Leaf Litter Decomposition Along an Elevation Gradient Across Two Contrasting Forest Types: Implications for Future Climate Change

Understanding elevational changes in ecosystem processes is important for predicting ecosystem responses to global warming. Plant litter decomposition is expected to increase with increasing temperature as elevation decreases. However, how decomposition varies along elevation gradients within and across forests dominated by different species remains unclear. We investigated in situ and downward‐transplanted leaf litter decomposition of two dominant species, deciduous broad‐leaved beech ( Fagus crenata ) dominating at lower elevations and evergreen coniferous Maries fir ( Abies mariesii ) dominating at higher elevations, in a montane range. For the downward‐transplanted treatment, litter from the highest elevation of each species' distribution was decomposed at lower elevations. Elevational changes in soil properties and litter traits of the two species were measured alongside. Within each species' range, the in situ decomposition generally increased with decreasing elevation, and the slopes of these relationships were not altered by the species‐specific elevational changes in litter traits. In contrast, the decomposition of A. mariesii litter was more temperature‐sensitive than that of F. crenata . Across forest types, A. mariesii at higher elevations had a greater in situ decomposition rate than F. crenata , possibly due to its lower lignin content compared to F. crenata . When the transplanted litter of A. mariesii was decomposed in F. crenata ‐dominated forests, its decomposition rate dropped to a level similar to F. crenata despite warmer conditions and its lower lignin. This study underscores the significance of considering plant traits and plant–soil interactions in predicting the responses of carbon and nutrient cycles in forest ecosystems to future climate change.