In the modern era, rapid anthropogenic activities in the vicinity of the Himalayas disturb the carbon sequestration potential resulting in climate change. For the first time, this study estimates the biomass and carbon storage potential of Northeast India’s diverse land uses through a biomass estimation model developed for this region. The mean tree density in tropical, subtropical, and temperate forests was 539, 554, and 638 trees ha−1, respectively. The mean vegetation carbon stock was the highest for temperate forests (122.09 Mg C ha−1), followed by subtropical plantations (115.45 Mg C ha−1), subtropical forests (106.01 Mg C ha−1), tropical forests (105.33 Mg C ha−1), tropical plantations (93.00 Mg C ha−1), and temperate plantations (50.10 Mg C ha−1). Among the forests, the mean soil organic carbon (SOC) stock up to 45 cm depth was the highest for tropical forests (72.54 Mg C ha−1), followed by temperate forests (63.4 Mg C ha−1) and subtropical forests (42.58 Mg C ha−1). A strong relationship between the tree basal area and biomass carbon storage was found for all land-use types. The land-use transformation from agriculture to agroforestry, and grassland to plantations increased both vegetation carbon (VC) and SOC stocks. The corresponding increase in VC and SOC was 40.80 and 43.34 Mg C ha−1, respectively, in the former, and 83.18 and 97.64 Mg C ha−1 in the latter. In general, the landscape-level estimates were drawn from site-level estimates in a given land-use type, and therefore, the corresponding values might be overestimated. Nevertheless, the results provide baseline information on carbon stock which may serve as a reference for devising appropriate land-use change policies in the region.

Abstract Aims Biodiversity is found to have a significant promotion effect on ecosystem functions in manipulation experiments on grassland communities. However, its relative role compared with stand factors or functional identity is still controversial in natural forests. Here we examined their relative effects on biomass and productivity during forest restoration. Methods We investigated stand biomass and productivity for 24 plots (600 m 2) across restoration stages in the subtropical forests of Mt. Shennongjia, central China. We measured five key functional traits and calculated functional diversity (functional richness, evenness, and dispersion) and community-weighted mean (CWM) of traits. We used general linear models (GLMs), variation partitioning methods to test the relative importance of stand factors (density, stand age, maximum height, etc.), functional identity, species and functional diversity on biomass and productivity. Important Findings Our results illustrated that stand biomass and productivity increased significantly as forest restoration, and that community species richness increased significantly, while functional dispersion decreased significantly. Variation partitioning analyses showed that diversity had no significant pure effects on biomass and productivity. However, diversity can affect biomass and productivity through the joint effect with stand factors and functional identity. Overall, we found that stand factors had the strongest effect on biomass and productivity, while functional identity significantly affects productivity but not biomass, suggesting that modulating stand structure and species identity are effective ways to enhance forest carbon storage and sequestrations potential in forest management.