放牧利用对金露梅灌丛土壤理化性质的影响

金露梅(Dasiphora fruticosa)灌丛是东祁连山广泛分布的一种放牧地,长期的过度利用下,使其土壤理化性质发生了相应的变化。随利用强度增加,土壤含水量不断减少,而土壤容重随之增加,在畜圈型样地容重为0.89 g/cm3,比轻牧型样地增加0.9 g/cm3;有机质、速效氮和水溶性全盐量呈单峰形变化,其中速效氮的峰值出现在重牧型样地,为0.049 7 %,有机质和水溶性全盐量的峰值出现在中牧型样地,分别为16.38 % 和0.24 %。土壤速效氮、土壤容重对放牧的响应敏感,可以定量反映草原利用演替状况。

Effects of different grazing levels on physical and chemical characteristics of soil under Dasiphora fruticosa shrubland

Dasiphora fruticosa shrub-land is very common grazing land in Tibet plateau. After overgrazing , its soil physical and chemical characteristics would be out of balance. The results showed that soil capacity in site of sheep pen was 0.89 g/cm3, and 0.9 g/cm3 bigger than the site of CK. The peak value of readily available nitrogen, 0.049 7 %, occurred in the site of over-used, and the peak values of organic matter content and total content of soluble salt, 16.38 % and 0.24 % respectively, occurred in the site of middle-used. In conclusion, both readily available nitrogen and soil bulk density are sensitive to grazing levels, and can be used in quantitative determination of grassland succession under utilization.