunteer participation in natural areas management activities. LOPR will
continue its current level of outreach opportunities while seeking out funding and other opportunities for
expanded volunteer recruitment, training, and appreciation events for completed projects. At park
entrances and throughout our natural areas, signage detailing educational materials, promoting
stewardship, indicating sensitive lands, and prohibiting destructive activities will be maintained and added
as necessary. These forms of passive information help educate recreators and amplify restoration
impacts.
Success Criteria: LOPR staff currently provide an annual presentation of their volunteer and outreach
efforts to the Parks Board. However, every 6 years the general trends of volunteerism will be evaluated to
identify what is working and to identify opportunities for successful citizen engagement. The results of this
evaluation will include recommendations that will be summarized in a Natural Areas Management Plan
Effectiveness Monitoring Report once every 6 years.
4.2 Management Prescriptions
Management prescriptions are strategies that could be applied to help achieve the objectives outlined in
Section 4.1. The management prescriptions are grouped into three categories:
General — apply to all parks and habitat types.
Habitat-specific — apply to specific habitat types across all parks based on existing condition.
Park-specific — apply to all habitat types within a park.
Repetition of management prescriptions in the three categories is intentional to allow LOPR staff to
quickly and comprehensively access recommendations based on the needs of the upcoming project.
Management strategies that are higher priority are shown in bold in Table 3. High priority strategies were
determined by considering the funding/feasibility of the project, as well as its impact on ecosystem health.
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4.2.1 General Prescriptions
Table 3. Summary of General Management Strategies by Objectives
Objective Management Strategies
1. Enhance Natural Area Health and
Resilience by Supporting Natural
Ecological Processes
Increase diversity of native species in all strata (tree, shrub,
groundcover) to create a wider array of drought tolerance and
susceptibility to pests or viral pathogens that can affect one or more
native species.
Support native pollinating insects by incorporating native pollinator support
seed mixes (native wildflower species attractive to bees) within restoration
projects.
Staff should attend training on emerald ash borer beetle so they can be
quick to recognize arrival and learn management techniques.
Plant using successional planting list to increase vegetation diversity and
increase habitat resiliency.
Consider soil restoration, decomposition, and nutrient cycling in restoration
efforts. Where appropriate, inoculate soils or bare root plant materials with
mycorrhizae as part of restoration efforts.
2. Reduce Target Noxious Weed
Species
Continue target invasive treatment that focuses on target species
(Clackamas SWCD WeedWise Program), as appropriate given annual
variability and site-specific priorities in infested areas, using broad-
spectrum herbicide application (for initial treatment), followed by spot
spraying and/or mechanical and hand removal.
Utilize Integrated Pest Management guidelines to optimize noxious weed
removal and limit use of herbicides.
During various park management activities, identify/map small populations
of target invasive species with potential to rapidly expand and prioritize for
treatment (e.g., a small patch of shining geranium (Geranium lucidum)
along the edge of a forested area that could quickly spread).
Continue to partner with agencies that outreach to private property owners
on target invasive species management and resources.
Replant treated areas with native trees, shrubs, and other plants as
appropriate for each habitat type and park location.
3. Minimize Habitat Fragmentation
and Protect Sensitive Areas
Identify locations of sensitive areas (e.g., recent restoration areas,
areas of high biological diversity) which may need additional
protection through restricted access through use of signs, fencing,
logs, woody debris, barbed plantings, or other measures.
Work with local and regional partners to strategically enhance wildlife
corridors and linkages, including within and between parks where
appropriate. Metro Title 13 Inventories identify habitat linkages between
parks and offer a good identifier for future conservation opportunity areas,
as funding allows. For example, the Springbrook Creek riparian corridor
provides habitat linkage between Springbrook, Pennington Park, and Iron
Mountain Natural Areas.
Work with local and regional partners to support regional trail development
by confirming that the alignment of proposed trails does not overlap with
sensitive areas. Trails through wetlands should seek funding to develop
elevated boardwalks that separate foot traffic from sensitive habitat and
surface flow conditions.
Work with Transportation Department to evaluate the potential for planned
upgrades to culverts or other road crossings for wildlife crossing support.
For example, larger culverts can be fitted with an internal bench to provide
wildlife with a way to cross under busy streets without the risk of vehicle
collision. Similarly, small rodent bridges can be constructed between poles
over street traffic. These efforts would require grants or other outside
funding support but could provide opportunities to improve habitat corridors
within and between natural areas and other habitat areas.
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Objective Management Strategies
4. Improve Climate Resilience Ensure restoration projects include a high diversity of plant species
and morphological diversity for enhanced ability to adapt to climate
change.
Plant successional plant species to increase vegetation diversity.
Protect and expand high-quality habitat through invasive species removal,
and restoration.
Implement climate-smart restoration practices such as incorporating native
species more capable of withstanding drought and heat in planting efforts
(e.g., Oregon white oak, Oregon grape, and bigleaf maple6) and
considering spacing of new plants and trees for water availability.
Consider incorporating species whose range may be projected to expand
to the area because of climate change that would be considered a neutral
or ecologically beneficial addition to the native ecosystem.
5. Reduce Wildfire Hazards Continue to implement fuel reduction efforts on City-owned forested
areas within 50 feet of natural area property lines, factoring in site-
specific conditions such as slope, health of trees, invasive species,
and areas that interface with dense residential development.
Include species that are heat and fire resistant for restoration efforts.
When leaving woody debris on-site to promote soil health/nutrients, debris
material should be scattered (not piled) and left in direct contact with soil.
Remove or modify brush piles or unlimbed fallen trees along natural area
margins.
Removal of woody weed species and ladder fuels.
Continue LOPR’s role in supporting Fire Department efforts in promoting
programs through outreach and communication.
6. Enhance Hydrologic Function and
RP Districts
Work with partner agencies and City departments to apply for grant
funding and support the planning and implementation of projects that
maintain or enhance natural flow conditions and riparian structural
integrity. These may include projects that:
Filter and disperse incoming runoff from impervious areas
Provide grade controls in channelized, erosional streams
Remove barriers that restrict stream flows and natural channel
migration zones (e.g., invasive species, debris, poorly designed
culverts, or channelized stream segments)
Allow for natural meandering of creeks and reconnection with floodplain
terraces for improved flood hazard reduction
Capture and treat stormwater runoff prior to it entering streams
Remove invasive vegetation on streambanks and replace with native
shrubs and trees
Maintain and build headwater canopy and vegetation for hydrologic
cycling and water retention.
Add woody material or alluvial (rounded) gravels to streams that lack
aquatic habitat complexity and have the potential to provide habitat for
resident fish populations
Work with the Engineering Department to evaluate the potential for
upgrades to culverts or other undercrossings for enhanced hydrologic
functioning.
Apply for a grant to have hydrologists and aquatic ecologists review
streams and wetlands in the City’s natural areas to identify aquatic
resource areas that may become costly restorations if not enhanced at
relatively low cost now. This would help with prioritizing ongoing aquatic
resource restoration efforts.
6 Oregon State University Extension, https://extension.oregonstate.edu/collection/trees-shrubs-drought-tolerance#high
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Objective Management Strategies
7. Selective Tree Removal to
Improve Safe and Healthy
Ecosystems
Manage hazard trees in a way that will enhance and improve the
health of the natural areas through ecologically sound maintenance
practices. This may include the creation of snags with cavities for
birds.
Identify areas with overly dense native or non-native sapling growth and
thin where such efforts would result in a healthier, safer native forest stand.
Remove high priority hazard trees in areas that interface with foot traffic,
auto traffic, or structures. Use available data, including citizen-led tree
inventories to identify hazard trees with signs of infestations, rot, poor soil
anchoring, or other indications of potential tree fall.
Remove and properly dispose of Oregon Ash trees that have been
identified to house emerald ash borers to prevent the spread of pests via
hatching.
When removing hazard trees, leave materials on-site to promote natural
ecological processes (e.g., decomposition) while avoiding brush piles or
other fire hazards. Do not place debris within fire management edge areas.
8. Adaptively Manage Ongoing
Public Engagement Opportunities
that Benefit Habitat Protection and
Enhancement
Use new or existing avenues for public outreach to encourage local
understanding and tolerance of the implementation of new or
different management or maintenance activities (such as trail
closures, seasonal restrictions, and/or prescribed fire).
Continue to engage with local school and volunteer groups for outreach
materials, interpretive signs, volunteer work events, and other
environmental education opportunities, but evaluate trends and monitor
which engagement efforts are most productive; update as necessary.
Work with volunteers to install, maintain, and monitor wildlife enhancement
features (e.g., osprey [Pandion haliaetus] nest platform, bat boxes, native
pollinator features). Wildlife cameras (secured) can be placed to record
use, which can be shared with public to build interest.
4.2.2 Habitat-Specific Prescriptions
Table 4 provides habitat management prescriptions tailored to the characteristics and condition of each
plant association.
Table 4. Summary of Management Strategies by Habitat Type
Name Condition Management Strategies
Mixed Conifer-
Deciduous Forest and
Upland Conifer Forest
High
Preserve or create snags with nesting cavities.
Maintain designated trails with clear signage to direct river
access and at approved points, and limit for off-trail usage using
woody debris or barbed plantings (e.g., rose [rosa spp.]).
Monitor for invasive species and tree pathogens and remove
infected vegetation from park.
Install raptor perches in riparian stands along the Tualatin and/or
Willamette Rivers.
Moderate
Enhance diversity in existing stands by planting additional native
trees and shrubs.
Treat and/or remove invasive species.
Provide dense native tree and shrub plantings along riparian
areas for bank stabilization, water shading, habitat, and flood
water energy dissipation.
