Community and Conservation Ecology Group, University of Groningen, PO Box 11103, 9700 CC, Groningen, The Netherlands.
Oecologia. 2012 Feb;168(2):511-8. doi: 10.1007/s00442-011-2093-y. Epub 2011 Aug 24.
Aboveground and belowground organisms influence plant community composition by local interactions, and their scale of impact may vary from millimeters belowground to kilometers aboveground. However, it still poorly understood how large grazers that select their forage on large spatial scales interact with small-scale aboveground-belowground interactions on plant community heterogeneity. Here, we investigate how cattle (Bos taurus) modify the effects of interactions between yellow meadow ants (Lasius flavus) and European brown hares (Lepus europaeus) on the formation of small-scale heterogeneity in vegetation composition. In the absence of cattle, hares selectively foraged on ant mounds, while under combined grazing by hares and cattle, vertebrate grazing pressure was similar on and off mounds. Ant mounds that were grazed by only hares had a different plant community composition compared to their surroundings: the cover of the grazing-intolerant grass Elytrigia atherica was reduced on ant mounds, whereas the relative cover of the more grazing-tolerant and palatable grass Festuca rubra was enhanced. Combined grazing by hares and cattle, resulted in homogenization of plant community composition on and off ant mounds, with high overall cover of F. rubra. We conclude that hares can respond to local ant-soil-vegetation interactions, because they are small, selective herbivores that make their foraging decisions on a local scale. This results in small-scale plant patches on mounds of yellow meadow ants. In the presence of cattle, which are less selective aboveground herbivores, local plant community patterns triggered by small-scale aboveground-belowground interactions can disappear. Therefore, cattle modify the consequences of aboveground-belowground interactions for small-scale plant community composition.
地上和地下生物通过局部相互作用影响植物群落组成，其影响范围可从地下几毫米到地上几公里不等。然而，大型食草动物在多大程度上选择其大范围的饲料与小范围的地上-地下相互作用对植物群落异质性的影响仍知之甚少。在这里，我们研究了牛（Bos taurus）如何改变黄草地蚁（Lasius flavus）和欧洲野兔（Lepus europaeus）之间的相互作用对植被组成小尺度异质性形成的影响。在没有牛的情况下，野兔有选择性地在蚁丘上觅食，而在野兔和牛联合放牧的情况下，脊椎动物的放牧压力在蚁丘上和蚁丘下相似。仅被野兔放牧的蚁丘的植物群落组成与周围环境不同：不耐牧的草 Elytrigia atherica 的盖度在蚁丘上减少，而更耐牧和适口性更好的草 Festuca rubra 的相对盖度增加。野兔和牛的联合放牧导致蚁丘上和蚁丘下的植物群落组成趋于均匀化，F. rubra 的总体盖度较高。我们得出结论，野兔可以对局部的蚁-土壤-植被相互作用做出反应，因为它们是小型、选择性的食草动物，可以在局部范围内做出觅食决策。这导致了黄草地蚁蚁丘上的小尺度植物斑块。在牛的存在下，牛是选择性较弱的地上食草动物，小范围地上-地下相互作用引发的局部植物群落模式可能会消失。因此，牛改变了地上-地下相互作用对小尺度植物群落组成的后果。
