Land-use-induced variability in soil profile carbon and carbon-associated nutrient pools in the Eastern Himalayan region

Context The Eastern Himalayan region exhibits strongly acid soils due to pedogenesis and topographical matrices under a sustained high precipitation regime. Prevalence of diverse and spatially varied land-use systems is a fundamental characteristic across these montane ecosystems and plays a key role in its impact on different soil nutrient pools. Aim The study was conducted to elucidate the impact of varied land use systems on nutrient mineralisation dynamics, including carbon (C) and its associated pools. Methods Throughout 14 selected land use systems, a random stratified sampling method was utilised with 56 quadrats that were exposed layer-wise down to a soil depth of 1.0 m. Result The analytical results indicated that the land use systems had a significant impact on soil pH. Likewise, total organic C (TOC) content showed significant variation (P < 0.01) across land uses (0.40–4.61%) and down the soil profile. Irrespective of land use type, the soil profile to a depth of 0.60 m had high TOC concentration (2.35–6.01%) and C-mediated microbial biomass nutrients (26.7–688.1 μg g−1). The bacterial and fungal populations were concentrated at the top 0.6 m, but suddenly decreased beyond that depth. Conclusion The association and clustering pattern of soil properties and different land use types, identified through principal component analysis, suggested that forest areas and oak, alder, and apple plantations favoured increases in microbial biomass, enzyme activities, and viable bacterial populations. Implications The choice of land use systems strongly controls vertical carbon distribution and microbial functioning in acidic Eastern Himalayan Region soils offering greater potential for long-term soil fertility and ecosystem sustainability.