This research was funded by USDA-FS Cooperative Grant no. 23-590 through NE-4301, Fernow Experimental Forest, Parsons, WV. The use of trade, firm, or corporation names in this paper is for the information and convenience of the user. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture or the Forest Service of any product or service to the exclusion of others that may be suitable. We are indebted to Steve Horsley for helpful discussion of fern data.