Stepping stones, or small patches of habitat spaced between larger fragments, are one strategy to keep species connected. This sort of connectivity will be important as climate change causes many species to shift their ranges. If individuals are going to move from their old, unsuitable habitat to new, better habitat, they need a way to get there safely.
A lot of connectivity modeling focuses on how suitable patches will shift across space. However, there is also a temporal aspect to finding suitable habitat, i.e. whether or not certain patches can act as stepping stones may also change across time. Models that consider both space and time when looking at future connectivity, called spatio-temporal models, may be more effective in predicting how species will track climate change than considering each one separately.
A new study looks at the importance of spatio-temporal connectivity models in predicting how connectivity will change under future climates. First, spatio-temporal connectivity models were compared to spatio-only connectivity models using simulations to determine where and under what circumstances one was more important than the other. Second, the potential distributions of three North American mammals who differ in their vulnerabilities to climate change (white-tailed deer, Canada lynx, and grey wolf) were modeled using spatio-temporal connectivity models.
Of the 300 virtual species that were run through simulations, 44% of them showed a higher importance of spatio–temporal connectivity relative to spatial‐only connectivity in the amount of reachable habitat under climate change. However, the relative importance of spatio-temporal connectivity depended on both the species’ response to climate change, and on changes in habitat quantity and suitability compared to changes in habitat configuration and dispersal.
Spatio–temporal connectivity was relatively more important for species predicted to experience range contractions under climate change, such as Canada lynx. For white-tailed deer and grey wolves, whose ranges are expected to expand, spatio-temporal connectivity proved less important. In addition, changes in habitat amount (both quantity and suitability) were more influential than changes in habitat configuration in determining the relative importance of spatio–temporal connectivity.
Providing connected habitat across both space and time ensures that species are more likely to persist under climate change. Using spatio-temporal models is likely to be a more effective and realistic way to predict where and when stepping stone habitats can provide connectivity.
Huang, J.L., Andrello, M., Martensen, A.C., Saura, S., Liu, D.F., He, J.H. and Fortin, M.J. 2020. Importance of spatio–temporal connectivity to maintain species experiencing range shifts. Ecography. DOI: 10.1111/ecog.04716.
Martensen, A.C., Saura, S. and Fortin, M.J. 2017. Spatio‐temporal connectivity: Assessing the amount of reachable habitat in dynamic landscapes. Methods in Ecology and Evolution 8(10): 1253-1264.