Poster, IBS 2015 - 7th International Conference of the International Biogeography Society, University of Bayreuth: 2015-01-08 - 2015-01-12
Treelines are one of the few fundamental borders in ecology, separating forests from treeless alpine systems. Already a century ago the concept of mass elevation effect (MEE; i.e. area of mountain chains) and continentality (i.e. distance from the ocean) were proposed to have positive effects on treeline elevation but have never been quantified. This study aims at globally quantifying the influence of MEE, continentality and isolation (i.e. the nearest distance to a mountain region with similar elevation) on the treeline elevation, by using the currently largest dataset of global treeline elevations (n = 672). We applied an innovative sampling method (GoogleEarth), enabling a global coverage of treeline elevations (74°N to 66°S). The global treeline pattern showed a distinct double hump, which may result from a tropical depression or from the lack of high mountains in the equatorial tropics. The MEE and continentaliy positively affected treeline elevation, probably because an increased solar radiation leads to better growing conditions at high elevations. However, evolutionary process might lead to fewer high elevation-adapted tree species with increasing isolation.