Ecology of environmental justice in metropolitan areas

Trees in the city provide a number of benefits that we take for granted as free services. Trees create shade, lessen climate extremes, reduce heating and cooling costs, reduce deaths and injuries from heat stress, provide habitat for wildlife, absorb pollutants, save costs for stormwater and wastewater treatment, and increase real estate values. Recently, a number of municipalities have decided to make their cities greener with new and ambitious tree planting programs. This project will measure ecosystem services, the benefits that ecosystems provide to people, in five metropolitan areas: Baltimore, Miami, Phoenix, Los Angeles, and Sacramento. These cities occupy different climate and vegetation zones, plus have different histories, population characteristics, and economies. We expect these differences will affect the amount and types of ecosystem services that are gained from trees in each of the metropolitan areas. We will measure ecosystem services in two ways, by calculating: 1.) the physical benefits from trees, such as tons of pollutants absorbed; and 2.) the monetary value of the benefits from trees, or what it would cost, for instance, to absorb pollutants using technology instead of relying on trees to perform the same function. Calculating ecosystem services will allow us to answer the central question of this research: who benefits most and least from ecosystem services from trees? Theory from environmental justice suggests that low-income and ethnic/racial minority populations will live in neighborhoods with the fewest environmental amenities while white and wealthy groups will live in neighborhoods with the greatest share of environmental benefits. However, the relationship between the social characteristics of neighborhoods and ecosystem services has not been tested before. We will also explore how biophysical, political, social, and economic characteristics of each city might explain differences in the amount, types, and distribution of ecosystem services found at each location. This research offers an opportunity to link ecology and environmental justice research and to suggest best ways for municipal governments and non-profit groups to reduce inequitable distributions of ecosystem services in cities.