Low density cattle grazing enhances arthropod diversity of abandoned wetland

Abstract

We studied the impact of low-density grazing on arthropod diversity in a small wetland (7 ha) in South Germany. The location was abandoned for 20 years, and was then grazed by Galloway for 4 to 5 years. The study site included the following habitat types: open land, a stand of alder (Alnus glutinosa), a stand of willows (Salix spec) and alder and a brookside. We counted higher species numbers on grazed than on neighbouring abandoned areas in ground beetles, rove beetles and spiders. Grazing explained a considerable amount of the variance of the species composition, and species typical for grazed plots could be identified. We found higher frequencies of insects during winter in Cirsium stems from grazed than from ungrazed areas. Grasshoppers and katydids (Saltatoria) of the grazed open land showed a general trend of increasing species number during the study period. Our findings show that low density grazing by cattle can favour habitat diversity even in small areas which enhances species numbers. However, special habitat types such as reed may need to be excluded from grazing in order to maintain the associated specific invertebrate community. © 2007, Penkala Bt.