Eastern United States Climate Change Tree Atlas - Suitable habitat for Juglans nigra (black walnut) as measured by importance
value (IV)
Dataset Identification:
Resource Abstract:
This dataset represents actual and predicted suitable habitat for Juglans nigra (black walnut, species code 602) in the Eastern
United States as measured by importance value based on data obtained from the Forest Inventory and Analysis (FIA) project,
current climate conditions, and future climate projections. This summary unit of this dataset is a 20 by 20 kilometer cell.
The actual importance value (IV) was calculated based on the number of stems and basal area of a given tree species relative
to other tree species on a plot using about 100,000 FIA plots (representing nearly 3 million tree records) in the 37 states
within the United States east of the 100th meridian. These importance values were summarized to 20 by 20 kilometer grid cells.
Current estimates of IV were obtained from regression tree and regression tree ensemble (using Random Forests) classifiers
using 38 environmental variables including measures of current climate conditions. Predictions based on future climate were
obtained from applying these classifiers to the environmental variables including projections of future climate conditions
derived from the downscaled output of selected general circulation models (HADCM3, PCM, and GFDL) for both low (B1) and high
(A1F1) emissions scenarios. The reliability of the predictions for this species is Medium. For more information about this
dataset, please see the Climate Change Tree Atlas web page: http://www.nrs.fs.fed.us/atlas/tree/tree_atlas.html
Citation
Title Eastern United States Climate Change Tree Atlas - Suitable habitat for Juglans nigra (black walnut) as measured by importance
value (IV)