Low
Enhance diversity in existing stands by planting additional native
trees and shrubs.
Treat and/or remove invasive species and implement restoration
plantings in treated areas to prevent regrowth or infestation of
different invasive species.
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Name Condition Management Strategies
Perform thinning in overcrowded stands, particularly along trails.
Install boot brushes at park entrances.
Deciduous Forest
High
Monitor trails for invasive species to avoid spread.
Preserve or create snags with nesting cavities.
Install raptor perches in riparian stands along the Tualatin and/or
Willamette Rivers.
Discourage off-trail foot traffic using woody debris or barbed
plantings (e.g., rose).
Maintain designated trails with clear signage to direct river
access and at approved points and limit for off-trail usage.
Monitor for tree pathogens and effectively manage infected
vegetation within park.
Moderate
Enhance diversity in existing deciduous stands by planting
additional native trees and shrubs.
Treat and/or remove invasive species.
Provide dense native tree and shrub plantings along riparian
areas for bank stabilization, water shading, habitat, and flood
water energy dissipation.
Low
Enhance diversity in existing deciduous stands by planting
additional native trees and shrubs.
Treat and/or remove invasive species and implement restoration
plantings in treated areas to prevent regrowth or infestation of
different invasive species.
Perform thinning in overcrowded stands, particularly along trails.
Install boot brushes at park entrances.
Wetlands
High Manage portions of high-quality wetland areas as conservation
sites and discourage recreational and off-leash pet access in
these areas.
Minimize points of access into high-quality wetland areas using
barbed shrubs (e.g., roses) or woody debris.
Plant native trees and shrubs in buffer areas (~100 feet)
surrounding wetland boundaries.
Moderate Target removal of reed canarygrass and other wetland invasive
species. In areas of dense reed canarygrass, an herbicide
approved for use in aquatic environments is recommended for
initial control efforts.
Plant native shrubs in areas dominated by reed canarygrass to
shade and displace the species.
Remove Himalayan blackberry (Rubus bifrons) along wetland
borders and replace with native riparian shrubs and trees.
Provide elevated trails through some wetlands for education and
recreation purposes (may require wetland permit).
Low Target removal of reed canarygrass and other wetland invasive
species.
Plant native shrubs in areas dominated by reed canarygrass to
shade and displace the species.
Oregon White Oak
Woodland
All Identify areas for oak woodland restoration, including intact
stands threatened by crowding from conifers.
Remove invasive species competing with healthy, mature oaks to
support oak release, canopy openings, and regeneration of oak
saplings.
In specific areas, obtain tree removal permits and remove
conifers competing with oaks to promote oak release.
Retain large-diameter standing dead trees (i.e., snags) to support
cavity-nesting birds and bats where there is no hazard to public
safety.
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Name Condition Management Strategies
Per Oregon Conservation Strategy (ODFW 2022b), use multiple
tools, including prescribed fire, mowing, and selective harvest, to
maintain open canopy. Ensure tools are site-appropriate and
implemented to minimize impacts to native species.
Re-establish native grasses, herbaceous plants, and shrubs.
Monitor, protect, and enhance habitats for rare, threatened, and
endangered species.
Upland Grassland All Maintain and/or restore grassland (prairie) habitat with high
diversity of native grasses and forbs (non-grass-like herbaceous
plants). Limit cover of native trees and shrubs (<10 % cover) and
promote cover of native forbs (>10% cover per ODFW 2022b).
Identify and implement appropriate management strategies
following restoration to maintain native prairie, such as, but not
limited to, prescribed burning.
Work in collaboration with partner organizations such as Metro
and ODFW for prairie restoration funding and best practices.
Direct recreational uses away from highly sensitive areas with
endemic native plant species and possibility of sensitive wildlife.
Per the Oregon Conservation Strategy (ODFW 2022b), minimize
disturbance during the grassland bird breeding/ground nesting
season (April 1-July 15).
Continue to install nest boxes adjacent to restored sites for
western bluebird (Sialia mexicana).
Include a high percentage of native wildflower species known to
support pollinators
Monitor, protect, and enhance habitats for rare, threatened, and
endangered species.
Shrubland Upland Remove invasive species and species associated with former
agricultural uses, such as orchard trees.
Restore using native upland shrub species and trees to preserve
a diversity of habitat forms and support natural succession.
Wetland Protect and restore wetland shrubland areas to provide wetland
buffers by removing invasive species and replanting using native
shrub species associated with wetlands.
4.2.3 Natural Area-Specific Prescriptions
Table 5 summarizes priority management strategies by natural area based upon a review of current
threats and opportunities. This list is not comprehensive. It is intended to synthesize data gathered during
development of this report to identify readily available enhancement opportunities. Many of these
strategies may already be in progress. Natural areas not mentioned in Table 5 are those that require
further, site-specific assessment to identify priority management strategies.
Table 5. Summary of Priority Management Strategies by Natural Area
Name Primary Management Strategies
Bryant Woods Park Target removal of invasive species (English hawthorn, reed
canarygrass, Himalayan blackberry, ivy).
Discourage and restore social (informal) trails.
Canal Acres Target removal of knotweed (Fallopia spp.).
Cooks Butte City Park Target removal of shining geranium.
Perform stream grade control/enhancement.
East Waluga Park Target removal of ivy.
Identify, close, and restore social trails along steep slopes.
Control reed canarygrass in wetland.
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Name Primary Management Strategies
Freepons Park Protect and expand existing camas patch.
George Rogers Park Target removal of English ivy and knotweed.
Protect existing paved pathways from erosion.
Glenmorrie Park Protect existing oaks and encourage recruitment of young oak
seedlings through a variety of management actions, including
thinning competing trees, reducing target invasive species, and
planting oak seedlings.
Hallinan Woods Perform thinning as needed to improve health and reduce wildfire
risk.
Iron Mountain Target removal of ivy, English holly, Himalayan blackberry, and old
man’s beard (Clematis vitalba).
Perform trail maintenance on established trails.
Repair and restore erosion areas.
Identify opportunities within and adjacent to existing Oregon white
oaks for habitat improvements including removal of conifers and
other competing species, such as target invasive species.
Lamont Springs Natural
Area
Target removal of geraniums.
Luscher Farm Natural
Areas
Expand and continue Oregon white oak planting and restoration.
Implement native grassland/prairie restoration.
Develop a plan for trail layout to preserve blocks of native habitat
with easy access for ongoing vegetation maintenance (e.g.,
mowing).
Pennington Seek grants to hire specialists to perform stream restoration
incorporating hydrologic enhancement/floodplain connectivity.
Target removal of knotweed.
Rassekh Site is being designed for a variety of improvements, including
natural area. Work with consultant to incorporate elements of this
Plan.
River Run Target removal of ivy, English hawthorn, and Scotch broom
(Cytisus scoparius).
Improve diversity of riparian trees and shrubs in shoreline areas
along river.
Close and restore seasonal social trail.
Monitor success of native plantings in wetland and wetland buffer
treatment area.
Roehr Natural Area Restore riparian corridor; diversify species to address issue of
aging cottonwoods. Work with Planning Department to ensure
enhancements are consistent with Willamette Greenway
ordinance.
Sierra Vista Protect existing oaks and encourage recruitment of young oak
seedlings through a variety of management actions. Consider
potential for thinning competing trees, reducing target invasive
species, and planting oak seedlings.
South Shore Natural Area Target removal of ivy and garlic mustard (Alliaria petiolata).
Close and restore social trail.
Southwood Park Close and restore social trail(s).
Springbrook Park Consider a boardwalk trail through the wetland area would allow
ongoing environmental education while removing foot traffic
impacts from the sensitive headwater wetland area.
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Name Primary Management Strategies
Seek opportunities to partner with private and public landowners to
maintain and enhance the Springbrook stream corridor as a viable
wildlife migration corridor connecting Springbrook and
Pennington/Iron Mountain Natural Areas.
Perform restoration and fuel reduction along park borders.
Conduct trail maintenance and reduce use of, and access to,
habitat-fragmenting social trails.
Repair erosion areas.
Install additional and diverse tree plantings to support succession
and drought resiliency.
Target removal of English holly, Himalayan blackberry, meadow
bindweed (Convolvulus arvensis), old man’s beard, ivy, and garlic
mustard
Stevens Meadows Implement upland grassland restoration.
Manage portions of the meadow for wildlife conservation via
signage or other soft barriers with goal of reducing human/pet
conflicts during breeding season for sensitive wildlife (April 15-July
15 per Oregon Conservation Strategy).
West Waluga Park Protect and expand existing camas patch.
Control reed canarygrass and English hawthorn in wetland areas.
Manage areas of dense oak per Oregon Conservation Strategy;
protect existing oaks and encourage recruitment of young oak
seedlings through a variety of management actions including
thinning competing trees, reducing target invasive species, and
planting oak seedlings.
Woodmont Natural Park Plant herbaceous pollinator species within the field grass.
Remove noxious weeds within the front shrub beds.
Target removal of Scotch broom, English hawthorn, and Himalayan
blackberry.
5. Coordination with Urban Forestry Planning
Policies
Habitat management involves both operations and policy. To support the successful implementation of
this plan, the City should review its Comprehensive Plan (Healthy Ecosystems Chapter), Development
Code, and Tree Code, and recommend any updates as needed to support the habitat management
objectives presented in this plan.
The City’s development code allows resource enhancement projects, which may include tree removal
from sensitive lands, including RP and RC districts, to enhance and restore natural resource functions
and values. Resource enhancement may be approved through a ministerial process (no public notice or
comment). A verification tree permit is required to confirm the correct trees approved for removal by the
resource enhancement project are to be removed before the project begins. However, this existing permit
process may not address changes in habitat functions and values over time due to climate change or
other factors. These changes, for example, may necessitate removal of target invasive tree species;
native saplings or young trees in areas where tree density is limiting growth or creating tree falling
hazards; or conifers in areas targeted for oak release, per the management strategy for oak woodlands,
an ODFW Conservation Strategy Habitat (ODFW 2022b).
