Ecological Orientors: Pattern and Process of Succession in Relation to Ecological Orientors

Abstract

A theoretical analysis reveals that the concept of "succession" is generally applied both to community and ecosystem phenomena, which must be kept strictly apart. "Succession" is also applied to phenomena which we call "dynamics". "change" and "development". Additionally. any satisfactory theory on the temporal behavior of ecological systems must account for both succession and its logical counterpart. constancy. Furthermore. it is shown that the community level is difficult to distinguish from both the population and the ecosystem level. Important community characteristics which enable us to delimit the community from other observation levels can be drawn from the analysis of semiautonomous behavior of hierarchically ordered levels. A list of aspects relating to semiautonomy distinguishing the community both from the ecosystem and the population is presented. The confusion relating to key concepts of spatial and temporal relations in ecological systems is outlined. Different terminologies are necessary to speak about observational and theoretical entities. "Pattern" and "process" are adequate terms of an observational terminology. while "structure" and "function" are terms of theoretical reasoning. Also. discreteness or continuity of phenomena must be described in different terms. The term "process" accounts for continuous phenomena. while the term "event" is necessary to describe discrete ones.An analysis of special problems of succession theory shows that descriptive succession theory must take into account three classes of change: changes in species composition. changes in important functional characters. and changes in type. An exhaustive causal repertoire of successional mechanisms is listed. The same mechanisms lead to either change or constancy. or to past. present. and future states of a system. Special emphasis is put on the deduction of zero-force laws. An inquiry of the reduction of community phenomena to population phenomena shows that invasion. maintenance. and extinction require different models of causality. While a causal theory for invasion is elaborated. maintenance and extinction are not yet well understood. Predictive succession theory is also not well developed. In an overview 15 successional theories are listed which F. Muller M. Leupelt (Eds.) Eco Targets. Goal Functions. and Orientors

Nuclear DNA in the determination of weighing factors to estimate exergy from organisms biomass

“…These ecological indicators may be understood as important measurable properties that are regularly optimized during the development of ecosystems. Several different indicators have been proposed and suggested as useful parameters to characterize the structure and function of systems under study (Bass, 1998;Brö ring and Wiegleb, 1998;Jørgensen and Nielsen, 1998a,b;Marques et al, 1998a;Patten, 1998;Svirezhev, 1998;Ulanowicz, 1998). Exergy, as an ecological quantitative indicator derived from thermodynamics, is a central concept expressing energy with a built-in attribute of quality (Jørgensen and Mejer, 1977, 1981Jørgensen, 1992a).…”

Untitled

“…With regard to environmental management, efforts have been directed to the identification and description of certain ecosystem features, which are regularly changed by self-organising ecological development (Odum, 1969;May, 1974;Wilson, 1975;Odum, 1983;Okubo, 1986;Weber et al, 1989;Costanza et al, 1992;Jørgensen, 1992;Jørgensen et al, 1992;Woodley et al, 1993;Schneider & Kay, 1994a;Müller, 1997;Baird, 1998). These systems attributes can be described as emergent or collective properties which are expected to be regularly optimised during ecosystems development (Müller 1996;Wiegleb & Bröring, 1996;Bröring & Wiegleb, 1998;Bossel, 1998;Müller & Fath, 1998). This means that certain states of such attributes can be taken as ecological orientors (Bossel, 1992) or attractors, that is, stages that an ecological system usually develops towards (Bossel, 1992(Bossel, , 1998Patten, 1997;Müller & Fath, 1998).…”

“…Some orientors have 'emerged' from interdisciplinary discussions embracing the fields of Thermodynamics, Succession Theory, and Network Theory (Bass, 1998;Bröring & Wiegleb, 1998;Jørgensen & Nielsen, 1998a, b;Marques et al, 1998a, b;Patten, 1998;Svirezhev, 1998;Ulanowicz, 1998). The exergy is a concept derived from Thermodynamics, interpreted as a function expressing energy with a built-in attribute of quality (in terms of energy potential to perform work) (Jørgensen & Mejer, 1977, 1979, 1981Jørgensen, 1992a), a measure of the contrast between a system and its surrounding environment (Wall, 1986;Schneider & Kay, 1994b;, or an estimate for the maximum capacity of energy to perform useful work as the system proceeds to equilibrium with its surroundings (Brzustowski & Golem, 1978;Ahern, 1980.…”