Environmental correlates of the forest carbon distribution in the
Central Himalayas
Abstract
In the Central Himalayas, where environmental conditions vary greatly,
understanding the biophysical limitations on forest carbon is crucial
for accurately determining the region’s forest carbon stocks. This study
investigates the role of climate and disturbance on the spatial
variation of two key forest carbon pools: aboveground carbon (AGC) and
soil organic carbon (SOC). Using field-observed plot-level carbon pool
estimates from Nepal’s national forest inventory and structural equation
modeling, we explore the relationship between forest carbon stocks and
proxies of environmental constraints. The forest AGC and SOC models
explained 25 % and 59 % of the observed spatial variation in forest
AGC and SOC, respectively. The climatic availability of water and energy
in broad-scale gradients combined with the fine-scale gradients of
terrain and disturbance intensity were found to influence forest carbon
stocks, but the sign and strength of the statistical relationships
differ for forest AGC and SOC. While AGC showed a negative relationship
to disturbance, SOC was impacted by the availability of climatic energy.
Disturbances such as selective logging and firewood collection result in
immediate forest carbon loss, while soil carbon changes take longer to
respond. The lower decomposition rates in the high-elevation region, due
to lower temperatures, preserve organic matter and contribute to the
high SOC stocks observed there. These results have important
implications for forest carbon management and conservation in the
Central Himalayas.