Typically, observance of City Code requires that applications for tree removal be filed with the City
Planning Department and approved prior to removal. The applicable code regulating tree removal
depends on whether the tree is in an RP or RC overlay district, and if not, whether the tree removal meets
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other criteria including standards for management of large, forested tracts. The typical process involves
filing an application identifying all trees for removal and procedures that include flagging trees and may
require a site visit by Planning Department staff.
As part of this general management plan, upon approval, LOPR will seek a programmatic permit for tree
removals. The goal of the programmatic permit will be to avoid the need to obtain individual project
permits that expire. The programmatic permit would apply where tree removals are consistent with the
management actions described in this Plan; specifically, where tree removal is part of an overall habitat
management strategy intended to benefit the ecological condition or safety of a natural area.
In addition to recommending process improvements for habitat management tree removal, this plan
contains information that may support an update to the Urban & Community Forestry Plan, which is
intended to be updated periodically to identify policy changes that are informed by periodic State of the
Urban Forest Reports, including the pending 2022 report. The State of the Urban Forest Reports are
based on the status and trends of trees and forests throughout the City of Lake Oswego, including those
on public and private lands. The condition assessment and management strategies for forest habitats
within Lake Oswego’s natural area parks, as described in this plan, may provide information beneficial to
the development of a subsequent Urban & Community Forestry Plan update.
6. Monitoring and Adaptive Management
Adaptive management is a systematic approach for improving natural resource management. It requires
that management actions be assessed over time for effectiveness and that improvements be made in the
management strategy as a result of the effectiveness assessment data. In order to assess the
effectiveness, periodic monitoring is required.
Monitoring a randomly selected subset of managed natural areas provides important information to inform
adaptive management while remaining within budget and effort constraints. The City should plan on
monitoring 10% of areas treated (randomly selected polygons within different habitat types) every 4 years
to determine if success criteria are being met. This monitoring data should inform management strategies
and may identify the need for corrective actions, which will inform the biennial budget. Monitoring could
be split into annual monitoring (2.5% each year) or every other year (5% every 2 years). To avoid placing
all monitoring effort on limited LOPR staff, monitoring may be incorporated in future restoration grants and
contractor scopes of work. Monitoring efforts may increase overall natural areas management program
costs. However, monitoring data may save much more over time by identifying inefficient or ineffective
strategies that can be altered for improved success. The budget for monitoring related to Objective 6 in
Section 4.1 above (Enhance Hydrologic Features) should be included in grant application budgets and
associated monitoring should be conducted in the early part of the growing season (March-April) when
wetland and stream hydrology indicators are most likely to be present.
Monitoring should include photo-monitoring and sample data collected along transects at established
locations. Vegetation monitoring should be performed in late summer or early fall when foliar cover is
most robust. To evaluate plant cover and native plant establishment success, appropriate monitoring
methods for woody plants include stem counts and line-intercept monitoring. Stem counts involve marking
off a rectangular sample area (e.g., 20 feet by 50 feet) and counting live woody stems (or plants for
individual plants with multiple stems) within the sample area. The species of each plant should be noted
as shown in the following example:
Cornus sericea: IIII
Amelanchier alnifolia: III
Corylus cornuta: II
Acer circinatum: I
Total: 10 live shrubs per 1,000 square feet (10 foot-on-center spacing)
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The results of one or more stem count plots collected within a habitat area can be compared to the initial
planting density to determine survival estimates.
Line intercept monitoring is done by establishing a
baseline using a measuring tape. This could be, for
example, a 50-foot-long measuring tape placed
along the southern boundary of a habitat area being
monitored (per example at right). Then, at a
randomly selected number between 1 and 10, a
sample transect can be run out perpendicular to the
baseline for 50 feet. Along this sample transect, the
start and end point of each species encountered can
be recorded in tenths of a foot (or meter). The
sample transect is then repeated every 10 feet along
the baseline transect, resulting in five, 50-foot-long
sample transects. The data gathered from these
transects are then quantified in a spreadsheet to
summarize total cover, by species, as a percentage
of total sample transect length. For example, if the
sum of species x totaled 100 feet within the 250 feet
of sampled transects, per graphic at right, that
species would be estimated to provide 40% (100/250) aerial cover within the sampled habitat area. Aerial
cover estimates are used to monitor growth of plants over time.
For herbaceous vegetation cover (noxious cover or native seed establishment monitoring), a 1-meter
square vegetation sample quadrat (frame) can be used to document representative cover by species.
Using the same sample design as shown above for line-intercept monitoring, the 1-meter quadrat can be
placed at a randomly selected number between 1 and 10 along each sample transect, beginning close to
the baseline. Then the quadrat can be placed every 20 feet along each sample transect. For example, if
the first sample quadrat is placed at 5 feet, the second is placed at 25 feet, and the third is placed at 45
feet from the baseline. This results in three quadrat data collection points for each transect, or 15 in total
for a sample design containing five sample transects. At each sample quadrat location, the total cover of
each herbaceous species and bare ground should be recorded. For detailed descriptions of these
methods please refer to Measuring and Monitoring Plant Populations (Elzinga et. al. 1998).
Monitoring results should be compared against the success criteria listed in Objectives 1 through 8
(Section 4.1.1- 4.1.8) or other site-specific criteria that are developed specifically for individual restoration
projects. These data will inform the success of ongoing herbaceous vegetation management activities.
Every 6 years (every three budgetary planning cycles), the City should prepare a Natural Areas
Management Plan Effectiveness Monitoring Report. The report should provide a brief summary of
ongoing management activities related to the objectives and recommendations outlined in this plan. It
should describe actions taken, effectiveness of prior treatments (based on data review or monitoring), and
recommendations for adaptive management, which may include updates to this Plan.
7. References
Barbero, R., J. Abatzoglou, N. Larkin, C. Kolden, and B.J. Stocks. 2015. “Climate Change Presents
Increased Potential for Very Large Fires in the Contiguous United States.” International Journal of
Wildland Fire 24 (7): 892-899.
City of Lake Oswego. 2001. Lake Oswego Open Space Plan.
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City of Lake Oswego. 2007. Lake Oswego Urban & Community Forestry Plan. Prepared by Lake Oswego
Planning Division, with advice and support of Urban Community and Forestry Technical Advisory
Committee. December 2007.
City of Lake Oswego. 2009. Lake Oswego’s State of the Urban Forest Report. Prepared by Lake Oswego
Planning Division, Urban and Community Forestry. June 2009.
City of Lake Oswego. 2012a. Parks Plan 2025: Lake Oswego. Parks, Recreation, and Natural Areas
System Plan. Adopted July 31, 2012, Resolution 12-44.
City of Lake Oswego. 2012b. Native and Invasive Plants. Available at:
native_and_invasive_plants_feb12_web.pdf (oswego.or.us). Accessed March 2, 2022.
City of Lake Oswego. 2014. Comprehensive Plan 2013. Adopted March 18, 2014.
City of Lake Oswego. 2020a. Sustainability and Climate Action Plan for Lake Oswego. May 2020.
City of Lake Oswego. 2020b. Lake Oswego Stormwater Management Manual. October 1, 2020.
City of Lake Oswego. 2022. Integrated Pest Management Practices. Available at:
https://www.ci.oswego.or.us/sites/default/files/fileattachments/Lake%20Oswego%20Parks%20%2
0Recreation%20IPM%202022.pdf
City of Portland. 2016. Portland Plant List. Available at: https://www.portland.gov/bps/environ-
planning/portland-plant-list. Accessed March 2, 2022.
Christy, J.A. 2004. Native Freshwater Wetland Plant Associations of Northwestern Oregon. Corvallis:
Oregon State University, Oregon Natural Heritage Information Center. Available at:
https://people.wou.edu/~taylors/luck/OWEB/wetland_plant_associations.pdf. Accessed March 2,
2022.
Clackamas County. 2017. Clackamas Community Wildfire Protection Plan. Clackamas County
Department of Disaster Management. Oregon City, Oregon.
CSWCD (Clackamas Soil and Water Conservation District). 2021. WeedWise. Available at:
https://weedwise.conservationdistrict.org/weeds. Accessed November 3, 2022.
Elzinga, C., D. Salzer, and J. Willoughby. 1998. Measuring and Monitoring Plant Populations. Bureau of
Land Management (BLM) Technical Reference 1730-1. BLM National Applied Resource Sciences
Center. Denver, Colorado.
ESA. 2017. Iron Mountain Park Master Plan. Portland, Oregon.
Fishman, 1992. Draft Local Wetland Inventory for the City of Lake Oswego. Available at:
https://docs.dsl.state.or.us/PublicReview/docview.aspx?id=863307&dbid=0. Accessed March 2,
2022.
Franklin J. and C.T. Dyrness. 1988. Natural Vegetation of Oregon and Washington. Oregon State
University Press. Corvallis, Oregon.
Kagan, J.S., J.A. Christy, M.P. Murray, and J.A. Titus. 2004. Classification of Native Vegetation of Oregon.
Portland State University, Oregon Biodiversity Information Center, Portland, Oregon.
May, C., C. Luce, J. Casola, M. Chang, J. Cuhaciyan, M. Dalton, S. Lowe, G. Morishima, P. Mote, A.
Petersen, G. Roesch-McNally, and E. York. 2018. Northwest. In Impacts, Risks, and Adaptation in
the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery,
D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global
Change Research Program, Washington, DC, USA, pp. 1036–1100. doi:
10.7930/NCA4.2018.CH24.
