Unravelling patterns of forest carbon stock along a wide elevational gradient in the Himalaya: Implications for climate change mitigation

In an era of climate change, quantifying forest biomass and carbon stock along elevational gradients in mountainous areas assumes immediate relevance for carbon budgeting and forest management. Here, we carried out extensive field studies to quantify the tree biomass and carbon stock of major forest types along a wide elevational gradient (350-3450 m) in Jammu and Kashmir, a region located in the northwestern Himalaya. We adopted a stratified random cluster sampling approach to generate ground-based data on structural variables (diameter at breast height-DBH, stem height, basal area, stem density, species richness), and quantified biomass and carbon stock volume using allometric equations in 12 major forest types in the region. We found a significant difference in all the tree structural variables among the forest types. Our results show a significantly positive correlation between DBH and height, but a significantly negative correlation of stem density with DBH and height. We observed a higher basal area in the forest types between 1750 and 3350 m elevation, with the highest value (104.4 +/- 29.0) found in Fir forest. We also found higher stem density values at mid- and high-elevations in comparison to low-elevation, but the trend was inconsistent. To evaluate the influence of elevation on the structural attributes, we fitted a Linear Regression Model (LM) for each variable, followed by F-test. We observed a significant effect (p < 0.008) of elevation on all the forest tree structural variables, species richness, biomass and carbon stock. All these variables, except species richness, showed a positive relationship with elevation. We found the highest aboveground-, belowground-, total biomass, and carbon stock in the forest types at high elevation above 1750 m. The most significant tree species in terms of biomass and carbon stock contribution was Abies pindrow, followed by Cedrus deodara and Pinus roxburghii, thus making them suitable tree species for forest conservation and restoration in this Himalayan region. Principal component analysis of anthropogenic disturbances revealed the fire mostly associated with the forest types dominated by P. roxburghii, stem cutting with those dominated by C. deodara, P. wallichiana and A. pindrow, and grazing with the high-elevation forest types. Overall, our study unravels the patterns of forest carbon stock along a wide elevational gradient in this Himalayan region, with immediate implications for climate change mitigation policy and practice in mountainous landscapes.

Automated summary

In an era of climate change, quantifying forest biomass and carbon stock along elevational gradients in mountainous areas is crucial for carbon budgeting and forest management. This study conducted extensive field studies in Jammu and Kashmir, northwest Himalaya, to quantify the biomass and carbon stock of major forest types across a wide elevational gradient. The findings show significant differences in tree structural variables among the forest types, and elevation has a significant effect on forest tree structural variables, species richness, biomass, and carbon stock.