Autochthone Gebirgswälder in der Schweiz anhand von baumbewohnenden Flechten erkennen

Abstract

Recognizing autochthonous mountain forests in Switzerland by means of epiphytic lichens Old undisturbed forest stands with a long forest history are of particular interest for nature and species conservation. Epiphytic lichens are often used as indicators for such autochthonous stands. In this study, we tested to what extent 14 taxa of epiphytic lichens, which are easy to identify by forest practitioners and have a low dispersal potential, have specific requirements for micro habitats and are often dependent on old trees, would be suitable indicator species for autochthonous forest stands in the Swiss mountain forests. As autochthonous, we considered forest stands with a near-natural conifer composition, a minimum age of 90 years, a continuous forest cover over 120 years and no evidence of historical intervention such as clear cutting or afforestation. For the study, the regular field teams of the Swiss National Forest Inventory (NFI) included the potential indicator species in the third survey (2004–2006) on all plots in the 1.4 km network on about three trees each. The data for the 3510 plots in the mountain forest were then evaluated using the NFI data on forest structure, forest history and forest management. Overall, the number of indicator species was significantly higher in autochthonous forest stands than in non-autochthonous ones, although it varied considerably with altitude and biogeographical region. Our investigations showed that fruticose lichens of the genera Bryoria and Usnea, Evernia divaricata and Letharia vulpina, foliose lichens such as Cetrelia olivetorum and Lobaria pulmonaria, and crustose lichens such as Lecanactis abietina and Microcalicium disseminatum, Calicium sp. div. and Chaenotheca sp. div. as well as Chrysothrix candelaris are reliable indicators for autochthonous stands in Swiss mountain forests, especially if several indicator species occur together. The lichens tested are therefore suitable in practice for a simple identification of autochthonous forest stands, e.g. for delimiting forest reserves or old forest patches. These stands are of high importance for the promotion of biodiversity in a forest landscape that has been managed for centuries.