diversity Article Deer Exclusion Changes Vegetation Structure and Hunting Guilds of Spiders, but Not Multitrophic Understory Biodiversity Roman Bucher 1,* , Jonas Rochlitz 1,2, Nathalie Wegner 1, Anna Heiß 1, Alexander Grebe 1, Dana G. Schabo 1 and Nina Farwig 1 1 Department of Biology, Conservation Ecology, University of Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany;
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[email protected]; Tel.: +49-(0)6421-282-3472 Abstract: Ungulate herbivores modify plant community compositions, which can modulate biodi- versity at higher trophic levels. However, these cascading effects on herbivorous and predatory arthropods in forest ecosystems remain poorly understood. We compared plant and arthropod com- munities between fenced exclosures and unfenced control plots in a permanent forest in Germany. After five years of deer exclusion, we quantified plant diversity and vegetation structure as well as the diversity of insects and spiders in 32 pair-wise plots. In addition, we compared spider communities with respect to different hunting guilds because they are expected to have different requirements for vegetation structure. Although we did not find differences in plant communities, vegetation height and heterogeneity were higher in exclosures compared to control plots. The diversity of insects Citation: Bucher, R.; Rochlitz, J.; and spiders was not affected by deer presence.