Detecting regional changes in California forest fuels treatments with GEDI spaceborne lidar

Faculty: Matthew Clark

Geography, Environment & Planning

College of Humanities, Social Sciences, and the Arts

This study evaluates the use of Global Ecosystem Dynamics Investigation (GEDI), a spaceborne lidar instrument, to detect changes in forest structure after wildfire fuels treatments and timber harvest activities. We analyzed 175 forest treatments from 2019 to 2022 in California, USA, with GEDI metrics that respond to canopy height, cover, plant area, and biomass density. Differences in measurements acquired before and after activities were compared to nearby control areas. Results showed that GEDI effectively detected reductions in structure (e.g., fuels) from moderate- and high-intensity treatments, such as selective thinning and clear-cutting, but not from low-intensity activities like prescribed burns and other sub-canopy fuels reductions. Significant changes included reduced sub-canopy canopy heights, foliage diversity, and cover, and an increase in the proportion of returned energy below 10-meter height. However, GEDI's current spatial and temporal data limitations ultimately reduce its practical utility for monitoring small treatment areas or frequent changes. Our study underscores GEDI's potential for tracking forest management practices across large areas, particularly those activities with higher intensity, while highlighting the need for improved data density and coverage for broader applicability.