Steen Harald, Mysterud Atle, Austrheim Gunnar
Program for Experimental Behavioral and Ecological Research (EBE), Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway.
Oecologia. 2005 Apr;143(3):357-64. doi: 10.1007/s00442-004-1792-z. Epub 2005 Feb 23.
Inter-specific competition, facilitation and predation influence herbivore assemblages, but no study has experimentally explored the interactions between large ungulates and small rodents. In a fully replicated, landscape scale experiment, we manipulated densities of domestic sheep in mountain pastures in Norway. We then determined population growth and densities of rodents by live trapping in each of the areas with different sheep densities. We found that the (summer) population growth rate and autumn density of the field vole (Microtus agrestis) was lower at high sheep density. This provides the first experimental evidence of negative interactions between an ungulate and small rodent species. There was no effect on the bank vole (Clethrionomys glareolus), whose diet differs from sheep. Sheep density, therefore, potentially alters the pattern of inter-specific population synchrony amongst voles. Our study shows that negative interactions between large ungulates and small rodents may be species-specific and negative population consequences for the rodent population appear above threshold ungulate densities.
种间竞争、促进作用和捕食会影响食草动物群落，但尚无研究通过实验探究大型有蹄类动物与小型啮齿动物之间的相互作用。在一项完全重复的景观尺度实验中，我们在挪威山区牧场操纵了家羊的密度。然后，我们通过在不同羊密度的每个区域进行活体诱捕，来确定啮齿动物的种群增长和密度。我们发现，在高羊密度下，田鼠（Microtus agrestis）的（夏季）种群增长率和秋季密度较低。这提供了有蹄类动物与小型啮齿动物物种之间负面相互作用的首个实验证据。对饮食与羊不同的林姬鼠（Clethrionomys glareolus）没有影响。因此，羊的密度可能会改变田鼠之间种间种群同步的模式。我们的研究表明，大型有蹄类动物与小型啮齿动物之间的负面相互作用可能具有物种特异性，并且对啮齿动物种群的负面种群影响会在有蹄类动物密度超过阈值时出现。