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Metro. 2005. Title 13 Resource Inventory. Available at:
https://databasin.org/datasets/afdbf390255549418f26855af59b2f79/#:~:text=The%20chief%20ma
pping%20data%20for%20the%20Metro%20Title,models%20for%20mapping%20riparian%20func
tions%20and%20wildlife%20values. Accessed November 3, 2022.
ODA (Oregon Department of Agriculture). 2020. Noxious Weed Policy and Classification System.
Available at:
https://www.oregon.gov/ODA/programs/Weeds/OregonNoxiousWeeds/Pages/AboutOregonWeed
s.aspx. Accessed March 12, 2022.
ODFW (Oregon Department of Fish and Wildlife). 2022a. Oregon Fish Habitat Distribution and Barriers
web map. Available at: https://nrimp.dfw.state.or.us/FHD_FPB_Viewer/index.html. Accessed Nov
4, 2022.
ODFW (Oregon Department of Fish and Wildlife). 2022b. Oregon Conservation Strategy, Habitats.
Available at: https://oregonconservationstrategy.org/strategy-habitats/. Accessed March 12, 2022.
Oregon Department of Forestry and ODA. 2021. Emerald Ash Borer: Readiness and Response Plan for
Oregon. March 2021.
Oregon Department of Forestry. 2021. The Oregon Department of Forestry Climate Change and Carbon
Plan. November 3, 2021.
ORBIC (Oregon Biodiversity Information Center). 2019. Rare, Threatened and Endangered Species of
Oregon. Institute for Natural Resources, Portland State University, Portland, Oregon.
Pacific Habitat Services, Inc. 2012. Mountain Park Homeowners Association Natural Areas Assessment.
Prepared for Mountain Park HOA. Lake Oswego, Oregon.
University of Oregon. 2019. City of Lake Oswego Addendum to the Clackamas County Multi-Jurisdictional
Hazard Mitigation Plan. Prepared for City of Lake Oswego by University of Oregon Institute for
Policy Research and Engagement and Oregon Partnership for Disaster Resilience. March 2019.
Appendix A
Natural Area Park Summaries
Appendix A: BASELINE CONDITION SUMMARY FOR LAKE OSWEGO NATURAL AREA PARKS
Name Size
(acres)
Description
Bryant Woods Park
19.7 Natural area for wildlife viewing with soft surface trails located north of Canal Acres and
adjacent to the Oswego Canal. Site has a seasonal wetland/meadow, upland forested area, and
a natural spring with an associated creek.
Dominant Habitat Type(s): Upland Mixed Conifer-Deciduous Forest
Threats: Invasive species, social trails
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs, bulbs, and bare-root planting since 2011. The City
received a Metro Nature in Neighborhood Grant in 2015. Annual trail maintenance.
Other Unique Features: camas (Camassia quamash) patch & headwater canal to Oswego Lake
runs through the park.
Canal Acres
27.3 Natural area for wildlife viewing with a soft surface trail located north of Tualatin River and
adjacent to the Bryant Woods Park.
Dominant Habitat Type(s): Upland Mixed Conifer-Deciduous Forest; Wetland Deciduous Forest
Threats: Invasive species including garlic mustard, social trails
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2011. Received a Metro
Nature in Neighborhood Grant in 2015. Annual trail maintenance.
Other Unique Features: Wet ash forest, Adjacent to Tualatin River Conservation Opportunity
Area1
Cooks Butte City
Park
43 Cooks Butte is an extinct volcano rising 728 feet above the Stafford Basin. Mixed forest with
spring native perennials. There is a soft surface trails system with varying topography.
Dominant Habitat Type(s): Wetland Mixed Conifer-Deciduous Forest, Upland Deciduous Forest,
Upland Conifer Forest
Threats: Invasive species, Lake Oswego Fire Community at Risk23, trail erosion
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2011. Trail renovation
project completed in 2010. Annual park maintenance.
Other Unique Features: Geologic features, two water towers located in the park.
1 Oregon Conservation Strategy
2 High Priority Community at Risk, Lake Oswego Addendum to Clackamas County MJHMP
3 Community at Risk, Lake Oswego Fire
Name Size
(acres)
Description
Cornell Natural
Area
3.2 Small, forested area with steep slopes known as the “Corridor of Trees.” One of the oldest
groves of Douglas-fir in the city. Restoration supported by Friends of Hallinan.
Dominant Habitat Type(s): Upland Conifer Forest
Threats: Invasive species, poor access
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plantings.
Other Unique Features: none identified
East Waluga Park
53 Hybrid park with a mix of active and natural passive areas, adjacent to West Waluga Park with
soft surface trails. Restoration supported by Friends of the Walugas
Dominant Habitat Type(s): Wetland Deciduous Forest and Upland Mixed Conifer-Deciduous
Forest
Threats: Invasive species, social trails, Lake Oswego Fire Community at Risk
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root planting since 2014. Annual park
maintenance.
Other Unique Features: Quarry Bike Skills Park in forested area
Freepons Park
5.9 Small hybrid neighborhood park located close to Hallinan Woods and Cornell Natural Area;
Natural Area includes soft surface trails connecting the neighbourhoods. Restoration supported
by Friends of Hallinan.
Dominant Habitat Type(s): Upland Deciduous Forest; Upland Conifer Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2015. Annual park
maintenance.
Other Unique Features: Right-of-way connects to Cornell Natural Area; camas patch.
George Rogers
Park
26 Hybrid regional park that contains active recreation facilities, access to the Willamette River, a
sandy beach, restrooms, a playground, a soft surface trail, and paved trails and bridges along
the Willamette River and Oswego Creek.
Dominant Habitat Type(s): Wetland Mixed Conifer-Deciduous Forest
Threats: Invasive species including garlic mustard and Japanese knotweed
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native seed and bare-root plants since 2011. Upgraded
pedestrian access in the lower portion of the park along the Willamette River (2005),
Other Unique Features: A historic iron furnace landmark with interpretive signage; adjacent to
Lower Willamette River Floodplain Conservation Opportunity Area.
Name Size
(acres)
Description
Glenmorrie Park 2.3 Small hybrid park accessing Glenmorrie Neighborhood for pedestrians and bikers from Highway
43. Natural area vegetation is to the west of the developed park.
Dominant Habitat Type(s): Upland Deciduous Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and bare-root planting since 2019.
Other Unique Features: Mature Oregon white oak in deciduous forest.
Glenmorrie
Greenway
3.9
Narrow strip of forest with one endpoint near the Willamette River.
Dominant Habitat Type(s): Wetland Deciduous Forest
Threats: invasive species, social trails
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2015.
Other Unique Features: none identified
Hallinan Woods
3.8 Natural woodland area containing a creek. Paved trail connects neighborhood to Hallinan
Elementary School. Also includes soft surface trails. City purchased adjacent property in 2020.
Restoration supported by the Friends of Hallinan with previous work done by Oswego Lake
Watershed Council.
Dominant Habitat Type(s): Wetland and Upland Mixed Conifer-Deciduous Forest
Threats: crowding, Invasive species, wildfire
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2012.
Other Unique Features: None identified
Name Size
(acres)
Description
Iron Mountain
51 Located on a south-facing hillside, overlooking Iron Mountain Boulevard. Site of old iron mining
operation. Contains a unique plant community, a variety of wildlife, and 1.5 miles of trails.
Located within a quarter mile of Springbrook Park but separated by residential neighborhood.
Restoration and site education supported by Friends of Iron Mountain Park.
Dominant Habitat Type(s): Upland Conifer Forest, Riparian Forest, and Wetland
Threats: Invasive species including garlic mustard, Lake Oswego Fire Community at Risk, and
erosion.
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root planting since 2014. 2015 Capital
Improvement Program project in lower area of park included relocation of stream and
enhancement of stream and wetlands; removal of trees and re-grading on-site; installation of
native trees, shrubs, groundcovers, seed mixes, bark mulch, logs, boulders, permanent and
temporary irrigation; and construction of pathways, parking lot, play area, restroom, and picnic
shelter. Project completed in 2021.
Other Unique Features: Upper portion of the park contains mature conifer forest and a high
density of Oregon white oak. Also, home to endangered white rock larkspur.
Kelly Creek
3.7 This small natural area is adjacent to Tryon Creek State Park and contains stands of old (50+
years) Douglas-fir and younger deciduous trees (e.g., bigleaf maple). Nettle Creek flows through
the park.
Dominant Habitat Type(s): Upland and Wetland Mixed Conifer-Deciduous Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root planting since 2014.
Other Unique Features: No trail access.
Lamont Springs
Natural Area
0.5 Small, forested natural area just west of the West Bay of Lake Oswego Lake with a natural spring
creek and soft surface trails.
Dominant Habitat Type(s): Upland and Wetland Mixed Conifer-Deciduous Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root planting since 2011. Annual park
maintenance.
Other Unique Features:
Name Size
(acres)
Description
Lily Bay 1.8 Upland forested habitat adjacent to Lily Bay, a semi-enclosed bay of Lake Oswego on the north
shore. This small natural area contains mature conifers and steep slopes. Restoration supported
by the Friends of Lily Bay.
Dominant Habitat Type(s): Wetland and Upland Mixed Conifer-Deciduous Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2019.
Other Unique Features: Connected to privately owned Lily Bay.
