The adaptive cycle: More than a metaphor

The adaptive cycle and its extension to panarchy (nested adaptive cycles) has been a useful metaphor and conceptual model for understanding long-term dynamics of change in ecological and social–ecological systems. We argue that adaptive cycles are ubiquitous in complex adaptive systems because they reflect endogenously generated dynamics as a result of processes of self-organization and evolution. We synthesize work from a wide array of fields to support this claim. If dynamics of growth, conservation, collapse and renewal are endogenous dynamics of complex adaptive systems, then there ought to be signals of system change over time that reflect this. We describe a series of largely thermodynamically based indicators that have been developed for this purpose, and we add a critical and heretofore missing component–namely, that of understanding dynamics of change (adaptive cycles) at objectively identified spatial and temporal scales nested within each system, instead of solely at the system level. The explicit consideration of scales, when coupled with selective indicators, may circumvent the need for multiple indicators to capture system dynamics and will provide a richer picture of system trajectory than that offered by a single-scale analysis. We describe feasible ways in which researchers could systematically and quantitatively look for signatures of adaptive cycle dynamics at scales within ecosystems, rather than relying on metaphor and largely qualitative descriptions

The adaptive cycle: More than a metaphor

The adaptive cycle and its extension to panarchy (nested adaptive cycles) has been a useful metaphor and conceptual model for understanding long-term dynamics of change in ecological and social–ecological systems. We argue that adaptive cycles are ubiquitous in complex adaptive systems because they reflect endogenously generated dynamics as a result of processes of self-organization and evolution. We synthesize work from a wide array of fields to support this claim. If dynamics of growth, conservation, collapse and renewal are endogenous dynamics of complex adaptive systems, then there ought to be signals of system change over time that reflect this. We describe a series of largely thermodynamically based indicators that have been developed for this purpose, and we add a critical and heretofore missing component–namely, that of understanding dynamics of change (adaptive cycles) at objectively identified spatial and temporal scales nested within each system, instead of solely at the system level. The explicit consideration of scales, when coupled with selective indicators, may circumvent the need for multiple indicators to capture system dynamics and will provide a richer picture of system trajectory than that offered by a single-scale analysis. We describe feasible ways in which researchers could systematically and quantitatively look for signatures of adaptive cycle dynamics at scales within ecosystems, rather than relying on metaphor and largely qualitative descriptions

The Role of Vegetation on the Ecosystem Radiative Entropy Budget and Trends Along Ecological Succession

Ecosystem entropy production is predicted to increase along ecological succession and approach a state of maximum entropy production, but few studies have bridged the gap between theory and data. Here, we explore radiative entropy production in terrestrial ecosystems using measurements from 64 Free/Fair-Use sites in the FLUXNET database, including a successional chronosequence in the Duke Forest in the southeastern United States. Ecosystem radiative entropy production increased then decreased as succession progressed in the Duke Forest ecosystems, and did not exceed 95% of the calculated empirical maximum entropy production in the FLUXNET study sites. Forest vegetation, especially evergreen needleleaf forests characterized by low shortwave albedo and close coupling to the atmosphere, had a significantly higher ratio of radiative entropy production to the empirical maximum entropy production than did croplands and grasslands. Our results demonstrate that ecosystems approach, but do not reach, maximum entropy production and that the relationship between succession and entropy production depends on vegetation characteristics. Future studies should investigate how natural disturbances and anthropogenic management—especially the tendency to shift vegetation to an earlier successional state—alter energy flux and entropy production at the surface-atmosphere interface