Quantifying Carbon Stock Variability and Aspect-Slope Impact in Sal and Pine-Dominated Forests of Nepal

Forests play a crucial role in mitigating climate change by storing carbon dioxide. However, different tree species and forest types have varying carbon stock potentials. Therefore, this study delved into a comparative analysis of two contrasting forest types: Sal (Shorea robusta) dominated and pine (Pinus roxburghi) dominated forests to understand their unique contributions to carbon storage. We also aimed to evaluate the carbon stocks of these forest types across environmental variations, including factors like slope and aspect. We employed a systematic random sampling approach with a 1% sampling intensity. Specifically, we established a total of 64 sample plots, with 27 in Sal-dominated forests and 37 in pine-dominated forests, each covering an area of 250 m2. We measured trees and saplings in these plots using dendrometric methods and collected leaf litter samples and herbaceous vegetation. Sal-dominated forest (158.56 ± 15.23 ton ha−1) exhibited significantly higher carbon stocks than pine-dominated forest (77.38 ± 6.44 ton ha−1). Only aboveground sapling carbon showed a significant difference in Pine-dominated forests, with ‘moderate’ slopes (p < 0.05). However, no significant differences were found in carbon pools in Sal-dominated forests across the different slope categories. Similarly, in the pine-dominated forest, the north aspect had significantly higher (p < 0.05) aboveground tree carbon (40.11 ± 5.38 ton ha−1), belowground tree carbon (8.02 ± 1.08 ton ha−1) and deadwood carbon (5.29 ± 0.71 ton ha−1) than south aspect. Aspect-wise, the Sal-dominated forest did not yield significant differences in the carbon pools. These findings highlight the complex interplay between forest type, environmental gradients, and carbon dynamics. While slope and aspect variations had a notable impact on certain carbon pools within pine-dominated forests, Sal-dominated forests exhibited more consistent carbon stocks across these gradients. Given the critical role of soil carbon dynamics, including them in future research is imperative. Additionally, investigations into the impacts of diverse forest management practices on carbon stocks within pine-dominated and Sal-dominated forests are essential for a comprehensive understanding of guiding strategies that optimize carbon sequestration and ecosystem well-being.