多梯度氮磷添加对高寒草甸植物群落生物量与氮磷含量的影响

为研究不同梯度氮、磷单独及混合添加对高寒草甸植物群落生物量、植物养分含量及化学计量比的影响，本实验分析了青海省门源县典型高寒草甸植物群落地上总生物量，功能群水平地上生物量，植物全氮、全磷含量及氮磷比对多梯度氮、磷添加的响应情况。结果表明：氮、磷添加均对群落地上生物量影响极显著(P<0.001);氮添加对禾草类和豆科生物量影响极显著(P<0.001);磷添加对禾草类和莎草类生物量影响极显著(P<0.001);氮磷交互作用对豆科和莎草类生物量影响显著(P<0.05)。群落水平上，氮添加显著提高了植物全氮含量，对植物氮磷比(N∶P)有正效应，磷添加显著提高了植物全磷含量，对植物N∶P有负效应，植物全磷对N∶P的负效应大于全氮对N∶P的正效应。本研究表明氮、磷添加可能会使高寒草甸植物群落组成和植物养分含量发生改变，植物群落逐渐向禾草类发展；此外，高寒草甸植物生长趋向于受氮磷共同限制。

Effects of Multi-gradient Nitrogen and Phosphorus Additions on Biomass and Nitrogen and Phosphorus Content of Alpine Meadow Plant Community

Under the background of global climate and environmental change, to explore the effects of different gradients of nitrogen and phosphorus additions on plant community biomass, plant nutrient content and stoichiometric ratio of alpine meadow, this paper analyzed the responses of the total aboveground biomass, the aboveground biomass of functional groups, total nitrogen and total phosphorus content, and nitrogen and phosphorus ratio of plants to the multi-gradient nitrogen and phosphorus additions of typical alpine meadow in Menyuan County, Qinghai Province. The results showed that:the additions of nitrogen and phosphorus had a significant effect on the aboveground biomass of the community (P<0.001);the nitrogen addition significant effects on the biomass of grasses and legumes (P<0.001);the phosphorus addition significant effects on the biomass of grasses and sedges (P<0.001);the interaction of nitrogen additions and phosphorus additions significant effects on aboveground biomass of legumes and sedges (P<0.05). At the community level, nitrogen addition significantly increased the total nitrogen (TN) content of the community plants, and had a positive effect on the nitrogen to phosphorus ratio (N:P) of the community plants. Phosphorus addition significantly increased the total phosphorus (TP) content of the community plants, and had a negative effect on plant N:P ratio in community. The negative effect of plant TP on N:P was greater than the positive effect of TN on plant N:P ratio. Our study demostrated that the addition of nitrogen and phosphorus may change the composition and nutrient content of alpine meadow plant community, and the community would gradually develop to grassland;In addition, the growth of alpine meadow plants tends to be restricted by both nitrogen and phosphorus.