Quantifying biogenic volatile organic compound (BVOC) emissions is critical in the development of effective ozone
and fine particle control strategies in certain of California's airsheds. The ARB and the California academic community
have promoted research in this area for more than two decades. Among our principal findings are that plant taxonomy
provides a useful framework for categorizing emitting plant species, genera, and families, and that the volumetric
method for estimating leaf masses for urban trees and oaks provides good agreement with field measurements, including
whole-tree harvests. These taxonomic and volumetric methods facilitate use of species-specific databases to model
natural and urban forest emission scenarios.
Many local governments in California have large-scale tree planting programs in cooperation with such groups as
the Tree People. Increased tree cover reduces atmospheric carbon by sequestering carbon dioxide and by shading
structures so that less fossil fuel is burned to power air conditioning. This reduces the overall pollution produced
by the city, and contributes to the reduction of greenhouse gases in the atmosphere. There are also substantial
energy cost-savings realized through the shading effect and by lowering urban temperatures (i.e. reducing urban
heat islands). Additional canopy cover can also remove particulate matter and ozone by dry deposition on the leaves
and by stomatal uptake. A case study of these beneficial phenomena while accounting for the biogenic emissions
potential of certain tree species is the Los Angeles Department of Water and Power’s Cool Schools Program. |