Luscher Farm
Natural Areas
19+ Luscher Farm Complex is a grouping of properties supporting a variety of agricultural activities,
active recreation, and natural resource conservation. The suggested restoration areas are shown
in the Luscher Area Master Plan. These sites are actively being enhanced and will add several
acres of oak habitat and upland conifer forest. It also has the unique opportunity to provide
native prairie habitat. Prairies were common in the Willamette Valley prior to European arrival
but are relatively rare now, having largely been converted to agriculture. The site currently
contains a paved path along active and former agricultural fields and is popular for walking,
biking, and bird watching. Partnerships include the Friends of Luscher Farm and the Friends of
Rogerson Clematis Garden
Dominant Habitat Type(s): Upland grassland
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species since 2011, wetlands mitigation and the planting of 150 native Oregon white oak
in 2018-2019.
Other Unique Features: The historic farm house is surrounded by The Rogerson Clematis Garden.
Interpretive signage along paved path describing history of the historic farm and Stafford Basin
area.
Pennington 2.4 Small natural area with native vegetation and Spring Brook Creek running through it.
Dominant Habitat Type(s): Wetland Mixed Conifer-Deciduous Forest
Threats: Invasive species including garlic mustard and seasonal flooding
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2011. Stream realigned
and enhanced to improve flow and habitat. Annual park and trail maintenance.
Other Unique Features: Adjacent to and providing some connectivity to Springbrook Park and
Iron Mountain Park, though habitat connectivity is disrupted by residential streets.
Name Size
(acres)
Description
Rassekh
2.1 Located close to Luscher Farm and contains a narrow stream corridor of Pecan Creek that leads
to the Tualatin. Adjacent to the natural area is a project in the design phase for development of a
multisport athletic field, restroom, parking area, skatepark, and playground.
Dominant Habitat Type(s): Wetland Mixed Conifer-Deciduous Forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native seeds and bare-root plants since 2015.
Other Unique Features: Active beaver dam.
River Run
10.8 Natural area located adjacent to the Tualatin River and the Oswego Lake canal. The area
provides nature and wildlife viewing.
Dominant Habitat Type(s): Riparian; Upland Deciduous
Threats: Invasive species
Prior Management Actions: Habitat restoration activities including removal of invasive species
and planting of native seeds and bare-root plants since 2015. City received a Metro Nature in
Neighborhood Grant in 2015 to help restoration. Annual park maintenance.
Other Unique Features: Adjacent to Tualatin River Conservation Opportunity Area
Roehr Natural Area
7.9 Waterfront park that features a pathway along water, City-owned Water Sports Center, and an
amphitheatre overlooking the Willamette River.
Dominant Habitat Type(s): Riparian; Upland Deciduous Forest
Threats: Aging black cottonwoods
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species since 2016.
Other Unique Features: Adjacent to Lower Willamette River Floodplain Conservation Opportunity
Area. Willamette Greenway Overlay.
Sierra Vista 1.3 Small pocket of forest located in a residential neighborhood with a soft surface trail.
Dominant Habitat Type(s): Upland deciduous forest
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2019.
Other Unique Features: Connects two neighborhoods and has Oak Woodland potential.
Name Size
(acres)
Description
South Shore
Natural Area
9.2 Steeply sloped, small, and narrow strip of natural habitat on the south shore of Lake Oswego.
Dominant Habitat Type(s): Upland Mixed Conifer-Deciduous Forest
Threats: Invasive species including garlic mustard; small social trail
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native seeds and bare-root plants since 2012.
Other Unique Features: Extremely steep along the northern edge with netting to protect
roadway from rockfall.
Southwood Park 2.45 A mixed conifer-deciduous forest neighbourhood park and natural area with mixed-use trails.
Ball Creek flows through the park with a riparian zone filled with dense native vegetation.
Noxious weed cover throughout park is very low. Restoration is supported by Friends of
Southwood Park.
Dominant Habitat Type(s): Mixed Conifer-Deciduous Forest
Threats: Invasive species, off-leash dogs, rogue trail building
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native seeds and bare-root plants since 2013.
Other Unique Features: Unofficial work parties began in 1992.
Springbrook Park
52 A tributary to Springbrook Creek flows through the park which feeds into Lake Oswego. The park
was saved from development in 1969 with the help of local citizens and the Friends of
Springbrook. The property was last logged in the 1950’s. The park offers great hiking and wildlife-
viewing opportunities and contains nearly 2 miles of trails. Restoration and trails maintenance
are supported by the Friends of Springbrook Park.
Dominant Habitat Type(s): Upland Deciduous Forest
Threats: Invasive species, Lake Oswego Fire Community at Risk, trail erosion
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs, seeds, and bare-root plants since 2014. Annual park
maintenance
Other Unique Features: Nature Play Area
Stevens Meadows
27.8 Open area adjacent to Cooks Butte City Park offering a short loop trail. Like Luscher Farm, this
site has the unique opportunity to provide native prairie habitat. This would increase the
diversity of natural area habitat types managed by the City and made available to the public.
Dominant Habitat Type(s): Upland Grassland
Threats: Invasive species including Canada thistle
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species since 2011.
Other Unique Features: None identified
Name Size
(acres)
Description
Sunny Slope 12 Located north of the Tualatin River, this park is close to other natural areas. This park features
mixed-use soft surface trails through forested habitat.
Dominant Habitat Type(s): Upland Mixed Conifer-Deciduous Forest
Threats: Invasive species including garlic mustard
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2018.
Other Unique Features: Through offsite lands containing forest habitat, this site provides a
moderate wildlife corridor that connects with Bryant Woods Natural Area, Canal Acres, and River
Run.
West Waluga Park
22.8 Located adjacent to East Waluga Park, this park features a mixture of active and passive
recreational opportunities, including nature trails. Restoration supported by Friends of the
Walugas.
Dominant Habitat Type(s): Wetland Deciduous Forest
Threats: Lake Oswego Fire Community at Risk, invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species since 2021.
Other Unique Features: Headwaters for Three Sisters Creek, which drains east through East
Waluga Park to its confluence with Springbrook Creek; camas patch
Woodmont Natural
Park
6.8 Provides scenic overlooks, wildlife viewing, and interactive natural play areas featuring
installations by a local artist. In 2021 the park opened after undergoing substantial
enhancements and park improvements consistent with a master plan for the sites. Restoration
supported by Friends of Woodmont.
Dominant Habitat Type(s): Upland Grassland; Conifer Forest; Upland Shrubland
Threats: Invasive species
Prior Restoration/Management Actions: Habitat restoration activities including removal of
invasive species and planting of native forbs and bare-root plants since 2018 in riparian area.
Capital Improvement Program 2015, new native trees, shrubs, and perennials planted, with 0.5
mile of trail improvements completed 2021. Restored oak savannah and wetland habitats.
Other Unique Features: Local nature-inspired artwork
Photo Credits: AECOM and City of Lake Oswego 2022
Appendix B
Habitat Inventory and Classification Map
Set
CLASS II
CLASS II
CLASS II
CLASS III CLASS III
SIERRA
VISTA
DR
ROGERS
RD
WESTCOTTCT
MEADOWCREEK CT
SOUTHWOOD
CT
K
RUS
E
OAKS
BLV
D
BAY
POINT
DR
SW
63RD
PL
MEADOWCREEK
LN
TWIN
CREEK
LN
SANDALWOOD
CT
SW SOUTHWOOD DR
T W IN C R EE K C T
SW PAMELA ST
BAY CREEK DR
SW
63RD
AVE
H
I
D
D
E
N
B
A
Y
C
T
LA MESA CT
SW
62ND
AVE
SOUTHWOOD DR
DEERFIELD CT
SIERRA
CT
GRAND OAKS DR
SUNBROOK DR
SUNCREEK DR
SW
61ST
AVE
SW
64TH
AVE
SW
63RD
PL
SW
61ST
AVE
SW
64TH
AVE
Sierra Vista
SouthwoodNatural Area
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Waterway
!Oak Tree
Trail/Pathway
Habitat Type
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS III
CLASS III
CLASS II
CLASS III
CLASS II
CLASS II
CLASS III
CLASS III
CLASS III
H
E
A
T
H
R
O
W
L
N
SW
KNAUS
RD
SW
KNAUS
RD
KNAUS RD
KNAUS
RD
SW
KNAUS
RD
TIMBERLINE DR
LESLIE LN
ATWATER RD
VERTE
CT
ATWATER
LN
F
O
X
R
U
N
KNAUS
RD
CAMEO
CT
CARRERALN
SW ATWATER RD
ATWATER
LN
COUNTRY COMMONS
Woodmont Park
KellyCreek
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Mixed Conifer-Deciduous Forest
Shrubland
Upland Grassland
1 2 34 115678910
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS III
CLASSII
CLASS III
SW ATWATER RD
A N D R E W S R D
IRONMOUNTAINBLVD
FOX RUN
COUNTRY CLUB RD
SUNNINGDALECT
COUNTRY CLUB RD
ATWATER RD
BOCA
RATAN
DR
TIPPECANOE CT
MILBURN CT
W OODWAY CT
PEBBLE BEACH CT
B A Y B E R R Y R D
COUNTRYCOMMONS
SUNNINGDALERD
SW COUNTRY CLUB RD
R
Y
E
R
D
CARRERA LN
C AVE
