Abstract: To explore the divergent responses of nutrient dynamics of plants with different functional groups and plant community to grazing and fencing， a randomized block experiment was set up in a desert steppe with different grassland measures （fencing， light grazing， and moderate grazing） in Inner Mongolia， China. We determined the concentrations of nitrogen （N） and phosphorus （P） in aboveground parts of plants within different functional groups （Stipa breviflora，Cleistogenes songorica，Artemisia frigida and Convolvulus ammannii） during the growing season. The results showed that grassland management measures， plant functional groups， and their interactions significantly affected nutrient concentrations， nutrient utilization efficiency， and nutrient resorption efficiency of N and P. At the beginning of growing season， N and P concentrations among S. breviflora， C. songorica， C. ammannii， andA. frigida were not significantly different between grazing and fencing， but at the peak of growing season and at the end of growing season， they were significantly higher in the moderate grazing than those in the fencing. N and P utilization efficiencies for all four species were significantly higher in fenced grasslands than those in grazed grasslands， with N use efficiency of S. breviflora and C. songorica reaching 58.1% and 55.3%， respectively. Moderate grazing significantly reduced N and P resorption efficiencies in S. breviflora but increased in C. songorica. Community aboveground N and P pools in the fenced grasslands were 4.15 and 4.83 times higher than those in moderate grazing grasslands. This study demonstrated that compared with grazing， fencing increased nutrient utilization efficiency by reducing plant nutrient concentrations and increased the community aboveground nutrient pools by increasing aboveground biomass. This study deepens the understanding of nutrient cycling in desert grassland ecosystems and provides data support for scientific management of desert grasslands.

Key words: Nutrient resorption, Nutrient utilization, Community nutrient, Grazing, Fencing

摘要： 为了解荒漠草原不同功能群植物和群落养分对放牧和围封的差异性响应，在内蒙古施加不同草地管理措施（围封、轻度放牧和中度放牧）的荒漠草原设置随机区组实验。生长季中对不同功能群植物[短花针茅（Stipa breviflora）、无芒隐子草（Cleistogenes songorica）、冷蒿（Artemisia frigida）和银灰旋花（Convolvulus ammannii）]地上部分氮（N）和磷（P）浓度测定后发现：草地管理措施和植物功能群及其交互作用对植物N和P浓度、养分利用效率和重吸收效率具有显著影响。在生长季初期，短花针茅、无芒隐子草、冷蒿和银灰旋花之间的N和P浓度在放牧和围封间无显著差异，但在生长季旺季和生长季结束后表现为中度放牧显著高于围封。4种植物在围封下N和P利用效率显著高于中度放牧下的，其中短花针茅和无芒隐子草的N利用效率达到58.1%和55.3%。中度放牧显著降低短花针茅N和P重吸收效率，提高无芒隐子草的N和P重吸收效率。围封处理下群落地上N和P库是中度放牧下的4.15倍和4.83倍。本研究表明围封通过降低植物养分浓度，提高养分利用效率并促进地上生物量的累积，增加群落地上养分库。本研究加深对荒漠草原生态系统养分循环的理解，为荒漠草原的科学管理提供数据支持。

关键词: 养分重吸收, 养分利用, 群落养分, 放牧, 围封