Self-Supervised Tree-level Biomass Estimation in Urban Environments From Airborne LiDAR and Optical Observations
This study addresses the lack of high-resolution, fine-scale quantification of urban tree biomass, which hinders the characterization of individual-tree heterogeneity. The authors propose a self-supervised dual-stream cross-attention network that fuses airborne LiDAR with near-infrared RGB imagery to generate semantic labels, enabling annotation-free crown delineation through multiscale watershed segmentation. Aboveground biomass is then estimated using species-specific allometric equations. The work introduces the first publicly available bitemporal non-forest tree biomass database and incorporates deep ensemble uncertainty maps to guide model refinement. On an independent test set, biomass predictions achieve R² values of 0.570–0.609. Applied to an 810 km² area in Ontario from 2018 to 2023, the approach reveals a net carbon stock increase of 39 Gg C, with localized densities reaching up to 140 Mg/ha.