Phenology and Seasonality Modeling

The pulse of life with the seasons is a classic theme of biology, equally capturing every man’s curiosity about early and late milestones of every year’s cycle and the critical physiologist’s inquiry into life’s subtle signals and responses. Natural historians of ancient and renaissance time as well as today have charted thecommonsense facts behind inspired traditions of poetry and practical rules for growing food and fiber. This volume brings together several ways of organizing the basic principles of phenology. These find order in the otherwise overwhelming mass of detail that captures our fleeting attention, like the daily newspaper, and then tends to fade into the overstuffed archives of history.Is this order so obvious and understandable that there is no longer any scientific challenge to “phenology” as a tradition? Or does apparent simplicity mask a complex and ultimately baffling obstacle to the understanding of seasonality in even those few indicator plants and animals we know best, not to mention the less known species or races making up the rest of each major land­ scape unit or ecosystem? Denying both these hasty opinions, we think that this volume well illustrates a range of questions and answers—from soundly established (but not trivial) doctrine to exciting inquiry about how ecosystems are organized. Indeed, phenology has traditionally emphasized the “wrapping up” of seasonal history after it has occurred or just as it was occurring. In doing so, much has been learned about biological variables, which could be predicted (within limits) if key environmental factors were known, and preferably understood in terms of physical and physiological mechanisms. Such understanding and some mathematical expressions of mechanism, that are even better than mechanical, blind exercise of statistical technique now do seem to be improving our capacity to predict the future. Of course we are speaking of conditional probabilities: forecasting most probableoutcomes and some upper and lower bounds (e.g., for time to 50% leafing of plants or migration of animals, if certain weather input is given (average year; early warmth; late frost). If the weather itself remains almost as unpredictable in the future as it has been in the past, this alone would limit the biological forecasts from the very best phenological models.One reason that phenology was highlighted in 1966 as a distinct thrust in the United States National Committee for the International Biological Program (IBP)was a natural partnership with other models for biological productivity. The latter models might probe the reasons for differences in an ecosystem’s intake of energy and cycling of nutrient from one place to another over the Earth or at one place, when a pioneer community is replaced by a mature one. Phenologic models are left to answer how much (and why) growth and biological activity varies around a typical year or between years with very atypical seasons. Besides providing a crucial part of the few intensive ecosystem studies which IBP undertook, a second prospect that phenology offered was one basis for interpolating and extrapolating a few parameters on growth (or seasonal limits on growth) over wide areas in which no intensive analysis of total ecosystems could be expected. The emphasis on mapping and on ties to crops and other economic plants still offers such promise as part of “biome-wide” and regional studies. A third reason for special, and at times almost separated emphasis on phenology (as distinct from highly instrumented local experimental study of ecological process), was the simple reality noted at the beginning of this foreword. A broad appeal is made for coordinated interest among teachers and many nonspecialists who might do extensive work well, but never have opportunity for the intensive work; also among students who might thereby become motivated toward more advanced studies that might never have come to their attention. We hope that this book will further interest just such a wide range of less specialized readers to explore the current “state of the art” of phenology, while helping specialists place their own new research in a broad perspective.