放牧强度对草甸草原植物群落主要功能群碳氮磷贮量的影响

Effects of Grazing Intensity on the Carbon,Nitrogen and Phosphorus Storage of the Main Functional Groups of Meadow Steppe Plant Community

本试验以呼伦贝尔草甸草原中禾本科、杂类草和灌木这3种功能型植物为研究对象,开展放牧强度对不同功能型植物碳、氮、磷含量,化学计量特征以及贮量的影响研究。结果表明:禾本科有机碳含量在各放牧强度下均最高;氮磷含量杂类草最高;3种功能群的有机碳含量均在适度放牧时最高,过度放牧时降低;轻度放牧使得禾本科、灌木的碳氮比、碳磷比升高,重度放牧时降低;放牧使得杂类草的碳氮比、碳磷比、氮磷比以及禾本科和灌木的氮磷比线性降低;禾本科以及杂类草的碳、氮、磷贮量随着放牧强度的增加而降低。本研究表明:禾本科、杂类草和灌木在不同放牧强度下,均表现为受氮元素限制,如果想获得较大的碳、氮、磷贮量则需要控制放牧强度,放牧强度为0.34~0.46 cow.Au·hm^(-2)(其中Au表示以500 kg肉牛为一个标准家畜肉牛单位)较为适宜,适度放牧利于提高草地的利用效率,促进草地可持续发展。

Taking the three functional plants,gramineous,forbs and shrubs,in the Hulun Buir meadow grassland as the research object,the effect of different grazing intensities on the carbon,nitrogen,phosphorus nutrients,stoichiometric characteristics and storage of different functional plants was studied.The results showed that:the carbon content of gramineae was the highest for all grazing intensities,and the nitrogen and phosphorus content of forbs was the highest.The carbon content of the three functional groups was the highest in light grazing,and decreased in overgrazing.Light grazing increased the C/N and C/P of grasses and shrubs,and decreased when overgrazing;grazing reduced the C/N,C/P,N/P of forbs and also reduced the N/P of gramineous and shrubs.The carbon,nitrogen and phosphorus storage of gramineous grasses,and the carbon and phosphorus storage of forbs decreased significantly with the increase of grazing intensity.This study showed that under different grazing intensities,gramineous,forbs,and shrubs were all restricted by nitrogen under different grazing intensities,and in order to obtain larger carbon,nitrogen and phosphorus storage,it is necessary to control the grazing intensity.The appropriate grazing intensity was 0.34~0.46 cow.AU·hm^(-2)(Au takes 500 kg beef cattle as a standard livestock beef cattle unit).Suitable grazing is beneficial to improve the utilization efficiency of grassland and promote the sustainable development of grassland.