The link between topography and climate extinction risks in mountain ecosystems

Populations in mountain ecosystems face the risk of extinction due to climate change. Yet, how these risks will materialise remains unclear because many ecological parameters are unknown. We show that progress can be made by examining how habitats get fragmented and isolated as populations shift to higher elevations. When this shift is slow relative to dispersal, the amount of aggregation and connectivity between habitat fragments determine the warming threshold beyond which populations cannot sustain themselves. If the shift is rapid compared to dispersal, there is also a critical warming rate beyond which populations cannot track their preferred range and go extinct. Through simulations and analyses of stochastic spreading processes on real and artificial landscapes, we investigate how mountain topography, warming rates, and demographic mechanisms affect extinction thresholds. Understanding the link between mountain topography and extinction risks may enable targeted interventions to mitigate these risks, especially in areas with fragmentation bottlenecks.