From: Jõrgensen, S.E. 1992. Integration of Ecosystem Theories: A Pattern . Kluwer Academic Publishers, Dordrecht.

Proposition 1

Ecosystems are open systems and are dependent on a through-flow of first class energy (=exergy). When the energy needs for maintenance (catabolic processes) have been covered, the exergy is stored and the system thereby moves away from thermodynamic equilibrium.

Proposition 2

Developments of methods to maintain the biogeochemical energy already stored, i.e., increase in the level of organization and information of the ecosystems, are important milestones in the evolution.

Proposition 3

Ecosystems show a very wide spectrum of solutions to survival and growth under all even extreme conditions on the earth. The wide spectrum observed may be considered a result of the combination of 1) ELT (Ecological Law of Thermodynamics), 2) the very long time that has been available for the evolution (4 billion years), 3) the immense heterogeneity in time and 4) in space. The examinations of the development tendencies due to the available spectrum of solutions may be performed by use of ELT and models that must reflect the possibilities that the ecosystem may offer for utilization of the through flow of exergy.

Proposition 4

A wide spectrum of strategies from clear K-strategies to clear r-strategies is available to assure survival and growth under all conditions and in spite of the immense heterogeneity in time and space.

Proposition 5

Life in the form that we know from the earth is not possible without the presence of 1) 20-30 essential elements, 2) the temperature range presented on earth (approximately from -40oC to +90oC) and 3) water.

Proposition 6

The long period of selection pressure under the influence of all other biological components throughout the entire evolution (about 4 billion years) has developed a high extent of symbiosis or network mutalism, which explains the emergence of the Gaia-effect.

Proposition 7

As a result of the endeavor of ecosystems to find new pathways to move farther away from thermodynamic equilibrium, self-organization abilities of ecosystems and feedbacks that allow the circuit to learn from previous experience, have been developed.

Proposition 8

Ecosystems have a balanced (medium) connectivity. Too high a connectivity would create instability (chaos) and too low a connectivity would reduce the indirect effects which are beneficial for the ecosystem.

Proposition 9

The biological components of ecosystems adjust their properties (parameters) to obtain the highest possible organization and avoid chaos. The boundary between high organization and chaos offers a poised system with high adaptability and probability of survival and growth.

Proposition 10

Both matter and energy cycle in ecosystems, as a consequence of the flow of exergy through the system.

Proposition 11

Due to the high complexity of ecological networks, the indirect effect becomes dominant.

Proposition 12

The selection process must consider the forcing functions as well as all other components in the ecosystem which, together with the long evolution period, may explain why the indirect effects are beneficial for the entire system in contrast to many direct effects and why a network mutalism is formed as a result of the evolution process.

Proposition 13

Ecosystems have developed many pathways to assure survival of the selfish gene, i.e., the selection processes use a wide spectrum of different methods.

Proposition 14

Ecosystems possess buffer capacities, i.e., an ability to meet changes in external variables by such changes in the internal variables that the direct influence of the changes in the external variables is reduced.

Proposition 15

Ecosystems meet changes in external factors by such changes in internal variables that the buffer capacities, which are related to meet the changes caused by the external factors, are increased.

Proposition 16

High diversity does not necessarily give higher stability, buffer capacity or less probability for chaotic behavior, but gives more possibilities to find a better solution by selection processes for the ecosystem as entity, i.e., to find solutions for a higher probability of survival and growth.

Proposition 17

Ecosystems attempt by use of the entire hierarchy of regulation mechanisms to prevent catastrophic events. This ability is covered by the concept of buffer capacity (see proposition 14). Catastrophic events may, however, occur due to a sudden emergence of particular combinations of external factors, which cause a shift in the focal buffer capacity. The maintenance of certain levels of buffer capacities explains the appearance of hysteresis phenomena in relation to catastrophic behavior.

Proposition 18

A sudden change in the life conditions of an ecosystem is utilized by r-strategists, as they are characterized by the ability to grow rapidly. It can explain the occurrence of catastrophic behavior (jumps) of ecosystems. K-strategists on the other hand are associated with relatively predictable environment and biologically crowded communities.

Proposition 19

As the conservation principles, valid for energy and matter, limit further development of ecosystems based upon matter and energy, increase of information plays a major role in ecosystem development. It implies that diversity, organism size, organization of patterns, niche specialization, the complexity of life and mineral cycles, internal symbiosis, homeostatis and feedback control will all increase to make the fullest possible use of the available resources.

Proposition 20

An ecosystem attempts to find a steady state at the optimum operating point, which may be considered a balance between the thermodynamic and environmental forces.

Proposition 21

An ecosystem will never return exactly to the same operating point again, because the history and the combination of internal and external factors will never be the same again.

Proposition 22

The steady state of ecosystems may be considered as attractor points. An ecosystem will never get the same attractor point (equal to the steady state) again, because the history and the combination of internal and external factors will never be repeated.

Proposition 23

The entire ecosystem evolves as all the components of the ecosystem are linked in a network. The evolution of the ecosystem is irreversible, because it is dependent on the history of the system.

Proposition 24

Ecosystems (and the entire ecosphere) are characterized by an intermediate number of components (medium number systems). The components are all different and show a structured interrelationship.

Proposition 25

Both "bottom-up" and "top-down" effects may be of importance for ecosystem dynamics.

Proposition 26

The ecosystems have evolved to utilize the oscillations of forcing functions and the spatial heterogeneity to the benefit of the ecosystem, i.e., to gain exergy.

Proposition 27

The development and evolution of ecosystems can be described in many parallel ways: by the use of entropy production, exergy destruction, exergy production and ascendency. The selection of the most appropriate description method is dependent on the case study, the data and the aim of the description.