内蒙古典型草原主要草食动物食性及其营养生态位研究——以羊草群落为例

摘要

为探讨典型草原主要食草动物(绵羊、达乌尔黄鼠和亚洲小车蝗)的食性及其种间生态位变化与草原退化的关系,以内蒙古典型草原为研究对象,于2003年7-8月运用饱和链烷技术研究羊草群落不同放牧强度下绵羊、达乌尔黄鼠和亚洲小车蝗的食性及其生态位变化.结果表明,随牧压的增大,群落中羊草和克氏针茅的数量减少,星毛委陵菜比例增加；随牧压的增加,绵羊采食黄囊苔草的比例显著增加,在重度放牧区,绵羊没有采食西伯利亚羽茅和米氏冰草,而是增加了对星毛委陵菜的采食；达乌尔黄鼠在围栏内采食羊草的比例显著高于围栏外放牧区；但在围栏内没有采食米氏冰草、黄囊苔草和星毛委陵菜；围栏内无法捕捉亚洲小车蝗,在放牧区亚洲小车蝗对克氏针茅的采食随牧压的增加显著降低,但增加了对米氏冰草和星毛委陵菜的采食.三者同时采食羊草和糙隐子草,且对羊草的选择性指数最高；随牧压的增大,绵羊的生态位宽度变宽,而达乌尔黄鼠和亚洲小车蝗的生态位宽度变窄,三者生态位重叠程度类似.因此,重度放牧改变了羊草群落的植被组成,使其演替为星毛委陵菜群落,从而导致了草地的退化,而鼠类和蝗虫的危害则加剧了草地的退化演替,三者对草地资源的共同掠夺导致草原严重退化.%In order to discuss the relations of grassland degradation and the diet composition and trophic niche of main herbivores (Ovis aries, Spermophilus dauricus, Oedaleus asiaticus) in the Inner Mongolia steppe, we research change of diet composition and trophic niche of main herbivores in the different grazing intensity in June-July 2003 by using n-alkane technique. The results showed that the richness of Leymus chinensis and Stipa krylovii decreased significantly with the increase of grazing intensity, while the proportion of Potentilla acaulis in the community increased at the same time. The proportion of Carex korshinskii ingested by O. aries increased significantly with the increase of grazing intensity, and Achnatherum sibiricum and Agropyron michnoi were not ingested by O. aries instead of P. acaulis. The proportion of L. chinensis ingested by S. dauricus inside fence more than outside fence significantly, but A. michnoi, C. korshinskii and P. acaulis were not ingested inside fence. There was no comparison of dietary in O. asiaticus between inside and outside fence due to having no capture it, but the proportion of S. krylovii ingested by O. asiaticus reduced significantly with the increase of grazing intensity, and instead of increasing the proportion of A. michnoi and P. acaulis. The same plant species of ingested were L. chinensis and C. squarrosa. Furthermore, the selected index of L. chinensis was highest. The tropic niche of O. aries was broadened with the increased grazing intensity, on the contrary S. dauricus and O. asiaticus, furthermore, the overlap of trophic niche among three herbivores were similar. In conclusion, an action of heavy grazing in Inner Mongolia steppe changed the L. chinensis community into the P. acaulis community, and this succession lead to the degradation of grassland. While the spoliating grassland resources by O. aries, S. dauricus, O. asiaticus have accelerated the process.