关键词: 高寒草甸, 黄帚橐吾生物量, 凋落物重量损失, 氮释放, 分解混合效应

Abstract: Ligularia virgaurea, as “indicator species of alpine meadow degradation”, gradually expanded and became a dominant species in alpine meadow due to disturbances (e.g., overgrazing), and threatened ecosystem function and nutrient cycling. However, little is known about how litter decomposition and nitrogen release respond to dominance of L. virgaurea in alpine meadow. Litter decomposition is a key process linking carbon and nitrogen cycle and plays an important role in maintaining ecosystem function. In this study, a litter decomposition experiment with a mixture gradient of L. virgaurea and other species was conducted in a L. virgaurea dominated alpine meadow. The mass loss and nitrogen release of L. virgaurea and other species litter were measured and the effects of L. virgaurea litter on the decomposition of other species litter were determined. The results showed that: (1) Litter decomposition rate of L. virgaureawas lower than that of other species; (2) Total mass loss and nitrogen release of litter decreased with increasing proportion of L. virgaureain litter mixture; (3) Mass loss and nitrogen release of other species litter were inhibited by the presence of L. virgaurea. The antagonistic non-additive effect further decreased the decomposition of litter mixture. Our results suggested that increasing proportion of L. virgaureacould inhibit litter decomposition and nitrogen release, reduce nutrient input to soil, and thus disturb carbon and nitrogen cycling in degraded grasslands.

Key words: alpine meadow, biomass of Ligularia virgaurea, litter mass loss, nitrogen release, litter mixed effect.