牦牛和藏羊夏季划区轮牧对高寒草甸3种植物凋落物分解的影响

Effects of Summer Rotational Grazing of Yak and Tibetan Sheep on Decomposition of 3 Kinds of Plant Litter on Alpine Meadow

为深入理解放牧牦牛和藏羊及放牧强度对青藏高原高寒草地凋落物分解的分异影响,在天祝高寒草甸夏季牧场,采用凋落物袋法研究了牦牛和藏羊轮牧强度对垂穗披碱草(Elymus nutans)、矮生嵩草(Kobresia humilis)和珠芽蓼(Polygonum viviparum)凋落物损失率及碳(C)、氮(N)和磷(P)含量的影响。结果表明:3种植物凋落物损失率随处理时间的增加和放牧强度的增大均呈增大趋势。处理15个月后,垂穗披碱草、矮生嵩草和珠芽蓼凋落物损失率分别为24.71%~32.70%,30.56%~38.83%和32.27%~42.96%。放牧藏羊草地上的3种凋落物损失率小于牦牛放牧草地。在同一放牧家畜及放牧强度下,垂穗披碱草的损失率显著小于矮生嵩草和珠芽蓼。3种植物凋落物C含量随着放牧强度的增加依次呈降低趋势,C含量大小依次为:垂穗披碱草>矮生嵩草>珠芽蓼,但C含量的变化大小依次为:垂穗披碱草<矮生嵩草<珠芽蓼。3种植物凋落物N含量随放牧强度增加呈现降低趋势;随着时间的增加凋落物N呈现先降低再增加后又降低的趋势。随着放牧强度的增加,珠芽蓼凋落物的P含量总体呈降低趋势;随着放牧时间的增加,珠芽蓼凋落物P含量总体呈增加趋势。藏羊和牦牛对P含量的富集均有抑制作用,并且牦牛的抑制作用大于藏羊。

In order to understand the effect of grazing intensity of domestic animal species yak and Tibetan sheep on the decomposition of litter in the alpine grassland of Qinghai Tibet Plateau,the loss rate and carbon,nitrogen and phosphorus content of Elymus nutans,Kobresia humilis and Polygonum viviparumlitter were measured using the litter bag method in the summer of Tianzhu alpine meadow.The results showed that the loss rate of 3 kinds of litters increased with the increase of treatment time and the grazing intensity.After 15 months of treatment,loss rate of E.nutans,K.humilis and P.viviparum litter ranged from 24.71% to 32.70%,30.56% to 38.83%,and 32.27% to 42.96%,respectively.The loss rate of litters from Tibetan sheep grazing was less than that from yak.Under the same grazing livestock and grazing intensity,E.nutans loss rate was significantly lower than K.humilis and P.viviparum.Meanwhile,the carbon content of the 3 kinds of litters decreased with grazing intensity increasing.The carbon content of E.nutans litter was higher than that of K.humilis and P.viviparum,and the decreasing order of carbon content was P.viviparum,K.Humilis and E.nutans.N content of three kinds of litters showed a decrease trend with the increase of grazing intensity,while showed decreased firstly,andincreased,then decreased with the grazing time increasing.With the increase of grazing intensity,the phosphorus content of P.viviparumlitter showed a decreasing trend;but with the grazing time increasing,phosphorus content of P.viviparumlitter generally showed an increasing trend.Tibetan sheep and yak had inhibitory effect on the concentration of phosphorus,but the effect of yak was greater than Tibetan sheep.