Local and Regional Effects of Land-Use Intensity on Aboveground Biomass and Tree Diversity in Tropical Montane Cloud Forests

The quantity and spatial patterns of aboveground biomass (AGB) are expected to correlate with ecosystem structure and biodiversity across biomes. However, the local and regional variations in the strength of such relationships remain poorly understood partly due to the influence of ecosystem disturbances, such as land-use change. Here, we quantified AGB in tropical montane cloud forest (TMCF) in southern Mexico and analyzed its distribution patterns at local and regional scales. Specifically, we investigated how land use and environmental factors (that is, topography and climate) influence AGB spatial patterns and the relationship between forest structure, AGB, and tree species diversity across forests with different levels of disturbance, using 160 plots from the Mexican National Forest Inventory (FI) database. Our results show that AGB (averaging 137 Mg ha(-1)) is strongly influenced by variations in forest structure such as stand basal area and the density of large trees, with a weak but positive relation with tree species diversity. AGB increased with elevation and slope and decreased with very high levels of precipitation and land-use intensity, suggesting that spatial variation in AGB across the region can be best predicted by the interactive effects of land use and environmental factors, with land use having a larger role. Our results challenge general assumptions about the structural and compositional properties of montane forest ecosystems and emphasize the need to explicitly include interactions between environmental and human drivers when analyzing changes in AGB and devising sustainable management plans.