AT
W
AT
ER
R
D
YORK
RD
Kelly Creek
Boca Ratan
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
SpringBrookCreek
CLASS II CLASS II
TEMPEST DR
BOONESFERRYRD
W EM BL EY PARK RD
SHERBROOKPL
CRES
T
DR
COUNTRYCLUBRD
WEMBLEYPL
RAINBOW DR
DI ANE DR
DORIS
CT
SHIREVA
DR
K
E
R
R
P
K
W
Y
UPLANDS
DR
DUNCANDR
C O U N T R Y C L U B R D
SUNDELEAF
DR
WEMBLEY
PARK
RD
DORIS
AVE
SpringbrookPark
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASSI
CLASSII
CLASSII
CLASS III
CLASS III
TRILLIUM WOODS
H A R T F O R D P L
INVERURIE
RD
SW
BONAIRE
AVE
LANGFORD LN
FIELDSTONE CT
OAKRIDGE RD
B
O
NAIRE
AVE
SW
INVERURIE
RD
OAKRIDGE RD
STONE
AVE
M
A
N
C
H
E
S
T
E
R
D
R
W
A
L
U
G
A
D
R
FIRWOOD RD SW FIRWOOD RD
C
A
N
D
L
E
W
O
O
D
C
T
SW CARMANDR
FIRWOOD RD
C ARM A N GROV E L N
SW
WALUGA
DR
O
A
K
R
I
D
G
E
C
T
ROYALOAKSDR
G R E Y S T O K E D R
SW LANGFORD LN
FIELDSTONE
DR
BONITA RD
C A R M A N D R
PARKHILL ST
S
W
W
A
L
U
G
A
D
R
P A R K B L U F F P L
Y O R K S H I R E P L
SW BONITA RD
S W O A K R I D G E R D
W
HIT
E
O
A
K
S
D
R
East Waluga
West Waluga
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS III
CLASS III
H A R T F O R D P L
R O Y A L O A K S D R
OAKRIDGE RD
CARMANDR
HERITAGE
CT
STONE
AVE
M
A
N
C
H
E
S
T
E
R
D
R
W
A
L
U
G
A
D
R
COUN
T
R
Y
W
O
O
D
S
CT
SW
WALUGA
DR
T R I L L I U M W O O D S
CANDLEWOOD
CT
GALE
W
O
OD
ST
PARKHILL ST
BEASLEY WAY
S W O A K R I D G E R D
P A R K B L U F F P L
QUARRY
RD
H E R I T A G E L N
B O O N E S F E R R Y R D
HARVEY WAY
COLLINS WAY
DOUGLAS WAY
East Waluga
West Waluga
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
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_
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N
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v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 6 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
S prin g B r o o k C r e e k
CLASS II
CLASS II
BOONESFERRYRD
BOONES
WAY
DEVONSHIRE
BROOK CT
HARVEY WAY
MURWOOD
CT
TWIN
FIR
RD
TWIN FIR CT
FIR RIDGE RD
KRUSEWAY
G A L E W O O D S T
WEMBLEY PARK RD
EDGEMONT RD
HALLMARK
DR
DANIELWAY
COLLINS WAY
DOUGLAS
CIR
DOUGLAS WAY
SPRING LN
RED CEDAR WAY
LANEWOOD ST
MERCANTILEDR
KRUSE WAY PL
PenningtonPark
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
a
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_
N
o
v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 7 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
SpringBrookCreek
CLASS II
CLASS IICLASS II CLASS II
CLASS I
CLASS I
CLASS I
CLASS I
CLASS I
CLASS I CLASS I
CLASS I
W E M B L E Y P A R K R D
EDGEMONT RD
I R O N M O U N T A I N B L V D
SPRINGBROOK
CT
L
A
K
E
VIE
W
B
L
V
D
GLENEAGLESPL
S U M M I T D R
UPPER DR
TWIN
FIR
RD
FIRGROVE
CT
DOUGLAS CIR
G L E N E A G L E S C T
CRES
T
DR
PRESTWICK
RD
BROOKSIDE RD
R I D G E W O O D R D
GLENEAGLESRD
FIR RIDGE RD
IronMountainPark
SpringbrookPark
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Shrubland
Developed
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
a
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_
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N
o
v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 8 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II
CLASS I
CLASS I
CLASS I
CLASS I
CLASS I
CLASS II
BAY VI EW LN
CRESTDR
VILLAGEDR
GLENEAGLES RDPRESTWICK
RD
RIDGEWOOD
RD
L
I
LY
B
AY
C
T
WEMBLEYPARK
RD
VILLAGEPARKCT
RIDGECREST DR
V I L L A G E D R
SUMM
IT
DR
V I L L A G E P A R K L N
U P L A N D S D R
I R O N M O U N T A I N B L V DIronMountainPark
SpringbrookPark
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Shrubland
Developed
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
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_
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_
N
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v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 9 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS III
CLASS IIIRONMOUNTAINBLVD
V
I
L
L
A
G
E
D
R
FAIR
W
AY
RD
L
I
LY
B
AY
C
T
R I D G E C R E S T D R
NORTHSHORE RD
VILLAGEPARKLN
B
A
Y
VIE
W
L
N
H
A
L
V
E
R
S
O
N
L
N
DIA M OND HEAD RD
IronMountainPark
Lily Bay
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Conifer Forest
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
a
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_
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A
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N
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_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 10 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
F o r e st C r e ek
WillametteRiver
CLASS II
CLASS I
CLASS II
S
E
RI
M
R
O
C
K
L
N
SE OAK GROVE BLVD
SE DOHN CT
CHURCH ST
FOOTHILLS
RD
SE
FAIROAKS
LN
SERIVERFORESTDR
S
E
D
O
G
W
O
O
D
L
N
LEONARD ST
SE
WAGNER
LN
FOOTHILLS RD
OSWEGOPOINTEDR
F O O T H I L L S D R
F
U
R
N
A
C
E
S
T
Roehr Park
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Habitat Type
Wetland (Estimated)
Deciduous Forest
Developed
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
a
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_
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s
w
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A
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M
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2
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2
2
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a
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t
o
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_
N
o
v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 11 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
Os w e g o C r e e k
CLASS III
CLASS I
CLASS II
CLASS II
CLASS III
CLASS III CLASS III
CLASS III
CLASS III
CLASS IICLASS II CLASS II
Y
A
R
M
O
U
T
H
C
I
R
DURHAM
ST
R I D G E W A Y R D
BEDFORD CT
H A LLIN A N CIR
FURNACE
ST
M C V E Y A V E
ASH ST
MAPLE ST
H
A
LLIN
A
N
CT
PACIFIC
HWY
LEXINGTON CT
ASH ST
CHAPIN
WAY
BULLOCK
ST
YATES
ST
HALLINAN
ST
LUND
ST
LAUREL ST
G L E N M O R RIE T E R
GANS
ST
OBRIEN
ST
O A K S T
BURNHAM RD
LADD ST
S
STATE
ST
W E L L S S T
GREEN ST
GlenmorrieGreenway
HallinanWoods
GeorgeRogers Park
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Deciduous Forest
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
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_
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A
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_
N
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v
_
2
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2
2
_
S
B
.
m
x
d
November 2022
Map 12 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
Os w e g o C r e e k
Will
a
m
e
t
t
e
R
i
v
e
r
CLASS I
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS III
PACIFIC
HWY
M O RN I N G S KY CT
BEDFORD CT
G L E N M O R RIE T E R
GLENMORRIE DR
ASH ST
LAUREL ST
S
E
W
A
L
D
E
N
W
A
Y
O
L
D
RIV
ER
R
D
LILLI L N
S
E
R
I
V
E
R
F
O
R
E
S
T
D
R
Y
A
R
M
O
U
T
H
C
I
R
H E A DLEE L N
LEXINGTON CT
BULLOCK
ST
GLENMORRIE LN
IVY
LN
P O P L A R W A Y
S E R I V E R F O R E S T C T
G
L
E
N
W
O
O
D
C
T
BURNHAM RD
W E L L S S T
G
L
E
N
M
O
R
R
I
E
D
R
CHERRY
LN
ST
O
N
E
B
RID
G
E
W
AY
GlenmorrieGreenway
GeorgeRogers Park
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Deciduous Forest
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
L
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_
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N
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2
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2
2
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B
.
m
x
d
November 2022
Map 13 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS III
CLASS III
C H E R R Y L N
C
H
A
P
I
N
W
A
Y
G
L
E
N
W
O
O
D
C
T
G
R
A
N
D
V
I
E
W
C
T
MARYLBROOKDR
M A R Y L H A V E N P L
WOODHURSTPL
BROOKHURST
CT
GLENMORRIEDR
H O L Y N A M E S D R
MESNARD
ST
G R E E N A C R E S L N
EASTVIEW CT
BROOKHURST DR
G
R
E
E
N
B
L
U
F
F
D
R
P
A
CIFIC
H
W
Y
STONEBRIDGE
WAY
VIE W C R E S T L N
STONEHURST CT
GLENMORRIE LN
O A K H U R S T L N
P
R
O
V
O
S
T
S
T
P O P L A R W A Y
GLENMORRIE DR
GlenmorriePark
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Waterway
!Oak Tree
RP District(Riparian/Wetland)
Habitat Type
Oregon Oak Woodland
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
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B
.
m
x
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November 2022
Map 14 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II
CLASS III
CLASS III
CLASS III
CLASS III
CLASS III
C O R N ELL
S T
ERICKSON
ST
DYER
ST
HA
L
L
I
N
A
N
S
T
CEDAR ST
ASPEN ST
LARCH ST
CORNELL
CT
PINE ST
HEM L O CK S T
S CHERRY CIR
UP P ER DEV ON L N
CHERRY
CT
H
A
L
L
I
N
A
N
C
T
DEVON LN
BICKNER
ST
S
U
P
P
E
R
C
H
E
R
R
Y
L
N
LA UREL S T
LARCH ST
LEE
ST
MEADOWS
DR
SPRUCE ST
HEML OCK ST
UPPER CHERRY LN
O
X
F
O
R
D
D
R
WORTHINGTON
ST
H A L L I N A N C I R
CHERRY CIR
Freepons Park
Cornell
Natural
Area
µ
CITY OF LAKE OSWEGO
PARKS AND RECREATION DEPARTMENT
NATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGO
NATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural Area
Study Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District
(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
1 2 3
4
11
5 6 7 8 9 10
17
16 12
13
24
15
14
18 2223
1920 21
K:
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_
N
o
v
_
2
0
2
2
_
S
B
.
