Positive species interactions and climate change at global scales
Results/Conclusions: The GSGH predicts that positive and negative species interactions vary in a function of latitude and climate, with competition most frequent in temperate zones and facilitation more frequent in tropical and arctic zones. Facilitative interactions are likely frequent in the tropics due to strong biotic (e.g. consumer pressure in rain forests) or abiotic stresses (e.g. desiccation stress in tropical deserts and rocky intertidal shores), whereas in the arctic zones facilitative interactions are frequent mainly due to high abiotic stress such as cold. The GSGH also predicts that the impact of climate change on competition and facilitation vary globally in a function of ecosystem and climate background. These predictions appear to be supported by a preliminary, global meta-analysis of plant-plant interactions. To conclude, we advocate that a shift in the current, local focus of the SGH research to global scales is of paramount importance to advancing our understanding of the SGH and its practical values in conservation strategies and climate change predictions.