Elevation-Driven Divergence in Forest Litter Decomposition and Stabilization: Disentangling Thermal, Nutrient, and Topographic Controls

Abstract

Litter decomposition in forests governs nutrient turnover and carbon sequestration, but litter decomposition and stabilization may not follow the same trends along an elevation gradient. This needs to be understood to predict forest carbon response to environmental change. This study examined elevation-driven variation in forest litter decomposition and stabilization and identified the relative influence of thermal, nutrient, and topographic controls. A quantitative cross-sectional analysis was conducted using 451 observations from multiple mountain systems. Decomposition rate (K) and stabilization factor (S) were analyzed as response variables using descriptive statistics, elevation-gradient regressions, multiple regression, and mixed-effects models, with mountain included as a random effect. Decomposition rate decreased significantly with elevation, whereas stabilization factor increased, indicating divergent responses along the gradient. Elevation explained 19.8% of the variation in K and 5.2% in S. Mean soil temperature emerged as the strongest predictor, exerting a positive effect on K but a negative effect on S. Soil total phosphorus significantly influenced both processes, while slope affected stabilization only. Limited mountain-level clustering indicated that environmental controls were consistent across sites. These findings demonstrate that decomposition and stabilization are governed by distinct mechanisms and should be evaluated separately to better understand carbon cycling in mountain forest ecosystems under changing environmental conditions.