Lebensraum-Hotspots für saproxylische Arten mittels LFI-Daten erkennen

Abstract

Identifying habitat hotspots for saproxylic species using NFI data Old wood and deadwood are the most important habitat features for thousands of typical wood-dwelling animal, fungi and plant species. In this paper, we explore the question of whether Swiss National Forest Inventory (NFI) data can be used to identify so-called habitat hotspots in order to promote species nationally and regionally. We therefore used NFI data to analyse old wood, deadwood and habitat trees, which are the three most important habitat indicators for old and deadwood specialists, and developed a structural index based on all three. The results show that national distribution maps of selected saproxylic species differ in how well they correspond with NFI habitat indicators, most probably because field observations are not representative. The indicators were therefore compared with modelled distribution areas of potential hotspots for saproxylic species. It seems that today deadwood in particular is seldom very frequent in those areas where it would most help to maintain biodiversity. Deadwood is especially plentiful in the western edges of the Alps. There are large supplies of old wood in Valais and the Engadine, and hotspots of habitat trees in Ticino, the central Jura and lower Valais. The NFI data on site characteristics, management forms and main forest functions were analysed to find out how much influence these factors have. For example, spruce-silver fir forests contain twice as much deadwood as beech forests (32 vs. 16 m3/ha), and old stands in spruce-silver fir forests untended for over 30 years as much as 50 m3/ha. Deadwood supplies tend to be greater at higher altitudes, on steep slopes and in forests difficult to access, regardless of the forest function. Protection forests tend to contain the most old stands (27% older than 120 years) and deadwood (26 m3/ha), while forests mainly used for recreation and timber production contain 12–13 m3/ha of deadwood and 17–20% of old stands. During the past two decades, the amount of old wood and deadwood has greatly increased in forests regardless of their function. The NFI inventories are very suitable for monitoring changes in forest habitats across space and time, and for assessing the influence of site characteristics, forms of management and natural events. Detailed analyses of NFI data can help in deciding on the best nature conservation strategies, for example, the geographical focus for conservation or promotion, the potential of forests that have not been used for a long time or the synergy with protection forests. NFI data should be used more for such purposes in future.