Elevation-driven climatic variation shapes detrital pathways and nutrient dynamics in forests of Eastern Himalaya:...

Litter production and decomposition are fundamental biogeochemical processes regulating soil fertility in forests. This study examined the detrital pathway-litter production, decomposition, and nutrient release across tropical (TRF), subtropical (STRF), and temperate (TMF) forests in Mizoram, northeastern India, to evaluate the influence of elevation-mediated climatic variation. Total annual litter production differed significantly among sites (p < 0.001), with STRF showing the highest input (6169 kg ha⁻¹), followed by TRF (3576.7 kg ha⁻¹) and TMF (2301.5 kg ha⁻¹). Leaf litter accounted for 71.6-74.5% of total litterfall and 60-75% of total annual nutrient return across forests. Litter decomposition followed a negative exponential decay model, with the fastest (1.81 yr⁻¹) annual decay constant (k) in TRF and slowest (0.67 yr⁻¹) in TMF. After 360 days of litter incubation, cumulative mass loss was 83.7%, 66.7%, and 48.9% in TRF, STRF, and TMF, respectively. Mass loss exhibited a significant positive correlation with total monthly rainfall (r = 0.75, p < 0.01) and mean monthly temperature (r = 0.60, p < 0.05) in TMF, indicating that climate imposes significant constraints on microbial activity at higher elevations. Nutrient release followed the general order K > C ≈ N > P. Principal component analysis confirmed that elevation-driven climatic gradients structure detrital pathways, suggesting that rising temperatures are likely to disproportionately destabilise temperate forest nutrient economies by eroding their retention-based resilience. These results highlight the sensitivity of litter-driven nutrient cycling to elevation-mediated climatic variation, providing a baseline for predicting forest responses to climatic change.