A novel framework for assessing shrublines and their geophysical constraints in alpine regions through probabilistic vegetation mapping and seed-filling algorithm

Alpine shrublines are assumed to be highly sensitive to climate change and play a vital role in maintaining biodiversity and ecosystem functions. However, where and how alpine shrublines are distributed is poorly understood due to the difficulty in distinguishing between dwarf shrubs and grass. In this study, we proposed a novel framework to map alpine shrublines in Xizang Rezhen National Forest Park in 2020 using multi-source spatial data, probabilistic vegetation mapping, and seed-filling algorithm. Validation against high-resolution Google Earth imagery demonstrated a high accuracy, with a mean absolute error (MAE) of 3.13 m and R² of 0.99. The results indicated that the average elevation of alpine shrublines was about 4,873 m, ranging from 4,518 m to 5,195 m. South-facing alpine shrublines averaged approximately 145 m higher than north-facing counterparts. Meanwhile, shrublines at higher elevations exhibited lower EVI2 and NDVI values along with reduced soil quality compared to those at lower elevations. This study reveals geographical influencing factors of alpine shrubline patterns, thus offering insights into the ecological responses of high-altitude woody ecosystems to climate change.