不同放牧强度下祁连山东段草地生态系统氮磷计量特征

摘要

The study on stoichiometric characteristic and balance of nitrogen and phosphorus were conducted in east of Qilian mountain on the Qinghai-Tibet plateau to explore technology on the livestock management and evaluation of alpine grassland health.The grazing intensity was set according to watering place distance,ie,the relatively heavy grazing intensity (300 meters),moderate grazing intensity (1000 meters) and light grazing intensity(2000 meters).The result showed that:it was significantly lower for the species diversity and grassland biomassinheavy grazing than light grazing and moderate grazing (P＜ 0.05).The total soil phosphorus content for heavy grazing was greater than the light grazing and moderate grazing in the soil layer of 0～10 cm and 10～20 cm (P＜0.05),but moderate grazing was greater than light grazing and heavy grazing in the soil layer of 20～30 cm (P＜0.01);the total soil nitrogen content for heavy grazing was greater than the other two in the soil layer of 0～10 cm and 10～20 cm (P＜0.01),moderate grazing was greater than others in the soil layer of 20～30 cm (P=0.016).With the increase of grazing intensity,the total grass phosphorus decreased linearly (P＜0.001) and the N/P increased linearly (P＜0.001),but the total grass nitrogen was not in response to grazing intensity (P＞0.05).In addition,the retention of nitrogen in lactation yak is 27.95g/d,but the phosphorus is-1.95 g/d.In a word,it plays an important role to maintaining the grassland sustainable utilization and livestock health growth by reasonable grazing and maintaining the soil nitrogen and phosphorus balance.%通过研究青藏高原祁连山东段高寒草甸牧区土草畜氮磷特征,以及高寒草甸放牧区家畜氮磷平衡现状,以期为高寒草地健康评价及家畜管理提供理论及技术支持.依饮水点为中心,由近及远设置3个相对放牧强度,研究地上植物群落特征、牧草及土壤营养成分及家畜氮磷平衡.结果表明:物种多样性和草地生物量轻牧和中牧强度均显著高于重牧强度(P＜0.05);土壤全磷含量在0～10 cm和10～20 cm土层中重牧强度显著高于轻牧强度和中牧强度(P＜0.05),而在20～30 cm土层中中牧强度下显著高于轻牧强度和重牧强度(P＜0.01);土壤全氮含量0～10 cm土层中重牧强度显著高于轻牧强度和中牧强度(P＜0.01),10～20cm土层中中牧强度显著高于轻牧强度(P=0.016),20～30 cm土层中不同放牧强度下氮含量无显著性差异(P＞0.05);随着放牧强度的增加,牧草全磷含量线性下降(P＜0.001),N/P线性增加(P＜0.001),而全氮含量对放牧强度的响应不显著(P＞0.05);此外,高寒草甸泌乳牦牛体内氮沉积量为27.95 g/d,呈正平衡,磷沉积量为-1.95 g/d,呈负平衡.综上,合理放牧,维持高寒草甸土草畜氮磷流的平衡,对于家畜的健康生长以及草地的可持续利用具有重要作用.