29-19 Interactions among redlining, tree biodiversity, and the urban heat island effect in Richmond, VA

Session: Undergraduate Research, Part II (Posters)

Presenting Author:

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Abstract:

The urban heat island effect causes urban areas such as Richmond, VA to experience higher temperatures than surrounding rural regions, exposing residents to increased health risks. This effect has been found to disproportionately impact low-income communities of color due to the legacy of historic policies like redlining by the Home Owners’ Loan Corporation (HOLC). A contributing factor to this inequity is disinvestment in greenspaces and street trees in redlined areas. Urban trees provide heat mitigation, which means lower tree cover leads to higher temperatures. High urban tree biodiversity supports cooler temperatures and resilience to climate change. The goals of this research are to determine differences in the biodiversity of tree communities and temperatures between HOLC neighborhood grades. We hypothesized redlined neighborhoods have lower tree biodiversity and higher temperatures than non-redlined neighborhoods. 

Street segments with consistent percent tree cover in twelve neighborhoods across Richmond were selected for study. Temperature and humidity data were collected using a mobile weather station during high temperature days in August 2025. Tree biodiversity surveys were conducted along each street, including data describing tree species, size, pit type, and condition. Temperature and relative humidity data were adjusted for daily and hourly variation, as well as speed. The Heat Index was calculated for each HOLC grade using temperature and humidity data collected. Preliminary results showed higher average temperatures and lower humidity in redlined neighborhoods compared to their greenlined counterparts. Redlined neighborhoods also experienced higher Heat Index, meaning residents feel the impact of those higher temperatures. Shannon’s Diversity Index, species richness, and species evenness were calculated for each HOLC neighborhood grade. Preliminary results showed lower richness and Shannon’s Diversity Index in redlined neighborhoods than greenlined neighborhoods. Redlined neighborhoods also had greater species evenness. Findings of this project will be useful to inform urban planning in Richmond to address disparities and build resilience to climate change.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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