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Biogeochemical processes influencing urban ecosystems

Project Details

Principal Investigator

Oak Ridge National Laboratory scientists are gathering and analyzing data on biogeochemical processes in urban areas to better understand how the natural and built environments interact and affect the microclimate of people who reside there. Their discoveries provide insight into how tree plantings and greenspace could alleviate heat in urban areas, where most of the world’s population resides.

Scientists meet with representatives of SEEED in Knoxville.
From left, Stan Johnson of SEEED, ORNL’s Yaoping Wang, SEEED’s Laurel Bowen, UTK’s Jennifer First and ORNL’s Jeff Warren at SEEED where ORNL is installing sensors to monitor environmental conditions related to urban microclimate. Credit: ORNL, U.S. Dept. of Energy

Knoxville, TN: Urban forest temperature study

The goal of this project in Knoxville, Tennessee, is to understand how microclimate variables such as temperature and relative humidity in urban environments are affected by soil moisture and plant evapotranspiration, i.e., the process by which water moves through the soil into plant roots, up the stem, and into the air through leaf stomata. ORNL and University of Tennessee, Knoxville, scientists are installing small weather stations and sensors in Knoxville city parks to measure variables such as soil moisture and sap flow to understand tree evapotranspiration and relationships with urban microclimate.

The data will be used to assess the utility of computer models in simulating urban heat island effects and how these effects can be moderated by natural ecosystem components such as trees and green space. One of the instrumentation sites will be located at the headquarters of Socially Equal Energy Efficient Development, or SEEED, an organization providing career readiness training,  energy-efficient housing, and community engagement in East Knoxville. The 2022 Knoxville Heat Mapping Report provides recent maps of the city where excessive heat may occur.

Field site at NIST
Field site at the National Institute of Standards and Technology. Credit: ORNL, U.S. Dept. of Energy

Gaithersburg, MD: Biogeochemical cycling along the natural-built environment interface

This project on the campus of the National Institute of Standards and Technology in Gaithersburg, Maryland, analyzes the impacts of forest distribution and how soil water affects soil respiration and tree evapotranspiration. ORNL scientists are exploring topics such as how much carbon trees on the forest edge are incorporating into their biomass and what belowground resources—nutrients, soil moisture, microbial community—fuel their growth. They are incorporating data into a model that will expand their understanding of soil-climate interactions in green spaces in highly urbanized areas. The project with NIST also helps them reach their goal of developing instrumentation to measure plant photosynthesis and plant characteristics (greenness, leaf area index and biogenic emissions) on its campus.


Distinguished Staff Scientist and Biogeochemical Dynamics Group Leader
Melanie A Mayes