Effect Of Different Micro-sites And Soil Fauna On Litter Decomposition In An Alpine Swamp Meadow Of The Tibetan Plateau

Litter decomposition plays a very important role in nutrient cycle and energy flow in ecosystem. Therefore, litter decomposition occupies a pivotal position in maintaining the structure and function of ecological system. Although there have been many studies on the influencing factors of litter decomposition, few studies focus on alpine swamp meadow, especially the effects of micro-sites and soil fauna.This experiment selected the leaf litter of three common species in an alpine swamp meadow of the Tibetan Plateau:Carex alrofusca, Potentilla anserina, Nardostachys chinensis. We have set two different mesh size of litter decomposition bags:big mesh size (4.5 mm) and small mesh size (0.1 mm), and two kinds of micro-sites:mound and pit. Our objects were to examine how litter quality, soil fauna and micro-sites affected litter decomposition during one year.The main research results:(1) the mass loss of litter decompositionLitter mass loss of Nardostachys chinensis was higher than that of Carex alrofusca and Potentilla anserina; Litter mass loss in mound was higher than in pit; Litter mass loss in big mesh size was higher than in small mesh size. Species, mesh size, micro-sites have a significant impact on the litter mass loss rate, and there was a significant interaction among them.(2) N, P nutrients dynamics of litter decompositionSpecies, mesh size, micro-sites have a significant impact on the litter mass loss rate, and there was also a significant interaction among them. Of three litter species, there were different patterns of nitrogen dynamics with release or enrichment. The nitrogen release occurred in Carex alrofusca in all of treatments, was higher in mound than in pit; In Potentilla anserina and Nardostachys chinensis, nitrogen release occurred only in big mesh size and mound treatment, and nitrogen enrichment in the rest of treatments, and no significant difference between the two species.Species, mesh size, micro-sites have a significant impact on the litter mass loss rate, and there was also a significant interaction between litter species and mesh size. After one year decomposition, phosphorus were characterized by release, and the rank was Carex alrofusca>Potentilla anserina>Nardostachys chinensis; The phosphorus released higher in mound than in pit; The phosphorus release was higher in big mesh size than in small mesh size.In all, litter quality, soil fauna and the micro-sites had significant effects on litter mass loss and release of nitrogen and phosphorus in an alpine swamp meadow of the Tibetan Plateau. Our results suggest that litter species composition, the type of soil fauna and the change of micro-sites have influence on litter decomposition and nutrient cycle, and they play a very important role to maintain the structure and function in this ecosystem.