施氮磷肥对青藏高原高寒草甸土壤线虫群落组成的影响

对典型高寒草甸放牧不施肥(G),放牧施氮肥(GN)(5,10,15 g/m²)和放牧施磷肥(GP)(2,4,8 g/m²)条件下的土壤线虫群落组成进行研究,结果表明,放牧草甸施肥条件下,土壤线虫多样性升高、成熟度指数随施肥梯度升高而降低,但各处理间土壤线虫多样性指数、成熟度指数和数量没有显著差异。放牧施氮肥、放牧施磷肥处理中食真菌和捕食性土壤线虫数量降低,食细菌土壤线虫数量增加,且食细菌土壤线虫在施磷肥处理中增加显著。在少量施氮肥和磷肥时,植食性土壤线虫数量较低,但杂食性土壤线虫数量较高。土壤线虫cp-1和cp-3类群的数量随施肥梯度的升高而增多,其他类群的数量降低。除食细菌土壤线虫外,其他类群土壤线虫与土壤理化性质之间没有显著相关关系。

Effects of nitrogen and phosphorus on the soil nematode community in Tibetan Plateau alpine meadows

Soil nematodes are sensitive to environmental changes and are widely used as indicators of soil condi-tions.Here we monitored temporal dynamics of the soil nematode community using a multi-level N and P addi-tion experiment in the eastern Tibetan Plateau alpine meadow under grazing conditions.The results showed N and P fertilizer applications slightly improved the diversity (H′)and the total number of soil nematodes,but that the maturity index (MI)declined with increases in the fertilizer gradient.The abundance of fungivores and predators decreased whereas bacterivorous nematodes significantly increased after P input.With lower-level ap-plications of N and P fertilizer,the abundance of herbivorous nematodes was low but that of omnivores was high.The abundance of cp-1 (colonizer-persister)and cp-3 group nematodes increased with increases in the fer-tilizer gradient.The largest abundance of cp-1 and cp-3 appeared in treatments with moderate N and P fertilizer applications.We found a significantly positive relationship between bacterivorous nematodes,cp-1 and available phosphorus.The response of soil nematodes to different kinds of fertilizer is probably caused by grazing.