Skip to main content
2023 ESA Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Contributed Talk

Session: : Physiological Ecology 7

COS 267-6 - Characterizing hydraulic stress from reflective heating in the urban forest of Athens, Georgia

Thursday, August 10, 2023
11:15 AM – 11:30 AM PDT
Location: E142

    Presenting Author(s)

  • CN

    Clara Nibbelink

    M.S. student
    University of Georgia
    Athens, Georgia, United States

    • Coauthor(s)

  • DJ

    Daniel M. Johnson

    Advisor, Associate Professor of Tree Physiology and Forest Ecology
    University of Georgia
    Athens, Georgia, United States

  • RA

    Rebecca B. Abney

    Assistant Professor of Forest & Disturbed Soils
    University of Georgia
    Athens, Georgia, United States

  • JG

    Jason Gordon

    Associate Professor of Community Forestry
    University of Georgia
    Athens, Georgia, United States

  • RH

    R. Preston Harden

    research assistant
    University of Georgia
    Athens, Georgia, United States

Abstract: The 2022 IPCC Climate Report identified urban greening as a key climate change mitigation tool for cities, given the myriad of ecosystem services that trees provide. However, transpiration is less effective at cooling when temperatures are higher and there is no corresponding increase in water availability. Both water and temperature stress reduce the ecosystem service potential of a tree and increases its likelihood of mortality. Given the impact that reflective heating due to hardscapes has on microclimates within cities, it is important to understand how the siting of trees–with or without buffers from reflective heating–will impact a tree’s ability to fulfill its potential in providing needed ecosystem services.



This study investigates hydraulic stress in recently established trees in the urban forest of Athens, Georgia. Our field sites are three elementary school playgrounds, where the same species mix were planted as young trees during approximately the same time period, in similar sites, for similar purposes of cooling and shade. Trees were planted in 2020 and are now approximately 15 feet tall. Each tree experiences some exposure to reflective heating due to hardscapes. We quantified percent exposure to reflective heating, and, over the course of a growing season, measured hydraulic stress in our sample trees. To quantify hydraulic stress, sap flow, predawn and midday water potentials were measured and compared to controls. Preliminary results indicate that hydraulic stress is significantly higher in trees at a threshold of 25% exposure to reflective glare due to hardscape, indicating a need for buffer zones when planting urban trees for ecosystem benefits. These results provide guidelines for site and species selection in the urban landscape, as well as physiological data to improve our ecosystem services models.