To understand biodiversity patterns and to improve conservation measures, detailed knowledge of the influencing environmental factors is needed. One of the most important factors is the availability of specific required habitats. Instead of looking into size and connectivity of habitat patches, the new habitat amount hypothesis proposes that only habitat amount in the local landscape affects species. In forest ecosystems, dead wood plays a major role as habitat for hundreds of species that depend on it, so called saproxylic species. This species guild is often used as an ecological indicator for near natural forests because saproxylic species are sensitive to the amount and quality of dead wood and other old-growth structures. Considering this, the communities of saproxylic beetles, wood inhabiting fungi, mosses and lichens are investigated in this study in the Zurich Wilderness Park Sihlwald.