Aim

Climate change is driving species to migrate to novel areas as current environments become unsuitable. As a result, species distributions have shifted uphill in montane ecosystems globally, leading to projections of severe impacts on upland specialist species. Heterogenous dispersal rate among shifting species could result in complex changes to community assemblages. For example, interspecific differences in dispersal ability could lead to the disruption, or creation, of species interactions and processes within communities, likely amplifying the impact of climate change on ecosystems. Here, we provide a comprehensive assessment of the impacts of climate change on communities and ecosystems by developing a novel spatially explicit approach focussing on changes in local populations.

Location

The Australian Wet Tropics.

Method

We used a spatially explicit approach to simulate the elevational shift of 7,613 community assemblages (defined at the patch level) along the elevational gradient, using empirical information about the distribution of 202 vertebrate species. We analysed changes in community structures and species co-occurrence derived from the elevational shift as a proxy for potential changes in species interactions.

Results

Our results showed a consistent pattern of increasing temporal β-dissimilarity between community assemblages along the elevational gradient resulting from local species extinctions. The local extinction rate was especially remarkable at high elevations, suggesting potential mass local extinctions of upland species unable to shift to the isolated mountaintops. Furthermore, the increasing local extinction rate with elevation resulted in a marked decline in species co-occurrence towards mountaintops.

Main conclusions

Our study highlights the escalating impact of climate change on community assemblages in response to climate-induced elevational shifts in species' ranges, providing a classic example of the "escalator to extinction". Future predictions of the impacts of climate change on ecosystems will benefit from improvements in understanding species interactions and species potential to adapt to a changing environment.

Data collection and processing can be found at https://doi.org/10.1890/09-1069.1