Loe Leif Egil, Mysterud Atle, Stien Audun, Steen Harald, Evans Darren M, Austrheim Gunnar
Centre of Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.
Biol Lett. 2007 Feb 22;3(1):109-11. doi: 10.1098/rsbl.2006.0571.
Grazing by large herbivores may negatively affect bird populations. This is of great conservation concern in areas with intensive sheep grazing. Sheep management varies substantially between regions, but no study has been performed in less intensively grazed systems. In a fully replicated, landscape scale experiment with three levels of sheep grazing, we tested whether the abundance and diversity of an assemblage of mountain birds were negatively affected by grazing or if grazing facilitated the bird assemblage. Density of birds was higher at high sheep density compared with low sheep density or no sheep by the fourth grazing season, while there was no clear effect on bird diversity. Thus, agricultural traditions and land use politics determining sheep density may change the density of avifauna in either positive or negative directions.
大型食草动物的啃食可能会对鸟类种群产生负面影响。在绵羊密集放牧的地区，这一问题备受保护关注。不同地区的绵羊管理方式差异很大，但尚未有研究在放牧强度较低的系统中开展。在一项具有三个绵羊放牧水平的完全重复的景观尺度实验中，我们测试了山地鸟类群落的丰富度和多样性是否受到放牧的负面影响，或者放牧是否对鸟类群落有促进作用。到第四个放牧季节时，与低绵羊密度或不放牧相比，高绵羊密度下鸟类的密度更高，而放牧对鸟类多样性没有明显影响。因此，决定绵羊密度的农业传统和土地利用政策可能会使鸟类群落密度朝正向或负向发生变化。
