Habitat Suitability Analysis
Buckleya distichophylla
Buckleya distichophylla is a rare endemic shrub found in the mountains of Tennessee, Virginia and North Carolina. A member of the Santalaceae family, it is considered threatened at state and global levels. It is semi-parasitic on Tsugae canadensis and other tree roots. The literature indicates that it prefers locations where there are periodic fires. Threats to this rare species are said to include fire suppression and the decline of Hemlocks due to adelgid infestation.
This analysis requires a statistical determination of the variables affecting the ditribution of the species. In this instance, each varibale was tested for Shannon entropy. Variables with very low (~0) scores are considered important distribution factors. It turns out that fire is not an important factor. Forest type is important, after soil type and distance to a stream but the known populations of Buckleya distichophylla are not statistically associated with Hemlock as was supposed.
After Shannon analysis of several variables, soil and forest type along with distance to streams, elevation and aspect were included in the weighted overlay. Only Cherokee National Forest was analyzed for highly suitable habitat ( >90% environmental similarity to known populations) as public lands faciltate the search for undiscovered populations and re-introduction experiments.
click on map for larger image
Watch a video describing the code I wrote to
streamline this HSI analysis.
NC
TN
VA
All material Copyrighted.
Bridget Nelson. April 2014
Background Image: Black Balsam from Sam's Knob
N 35.3281 W 82.8940
by Bridget Nelson 11Nov2013