Lenoir, Jonathan5; Graae, Bente Jessen3; Aarrestad, Per Arild3; Alsos, Inger Greve3; Armbruster, W Scott3; Austrheim, Gunnar3; Bergendorff, Claes3; Birks, H John B3; Bråthen, Kari Anne3; Brunet, Jörg3; Bruun, Hans Henrik4; Dahlberg, Carl Johan3; Decocq, Guillaume3; Diekmann, Martin3; Dynesius, Mats3; Ejrnaes, Rasmus6; Grytnes, John-Arvid3; Hylander, Kristoffer3; Klanderud, Kari3; Luoto, Miska3; Milbau, Ann3; Moora, Mari3; Nygaard, Bettina6; Odland, Arvid3; Ravolainen, Virve Tuulia3; Reinhardt, Stefanie3; Sandvik, Sylvi Marlen3; Schei, Fride Høistad3; Speed, James David Mervyn3; Tveraabak, Liv Unn3; Vandvik, Vigdis3; Velle, Liv Guri3; Virtanen, Risto3; Zobel, Martin3; Svenning, Jens-Christian5
1 Department of Bioscience - Ecoinformatics and Biodiversity, Department of Bioscience, Science and Technology, Aarhus University2 Department of Bioscience - Biodiversity and Conservation, Department of Bioscience, Science and Technology, Aarhus University3 unknown4 Sociologisk Institut5 Department of Bioscience - Ecoinformatics and Biodiversity, Department of Bioscience, Science and Technology, Aarhus University6 Department of Bioscience - Biodiversity and Conservation, Department of Bioscience, Science and Technology, Aarhus University
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