Present-day Street Tree Communities Reflect 1930’s Race-based Housing Policy and Modern Attempts to Remedy Environmental Injustice

Keywords: street trees, biodiversity, community, Baltimore, redlining
Session Type: Virtual Paper Abstract
Day: Friday
Session Start / End Time: 2/25/2022 11:20 AM (Eastern Time (US & Canada)) - 2/25/2022 12:40 PM (Eastern Time (US & Canada))
Room: Virtual 40

Abstract

Humans directly and indirectly promote and inhibit the occurrence of other species on the urban landscape, which strongly affects urban biodiversity patterns. One relatively underexplored social factor that may drive patterns of species diversity is the consequences of institutionalized racism and segregation. Institutionalized racism and segregation create disproportionate distribution of resources in space and over time, which have consequences for the the processes that govern species distribution and patterns of biodiversity. In the United States of America, the practice of “redlining,” which originated with the Federal Government's Homeowners’ Loan Corporation (HOLC) in the 1930s, is an example of institutionalized racism. A key aspect of the HOLC was to classify and map cities in terms of risk--from most desirable to least desirable for investment--with corresponding colors from green to red. Analyzing the street tree inventory in Baltimore, Maryland (USA), we geographically delineated street tree communities in neighborhoods classified by HOLC. We expected that redlined neighborhoods would show (1) reduced tree diversity, (2) reduced occupancy of large (older) trees (3) different tree community composition compared to more highly-rated HOLC neighborhoods, and (4) lower among-neighborhood turnover, or homogenization. Redlined neighborhoods had the lowest biodiversity indices and were less likely to have large (old) trees present. Simultaneously, these redlined neighborhoods were also locations of recent active tree plantings as shown by larger proportion of small (younger) trees. Neighborhoods differed markedly in tree size and species composition across HOLC. We conclude that redlining in Baltimore helps explain variation in street tree biodiversity and community composition.