Ecosystems and the Biosphere as Complex Adaptive Systems

Ecosystems are prototypical examples of complex adaptive systems, in which patterns at higher levels emerge from localized interactions and selection processes acting at lower levels. An essential aspect of such systems is nonlinearity, leading to historical dependency and multiple possible outcomes of dynamics. Given this, it is essential to determine the degree to which system features are determined by environmental conditions, and the degree to which they are the result of self-organization. Furthermore, given the multiple levels at which dynamics become apparent and at which selection can act, central issues relate to how evolution shapes ecosystems properties, and whether ecosystems become buffered to changes (more resilient) over their ecological and evolutionary development or proceed to critical states and the edge of chaos. Received 14 April 1998; accepted 26 May 1998.     

Use of Complex Adaptive Systems for Modeling Global Change

Global modeling has been used for decades to assess the possible futures of humanity and the global environment. However, these models do not always satisfactorily include the adaptive characteristics of systems. In this article, a general approach is used to simulate change and transition at a macrolevel due to adaptation at a microlevel. Tools from complex adaptive systems research are used to simulate the microlevel and consequently determine parameter values of the equation-based macrolevel model. Two case studies that applied this approach are reviewed. The first study assessed the efficacy of efforts to control malaria, whereas the second study used an integrated model to construct climate change scenarios by using various possible views on the nature of the climate system. Received 14 April 1998; accepted 7 July 1998.     

Motivation and Benefits of Complex Systems Approaches in Ecology

Studies of complex systems in other disciplines provide models and analytical strategies for understanding ecosystems and landscapes. The emphasis is on invariant properties, particularly processes that create scaling relations over wide ranges of scale, both in time and space. Translations between levels of ecological organization may be accomplished by succinct characterizations of processes that operate at fine scales, followed by renormalization group analysis to reveal patterns at broad scales. The self-organized patterns found in simple ecosystem, landscape, and forest-fire models may be explained as feedback between the system state and control parameters. Critical phenomena and phase transitions are expected in open, dissipative systems where long-range correlations defy predictions based on average population densities, a concept that becomes irrelevant as nonstationary conditions prevail. Thus, complexity theory for open systems relates to the ecology of self-entailing ecosystems that function as their own environments and thereby create constraints through emergence. Received: 14 April 1998; accepted 26 May 1998     

Complex Adaptive Systems and the Evolution of Reciprocation

Complex adaptive systems play a major role in the theory of reciprocal altruism. Starting with Axelrod's celebrated computer tournaments, a wide variety of computer simulations show that cooperation can evolve in populations of selfish agents, both with direct and indirect reciprocation. Received 14 April 1998; accepted 16 June 1998.     

Biological Motion as an Innate Perceptual Mechanism Driving Social Affiliation

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Understanding the Complexity of Economic, Ecological, and Social Systems

Hierarchies and adaptive cycles comprise the basis of ecosystems and social-ecological systems across scales. Together they form a panarchy. The panarchy describes how a healthy system can invent and experiment, benefiting from inventions that create opportunity while being kept safe from those that destabilize because of their nature or excessive exuberance. Each level is allowed to operate at its own pace, protected from above by slower, larger levels but invigorated from below by faster, smaller cycles of innovation. The whole panarchy is therefore both creative and conserving. The interactions between cycles in a panarchy combine learning with continuity. An analysis of this process helps to clarify the meaning of “sustainable development.” Sustainability is the capacity to create, test, and maintain adaptive capability. Development is the process of creating, testing, and maintaining opportunity. The phrase that combines the two, “sustainable development,” thus refers to the goal of fostering adaptive capabilities and creating opportunities. It is therefore not an oxymoron but a term that describes a logical partnership. Received 7 March 2001; accepted 16 March 2001.     

Ants resort to majority concession to reach democratic consensus in the presence of a persistent minority

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Reconciling Ecosystem Rehabilitation and Service Reliability Mandates in Large Technical Systems: Findings and Implications of Three Major US Ecosystem Management Initiatives for Managing Human-Dominated Aquatic-Terrestrial Ecosystems

How can decision makers reconcile the demand for increasingly reliable services drawn from the environment (including water and power) with the desire for both a better environment and more environmental amenities? In this paper, which is based on US case studies of ecosystem rehabilitation initiatives in the San Francisco Bay-Delta, the Columbia River Basin in the Pacific Northwest, and the Florida Everglades, we focus on several notable problems in current management practice. We assess the role of adaptive management and identify five areas of major innovation by which ecologists and the authorities that operate large water and hydropower systems attempt to reconcile the tension between maintaining service reliability and promoting ecological rehabilitation. The implications of the findings for a wider framework within which ecosystems can be matched to the most appropriate management regime are related specifically to aquatic-terrestrial ecosystems. Finally, we emphasize the importance of redefining ecosystem functions and services so that the inherent conflict between high-reliability services and ecosystem rehabilitation can be reconciled.