Effect of livestock grazing on the bird communities in Xinbarhuyouqi, western Hulunber grassland, northern Inner Mongolia

概要

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The impact of livestock grazing on grassland bird communities was investigated at 15 sites in the Xinbarhuyouqi district on 3-4 June 1997 and 14-21 June 1998. Sixteen species of birds were recorded from the 15 sites, which lie near the national border with Mongolia and Russia, at the west end of the Hulunber grassland in northern Inner Mongolia, China. Bird communities at the 15 sites were clustered into seven units, by using Whittaker's similarity index and the group average method. Both the number of species and the individual density of birds decreased due to retrogressive changes in vegetation impacted by grazing and mowing. Furthermore, the formation of bird communities was altered. Natural grasslands (not used for grazing) supported the Anthus godlewskii-Emberiza schoeniclus community, because tall dicotyledonous plants in this habitat provided perches for Emberiza buntings. This bird community may appear when vegetation cover exceeds 89% and vegetation height is greater than 24cm. Mown grasslands were dominated by the Alauda arvensis community. In grazed grasslands, Calandrella cinerea, Eremophila alpestris, or Oenanthe isabellina predominated depending on grazing intensity and rodent density. In heavily grazed, eroded grasslands with extremely poor vegetation, few bird species and individuals were found.
野生生物保護学会の論文