Aim: Scale-dependence of patterns and processes remains one of the major unresolved problems in ecology. Ecosystem responses to environmental stressors are reported to be strongly scale-dependent, but projections of climate-change effects on species’ distributions are still restricted to particular scales and knowledge about scale-dependence is lacking. Here we propose that the scale-dependence of species’ niche dimensions related to climate change is strongly related to the strength of climatic cross-scale links. More specifically, we hypothesize that the strong cross-scale links between micro- and macro-climatic conditions are related to high cross-scale similarity (low scale-dependence) of species’ realized temperature niches and, thus, species’ spatial distributions.
Location: The study covers seven orders of magnitude of spatial scale, ranging from local (below metre) and regional (kilometre) scale investigations in Central European wetland ecosystems to continental scale (thousands of kilometres) studies of species’ distributions.
Methods: We combined species’ spatial occurrence data (vegetation records at local and regional scales, digitized distribution maps at the continental scale) with information about the corresponding temperature regime of vascular plant species occurring in environmentally stable wetland ecosystems characterized by strong cross-scale links between micro- and macro-climatic conditions.
Results: We observed high cross-scale similarity of species’ temperature niche characteristics across seven orders of magnitude of spatial scale. However, the importance of temperature as an abiotic driver decreased non-linearly with decreasing scale, suggesting greater importance of additional (biotic) drivers of species’ occurrence on small spatial scales.
Main conclusions: We report high cross-scale similarity of realized temperature niches for species inhabiting ecosystems where small-scale environmental noise is low and cross-scale links between micro- and macro-climatic conditions are strong. By highlighting a strong relationship between abiotic and biotic cross-scale similarity, our results will help to improve niche-based species distribution modelling, one of the major assessment tools for ecological climate change effects.