Scientists & Staff

Greg McPherson

E. Gregory McPherson

Emeritus Scientist
1731 Research Park
Davis, CA, 95618
Phone: 530-759-1723

Contact E. Gregory McPherson


Current Research

Dr. Greg McPherson is a Research Forester with the USDA Forest Service's Pacific Southwest Research Station located in Davis, CA, Greg grew up under a canopy of American elm trees in Howell, Michigan. Despite attempts to save the trees, all were lost to Dutch elm disease, and having felt the sting of that loss he became a green accountant, developing new methods and tools for quantifying the value of nature's benefits from city trees. He works with a team of scientists to measure and model effects of trees on energy use, urban heat islands, air pollutant uptake, carbon sequestration, and rainfall interception. Their research is helping justify investments in urban forest planning and management. In 2000, Greg received the International Society of Arboriculture's L.C. Chadwick Award for Research. Greg was a co-founder and Chair of the Tree Growth and Longevity Working Group and serves on the California Urban Forest Advisory Council. He attended University of Michigan (BGS), Utah State University (Masters in Landscape Architecture), and SUNY College of Environmental Science and Forestry (Ph.D. Forestry).

Featured Publications & Products

Publications & Products

National Research Highlights

The General Technical Report and Urban Tree Database provide species-specific data on tree growth that are critical to projecting uptake of air pollutants and other services that trees provide.

Database captures urban tree sizes, growth rates across U.S.

Year: 2017

Sometimes in the cramped environs of U.S. cities every inch counts, especially if attempting to make space for nature. City planners and urban foresters now have a resource to more precisely select tree species whose growth will be a landscaping dream instead of a maintenance nightmare.

Street trees lining California’s roadways provide $1 billion in services each year.  U.S. Department of Agriculture Forest Service.

California ‘Street’ Tree Benefits Valued at $1 Billion

Year: 2016

Forest Service researchers use a computerized tree inventory and management program to quantify the number and types of tree species lining California streets, as well as to calculate the value of their various ecological benefits.

Two members from the Los Angeles Conservation Corps plant a tree. The Los Angeles tree programknown as

Trees in Los Angeles: Carbon Dioxide Sink or Source

Year: 2014

Tree planting is considered to be among the most effective approaches to cooling urban environments and mitigating carbon dioxide emissions. The Los Angeles tree program known as "City Plants" is one of several mayoral tree planting initiatives launched in the largest U.S. cities. Altogether, the largest cities have pledged to plant nearly 20 million trees, in most cases for climate protection. The assumption behind these tree planting initiatives is that trees are a net long-term carbon dioxide sink, but because there has never been a full accounting of carbon dioxide emissions for a tree planting initiative, some people question their effectiveness.

Tree height, crown base, and leaf area for same-aged green ash in Fort Collins, CO and Cheyenne, WY. Upper lines represent height, lower lines represent height to first branch.  Ash have only 55 % of the Fort Collins' ash leaf area, largely due to differences in climate and soils. Forest Service

New Model Predicts Urban Tree Growth

Year: 2012

New study developed growth equations for urban tree species throughout the United States

Existing and potential tree canopy cover percentages for Los Angeles by Council District. Greg McPherson, Forest Service)

One Million Trees LA Canopy Cover Assessment

Year: 2011

The day after Antonio Villaraigosa was elected mayor of the City of Los Angeles he planted a tree and announced his plan to plant one million trees over the next several years. To guide this initiative he called upon PSW scientists to answer some questions: How green is LA today Is there room for a million trees Where should we plant them What environmental and other benefits will our trees provide Using geographic information systems, satellite images of the city and numerical models, the PSW team answered these questions and found that over a 35-year period, benefits from one million trees will range from $1.3 to $2.0 billion. Million Trees LA has planted over 300,000 trees to date, and PSW's tree canopy cover maps have helped the program target trees for residential neighborhoods and commercial areas with the least tree canopy cover.

Community Tree Guides Help Managers Show that Trees Pay Us Back

Year: 2010

The 16th and final Community Tree Guide was published for Central Florida based on research conducted in Orlando. Providing complete coverage of the US, any user can now compare future net benefits from alternative tree planting scenarios. In Minnesota, a series of workshops helped communities use a spreadsheet template with data from the 'Midwest Community Tree Guide' to calculate net benefits for their tree planting projects. In California, data from 'Tree Guidelines for Inland Empire Communities' was used by United Voices for Better Communities to estimate future air pollutant uptake benefits for a planting project funded by the South Coast Air Quality Management District.

Last modified: Friday, July 31, 2015