Abstract
Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale.
Highlights
Plants and animals have responded to past climatic changes by shifting the spatial boundaries of their geographic ranges
When the entire model domain is hospitable to seedling growth, heavy-tailed dispersal distances drive front migration rates of approximately 130 m yr21 that are nearly double those driven by diffusive dispersal (Fig. 2)
The independent biological variables in the model are constrained by parametric distributions that are similar to those used in other studies, migration rate is an implicit variable that arises from the collective state of the full model domain over time
Summary
Plants and animals have responded to past climatic changes by shifting the spatial boundaries of their geographic ranges. Existing models of tree migration by long-distance dispersal produce migration rates between approximately 100–200 m yr21 [9,10,12]. Our results suggest that relatively small changes in the annual number of successful seedlings could have a comparatively large effect on biome migration rates.
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