Spatiotemporal dynamics of typhoon-induced landslides and associated biomass loss over three decades

Long-term spatiotemporal mapping of landslides is crucial for understanding the dynamics of landslide, their impact on forest carbon stocks, and their interactions with environmental factors, climate variability, and disturbances. This study analyzed 33 years (1990-2022) of Landsat imagery and topography using machine learning (Random Forest) to map landslide dynamics in a 24,386-ha subtropical montane forest in Northeast Taiwan. We also quantified forest aboveground biomass (AGB) losses from landslides using temporally corresponding Landsat and lidar data. We observed pronounced interannual variability, with total landslide coverage ranging from 0.68% to 3.19%, and forest-to-landslide transitions driving annual AGB losses of 2 to 85 Gg yr⁻¹. Temporal analysis revealed exponential declines in landslide frequency (median = 2 events), persistence (one year), and reoccurrence (two times), indicating most landslides were short-lived. However, nearly half of affected sites reoccurred multiple times, indicating spatially persistent susceptibility. Topographic attributes, including elevation, aspect, slope, and local relief, exhibited greater sensitivity to extreme events. Crucially, typhoon-driven extreme rainfall, particularly daily maximum precipitation (r = 0.559, p = 0.004), showed a stronger relationship with newly formed landslides than daily maximum precipitation during the rainy season (r = 0.399, p = 0.026), emphasizing typhoon’s dominant triggering role. AGB losses from typhoon-triggered landslides were roughly 14-fold greater than in quiet years, profoundly impacting the regional forest carbon budget. Post-landslide vegetation recovery exhibited a highly variable trajectory and plateaued at ~63% of pre-disturbance biomass within 25 years, based on a non-linear asymptotic model. As climate change is projected to intensify typhoon activity and extreme rainfall, landslide risks and associated forest carbon losses will increase, particularly in vulnerable, typhoon-prone regions like Asia. These findings highlight typhoons are not only a principal driver of landslide activity but also a major disruptor of forest carbon budgets, underscoring their critical inclusion in carbon accounting frameworks for vulnerable montane ecosystems.