We used the Conversion of Land Use and its Effects (CLUE-s) model to simulate scenarios of land-cover and land-use change (LCLUC) in Montane Mainland Southeast Asia (MMSEA), a region on the cusp of change due to projected rapid intensification of agriculture and expansion of regional trade markets. Simulated changes affected approximately 10% of the MMSEA landscape between 2001 and 2025 and 16% between 2001 and 2050. Roughly 9% of the current vegetation, which consists of native species of trees, shrubs, and grasses, is predicted to be replaced by tree plantations, tea, and other evergreen shrubs during the 50-year period. Importantly, 4% of this change would be due to the expansion of rubber, a tree plantation crop that may have important implications for local-to-regional scale hydrology because of its relatively high water use for leaf flushing during the driest part of the year.