Wednesday, December 30, 2009

Nominations Open for 2010 Oregon Urban and Community Forestry Awards

Oregon Community Trees (OCT) is pleased to announce the 17th annual Urban and Community Forestry Awards for 2010. Join OCT, the Oregon Department of Forestry and the USDA Forest Service in recognizing the accomplishments of individuals, groups and businesses that have been leaders in the efforts to enhance and maintain Oregon’s community forests (trees and related vegetation growing within a city’s urban growth boundary).

OCT is a non-profit organization that is dedicated to promoting healthy community forests and citizen awareness of urban and community forestry issues statewide. This is your chance to see the individuals or groups in your community that have been instrumental in local tree issues during 2009 are recognized for their efforts. All nominations must be submitted to Oregon Community Trees @ P.O. Box 13074, Salem, OR 97309-1074 to be received no later than March 31, 2010. A nomination application is included with this letter.

Award recipients will be announced during Oregon Urban Forestry Conference, being held at the Oregon Garden, on June 3, 2010. For further information on the Oregon Urban Forestry Awards Program, please contact Mark Snyder, OCT Awards Committee chair, at (541) 682-4819, or by e-mail at

Wednesday, December 23, 2009

Call for Presentations - Oregon Urban & Community Forestry Conference
June 2-3, 2010 - - Deadline for submissions - Jan 22, 2010.

The Oregon Department of Forestry and Oregon Community Trees, in cooperation with the USDA Forest Service, will hold the 2010 Oregon Urban and Community Forestry Conference on June 2-3, 2010. Wednesday June 2nd will be an outdoor field day at the J. Frank Schmidt & Son Nursery in Boring, and Thursday June 3rd will be an indoor educational session at the Oregon Garden Resort in Silverton. The conference planning committee invites potential speakers to submit a presentation proposal for inclusion in the conference program. The theme of this year’s Annual Conference is “From Seed to City: The Journey of An Urban Tree“, focusing on nursery production, species selection, and planting of landscape trees in cities. This annual conference usually attracts around 75-125 urban forestry professionals and advocates.

Download the submission form at

Friday, December 18, 2009

Trees & Parking Lots

Parking lots have significant environmental impacts that can be partially mitigated by planting trees. Growing trees in parking lots presents some challenges that can be addressed by giving them enough space. Structural soils can give tree roots the space they need while supporting parking loads and maximizing the number of parking spaces.

Environmental Impacts of Parking Lots
On a naturally vegetated landscape west of the Cascades, rainfall is intercepted by trees or soaks into the ground where much of it is taken up by plant roots. Studies by Chris May at University of Washington show that there is virtually no runoff from a forested landscape.

When it rains on asphalt or concrete, water runs off rather than soaking into the ground. This runoff carries pollutants from brake linings, tires, and automobile fluids, as well as other pollutants from the urban landscape. Nat Scholz at NOAA Fisheries has shown that copper from brake linings is very toxic to our native salmonids. Approximately 20% of impervious area in urban watersheds comes from parking lots.

Storm drains from parking lots are generally connected to a storm sewer system. In many areas, storm sewers dump into the nearest stream. Besides carrying pollutants to these streams, the runoff causes streams to rise quickly during storm events, eroding banks and stirring up sediments and legacy pollutants from the stream bed.

In many larger cities, including Portland, storm sewers connect to the sanitary sewers and go to a wastewater treatment plants. During storms, the combination of sewage and runoff is greater than the capacity of the system and a “combined sewer overflow” occurs, dumping into the nearest river.

Parking lots also contribute to the heat island effect. On a hot summer day, the temperature of an asphalt parking lot can be 50F warmer than the surrounding area. The heat gain from a lighter colored concrete parking lot is less severe.

Overcoming Difficulties of Growing Trees in Parking Lots
Many trees are not adapted to the high temperatures that occur in asphalt parking lots. Soil compaction that typically happens with any paving project is not conducive to tree growth. Trees also need protection from cars, trucks, shopping carts and other equipment that might collide with a tree in a parking lot.

