Distribution patterns, range size and niche breadth of Austrian endemic plants

Endemic species are not a uniform group in terms of range size, habitat preferences, and ecological plasticity. Based on a recent inventory of endemic vascular plant species in Austria, we analysed distribution patterns, altitudinal distribution and habitat preferences of endemic species and analysed the correlation of range size and niche breadth. The inventory includes 103 vascular plant taxa (species and subspecies) endemic to Austria. Grid cells (cell size ca. 35 km(2)) with highest taxon numbers (max. 25 taxa) are limited to the Northeastern Calcareous Alps, whereas highest numbers of acidophilous endemics occur in the easternmost high-mountain chains of the Central Alps. The majority of endemics (61 taxa: 59.2%) are found on calcareous bedrock, 6 taxa (5.8%) on intermediate substrates, and 29 (28.2%) on siliceous bedrock. The range size of endemic vascular plant taxa is strongly skewed towards very narrow distributions - 45 taxa are restricted to <20 grid cells. Average range sizes differ markedly between endemics of different broad habitat types, endemics of habitats with limited and patchy distribution (serpentine vegetation, dry grassland) having the smallest ranges. The altitudinal distribution of endemic plant taxa peaks at high altitudes, in the subalpine and lower alpine altitude belt. Below the tree line, endemics predominantly colonize extra- and azonal dry or wet habitats, whereas above the tree line, zonal alpine grassland and azonal vegetation types (scree, rocks, snowbeds) are equally essential to the endemic flora. Niche breadth of endemics is positively, however moderately, correlated with range size. This correlation is stronger for the altitudinal distribution than for the number of habitats colonized. The distribution patterns and ecology of endemics differ considerably from overall biodiversity patterns and must be addressed appropriately in conservation strategies. Small niche-breadths and the specific habitat requirements of endemics of very localized distribution render these taxa highly vulnerable to climate change. (C) 2009 Elsevier Ltd. All rights reserved.