放牧对高寒草甸优势植物和土壤氮磷含量的影响

Effects of Grazing Intensity on N and P Content in Dominant Plants and Soil in the Northeast Regions of Qinghai-Tibetan Plateau

对不同放牧强度下青藏高原东北缘高寒草甸优势植物和土壤N、P含量及其计量比进行研究,结果表明：放牧增加了珠芽蓼叶片N含量,中度放牧时最大,降低了线叶嵩草叶片N含量.珠芽蓼和线叶嵩草叶片P含量随着放牧强度增加表现为先增加后降低,峰值分别出现在中度放牧和轻度放牧条件下.放牧增加珠芽蓼的N∶P计量比,降低了线叶嵩草的N：P计量比.放牧对土壤N含量的影响主要在0～10cm土层,表现为中度放牧最小,重度放牧最大,对20cm以下土层N含量没有明显影响;土壤P含量随放牧强度增强均表现为先减小后增大,中度放牧时最大;土壤N∶P计量比在0～20cm层变化不大,20～30cm层略有变化.

An experiment was carried out to determine the effect of grazing intensity on N and P content in dominant plants and soil of summer grassland in the northeast regions of Qinghai-Tibetan plateau.The results showed that the grazing increased the nitrogen content in leaves of Polygonum viviparum,the nitrogen content was the highest under moderately grazing intensity,and the nitrogen content in leaves of Kobresia capillifolia decreased.The phosphorus content in leaves of Polygonum viviparum and Kobresia capillifolia firstly increased and then decreased as the grazing intensity increased,the phosphorus content was the highest under moderately and slightly grazing intensities,respectively.The grazing increased the N ∶ P value of Polygonum viviparum and decreased the N ∶ P value of Kobresia capillifolia,indicating that the different plants had the different use strategy for nitrogen and phosphorus.Grazing affected the soil N content in soil of 0～10cm,and the soil N content was the lowest under moderately grazing intensity and was the highest at highly grazing intensity; however the grazing did not affect the soil N content when the soil depth was below 20cm.The soil P content firstly decreased and then increased with the increase of grazing intensity,the soil P content was the highest under moderately grazing intensity.The soil N ∶ Pvalue did not varied greatly in the soil of 0 to 20 cm,and slightly varied in 20～30cm layer.