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Soil organic carbon (SOC) is the largest active terrestrial carbon reservoir, which behaves both as a sink and source for atmospheric carbon. The same is maximum in the forest soil ofAbies pindrow(128 t ha−1) and minimum inPinus roxburghii(69 t ha−1). The mitigation potential is also found to be maximum in Alpine forest soil (i.e., 1.84) inAbies pindrowand minimum in the chir (i.e., 1.00) inP. Roxburghii. This indicates that alpine forest soil can hold nearly two times more SOC than chir and hence it behaves as a CO2sink. The overall average content of SOC and carbon dioxide equivalent under all land use was estimated at 91.29 t ha−1and 334.11 t ha−1, respectively. The objective of this study is to estimate the spatial variability of SOC stocks in the catchment of both the Tehri and Koteshwar hydroelectric reservoir using field investigations, laboratory measurements, and geostatistical methods. The study provides an estimation for the amount of carbon reaching to the reservoir through various sources, where it undergoes aerobic and anaerobic degradation, thereby releasing green house gases (GHGs) to the atmosphere. The information provided in this article will be useful for policy-makers and environmentalists for undertaking appropriate conservation plans to mitigate GHGs. [ABSTRACT FROM AUTHOR]

• The soil stoichiometric ratios (C:N:P) were invariant in lower Himalaya. • The studied region has low C:N ratio indicating prospect for N 2 O emission. • Abies species have a higher C sequestration potential and carbon credit. • The findings are helpful to understand nutrient dynamics in forest. Understating of forest functioning is crucial for ensuring the sustainable flow of forest ecosystem services. Climate regulation service of a forest ecosystem can be ensured through emission reduction by increasing carbon sequestration in forests. However, understanding about the functioning of forests for carbon sequestration is constrained due to lack of information on nutrient stocks and stoichiometry of soils of forests of India. Present study focuses to examine the stoichiometry of major nutrients; nitrogen (N), phosphorus (P), carbon (C) of forest soil to understand the dynamics of the forests of Uttarakhand, India. The study also attempted to supplement the information about the soil carbon sequestration potential of important tree species of the forest. Soil samples were collected randomly for the evaluation of physico-chemical characteristics and stoichiometry of forest soil at four altitudinal ranges i.e., <1000, 1000–1500, 1500–2000, and >2000 m a.s.l in the Himalayan region of Uttarakhand, India. The analysis shows that total nitrogen, total phosphorous, and soil organic carbon contents in forest soil were 0.35 ± 0.11%, 0.10 ± 0.04% and 3.36 ± 0.84%, respectively, which increases with altitude. The stoichiometric ratios viz., C:N:P, N:P, C:N, and C:P, and N:P were reported of 51.6:5.4:1, 4.30 ± 2.39, 9.60 ± 1.48, and 41.94 ± 23.35, respectively which were invariant with altitude. The low C:N ratio may be attributed to either increase in the nitrous oxide (N 2 O) emissions with an increase in nitrogen, or low in carbon stock leading to decrease in carbon dioxide (CO 2) and methane (CH 4) emissions. Moreover, the soil C sequestration potential in the forest tree species follow the order of Abies pindrow > Cedrus deodara > Quercus leucotrichophora > Pinus roxburghii. The information of the study would facilitate for broadening the understanding about the soil properties and stoichiometry of forest ecosystem and would provide an aid to forest management besides contributing to the mitigations strategies of the forests. [ABSTRACT FROM AUTHOR]