Sub-pixel mapping of disturbance and tree mortality dynamics from Sentinel-2 time series around the globe

作者：Clemens Mosig, Teja Kattenborn, David Montero Loaiza, Janusch Vanja-Jehle, John Brandt, Nathan Jacobs, Subash Khanal, Eric Xing, Martin Schwartz, Helene C. Muller-Landau, Mirela Beloiu, A. Bozzini, Yan Cheng, Keenan Ganz, Björn Grüning, Henrik Hartmann, Jan Hempel, Stéphanie Horion, Samuli Junttila, Kirill Korznikov, Guido Kraemer, Milena Mönks, Davide Nardi, Paul Neumeier, Jonathan Schmid, Salim Soltani, Marie Therese-Schmehl, Josh Veitch-Michaelis, Miguel Mahecha · 年份：2026 · DOI：10.31223/x5b18w · 被引用次数：1 · 研究领域：Remote Sensing and LiDAR Applications、Forest Ecology and Biodiversity Studies、Wood and Agarwood Research

Elevated forest disturbances and excess tree mortality are increasingly reported worldwide. Yet existing assessments are either based on patchy terrestrial observations or on large-scale satellite products, which are limited in resolution to pixel-level, binary tree loss detection. This leaves a blind spot on fine-scale disturbances where only a few trees are declining in an otherwise intact canopy. Here, we present a methodology for annually mapping sub-pixel fractional cover of standing deadwood and trees from rolling four-year windows of Sentinel-2 time series. Fractional cover is the proportion of each pixel covered by dead or live tree crowns. To obtain globally distributed sub-pixel reference labels, we leveraged the crowd-sourced archive deadtrees.earth of centimeter-scale drone orthophotos with two globally calibrated semantic segmentation models to derive tree and standing deadwood masks, yielding 6.2 million labeled Sentinel-2 pixels. Spatial block cross-validation shows high performance for tree cover, Pearson’s r = 0.58–0.64, across biomes, and moderate performance for standing deadwood cover, Pearson’s r = 0.30–0.56. Viewed as a binary classification task, the model achieves a mean precision of 91% and recall of 90% for tree cover, and a precision of 54% and recall of 82% for standing deadwood. Validation against independently obtained and ground-validated data in all major biomes reproduced known disturbance patterns and timing at unprecedented spatial detail co...