Warming effects on the early decomposition of three litter types, Eastern Tibetan Plateau, China

Temperature and litter quality are two of the key factors controlling litter decomposition. Predicted global warming and vegetation succession will therefore have profound impacts. This study was conducted to assess effects of experimental warming on litter decomposition and nutrient dynamics of two contrasting tree species (red birch, Betula albosinensis Burk., and dragon spruce, Picea asperata Mast.) and a mixture of the two with the heating cable method in the eastern Tibetan Plateau of China. This treatment raised surface soil temperature by 3.2 degrees C and resulted in a 5.2% decline in soil moisture 10 cm below the soil surface. The water content of dragon spruce, red birch and mixed litter was decreased by 18, 11 and 13%, respectively. Marked differences between the two species in the decomposition rates and nutrient remaining percentages were detected. Moreover, we found positive, non-additive effects of litter mixture. Experimental warming did not affect mass loss and nutrient release of dragon spruce litter but significantly increased mass loss and affected nutrient release of red birch and mixed litter during the early decomposition period. Overall, inter-specific (red birch and dragon spruce) differences in decomposability were substantially larger than warming-induced responses. Thus, a warming-induced community succession towards dragon spruce forests in the Tibetan Plateau region could have a greater impact on early litter decomposition than warming itself