Brian D. Fath

Review of the Foundations of Network Environ Analysis

ABSTRACT This article introduces and summarizes the foundations of network environ analysis and describes four primary properties resulting from this research. These properties—dominance of indirect effects (Higashi and Patten 1986), network amplification (Patten and others 1990), network homogenization (Patten and others 1990), and network synergism (Patten 1991)—provide insight into the behavior of holistic network interactions. In short, amplification, homogenization, and indirect effects demonstrate the influence of the indirect flows in a system to show that energy or matter cycling allows flow to return to the same component many times and tend to become evenly distributed within the network. Synergism relates direct and indirect, qualitative relations to show that network organization is, on the whole, more mutualistic than is apparent from direct interactions alone. Using network analysis, objects can be studied as part of a connected system and the indirect effects can be identified and quantified. This is a fundamentally different way of investigating ecosystems, and it gives a quantitative foundation to the widely held perception of the interconnectedness of nature.

Network synergism: Emergence of positive relations in ecological systems

Abstract Traditional evolutionary theory depicts survival of the fittest as a difficult existence based on danger, conflict and strife. But, another view is emerging of a more synergistic organization in which ecosystems on the whole provide hospitable conditions for life. This world is populated by organisms mutually adapted and beneficial by virtue of their direct and indirect interactions. Many examples of mutualism have been explicitly observed (Bronstein, J.L., 1991. Bull. Ecol. Soc. Am. 72, 6–8; Cushman, J.H., Beattie, A.J., 1991. Trends Ecol. Evol. 6, 193–195; Casti, J.L., Karlqvist, A. (Eds.), 1995. Cooperation and Conflict in General Evolutionary Processes, Wiley, New York, 435 pp.), and we view mutualism as an implicit consequence of indirect interactions and ecosystem organization. This paper extends a methodology based on input-output analysis that models these synergistic relationships (Patten, B.C., 1991. Theoretical Studies of Ecosystems: The Network Perspective, pp. 288–351; Patten, B.C., 1992. Ecol. Modell. 62, 29–69). We show for simple storage-flow models that direct zero-sum resource transactions between organisms, when considered in context of the whole-system organization, produce integral (direct plus indirect) relationships more positive than the direct ones. This phenomenon, `network synergism, is demonstrated for two simple networks and a complete three component model. We also show, by looking at a limiting case, that system-wide synergism is ubiquitous, occurring in all models of any size or complexity. Network synergism emerges in these models because of three network properties: symmetry, indirectness and openness.

Towards a theory of sustainable systems

Abstract While there is tremendous interest in sustainability, a fundamental theory of sustainability does not exist. We present our efforts at constructing a theory from Information Theory and Ecological Models. We discuss the state of complex systems that incorporate ecological and other components in terms of dynamic behavior in a phase space defined by the system state variables. From sampling the system trajectory, a distribution function for the probability of observing the system in a given state is constructed, and an expression for the Fisher information is derived. Fisher information is the maximum amount of information available from a set of observations, in this case, states of the system. Fisher information is a function of the variability of the observations such that low variability leads to high Fisher information and high variability leads to low Fisher information. Systems in stable dynamic states have constant Fisher information. Systems losing organization migrate toward higher variability and lose Fisher information. Self-organizing systems decrease their variability and acquire Fisher information. These considerations lead us to propose a sustainability hypothesis: “sustainable systems do not lose or gain Fisher information over time.” We illustrate these concepts using simulated ecological systems in stable and unstable states, and we discuss the underlying dynamics.

Quantifying resource homogenization using network flow analysis

Abstract This paper formally introduces the rheomode orientation to network flow analysis and provides a quantitative test for the ecological property of network homogenization. Using network flow analysis, it is possible to identify and quantify the direct, indirect, and integral contributions of flow between any two components in a reticulated system. Inspection of the integral (direct plus indirect) flow matrix reveals many interesting properties not obvious from an empirical investigation of proximate transactions. Using network flow analysis, we observe that the composition of direct flows is comprised of a fairly uniform mixture of resources from all the system components. We call this evening out of flow network homogenization (Patten, B.C., Higashi, M., Burns, T.P., 1990. Ecol. Model. 51, 1–28). Here we introduce a standard statistical technique to provide a quantitative test for network homogenization. This property is the direct result of a flow oriented analysis of ecological systems. This has broader implications for the standard trophic dynamics paradigm currently dominating ecological research. The central results from this approach indicate that networks are holistic entities which must be analyzed as such.

A Utility Goal Function Based On Network Synergism

Network synergism is the property inherent in all complex adaptive systems that the direct resource transactions between organisms and their environments, when integrated across a whole-system organization, translate into integral (direct plus indirect) relationships that are more positive than the local ones (Fath and Patten, in press). Ecosystems on the whole provide hospitable conditions for life. These positive relationships are observed in the integral utility of the system. An input-output analysis based methodology that measures the total integral utility has been developed to model these synergistic relationships (Patten 1991, Patten,1992). In this paper, we demonstrate how network synergism arises in simple systems, and compare its behavior with several other proposed ecological goal functions namely trophic transfer efficiency (Odum 1969), cycling (Finn 1976), maximum power (Lotka 1922), maximum indirect effects (Patten 1995), and connectivity.

