由于高寒草地退化、鼠害严重、大风频繁等原因,凋落物被频繁掩埋在土壤中.但凋落物的位置变化和氮富集对高寒草原凋落物分解速率和养分动态影响的认识尚不清楚.为了研究凋落物位置变化(地表、掩埋10 cm和悬空60 cm)和氮富集对高寒草原优势植物凋落物分解的影响,本研究依托2009年在新疆天山巴音布鲁克高寒草原设置的长期模拟氮沉降研究平台,以对照和氮富集处理样方的优势植物羊茅(Festuca ovina)和赖草(Leymus tianschanicus)凋落物为试验材料,测定分解过程中凋落物质量损失和碳氮磷含量的变化特征.研究结果表明,掩埋凋落物分解速率显著快于地表凋落物,悬空处理凋落物分解速率慢于地表凋落物.氮富集显著影响凋落物质量,进而影响凋落物分解.而凋落物质量残留在对照与氮富集土壤掩埋之间无显著差异.这些结果表明,氮富集通过凋落物质量而不是通过土壤环境因素,影响短期凋落物分解.不同处理的所有试验凋落物均有碳和磷的释放现象.对照处理的凋落物,凋落物氮以累积为主,而氮富集处理的凋落物,凋落物氮以释放为主.这表明凋落物分解可能受到氮元素限制,氮富集改变了凋落物分解调控的氮循环过程.本研究提供了直接证据,掩埋处理的凋落物有更快的质量损失和碳元素释放,土壤掩埋是旱地凋落物分解速率比模型预测的快的一个候选解释.“,”Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation,serious rodent infestation and frequent strong winds.However,the effects of various litter positions on litter decomposition rates and nutrient dynamics under nitrogen (N) enrichment in such areas remain unknown.Methods A field experiment was performed in the alpine grasslands of northwest China to investigate the influence of litter position (surface,buried in the soil and standing) and N enrichment on litter decomposition,using data from two dominant grass species (Festuca ovina and Leymus tianschanicus) in control and N-enriched plots.Important Findings Litter decomposition rates were much faster in buried litter and slower in standing litter than in surface litter.N enrichment significantly affected litter quality and then influenced decomposition.But no significant differences in litter mass remaining were observed between control and N-enriched soil burial.These results indicated that N enrichment significantly affected litter decomposition by changes in litter quality.In addition,all litter exhibited net carbon (C) and phosphorus (P) release regardless of treatments.Litter exhibited net N accumulation for litter from the control plots but showed N release for litter from N enrichment plots.These suggested that litter decomposition can be limited by N and N enrichment influenced N cycling of litter.Current study presented direct evidence that soil buried litter exhibited faster mass loss and C release,and that soil burial can be a candidate explanation why litter decomposes faster than expected in dryland.