A Phenological Model for Southeastern United States

Abstract

In 1938, A. D. Hopkins introduced his magnum opus, Bioclimatics, A Science of Life and Climate Relations, culminating twenty years of research in entomology. (1) In this massive work, he set forth the prin- ciples of bioclimatics and provided a phenologic model for predicting the annual occurrence of natural phenomena in space and time. Remaining obscure for many years, this manuscript found periodic revival and has recently been rediscovered and reevaluated by some botanists. In a recent response to a request by Bliss (2) for help in establishing a phe- nology program as part of the International Biological Program, Leith and Radford (3) suggested the adoption of a modified phenologic model originally presented by Hopkins and subsequently adapted by Schnelle (4) and Kopec (S) to their needs. It is believed that an examination of phenology and Hopkins' Bioclimatic Law may serve to introduce and provide physical geographers and climatologists, by way of illustration, with a practical analytical tool in their studies of the physical environ- ment. Phenology, defined as that science which deals with the influence of climate on the cyclic activity of natural phenomena, has been by and large ignored by practitioners of our discipline. With today's emphasis on ecological network studies and social concern with natural environ- ment systems, a reexamination of phenology seems well advised. The influence that climate exerts on all biotic activity is pervasive, and per- haps because it is, its significance is diminished. Yet geographers are constantly made aware that climate control remains the primary environ- mental parameter in determining the cyclic behavior of physical phe- nomena, be it diurnal, annual or seasonal. A phenologic model which would permit prediction, within reasonable tolerances, of such reoccur- rences as the beginning of the frost free season or the spatial character of annual insect migrations would be of considerable technical value. Further, a bioclimatic model would make possible the identification and understanding of the physical controls underlying cyclic aberration of phenomenal occurrence which would enhance the development of more realistic theoretical and empirical resource management models. Hopkins recognized the need for such a model and formulated the Principles of Bioclimatic Law which state as follows: