Analyzing environmental and social impacts of urban forestry practices in Tacoma, WA with PlanIT Geo

Urban forestry encompasses street trees, residential trees, park trees and greenbelt vegetation. Despite local groups’ efforts and trends in better forest management practices, there is an unequal distribution of urban forests and their associated ecosystem services across most of the United States. Evaluating canopy distribution is the first step to enable cities to better devote limited resources to marginalized communities, which often have additional equity concerns. Our project will help the urban forestry nonprofit, PlanIT Geo™, and their future clients in their urban forestry management plan recommendations and could increase the equitable dispersal of environmental benefits. 

In addressing the equity of Tacoma’s urban forests, we assessed trees' impacts on air quality and human health. We designed an equity index model to compare census block groups based on five indicators: canopy coverage, demographic, climate, air quality, and health. The air quality and health indicators were derived by analyzing PM2.5 reduction through the amount of canopy coverage and the associated health benefits from improved air quality in Tacoma, WA. We then calculated individual indicator scores and a composite environmental equity score for each census block group in Tacoma. Conclusions reveal that there is an overall unequal tree canopy distribution in Tacoma and considering additional indicators broadens PlanIT Geo’s awareness of the most vulnerable communities in Tacoma. Through this analysis, we identified priority areas in need of intervention and environmental considerations to maximize socio-economic and environmental benefits while minimizing harm post-intervention.

城市林业（urban forestry）涵盖行道树、住宅庭院树木、公园林木以及绿地植被。尽管地方团体已付出诸多努力，且森林管理实践正朝更优化的方向发展，但美国绝大多数地区的城市森林及其配套生态系统服务（ecosystem services）的分布仍存在不均衡问题。评估林冠覆盖率（canopy coverage）分布状况，是城市能够将有限资源更合理地倾斜至往往存在更多公平性诉求的边缘社区的首要步骤。本项目将助力城市林业非营利组织PlanIT Geo™及其未来客户制定城市林业管理规划方案，并推动环境效益的公平分配。

为探究塔科马市城市林业的公平性问题，我们评估了林木对空气质量与人类健康的影响。我们设计了一套公平性指数模型，基于林冠覆盖率、人口统计、气候、空气质量与健康五大指标，对普查街区组（census block groups）进行对比分析。其中，空气质量与健康指标通过分析华盛顿州塔科马市的林冠总量所带来的PM2.5降低效应，以及空气质量改善带来的相关健康收益推导得出。随后我们为塔科马市的每个普查街区组计算了单项指标得分与综合环境公平性得分。研究结论显示，塔科马市的林木林冠分布整体仍存在不均衡现象，而纳入更多指标后，PlanIT Geo™能够更全面地识别该市最易受影响的社区。通过本次分析，我们确定了需要开展干预的优先区域及环境考量要点，以在干预后最大化社会经济与环境效益，同时将潜在负面影响降至最低。