Abstract: To explore the relative contribution of rangeland management types, soil nutrient availability, climatic conditions, and plant community structure on the nutritional quality of different plant species and functional groups, plant and soils were sampled at four pairs of fenced versus grazed sites, which were chosen from natural alpine steppe and alpine desert communities across Changtang, Northern Tibetan Plateau, in the summer of 2020. Our results indicate that:(1) The crude protein content of forage species was significantly higher than that in desert steppes, whereas the ether extract content of forage species in alpine steppes was significantly lower than that in desert steppes;Livestock grazing significantly enhanced the crude protein content of forage species in alpine steppes whereas of forage species in alpine steppes was significantly lqler than that in desert steppes, compared to those in fenced steppes, but has no effects on other nutritional quality indicators. (2) The ether extract content of forage species decreases with the increase of the sum precipitation during the plant growing season, whereas content of neutral detergent fiber increases with increasing mean temperature during the plant growing season. (3) The contents of acid detergent fiber and cellulose of forage species significantly increase with the increase of soil organic carbon, whereas the content of ether extract decrease with the increase of soil organic carbon. In summary, the nutritional quality indicators of common forage species in alpine rangelands in Changtang are jointly regulated by climatic variables, soil nutrient levels, and rangeland management type. Therefore, it is recommended to improve the nutritional quality of common forage species through optimizing livestock and rangeland management and regulating soil nutrient availability in Northern Tibetan Plateau.

Key words: Rangeland management, Forage nutritional quality, Climate gradient, Soil nutrients, Plant diversity, Plant functional group

摘要： 为探究草地管理方式、土壤养分、气候条件、群落结构对不同功能群植物营养品质的相对影响，2020年夏在藏北羌塘地区的高寒草原与荒漠草原选取样地进行植物和土壤采样。结果表明：(1)高寒草原区牧草粗蛋白含量显著高于荒漠草原区，而粗脂肪含量显著低于荒漠草原区(P<0.05)；放牧管理显著提高了高寒草原区牧草的粗蛋白含量(P<0.05)；(2)高寒牧草的粗脂肪含量随生长季降雨增加而降低(P<0.01)；中性洗涤纤维含量随生长季温度升高而增加(P<0.05)；(3)牧草的粗脂肪含量随土壤有机碳含量的增加而降低(P<0.05)，酸性洗涤纤维和纤维素含量随土壤有机碳含量的增加而增加(P<0.05)。综上所述，藏北高寒草地常见牧草营养品质主要受气候条件、土壤养分和草地管理方式的多重调控。因此，建议未来通过优化草地管理、调控土壤养分有效性来改善藏北天然高寒草地常见牧草的营养品质。

关键词: 草地管理, 牧草品质, 气候梯度, 土壤养分, 植物多样性, 植物功能群