Relationships between ecological niche and expected shifts in elevation and latitude due to climate change in South American temperate forest plants

Aim Niche properties, such as breadth and position along environmental gradients, are hypothesized to determine plant responses to climate change. We explored the properties of different plant niches in a biodiversity hotspot, over a wide span of elevational and latitudinal ranges, to assess the relationship between niche characteristics and the modelled distributional shifts due to climate change. Location Methods We assessed the niche breadth and position of 118 plant species of South American temperate forests, using an Outlying Mean Index (OMI). Bioclimatic information was gathered for each species from WorldClim, and both present and future distributions were modelled using BIOMOD, considering migration constraints with MIGCLIM. The relationships between niche properties and shifts in elevational and latitudinal distributions were explored using linear regressions. Results South American temperate forests. Main conclusions Niche differences among species were related to two bioclimatic dimensions: the first one correlated with the mean diurnal temperature range and precipitation seasonality following the mediterranean-temperate-sub-Antarctic climatic gradient; the second one correlated with minimum winter temperature along a gradient from oceanic-influenced habitats to cold tree line habitats. The projected elevational shifts were inversely related to niche breadth and the forecast latitudinal shifts were directly related to niche breadth. The shifts in elevation and latitude for understorey plants were not consistent with the shifts of dominant trees. The plant niches were successfully discerned by OMI analyses and they were associated with specific morphological or physiological traits. South American temperate forest plants showed an inverse relationship between niche breadth and elevational shifts, but a positive relationship regarding expected latitudinal shifts. This may be related to the fact that niche drivers followed a latitudinal orientation and the species showed the Rapoport's effect. Thus, the niche breadth and latitudinal position of the species should be considered in climatic change studies.