Tree Care and Maintenance

Seasonal Tree Care Tips: Special Edition

After the Storm

Following the historic 2021 President’s Day weekend ice storm, people are in storm recovery mode and may be quick to think removal of storm damaged trees is the only option. The damage to trees across the region is dramatic, however not all trees that sustained damage are “goners” and many can be pruned and saved. The Oregon Department of Forestry has shared a variety of resources for the public to learn more about managing trees after the storm. These links and more are provided below.

  • Articles by the Oregon Department of Forestry, Urban and Community Forestry Program:

Can These Trees Be Saved? 
Tree First Aid After a Storm
Reducing Tree Damage in Future Storms

  • Tree City USA Bulletins by the Arbor Day Foundation:

When a Storm Strikes 
How to Make Trees Storm Resistant 
Do Your Trees Pose a Risk? 

Visit the Lake Oswego Tree Care and Maintenance Archives for additional information and resources in the Winter 2018 article on Tree Related Storm Damage. 
Information on residential tree debris disposal is available here

Tree Pruning

No permit is required to prune a tree; however, topping a tree is prohibited, and no more than 50% of the crown may be removed (cumulatively). In addition, no permit is required if an entire tree falls to the ground.

Emergency and Hazard Tree Removal

A permit is required to remove a hazardous or emergency tree. A tree qualifies under an Emergency permit if the condition of a tree presents an immediate danger of collapse, and is a clear and present hazard to persons or property. "Immediate danger of collapse" means that the tree is already leaning, and there is a significant likelihood that the tree will topple or otherwise fail and cause damage before a tree cutting permit could be obtained through the nonemergency process. "Immediate danger of collapse" does not include hazardous conditions that can be alleviated by pruning or treatment. You may proceed with removal of an emergency tree to the extent necessary to avoid the immediate hazard before obtaining a permit, but you must document the emergency situation in photographs. Within seven days of removal, the owner of the tree must apply for a retroactive emergency tree cutting permit and include photographs to demonstrate the emergency nature of the tree.

Tree removal application forms are at the following link: Permit Types, Requirements, and Applications | City of Lake Oswego. Submit the completed application to

City crews continue to remove dangerous debris. Please be aware that many parks and open space areas remain closed due to hazardous conditions.


Seasonal Tree Care Tips: Winter 2021
What is an Arborist?

Images courtesy of: Andrew Koeser, International Society of Arboriculture, 
Arborist conducting visual tree inspection.

Trees are a long-lasting investment that may require substantial care and maintenance to maximize their benefits. Informed property owners can handle many of these responsibilities, but sometimes you’re better off calling a professional.

By definition, an arborist is an individual who is trained in the art and science of planting, caring for, and maintaining individual trees. Moreover, an arborist is a professional in the practice of managing trees with a superior understanding of the structure and function of individual trees. Chapter 55.02.020 of the Lake Oswego Code defines an arborist as a person who has met the criteria for certification from the International Society of Arboriculture (ISA) and maintains their accreditation.

Some arborists are tree service providers who specialize in providing services like pruning, removal, emergency tree care, and tree planting and maintenance. They may also provide insect and disease diagnosis, soils analysis, and plant health care treatments such as soil aeration and root invigoration. Tree service providers may also specialize in installing cabling and bracing for structural support. Other arborists provide consulting services, such as tree risk assessments, developing tree inventories and writing arborist reports, developing specifications for tree protection during construction, preparing landscape plant appraisals, or providing expert witness testimony for legal matters.

The ISA is a worldwide member organization promoting proper tree care and research. ISA certification is a voluntary process for professional arborists to demonstrate their knowledge and experience by passing a comprehensive exam and then maintaining their Certified Arborist credential through required continuing education. In addition to the Certified Arborist credential, the ISA offers certification specifically for utility specialists, municipal arborists, tree workers and climbers, aerial lift specialists and, Board Certified Master Arborist, the highest level of certification offered by ISA. Certified Arborists can also become Tree Risk Assessment Qualified (TRAQ) to demonstrate their knowledge of the fundamentals of assessing tree risk to help property owners make informed management decisions. TRAQ arborists are required by Lake Oswego’s tree code when arborist reports are required for hazard tree removal permit applications.

Consulting arborists are generally ISA certified, but many are also members of the American Society of Consulting Arborists (ASCA), a distinct organization focusing exclusively on consulting. ASCA members demonstrate an investment in their professional development by building relationships with other professionals who share their expertise. ASCA also offers a Registered Consulting Arborist (RCA) credential.   

Arborists may also be members of the Tree Care Industry Association (TCIA), a worldwide trade association with a mission to advance tree care businesses.

Although these various types of arborist credentials cannot guarantee quality performance, they do attest to a certain level of knowledge. With so many different specialties in the world of arboriculture, make sure you are hiring the right arborist for your particular needs and don’t hesitate to ask for references, as well as proof of insurance.


Visit these sites to learn more:

Why Hire an Arborist, a brochure from the International Society of Arboriculture

Homeowner Resources:

Find an Arborist  (Tip! Search within 25 miles of your postal code for a more extensive listing) 
Verify an Arborist’s ISA Credentials 
Find a Consulting Arborist
Find a TCIA Tree Care Company

 Please check back for more seasonal tree care and maintenance advice!

Link to Tree Care and Maintenance Archives


Fall 2020: Soil Management  

Summer 2020: Retaining and Creating Snags for Wildlife

Spring 2020: Mulch: Numerous Benefits and Easy Application

Winter 2020: Tree Planting: To Stake or Not to Stake?

Fall 2019: Insects and Diseases

​Summer 2019: Drought Stress Revisited

Spring 2019: Trees and Construction

Winter 2019: Topped Tree

Fall 2018: Autumn Leaves

Summer 2018: Emerald Ash Borer

Spring 2018: Pruning Young Trees

Winter 2017: Tree Related Storm Damage

Fall 2017: New Tree Selection and Planting

Summer 2017: Trees and Turfgrasses

Spring 2017: English Ivy Removal

Winter 2017: Recognizing Tree Risk

Summer 2016: Drought Stress

Fall 2016: Preparing Trees for Winter


Additional Tree Care Resources:

National Arbor Day Foundation The Morton Arboretum
Oregon Department of Forestry Tree Care Info
ISA Find an Arborist Alliance for Community Trees
Oregon Department of Forestry  


Right Tree in the Right Place

Use this handy guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures.

"Right Tree Right Place" - helpful information such as "Use this guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures."

"Master Plant List" - a guide to the plants that are acceptable for mitigation requirements in Lake Oswego.