One Million Trees LA Canopy Cover Assessment
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.
In Los Angeles, the current urban forest covers 21% and consists of about 11 million trees. An innovative program was developed to determine the number of potential tree planting sites by training a computer to follow a series of decision rules. This virtual tree site detector found 2.5 million potential sites. There was plenty of room for LA's one million new trees.
Using research and models developed by PSW scientists, the team estimated the value, over a 35-year period, from one million trees in Los Angeles as $1.3 to $2.0 billion! Average annual benefits were $49 to $60 per planted tree. For example, by storing carbon as biomass, one million new trees will reduce carbon dioxide in the air by about one million tons. This reduction is equivalent to removing 7,000 cars from streets and highways each year.
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. This and other PSW research quantifying the benefits and value of California's urban forests was instrumental in the development and approval of Proposition 84. This bond measure is providing $90 million for urban forestry and urban greening projects in California.
Forest Service Partners