Land use and life history limit migration capacity of eastern tree species

Aim: Temperate tree species overwhelmingly responded to past climate change by migrating rather than adapting. However, past climate change did not have the modern human-driven patterns of land use and fragmentation, raising questions of whether tree migration will still be able to keep pace with climate. Previous studies using coarse-grained or randomized landscapes suggest that dispersal may be delayed but have not identified outright barriers to migration. Here, we use real-world fragmented landscapes at the scale of forest stands to assess the migration capacity of eastern tree species. Location: Eastern U.S.A. Time period: Present day to 2100. Major taxa studied: Eastern U.S. trees. Methods: We simulated dispersal over 100 years for 15 species common to the mid-Atlantic region and that are predicted to gain suitable habitat in the northeast. In contrast to previous studies, we incorporated greater realism with species-specific life histories and real-world spatial configurations of anthropogenic land use. We used simulation results to calculate dispersal rates for each species and related these to predicted rates of species habitat shift. Results: Our simulations suggest that land use in the human-dominated east-coast corridor slows species dispersal rates by 12–40% and may prevent keeping pace with climate. Species most impacted by anthropogenic land use were often those with the highest predicted species habitat shifts. We identified two major dispersal barriers, the Washington DC metropolitan area and central NY, that severely impeded tree migration. Main conclusions: Patterns of anthropogenic land use not only slowed migration but also resulted in effective barriers to dispersal. These impacts were exacerbated by tree life histories, such as long ages to maturity and narrow dispersal kernels. Without intervention, the migration lags predicted here may lead to loss in biodiversity and ecosystem functions as current forest species decline, and may contribute to formation of novel communities.