Mapping the structural diversity of Central African and Western US forests using GEDI

This study maps forest structural diversity, a key component of ecosystem diversity, using NASA’s GEDI spaceborne lidar at a range of spatial scales, essential for informing conservation and restoration strategies in the face of rapid climate change and biodiversity loss. Focusing on biodiversity hotspots in Central Africa and the Western US, we compared GEDI-derived data to 391 km2 airborne laser scanning (ALS) measurements for validation. Forest structural traits were evaluated at 1 km2 resolution, with GEDI showing robust correlations with ALS data, particularly in dense, flat Central African forests (r² up to 0.85) compared to more variable terrains like the California Sierra Nevada (r² up to 0.55). Structural diversity was assessed through probability density-based, multivariate functional diversity indices. GEDI canopy height (rh98), canopy cover, and foliage height diversity were effective metrics for capturing structural diversity with an r2 of 0.37 when compared to wall-to-wall ALS data at 1 km2 scale. Our results reveal high structural diversity in mid-elevation and coastal forests in the U.S. and in Central African forest-savanna transitions and volcanic ranges, aligning with ecological processes related to wildfires and topographic gradients. Despite challenges such as sampling density, waveform noise and terrain complexity, this study demonstrates GEDI’s capacity to map forest structural diversity in two structurally complex biodiversity hotspots at scales from 1 to 25 km, offering a valuable resource for policy and conservation efforts. These insights enhance our understanding of forest structure and biodiversity, supporting strategies to mitigate climate change impacts on global forest ecosystems.