1 Ecology and Evolution, Department of Biology, Faculty of Science, Københavns Universitet2 Institut for Bioscience - Økoinformatik og Biodiversitet3 Norwegian University of Science and Technology4 Norwegian Institute for Nature Research5 Tromsø University Museum6 Malmö Museer7 University of Bergen8 University of Tromsø9 Swedish University of Agricultural Sciences10 Stockholm University11 Jules Verne University of Picardie12 University of Bremen13 Umeå University14 Aarhus University15 University of Helsinki16 Tartu Uelikool (University of Tartu)17 Department of Biology, Faculty of Science, Københavns Universitet18 Telemark University College19 University of Agder20 Norwegian Institute for Agricultural and Environmental Research21 University of Oulu22 Norwegian University of Science and Technology23 Norwegian Institute for Nature Research24 University of Bergen25 Ecology and Evolution, Department of Biology, Faculty of Science, Københavns Universitet26 University of Bremen27 Department of Biology, Faculty of Science, Københavns Universitet28 University of Agder29 University of Oulu
Recent studies from mountainous areas of small spatial extent (<2500 km(2) ) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1000-m(2) units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km(2) units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km(2) units. Ellenberg temperature indicator values in combination with plant assemblages explained 46-72% of variation in LmT and 92-96% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km(2) units peaked at 60-65°N and increased with terrain roughness, averaging 1.97 °C (SD = 0.84 °C) and 2.68 °C (SD = 1.26 °C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km(2) units was, on average, 1.8 times greater (0.32 °C km(-1) ) than spatial turnover in growing-season GiT (0.18 °C km(-1) ). We conclude that thermal variability within 1-km(2) units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.
Global Change Biology, 2013, Vol 19, Issue 5, p. 1470-1481