m
x
d
November 2022
Map 15 of 24
Habitat Classes:,
Class I: Degraded
Class II: Marginal
Class III: Good
O s w e g o C r e e k
CLASS II
CARLSON CT
SCHUKART LN
T E R R A C E D R
CHERRYCRESTAVE
NELSON CT
W AL L S T
GREENTREE RD
SYLVAN
CT
MATTHEW
CT
HOFER
CT
SCOTT
CT
QUAIL
CT
ROBB
PLCRESTVIEWDR WOODSMANCT
E D G E C LIFF T E R
TYNDALL
CT
HIGHLAND DR
SOUTHSHOREBLVD
OAK TER
WOODLANDTER
South ShoreNatural Area
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
RP District(Riparian/Wetland)
Habitat Type
Mixed Conifer-Deciduous Forest
1 2 34 115678910
17 16 1213
24 15 14
18 2223192021
K:
\
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N
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v
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2
0
2
2
_
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B
.
m
x
d
November 2022
Map 16 of 24
Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS III
CLASS III
S W U P P E R D R
BRYANT
RD
R O S E W O O D S T
S W U P P E R D R
B O O NES FERRY RD
S W B O O NES FERRY RD
LAKEHAVENDR
D
E
P
O
T
S
T
L
A
M
O
N
T
C
T
S
U
N
R
I
S
E
C
T
U P P ER D R
WARRENCT
T
U
A
L
ATIN
S
T
L
O
W
E
R
M
E
A
D
O
W
S
D
R
SCHALIT
WAY
U P P E R D R
GRAEFCIR
VIRGINIA WAY
L O W E R D R
L A K EVIE W BLV D
WEST BAY RD
L A M O N T W A Y
WILDWOOD ST
CHAPMAN WAY
COBB WAY
Lamont SpringsNatural Area
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS IICLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS I
CLASS I
CLASS II
CLASS II
CLASS II
CLASS II
CLASSII
WAXWING ST
RED
WING
CT
ALBERTCIR
BRYANT
RD
MELISSA
DR
SW DAWN ST
CHAD DR
OLD GATE RD
INDIAN
CREEK
DR
INDIAN
SPRINGS
RD
BASS LNRIVERRUN
DR
SW
RED
WING
WAY
SAGEHENCIR
WOODDUCKWAY
EDENS
EDGE
DR
W
O
O
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D
U
C
K
C
I
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WOOD DUCK ST
S
A
G
E
H
E
N
W
A
Y
SW
INDIAN
SPRINGS
RD
CHI L DS R D
BRIAN CT
DEERBRUSH
AVE
C
A
N
A
L
R
D
CASEY CT
CANAL WOODS CT
SW
RED
WING
CT
CENTERWOOD ST
SW
INDIAN
SPRINGS
CIR
Canal Acres
Bryant WoodsNature Park
RiverRun Park 1
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
Tua la tin Rive r
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS I
CLASS I
CLASS II
CLASS IIICLASS II
CLASS II
CLASS II
CLASS II
CLASSII
RED
WING
CT
SW DAWN ST
SW CHILDS RD
OLD GATE RD
INDIAN
SPRINGS
RD
RIVERRUN
DR
TROUT WAY
SW
RED
WING
WAY
C O H O L N
SW
INDIAN
SPRINGS
RD
SWCANALRD
DOGWOOD DR SW DOGWOOD DR
PERCH
CT
CHILDS RD
BASS LN
SW WEST RD
SW
INDIANCREEK
AVE
SW
RED
WING
CT SW INDIAN SPRINGS CIR
CANAL
RD
SW
SYCAMORE
AVE
Canal Acres
Bryant WoodsNature Park
River RunPark 1
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Oregon Oak Woodland
Mixed Conifer-Deciduous Forest
Shrubland
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
T u a l a t i n R i v e r
CLASS II
CLASS II
CLASS II
CLASS II
CLASS III
CLASS II
CLASS IIICLASS II
CLASS II
CLASS II
SWCHILDSRD
35TH
CT
BRYANT
RD
SW
35TH
CT
RIVERRUN
DR
OLSON
AVE
EDENS
EDGE
DRCOHOLN
SWCANALRDSWWESTRD
TROUT WAY
PERCH
CT RIVERS
EDGE
DR
KOKANEE
CT
CHILDS RD
BASS LN
35TH
PL
MEGAN
PL
SW TUALASAUM DR
CANAL
RD
CanalAcres
Bryant WoodsNature Park
River RunPark 1
River RunPark 2
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Deciduous Forest
Mixed Conifer-Deciduous Forest
Shrubland
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
Tua latinRiver
CLASS III
SW
H
ILLTOPRD
RI V EN DEL L CT
RIVER
BEND
LN
SWBARTONRD
SW CHILDSRD
S W HI L L T O P RD
SW
EAST
SIDE
RD
Sunny SlopeOpen Space
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Trail/Pathway
Habitat Type
Mixed Conifer-Deciduous Forest
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
WESTVIEW DR
ANDUIN
TER
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T
C
L
AI
R
D
R
RAYRIDGE
DR
H
I
L
L
S
I
D
E
D
R
SUNDOWNCT
ATHERTON DR
M A Y O R S L N
RI D G E L A K E D R
RID G E P OINTE D R
CHERYL
CT
PALISADES CREST DR
MEADOW
LARK
LN
DELENKA
LN
StevensMeadows
CooksButte Park
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
!Oak Tree
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
Mixed Conifer-Deciduous Forest
Upland Grassland
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS I
CLASS II
CLASS II
CLASS I CLASS I
CLASS II
CLASS II
S
W
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RIDGE
POINTE
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RAYRIDGE
DR
SHIPLEY
DR
RIDGE POINTE DRST
CLAIR
DR
SW
STAFFORD
RD
SI ENA DR
AT H E R T O N D R
BELLA
TERRA
DR
M
EADOW
LARK
L
N
SROSEMONTRDCHERYL
CT
SW CHILDS RD
StevensMeadows
CooksButte Park
RassekhNaturalArea
µ
CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Steep Slope
Waterway
Trail/Pathway
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Conifer Forest
Deciduous Forest
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Upland Grassland
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
CLASS II
OAK MEADOW DR
BERGIS
RD
RI
DG
EV
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CT
OAK
MEADOW
CT
S BERGIS RD
RIDGEVIEW
LN
OAKMEADOWLN
STAFFORD RD
Luscher Farm
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CITY OF LAKE OSWEGOPARKS AND RECREATION DEPARTMENTNATURAL AREAS HABITAT MANAGMENT PLAN
LAKE OSWEGONATURAL AREA HABITAT TYPES
0 200 400
Feet
Legend
City Boundary
Natural AreaStudy Site
Taxlot
Waterway
!Oak Tree
RP District(Riparian/Wetland)
Habitat Type
Wetland (Estimated)
Mixed Conifer-Deciduous Forest
Shrubland
Upland Grassland
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Habitat Classes:,Class I: DegradedClass II: MarginalClass III: Good
Appendix C
Target Native Plants for Each Habitat Type
Trees Shrubs Herbaceous
Scientific name Common name Scientific name Common name Scientific name Common name
Pseudotsuga menziesii Douglas-fir Salix scouleriana Scouler's willow Polystichum munitum Sword fern
Acer macrophyllum Bigleaf maple Acer circinatum Vine maple Tellima grandiflora Fringecup
Thuja plicata
Western red
cedar Oemleria cerasiformis Indian plum Geum macrophyllum Large-leaved avens
Alnus rubra Red alder Berberis nervosa Oregon grape Oxalis oergana Oregon oxalis
Arbutus menziesii Pacific madrone Gaultheria shallon Salal
Populus balsamifera var.
trichocarpa
Black
cottonwood Amelanchier alnifolia Serviceberry
Fraxinus latifolia Oregon ash
Sambucus racemosa var.
arborescens Red elderberry
Crataegus gaylussacia
Suksdorf's
hawthorn Rubus ursinus Trailing blackberry
Abies grandis Grand fir Symphoricarpos alnus Snowberry
Cornus nuttallii
Western
flowering
dogwood
Frangula purshiana Cascara
References: Portland Plants List
Threats: Threats for mixed-conifer deciduous forest include invasive
species, changes to hydrologic patterns, loss of biodiversity,
fragmentation, and climate change.
Mixed Conifer-Deciduous Forest
Photo from Iron Mountain, K Roeland
This forest community is a common cover type within multiple natural areas that dominates
several of the City’s larger natural areas. Total area within Lake Oswego’s natural areas is 112.4
acres. The dominant species in the canopy include Douglas-fir and bigleaf maple. Additional
common canopy species include western red cedar, red alder, and Pacific madrone. Most of the
overstory trees are young to mature, with diameters ranging from 8 inches to a maximum of 24
inches diameter at breast height (dbh). Canopy cover typically ranges from 80 to 100 percent,
with variable canopy heights. This community is often found within many of the areas mapped
as Resource Protection (RP) overlay zones, which include the stream or wetland and a
protected riparian area.
