Invasive Plant Species Response to Climate Change in Alaska. Bioclimatic Models of Current and Predicted Future Ranges

摘要

Sustainable management efforts are limited by a lack of basic information about species behavior in a changing climate. Species may be limited by climate, dispersal limitations, or a combination of the two. Range map scenarios are a valuable tool for decision-making by land managers with limited resources for invasive plant control. Current and future range map scenarios were created for sixteen invasive plant species in Alaska. Selected species represent primarily aquatic, riparian, or wetland habitats and have a high to extremely high invasion potential. Selected species either occur in Alaska (9 species) or are currently absent (7 species). Species were modeling using two different predictive models (DIVA-GIS and MaxEnt), two different future climates (Hadley and CCC), two emissions scenarios (A2, high and B2, low), for current climate plus three time steps (2020, 2050, 2080). Models were assessed with test data, and then evaluated for accuracy in range prediction. All models showed that the 16 species have current potential range in the state that exceeds their known occurrence. MaxEnt models performed best, using Hadley future climate data with the B2 emissions scenarios, to produce the least conservative, most accurate current and future range maps. All species showed an increase in range over time, particularly aquatic species including hydrilla, Eurasian watermilfoil, and white waterlily. Appropriate control actions are listed for each species based on current and potential future range. An existing vegetation cover map was used to spatially assign ecotype categories (Arctic Alpine, Boreal Interior, and South Coastal) to assess species fidelity to assigned types. Species occurred mainly within assigned types with exceptions that limit the use of ecotype as a predictive tool.