Changes in foliar litter decomposition of woody plants with elevation across an alpine forest-tundra ecotone in eastern Tibet Plateau

To determine litter decomposition rates at different elevations in the alpine forest-tundra ecotone under climate change scenarios in which woody plants shift their ranges upward, litterbags containing foliar litter were incubated on the surface of forest, tree line, and alpine meadow soils (3900, 4000, and 4200 m above sea level, respectively) in the eastern Tibet Plateau of China in October 2012. The selected woody plant species were Abies faxoniana, Betula albosinensis, Sorbus rufopilosa, Rhododendron taliense, Lonicera lanceolata, and L. myrtillus. Mass loss, carbon (C), nitrogen (N), and phosphorus (P) release, and cellulose and lignin degradation in litter were examined from retrieved litterbags over a 6 month period at the end of one snow-covered season. The results showed that the mass loss of A. faxoniana, L. lanceolata, and S. rufopilosa litter, but not that of the other species, was accelerated at higher elevations. Abies faxoniana, B. albosinensis, and S. rufopilosa C release, A. faxoniana and S. rufopilosa N release, L. myrtillus, L. lanceolata, and S. rufopilosa P release, B. albosinensis, S. rufopilosa, and R. taliense cellulose degradation, and L. myrtillus lignin degradation significantly increased with increasing elevation. These results imply that changes in foliar litter decomposition with elevation, although species-specific, could indicate a possible shift in woody plant composition in the alpine forest-tundra ecotone under climate change scenarios. Thus, further studies regarding how elevation shifts could alter litter decomposition and ecosystem sustainability are warranted.