放牧强度对科尔沁沙地沙质草地植被的影响

Effects of Grazing Intensity on Vegetation in Sandy Grassland of Horqin

为了研究科尔沁沙地沙质草地在不同放牧强度下植被特征的变化规律,比较了围封、中度放牧、重度放牧3种条件下的植被盖度、群落组成、物种多样性、地上/地下生物量和凋落物量等植被特征的变化特征。结果表明:(1)围封、中度放牧和重度放牧沙质草地的优势植物均为一年生植物,但围封和中度放牧中多年生禾本科植物优势度高于重度放牧,重度放牧沙质草地一年生植物所占优势度最大;(2)放牧强度对沙质草地植被盖度、地上生物量及凋落物量有显著影响。随着放牧强度的增加,植被盖度、地上生物量和凋落物量均降低;(3)围封、中度放牧和重度放牧沙质草地物种丰富度及多样性差异均不显著;(4)放牧强度和土壤深度及其交互作用均能影响地下生物量。随着放牧强度的增加,总的地下根系生物量减小。而重度放牧草地中,3个土壤深度间地下根系生物量差异不显著。放牧改变了沙质草地植物群落的组成、极大降低了植被盖度和生产力;尤其是重度放牧急剧增加了一年生植物的优势、且对浅层根分布的减少影响最大。

To study the variation of vegetation characteristics in different grazing intensities in sandy grassland of Horqin sandy land,we contracted the variation of vegetation characteristics,such as cover,community composition,species diversity,above-under-ground biomass and litter biomass in enclosed,moderate grazing and heavy grazing sandy grassland.The results were as follows：（1）The dominant plant was annual among enclosed,moderate grazing and heavy grazing sandy grassland,but the dominance of grasses in enclosed and moderate grazing sandy grassland was higher than heavy grazing,the dominance of annual of heavy grazing sandy grassland was the biggest;（2）Grazing intensity had significant impacts on cover,aboveground biomass and litter biomass;and with the increase of grazing intensity,cover,aboveground biomass and litter biomass were declined;（3）The differences of species richness and diversity of enclosed,moderate grazing and heavy grazing sandy grassland were not significant.（4）The grazing intensity,the depth of soil and their interactions had significant impacts on underground biomass.The total underground biomass was decreased with the increase of grazing intensity.While,the underground biomass of three different soil depth in heavy grazing sandy grassland was not significant.Grazing changed the community composition of sandy grassland,and the cover and productivity were greatly reduced.Especially,heavy grazing dramatically increased the advantage of annuals,and had the greatest effect on the decrease of shallow rootsdistribution.