ForeCASTS Project Revisits Classic Tree Range Maps

A ForeCASTS map showing current range of northern red oak In 1971, U.S. Forest Service employee Elbert J. Little mapped the existing geographic ranges of each tree species in North America. He drew these range maps by hand, using nothing more than his expertise and field experience. Little's 45-year-old tree range maps have been so fundamentally useful that they are still in common use today. Now, using Forest Inventory and Analysis (FIA) data and other records of tree species occurrence, along with 17 variables describing environmental conditions across the United States, Eastern Threat Center researchers have redrawn Little's range maps as part of the ForeCASTS (Forecasts of Climate-Associated Shifts in Tree Species) project. ForeCASTS "predicts" and independently maps the current suitable range for more than 330 tree species using a statistical model of the tree's environmental niche envelope, which describes locations where environmental conditions could presently allow a particular tree species to grow. ForeCASTS also predicts future suitable geographic ranges for each species using projections from four alternative climate change model/scenario combinations by 2050 and 2100, quantifying different aspects of risk from shifting ranges due to climatic change for each tree species—a task that would have been impossible for Little himself. Digital range maps for each species are downloadable for use in a GIS system.

Pictured: ForeCASTS “predicted” the current range of northern red oak (Quercus rubra) using 17 environmental descriptors and occurrence locations from FIA data. Red areas indicate the predicted present range, with Little's original range boundary shown in green. Black/gray areas are unsuitable for this species, but are very similar to suitable environments. Click to enlarge.

External Partners/Collaborators:
North Carolina State University

Contact: William Hargrove

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