Large herbivore grazing and invertebrates in an alpine ecosystem.pdf

LA S a P b c d e N R A s a m s c A m o n d f Z a A e d K v 1 dBasic and Applied Ecology 11 (2010) 320–328 arge herbivore grazing and invertebrates in an alpine ecosystem tle Mysteruda,?, Ragnar Aaseruda, Lars Ove Hansenb, Kjetil ?krac, tefan Olbergd, Gunnar Austrheime Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, .O. Box 1066 Blindern, NO-0316 Oslo, Norway Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway Midt Troms museum, Pb. 82, NO-9050 Storsteinnes, Norway Biofokus, Gaustadalléen 21, NO-0349 Oslo, Norway Museum of Natural History and Archeology, Section of Natural History, orwegian University of Science and Technology, Trondheim NO-7491 Norway eceived 30 June 2009; accepted 2 February 2010 bstract The literature on how plants respond to grazing and other disturbance factors have advanced greatly in recent decades, but tudies of invertebrates are comparably few. We here quantify the effects of 3 levels of sheep grazing on selected invertebrates in n alpine ecosystem in Norway. We tested the hypothesis that invertebrates are more sensitive to grazing than plants (responding ainly at high density), and that primary consumers (herbivorous beetles) are more sensitive than predatory species (beetles and piders). We captured 1218 specimens belonging to 44 beetle species and 6672 specimens belonging to 66 species of spiders. The ommunity was dominated by few species: 5 beetle and 3 spider species made up 53.0% and 37.4% of the catch, respectively. t the local (plot) scale, most negative responses were only recorded at high sheep density, and invertebrates were thus not ore responsive than the plant community. Two dominant herbivorous beetles responded to grazing while 3 dominant species f predatory beetles did not (one marginally). Spider species richness and frequency of occurrence of 2 dominant species were egatively affected by sheep grazing, suggesting variation between diff