Ecosystems have connectivity

The web of life is an appropriate metaphor for living systems, whether they are ecological, anthropological, sociological, or some integrated combination, as most on earth now are. This phrase immediately forms the image of interactions and connectedness, both proximate and distal— a complex network of interacting parts, each playing off one another, providing constraints and opportunities for future behavior, where the whole is greater than the sum of the parts. The interconnected systems are viewed as networks because of the powerful exploratory advantage present when employing the tools of network analysis—graph theory, matrix algebra, and simulation modeling, etc. Networks are comprised of a set of objects with direct transaction among these objects. Although, the exchange is a discrete transfer, these transactions are viewed in total link direct and indirect parts together in an interconnected web, giving rise to the network structure. This chapter deals with that connectivity, provides an overview of systems approaches, introduces quantitative methods of ecological network analysis to investigate this connectivity, and concludes with some of the general insight that is gained from viewing ecosystems as networks.

Ecosystems have complex dynamics – disturbance and decay

This chapter discusses the role of destructive processes for ecosystem dynamics. Destructive processes are focal components of the overall ecosystem adaptability, and they can be found on all relevant scales. The growth and development processes in ecosystems remain incomplete if disturbance and decay are not taken into account. The individual living components of ecosystems have limited life spans that range from minutes to millennia. Death and decay of organisms and their subsystems are integral elements of natural dynamics. From a functional viewpoint, these processes are advantageous to replace highly loaded or exhausted components or to adjust physiologies to changing environmental conditions. In addition, populations have limited durations at certain places on earth. While operating in a hierarchy of constraints, populations break down. Following the thermodynamic argumentation in this chapter, in these situations a modified collection of organisms may take over, to increase the internal flows and to reduce the energetic, material, and structural losses into the environment in a greater quantity than the predecessors. Therefore, breakdown is the consequent reaction if the living conditions of a community change strongly. Thereafter, new potentials can be realized and the orientor behavior can start again with renewed site conditions. Adopting this argumentation, natural disturbances seem to be crucial for the long-term self-organization, for the ecological creativity, and for the long-term integrity of ecological entities.

Ecosystems have ontic openness

The term “ontic” relates to the term ontology, which is used in philosophy to designate the way the world is viewed by a person and the way it is composed. Ontic bears the slight difference that it refers to intrinsic properties of the world as the way it is constructed and its behavior, such that it addresses phenomenology as well. Therefore, this chapter complements the concepts of thermodynamic openness addressed in the previous chapter, by including the physical openness available to ecosystem development. It relates directly to the theme of this book and the systemness of ecosystems because ontic openness results in the natural world to form novel patterns due to the complex web of life that constantly combines, interacts, and rearranges. In addition, ontic openness is a partial cause of indeterminacy and uncertainty in ecology and thus, it is the reason that does not allow making exact predictions or measurements with such a high accuracy, as for instance in physical experiments. Therefore, when understanding ecosystems from a systems perspective, the importance of physical openness cannot be overlooked.

Introduction: A new ecology is needed

The political agenda imposed on ecologists and environmental managers has changed, since the focus is shifted on sustainability, which inevitably has made ecosystem functioning a core issue. In view of the different contributions to global environmental degradation, states have common but differentiated responsibilities. The developed countries acknowledge the responsibility that they bear in the international pursuit of sustainable development, in view of the pressures their societies place on the global environment and of the technologies and financial resources that they command. Ecosystem services are the benefits that people obtain from ecosystems. These include provisioning services such a food and water; regulating services such as flood and disease control; cultural services such as spiritual, recreational, and cultural benefits; and supporting services such as nutrient cycling, which maintain the conditions for life on earth. Currently, environmental managers have realized that maintenance of ecosystem structure and functioning by an integrated approach is a prerequisite for a successful environmental management strategy, which is able to optimize the ecosystem services for the benefit of mankind and nature.

Ecosystem principles have broad explanatory power in ecology

The criticism that ecology as a whole lacks universal laws and predictive theory is frequent, and there are authors who even argue that theoretical ecology is concerned with fitness and natural selection is not scientific. Scientific observations on natural phenomena usually give origin to possible explanations and provide tentative generalizations that may lead to broad-scale comprehension of the available information. Generalizations may be descriptive and inductive, deriving from observations that are carried out on observable characteristics, or that become much more eager, constituting the base of deductive theories. This chapter examines the compliance of ecosystem principles to a number of ecological rules or laws, and sees if other proposed non-universal explanations that are provided by different authors about different ecological problems can be further enlightened according to the same ecological principles. It is demonstrated that ecosystem principles—namely, translated in the Ecological Law of Thermodynamics, are fully compliant with the evolutionary theory and also encompass some of the most well known non-universal ecological theories.