Lake Oswego Natural Areas: Bryant Woods, Canal Acres, Cooke Butte, Cornell Natural Area, George Rogers, Glenmorrie Greenway,
Hallinan Woods, Iron Mountain, Lamont, Lily Bay, Luscher Farm, Kelly Creek, Pennington, South Shore, Southwood, Stevens Meadows,
Sunny Slope, Waluga (East and West), Woodmont
I
Trees Shrubs Herbaceous
Scientific name Common name Scientific name Common name Scientific name Common name
Acer macrophyllum Bigleaf maple Cornus sericea Red-osier dogwood
Polystichum
munitum Sword fern
Alnus rubra Red alder
Corlyus cornuta ssp.
californica Beaked hazelnut Tellima grandiflora Fringecup
Populus
balsamifera var.
trichocarpa Black cottonwood Oemleria cerasiformis Indian plum
Geum
macrophyllum Large-leaved avens
Thuja plicata
Western red cedar
(sapling)Physocarpus capitatus Pacific ninebark Oxalis oergana Oregon oxalis
Fraxinus latifolia Oregon ash Salix spp. Willows
Crategus
gaylussacia Suksdorf's hawthorn
Frangula purshiana Cascara
Threats: Threats for deciduous forest include invasive species,
changes to hydrologic patterns, fragmentation, and climate change. References: Portland Plants List
Deciduous Forest
Photo from Springbrook Park, K Roeland
In Lake Oswego, deciduous forests are the second most common habitat type totaling 82.2
acres within the City’s natural areas. In deciduous forest stands, very few mature conifers
are present in the overstory. Bigleaf maple is typically the dominant species, with red alder
occasionally abundant, particularly along draws and ravines. Black cottonwood is also seen
within this habitat type. Some stands contain conifer saplings (e.g., western red cedar),
indicating that they will become mixed conifer-deciduous forest over time. The shrub layer
is typically dominated by red-osier dogwood, beaked hazelnut, Indian plum, and Pacific
ninebark. This plant association is often found in riparian areas along streams and rivers.
Lake Oswego Natural Areas: Cooks Butte, Freepons, Glenmorrie Greenway, River Run, Roehr, Sierra Vista, Springbrook , Waluga
(West)
Scientific name Common name Scientific name Common name Scientific name Common name
Pseudotsuga menziesii Douglas fir Salix scouleriana Scouler's willow Polystichum munitum Sword fern
Tsuga heterophylla Western hemlock Acer circinatum Vine maple Tellima grandiflora Fringecup
Abies grandis Grand fir Oemleria cerasiformis Indian plum Geum macrophyllum Large-leaved avens
Thuja plicata Western red cedar Berberis nervosa Oregon grape Oxalis oergana Oregon oxalis
Acer macrohpyllum Bigleaf maple Gaultheria shallon Salal
Alnus rubra Red alder
Corlyus cornuta ssp.
californica Beaked hazelnut
Sambucus racemosa var.
arborescens Red elderberry
Rubus ursinus Trailing blackberry
Symphoricarpos alnus Common snowberry
Threats: Threats for upland conifer forest include invasive species and
climate change. References: Portland Plant List
HerbaceousShrubsTrees
Conifer Forest
Photo from Iron Mtn, K Roeland
In Lake Oswego’s natural areas, conifer forest stands encompass approximately 52.3 acres and
contain Douglas-fir as dominate and western hemlock as a subdominant species emerging below the
forest canopy. In more mature forests, this habitat may include additional conifer species, including
grand fir and western red cedar. Occasional bigleaf maple and/or red alder may be present as minor
understory stand components, but these species are typically not included within the forest canopy. The
shrub understory varies in diversity, with native areas dominated by sparse-to moderate-density native
shrubs (similar to those found in the mixed conifer-deciduous forest habitat).
Lake Oswego Natural Areas: Bryant Woods, Cooks Butte, Freepons, Iron Mountain, Lily Bay, Waluga (West)
Scientific name Common name Scientific name Common name Scientific name Common name
Quercus garryana Oregon white oak Amelanchier alnifolia Western serviceberry Bromus carinatus California brome
Fraxinus latifolia Oregon ash Berberis aquifolium Oregon grape Elymus spp.Wildrye
Acer macrophyllum Bigleaf maple Ceanothus cuneatus Buckbrush Festuca spp.Fescue
Alnus rubra Red alder Symphoricarpos spp.Snowberry Carex spp.Sedge
Arbutus menziesii Pacific madrone Ribes spp.Currant Polystichum munitum Sword fern
Frangula purshiana Cascara Oemleria cerasiformis Indian plum Clarkia amoena Farewell to spring
Prunus emarginata Bitter cherry Sambucus spp.Elderberry
Pseudotsuga menziesii Douglas fir
Trees Shrubs Herbaceous
Threats: According to the Oregon Conservation Strategy, the following are
threats for Oregon White Oak Woodland:
-Fire suppression and fir encroachment
-Land use conversion and continued habitat loss
-Loss of habitat structure
-Invasive species
-Climate change
References Portland Plants List, Oregon Conservation Strategy
Oregon White Oak Woodland
Photo from Iron Mtn, K Roeland
This habitat is dominated by Oregon white oak and is generally less common than the coniferous
forested habitat types in Lake Oswego. According to the Oregon Conservation Strategy, oak
woodland habitat is characterized by a tree canopy that obscures 30 to 70 percent of the sky and an
understory that is relatively open with shrubs, grasses, and wildflowers. Historically, oak woodlands
were most common on flat to moderately rolling terrain, usually in drier landscapes. Although
historically a common element of the Willamette Valley, today less than 5 percent of oak woodland
habitat remains. In Lake Oswego, this habitat type occurs on approximately 17.5 acres of natural
areas; however, many of these oak stands are overcrowded by large conifers and other species and
do not currently have an open understory as is characteristic of this habitat type. Because of its
uniqueness and regional loss of the habitat type, this habitat type is an important component of the
City’s biodiversity and would benefit from specific management actions. Oak woodlands are an
Oregon Department of Fish and Wildlife (ODFW) Conservation Strategy Habitat and support species
that have a high degree of fidelity to oak trees. Historical burning by indigenous communities was a
major factor in maintaining oak woodlands in this area, as frequent low-intensity fires exclude
conifers such as Douglas-fir. Within the City, it is common for oak woodlands to contain Oregon ash
as a subdominant species.
Lake Oswego Natural Areas: Iron Mountain, Freepons, Glenmorrie, Sierra Vista, Waluga (East and West)
Scientific name Common name Scientific name Common name Scientific name Common name
Alnus rubra Red alder Salix spp.Willows Bromus carinatus California brome
Crataegus gaylussacia Suksdorf's hawthorn Cornus sericea Redosier dogwood Elymus spp.Wildrye
Fraxinus latifolia Oregon ash
Spiraea douglasii spp.
douglasii Hardhack Festuca spp.Fescue
Populus trichocarpa Black cottonwood Physocarpus capitatus Pacific ninebark Carex spp.Sedge
Sambucus racemosa var.
arborescens Red elderberry
Polystichum
munitum Sword fern
Rosa spp.Rose Clarkia amoena Farewell to spring
Trees Shrubs Herbaceous
Threats: Threats for shrubland habitat include invasive species, fire, and
drought for new saplings (due to lack of shade).References: Portland Plant List
Shrubland
Photo from Woodmont (restored), K Roeland
In Lake Oswego, upland shrubland habitat type occurs primarily in former agricultural land
such as old orchards. This habitat type represents a relatively small portion of Lake
Oswego’s natural areas, with 8.6 acres mapped within the natural areas. Wetland
shrubland habitat often occurs within areas that have experienced frequent or recent
disturbance (such as regular flooding or recent fire) that would preclude tall overstory tree
species. Native shrub species often include willows, red-osier dogwood, hardhack, and/or
Pacific ninebark. Shrubland habitat is considered transitional, meaning that over time and
without repeated or continued disturbance, it will convert to a tree-dominated habitat type.
For this reason, young tree saplings can also be present within this habitat type.
Lake Oswego Natural Areas: Iron Mountain, Luscher Farm, River Run, Woodmont
Scientific name Common name Scientific name Common name Scientific name Common name
Quercus garryana Oregon white oak Amelanchier alnifolia Western serviceberry Achillea millefolium Yarrow
Arbutus menziesii Pacific madrone Berberis aquifolium Tall oregon grape Acnatherum spp.Needlegrass
Bromus cerinatus California brome
Clarkia spp. Clarkia
Festuca spp. Fescue grass
Trifolium spp. Clover
Allium spp. Onion
Camassia quamash Camas
Lupinus spp. Lupine
Elymus galucus ssp.
glaucus Blue wildrye
Carex unilateralis One-sided sedge
Trees Shrubs Herbaceous
Threats: According to the Oregon Conservation Strategy, the following are
threats for Upland Grassland:
-Altered fire regimes
-Invasive species
-Land management conflicts
-Reduction of habitat patch size and connectivity
-Loss of habitat complexity in oak savannas
-Recreational impacts
References: Portland Plants List, Oregon Conservation Strategy
Upland Grassland
Photo from Stevens Meadows (not restored); Photo by K Roeland
Historically, the Willamette Valley contained upland grassland habitat, also known as prairies,
which often occurred near oak woodlands where fire was also used to maintain the open
character of that habitat type. Camas is a native tuberous lily that was a staple in the diet of
local indigenous communities. As such, it is widely regarded as a culturally important native
plant and is often associated with relic or restored wet prairie habitats. Several native plant
species became adapted to growing only in (endemic to) these prairie habitats. As prairies have
largely been converted to agriculture or development, these endemic species are becoming
imperiled, and many have been placed on the Oregon Endangered Species list (e.g., Nelson’s
checker-mallow [Sidalcea nelsoniana ], Kincaid’s lupine [Lupinus oreganus ] and Willamette
daisy [Erigeron decumbens ]).
The City’s grasslands (approximately 38. acres) have the opportunity to be managed to
encourage the development of native prairie habitat.
Lake Oswego Natural Areas: Cooks Butte, Luscher Farm, Stevens Meadows, Woodmont
Natural Areas Habitat Management Plan
AECOM
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aecom.com