The plan envisions a future forest that can meet the challenges of a changing environment and a rapidly developing city. Trees, so much the character of Palo Alto's past small-town look and feel, will play an important future role in maintaining the city's quality of life while making economic contributions in the hundreds of thousands of dollars, Passmore said.
But disparities between the north and south residential areas, increasing use of reclaimed, more salinated water, increased conflict between trees and solar installations and development will need consideration for the tree canopy to maintain its present and future continuity, according to Passmore.
"We need to be very innovative," he said.
Only seven of 96 species planted in the city are good street trees. The rest are fast-growing forest giants that are raising sidewalks and interfering with utilities. As the city replaces the trees over time, the master plan will use more adaptable species and techniques that avoid costly damage to infrastructure such as sidewalks and building foundations. When considering new plantings, the city would choose species that have a lower "thirst rating" for street trees to reduce water usage and cost, according to the plan.
The master plan analyzed tree benefits to the city in real dollars. The urban forest has a net benefit of more than $4.5 million — $156.93 per tree — for right-of-way trees alone when considering energy, CO2, air quality, stormwater and aesthetics, according to analysis.
The findings will shape the types of trees to be planted in the urban forest in the years to come, since some are better at reducing energy needs and sequestering carbon dioxide. Palo Alto's trees reduce CO2 by a net 3,437.5 tons per year, at a saving of $1.77 per tree annually, according to the document.
Street trees alone also intercept 42,600,000 gallons of stormwater per year. As the trees mature, that number will increase, according to the plan.
Planning commissioners praised the document, while suggesting ways to strengthen its clout in terms of policy integration with the Comprehensive Plan and other city planning documents, enforcement and expansion of the city's tree-protection ordinance and developer requirements to maintain or replace trees.
"What is the greatest threat to our urban forest? As a public policy, it's urban development. I didn't see anywhere where we addressed a reaction or policy or program that addressed downtown development or development in neighborhoods," Commissioner Eduardo Martinez said.
A policy for urban development should include some responsibility of developers for the urban forest, he said.
Other commissioners noted concerns about conflicts between trees and the expansion of solar energy, since the panels require direct sunlight, as well as needing a more refined analysis in neighborhoods, since the plan did not count neighborhoods that are part of commercial/residential areas.
The forest master plan would also rectify a disparity between north and south Palo Alto, where there is a 10 to 20 percent deficit in the tree canopy in southern neighborhoods. The difference emerged as a hot topic among 600 respondents to a community survey, the plan noted.
City staff are developing a citywide "sustainability plan," which Passmore said provides an unprecedented opportunity to develop compatibility between the trees and other programs. He will incorporate the suggestions he has received from the Parks and Recreation and Planning and Transportation commissions. He expects to return to the planning and transportation commission in February for an endorsement of the master plan.
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