by S Pincetl, T Gillespie, D Pataki, S Saatchi, J Saphores
A number of U.S. cities have recently begun implementing large tree-planting initiatives without, the authors argue, seriously considering the effects, positive and negative, of such efforts. In addition, little research has been done into the origins of such programs or their implementation. This paper uses Los Angeles’ Million Tree Program as an interdisciplinary case study to address the following questions: (1) What are the expected impacts on water use, greenhouse gas reductions, and energy use? (2) Can the trees be expected to increase property values as predicted in other studies? (3) How has tree cover changed historically? (4) How was the Million Tree Program initiative implemented? The methods for addressing these questions included direct measurements, hedonic pricing analysis, analysis of remote sensing data and historical imagery, interviews, and content and historical analysis. The authors identify a number of benefits that can be expected, but note that transparency was lacking in the planning and implementation and there are no plans for monitoring the effects. They emphasize that the design of tree planting initiatives must account for regional differences in climate, ecosystems, and people’s preferences. Their methodology can serve as a framework for assessing the costs and benefits of ecosystem services–based programs in other cities.