緑の投資効果/北カリフォルニア

サンフランシスコ近郊のバークレイを対象地として実施した、マクファーソン先生の最新の研究成果が発表されています



これによると、住民は樹木の維持管理費など＄1あたりの投資に対して、平均＄4.56の便益を得ているとのことです



毎回議論になりますが、ここで示されている経費と便益は以下の通りです



Benefits

• Saving Energy


• Reducing Atmospheric Carbon Dioxide


• Improving Air Quality


• Reducing Stormwater Runoff and Improving Hydrology


• Aesthetics and Other Benefits

Costs

• Planting and Maintaining Trees


• Conflicts With Urban Infrastructure


• Wood Salvage, Recycling, and Disposal

評価手法など詳細はリンク先で確認してください



---要旨（転載）

Trees make our cities more attractive and provide many ecosystem services, including air quality improvement, energy conservation, stormwater interception, and atmospheric carbon dioxide reduction. These benefits must be weighed against the costs of maintaining trees, including planting, pruning, irrigation, administration, pest control, liability, cleanup, and removal. We present benefits and costs for representative small, medium, and large deciduous trees and coniferous trees in the Northern California Coast region derived from models based on research arried out in Berkeley, California. Average annual net benefits (benefits minus costs) increase with mature tree size and differ based on location: $29 (public) to $41 (yard) for a small tree, $42 (public) to $60 (yard) for a medium tree, $101 (public) to $122 (yard) for a large tree, $142 (public) to $146 (yard) for a large conifer. Two hypothetical examples of planting projects are described to illustrate how the data in this guide can be adapted to local uses, and guidelines for maximizing benefits and reducing costs are given.

Keywords: Ecosystem services, urban forestry, benefit-cost analysis.

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■原文リンク

http://www.fs.fed.us/psw/programs/cufr/products/2/psw_cufr790_psw_gtr228.pdf