Fuzzy Set Classification of Old-Growth Southern Pine
I propose the development of a fuzzy set ordination (FSO) approach to old-growth classification of southern pines. A fuzzy systems approach differs from traditional old-growth classification in that it does not require a "crisp" classification where a stand is either "old-growth" or "not old-growth", but allows for fractional membership in the set of old-growth stands. FSO produces a score ranging from 0.0 (highly different from old-growth) to 1.0 (completely residing in the set of old-growth stands). This value can also be interpreted as "apparent" age, or an approximation of stand age based on measured variables other than time. A FSO old-growth classification is less subjective than current regression or indexing procedures, most of which assign an arbitrary value to each classification variable. In this example highlighting southern pine, five characteristic features of old-growth (q-factor, maximum tree DBH, stand basal area, percent red heart infection, and large woody debris volume) are expressed as response functions to help differentiate between stands synthesized from historical descriptions of virgin timber in southern Arkansas.