Overview & Applicability
Forecasts of Climate-Associated Shifts in Tree Species (ForeCASTS) generates maps that depict future suitable habitat ranges for 213 North American tree species, in the United States and globally. It does this by using projections of future climate in combination with the concept of fine-scale, ecoregions—land areas that share similar environmental characteristics, such as soils, topography, and climate variables.
The ecoregions for this tool are statistically determined and quantitative; thirty thousand of these ecoregions were created globally across present and multiple alternative forecasted future conditions. USDA Forest Service Forest Inventory Analysis (FIA) plots were used to determine where tree species occur, and to develop a subset of the 30,000 ecoregions within which each tree species can survive. The subset of ecoregions is then tracked into the future to determine whether the geographic range for that tree species is predicted to grow, shrink, shift, or disappear.
So far, maps have been developed for 213 tree species under current climates, and under 2 different climate models and 2 emissions scenarios for the years 2050 and 2100. The ForeCASTS atlas also includes "minimum required movement" (MRM) maps that quantify the distances between current habitat locations that may become unsuitable in the future and the nearest future suitable habitat.
These maps are meant to help scientists, land managers, and policy makers target tree species for monitoring, conservation, and management activities by pinpointing locations where climate change pressures are likely to be most intense.
ForeCASTS:Current modeled habitat for Longleaf pine using ForeCASTS.
History
With support from the USDA Forest Service Forest Health Monitoring program, Bill Hargrove, Frank Koch (ecologists with the Eastern Forest Environmental Threat Assessment Center or EFETAC), and Kevin Potter (EFETAC cooperating scientist from North Carolina State University) are collaborating to develop Forecasts of Climate-Associated Shifts in Tree Species, or ForeCASTS. The first series of maps was produced in 2009. Results are currently considered usable but provisional, and at least two more revisions are expected for this project.
Outputs also show how habitat may change under different climate scenarios. So far, maps have been developed for 213 tree species under current climates, and under 2 different climate models and 2 emissions scenarios for the years 2050 and 2100. The ForeCASTS atlas also includes "minimum required movement" (MRM) maps that quantify the distances between current habitat locations that may become unsuitable in the future and the nearest future suitable habitat.
These maps are meant to help scientists, land managers, and policy makers target tree species for monitoring, conservation, and management activities by pinpointing locations where climate change pressures are likely to be most intense.
Plans for future versions of the atlas include adding additional species, measuring "optimal movement distance" (OMD) from a species' current location to the future habitat most environmentally similar, identifying the closest "lifeboat" areas for tree species that may migrate from multiple locations, and adding measures of growth performance to determine where species may thrive in future projected habitat ranges.
Inputs and outputs
The model inputs are pre-defined by the researchers, so no user-collected data are required. Inputs to the model include Forest Inventory and Analysis (FIA) data that describe current tree locations. Inputs also include projected climates from two different climate change models (GCMs) under two future emissions scenarios (SRES). A series of 17 environmental variables are also used in predicting suitable habitat; the exact list of variables can be seen for each individual tree species when that species is selected.
Outputs include four different sets of maps:
- Maps of currently acceptable habitat for each of 213 North American forest tree species
- Maps of the future location and quality of habitat for each tree species at two time steps (2050 and 2100), under two different
- Maps that depict the overlap of current and projected future suitable habitat for each species.
- Maps of the straight-line minimum required migration (MRM) distance from each 4 km2 grid cell in a species' current suitable habitat to the nearest favorable future habitat.
More detail on each of these map types can be found here on the ForeCASTS web page.
Additionally, a set of projected climate-change pressure statistics is provided for each species. These statistics include percent change in area of suitable range, percent overlap of future suitable range with current suitable range (a stability score), and mean minimum required movement distance (a measure of shift pressure).
Restrictions and limitations
ForeCASTS maps may be more useful for showing which portions of a tree species' present range are most likely to be at risk given a particular future climate projection, rather than for making predictions at the forest level.
This is because while the ForeCASTS model results are gridded at 4 km2, the actual resolution of the output maps relates more to the 30,000 global ecoregions. Also, the underlying ecoregions are delineated based on the values of the 17 environmental characteristics, which have been interpolated and modeled between measurements. All future predictions of environmental conditions (global climate models) result solely from modeling efforts that have occurred beyond the scope of the ForeCASTS project.
In addition, ranges mapped in ForeCASTS are depicting potentially suitable habitat rather than occupied habitat. Whether or not species actually end up occupying suitable habitats depends on many factors. One of these factors is migration distance, which is represented by the maps of minimum required migration; however, factors such as habitat fragmentation and species characteristics such as regeneration and dispersal ability will also play a role. Only abiotic environmental characteristics have been considered in ForeCASTS - no biotic limitations of habitat, such as competition, predation or parasitism, have been explicitly considered.
Accessing the tool and additional information
Visit ForeCASTS to learn more.
Several posters and presentations are also available upon request.