Ecosystem properties can only be revealed by a plurality of views. It is, therefore, not surprising that there are many different ecosystem theories published in the scientific literature. It is also important to try to understand the theories in relation to each other and examine if they are contradictory or form a pattern that can be used to give a better understanding of the nature of ecosystems and to solve the global environmental problems. The goal is to give a common framework of reference for further development of a more profound and comprehensive ecosystem theory than the one we are able to present today. The pattern should serve as a "conceptual diagram", which can be used as a basis for further discussion of ecosystems. We are still in an early stage of an ecosystem-theoretical development and it may be argued that this attempt is premature, but the experience from modeling has taught us that it is better to conclude one's thoughts in a conceptual diagram at an early stage and then be ready to make changes than to let all modeling efforts wait until all details are known, as this will never be the case due to the immense complexity of nature (Jorgensen, 2002). Moreover, recent development in ecosystem theory has made it possible to conclude that the theories presented here are indeed consistent and complimentary (Fath et al., 2001). The special issue in Ecological Modelling 158.3 (2002) has demonstrated that the theory can be applied to explain ecological observations, although the ecosystem theory presented here does not contain laws in the classical physical sense that we can make exact predictions. The theory is rather closer to quantum mechanics (we have to accept an uncertainty), chaos theory (sometimes predictions of complex systems are impossible), and the Prigogine thermodynamics (all processes are irreversible). Given the limitations in our theory, that ecosystems are enormously complex and we can, therefore, not know all details and that ecosystems have an ontic openness (see Chapter 3), it is still possible to apply the theory in ecology and environmental management.
The core pattern concerns the systemness of life and how these interactions lead to complex organization and dynamics. Understanding, measuring, and tracking these patterns is of paramount importance and the various holistic indicators have been developed to do so. Taken together, we can use this systems-oriented thermodynamic approach to formulate a limited number of propositions or hypotheses to explain a very large number of ecological observations. These recent developments in systems ecology represent a profound paradigm shift. The paradigm that is now receding has dominated our culture for several hundred years. It views the universe as a mechanical system composed of elementary building blocks. The new paradigm is based on a holistic worldview. The world is seen as an integrated whole and recognizes the fundamental interdependence of all phenomena.
In the paper by Jorgensen et al. (2000), Figure 6.9 illustrated the concomitant development of ecosystems, exergy captured (most of that being degraded) and exergy stored (biomass, structure, information). Data points correspond to different ecosystems (see Table 6.5, which shows the values). Debaljak (2001) showed that he gets the same shape of the curve when he determines exergy captured and exergy stored in managed forest and virgin forest on different stages of development (see Figure 6.10). The exergy captured was determined as in Table 6.5 by measurement of the temperature of the infrared radiation, while the exergy storage was determined by a randomized measurement of the size of all trees and plants. The stages are indicated on the figure, where also pasture is included for comparison. Catastrophic events as storm or fire may cause destructive regeneration, which is described below.
Holling (1986) (see Figure 6.11) has suggested how ecosystems progress through the sequential phases of renewal (mainly Growth Form I), exploitation (mainly Growth Form II), conservation (dominant Growth Form III), and creative destruction. The latter phase fits also into the three growth forms but will require a further explanation. The creative destruction phase is either a result of external or internal factors. In the first case (for instance hurricanes and volcanic activity), further explanation is not needed as an ecosystem has to use the growth forms under the prevailing conditions, which are determined by the external factors. If the destructive phase is a result of internal factors, then the question is "why would a system be self-destructive?"
A possible explanation is that a result of the conservation phase is that almost all nutrients will be contained in organisms which implies that there are no nutrients available to test new and possibly better solutions to move further away from thermodynamic equilibrium or expressed in Darwinian terms to increase the probability of survival. Holling also implicitly indicates this by calling this phase creative destruction.
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