Numerous studies correlate tree growth with the volume of soil available to them. One way of accommodating tree growth in parking lots is to provide large tree wells. Where land costs are prohibitive, “structural soils” can provide a healthy growing medium that can support parking loads. Trees thrive in structural soils 3’-4’ deep and 10’ or more wide.

Cornell University has been a pioneer in structural soils, with more than a decade of research documenting their performance. Structural soils contain load supporting crushed rock of sufficient size to provide voids for soil, air and water. Screened organic soil is mixed with the crushed rock for the roots to grow in. A soil binder is mixed with the coil and rock to keep the soil in place.

Cornell’s CU structural soil is a patented mix that is licensed to vendors across the country and comes with quality control assurances. Other recipes have been developed across the country using local materials. The University of California at Davis has developed a structural soil using locally available lava rock. Lava rock contains voids for air and water and is not as strong as other rock, so the Davis mixture uses rock of smaller size than other structural soils.

The City of Olympia Washington constructed a successful demonstration project in 2001 using structural soils in a linear tree well 100’ long x 10’ wide x 3’ deep, covered with concrete sidewalks. Three trees reside in 4’ x 4’ cutouts in the sidewalk. Across the street from this demonstration, 4 trees were planted in compacted native soils as a control for the experiment. The results as shown in this Google Earth image 8 years later are impressive.

Trees in parking lots need protection from collisions. Wheel stops are the most typical protection methods. Placement of wheel stops should consider whether a long-bed pickup truck might back into that parking space.

The 5000 Acres Initiative
Tualatin Riverkeepers is working with various partners to initiate a program to plant trees in parking lots for stormwater mitigation. The Tualatin River basin has more than 5000 acres in parking lots that cause runoff that erodes and pollutes streams. One of the goals of this project is to retrofit parking lots without losing parking capacity. Structural soils and linear tree wells designed by Maria Cahill of Green Girl Land Development Solutions a primary feature of the first two proposed project sites. Stormwater monitoring for the first year at these two sites is being contributed by Clean Water Services. Matt Stine of Ash Creek Forest Management is the consulting arborist for this program.

One of the proposed sites is at the Sunset Swim Center, owned by Tualatin Hills Parks & Recreation District (THPRD). THPRD had already planned to replace a ½ acre asphalt parking lot with pervious concrete. Tualatin Riverkeepers was interested in testing the stormwater interception capabilities of native conifers. High temperatures in asphalt parking lots are not conducive to the survival of native conifers, so this site with a cooler concrete parking lot is ideal for this trial.

The other proposed site is at the Mission of Atonement, a congregation of Lutherans and Roman Catholics interested in improving their environmental stewardship. Their current parking lot of gravel and asphalt produces significant runoff that pools offsite on a THPRD site. Linear tree wells with structural soils appear to be an ideal solution for runoff reduction on this site.

Tualatin Riverkeepers is looking for additional local partners for this project. We need to raise an additional $90,000 for the first year of the project and grant applications are pending for most of that. There are research opportunities for graduate students or others wishing to study rainfall interception of trees or performance of linear tree wells and structural soils. Potential partners for funding, in-kind donations, research or installation of trees on a parking lot are encouraged to contact Brian Wegener, Watershed Watch Coordinator of Tualatin Riverkeepers at 503-620-7507 or

Saturday, December 5, 2009

Save the Date - Oregon Urban Forestry Conference

Block out June 2 & 3, 2010 on your calendar for our Urban Forestry Conference. The theme this year is Seed to City: The Journey of an Urban Tree. We are focusing on the cultivation, planting and care of urban trees. Day one features a tour of the J. Frank Schmidt & Son Co. Nursery and Arboretum. Day two features presentations by the experts at the Oregon Garden Resort.

We have made this two-day conference quite affordable and expect a large turnout. CEUs will be available for professionals. Registration begins March 1.

Details as they become available will be on our website at