This symposium was presented at the 1993 Annual Meeting of the Ecological Society of America, held in Madison, Wisconsin. It was at this ESA meeting that the Theoretical Ecology Section was officially formed. Thus, the Section had not been in existence to formally sponsor a symposium for the 1993 meeting. However, the symposium listed here was the outgrowth of a series of workshops organized by Dr. Timothy F.H. Allen. The creation of a Theoretical Ecology Section was also initiated as a result of those workshops. Therefore, this symposium can be regarded, unofficially, as the first symposium of the Theoretical Ecology Section.
A review of this symposium was published in the September 1994Bulletin of the Ecological Society of America 75(3):172-173. The symposium was also mentioned in a news article in the 25 February 1994 issue ofScience 263:1090-1092.
ECOLOGICAL THEORY: ITS CHARACTER, PROBLEMS, AND REMEDIES.
Organized by: Timothy F.H. Allen, Department of Botany, University of Wisconsin, Madison, WI 53706. (608) 262-2692; and Sandra J. Turner, Department of Biology, University of New Mexico, Albuquerque, NM 87131. (505) 277-9173.
SUNDAY 1 AUGUST, 1993, 8:00 a.m.-12:00 p.m.
8:00 Allen Introduction
8:15 Milne Appropriate models for ecology from the new physics
8:45 Turner Issue and conflict: ecological theory in the resolution process
9:15 King A model of theory in ecology
10:00 Allen Theory for ecological suatainability
10:30 Austin Plant and animal community ecology: a clash of paradigms?
11:00 Wessman The influence of remote sensing on large-scale ecological theory
11:30 Johnson Defining and quantifying complexity in ecological systems
1. Milne, Bruce T. University of New Mexico, Albuquerque, NM 87131, USA. APPROPRIATE MODELS FOR ECOLOGY FROM THE NEW PHYSICS.
Ecology has a history of successfully borrowing models from other disciplines in which formal descriptions are well developed. Borrowed models, especially from physics, have been helpful under limited circumstances, primarily because the complex interactions and historical effects inherent in biological systems have not been the subject of classical physics. Recent developments in physics provide appropriate models of complex, evolving, self-organizing systems. The new approaches convey an inherent simplicity and economy of description despite the apparent complexity of the systems. Examples of problems with potential applications in ecology include self-organization, dendritic growth, anomalous diffusion, and the theory of spatial phase transitions. Formal treatments of these topics recognize the feedback between pattern and process which is of interest in studies of populations, communities, and landscapes. The models may find applications in studies of sustainability, the origin of dendritic forms, and in explanations of long term trends.
We define a scientific or management issue as expressing tension where there is perceived conflict of some sort. The conflict may be in values, in incompatible management agendas or it may arise from data sets which suggest that a given question is by its nature unanswerable. We present a theoretical distinction between a question, which is answerable by empirical observation, and an issue where observation cannot identify a superior answer. Resolution of an issue is not found in data but in translating between formal models of the system being investigated.
I offer a model of theory in ecology. Following Robert Rosen, the model recognizes a dualism of an external world of natural systems and an inner world of formal systems within the self or mind. Formalisms relate propositions within formal systems by logical inference or other explicit internal rules of relationship. Newtownian dynamics is an example of a formalism. Phenomena of external natural systems are related by causality. Theory attempts to explain the natural world by embodying formal systems with external referents in natural systems. Phenomena of a natural system are encoded into propositions of a formal system by abstraction and measurement. The inferential structure of the formal system generates precise internal theorems which are predictions about causal relationships in the natural system. The predictions are tested by decoding from the inferred propositions of the formal system to observations of the natural world. To this dualism is added a third informal system which exists within the self or mind of the ecologist and embodies individual intuition and experience. Informal systems generate questions and guide the choice of interesting phenomena and appropriate formalisms. I propose that it is a relative deficiency of formalisms that distinguishes ecology from many of the other natural sciences and is responsible for much of the discontent with theory in ecology.
last minute substitution - no abstract available.
Plant ecologists emphasize multispecies combinations, multivariate methods, continuum theory and environmental and competition as dominant processes. Animal ecologists emphasize single species, experimental methods, niche theory and competition and predation as dominant processes. The differences are discussed in terms of continuum/niche theory, the role of multivariate methods in both disciplines and the importance of different processes in determining community composition. It is agreed that both paradigms are inadequate. Some suggestions for integration and improvement of these paradigms are made.
Interest in global system dynamics presents the daunting task of integrating data and models from different scientific disciplines and different time and space scales. In particular, ecological and biophysical information, intrinsically derived at the scale of the individual organism, must be extrapolated to the regional and global scales of climate models. Research tools such as remote sensing provide a means for the ecologist to operate at scales which are traditionally the home of atmospheric scientists. However, the large scale nature of remotely sensed data generates a new body of theory that will require a reevaluation of current ecological understanding. To evaluate successfully ecological processes at these larger spatial and temporal scales, remote sensing technology and ecological theory must be considered jointly.
Ecological systems are widely conceded to be complex, but efforts to define precisely the nature of this complexity, or to derive measures that could quantify it, engender less agreement. Complexity is probably best treated not as an intrinsic property of a system per se, but as a feature of our observations or other interactions with a system. A system may be regarded as complex due to either its structural or its dynamical properties. The relationship between structural and dynamical complexity is not a simple one; a structurally simple system may exhibit complex dynamics and vice versa. Proposed measures of complexity, taken from the literature of both the biological and the physical sciences, will be summarized, including: number of components, connectivity, heterogeneity, unpredictability, irreducibility, algorithmic complexity, and logical or thermodynamic depth.
Alan R. Johnson
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