不同季节适度放牧对高寒草甸植物群落特征的影响

于2007~2011年对青藏高原高寒矮嵩草草甸在不同季节适度(牧草利用率35%~60%)放牧处理(不放牧、夏季放牧和冬季放牧)下的植物群落组成和物种多样性进行观测研究,结果表明:(1)经过长期的不同季节的适度放牧处理后,夏季放牧与冬季放牧均降低了禾本科植物功能群的比例,提高了杂草类植物功能群的比例。(2)与未放牧(对照)相比,夏季放牧处理下莎草科植物矮嵩草和杂类草蒙古蒲公英、鹅绒委陵菜的相对生物量分别增加了151.38%和318.87%、344.15%,禾本科植物异针茅相对生物量降低了41.16%;冬季放牧鹅绒委陵菜相对生物量增加了124.08%,禾本科植物草地早熟禾减少了45.99%,但夏季放牧和冬季放牧对二柱头藨草、紫羊茅、垂穗披碱草、花苜蓿和高山唐松草等植物的影响均不显著。(3)总体上不同季节适度放牧对植物群落物种丰富度、多样性指数以及均匀度指数的影响均不显著,但对这三者的影响随年份变化而变化。

Effects of Seasonal Moderate Grazing on Plant Community of Alpine Meadow

The effects of different seasonal grazing (i.e.summer grazing or winter grazing) on plant composition and diversity in Kobresia humilis alpine meadow were investigated from 2007 to 2011 on the Tibetan plateau using the quadrat method.This study shows that:(1) After long-term different seasonal grazing,the proportion of gramineous functional group reduced and the proportion of the forb functional group increased under both summer grazing and winter grazing;(2)Grazing in different seasons had significant influence on the proportion of different species in the plant community.Compared with no grazing,summer grazing increased the proportion of K.humilis,Taraxacum mongolicum and Potentilla anserina in the community 151.38%,318.87% and 344.15%,respectively,but decreased the proportion of Stipa aliena 41.16%;winter grazing increased the proportion of P.anserina 124.08%,but decreased the proportion of Poa pratensis 45.99%.However,they had no significant influence on the proportion of,Scirpus distigmaticus,Festuca rubra,Elymus nutans,Trigonella ruthenica and Thalictrum alpinum.(3)Generally,the influences of grazing in different seasons on the species richness,diversity index and evenness index of plant communities were not significant but varied with the year.