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In ecology, regime shifts are large, abrupt, persistent changes in the structure and function of a system.〔Biggs, R., et al. (2009) Turning back from the brink: Detecting an impending regime shift in time to avert it. ''P Natl Acad Sci Usa'' 106, 826–831〕 A regime is a characteristic behaviour of a system which is maintained by mutually reinforced processes or feedbacks. Regimes are considered persistent relative to the time period over which the shift occurs. The change of regimes, or the shift, usually occurs when a smooth change in an internal process (feedback) or a single disturbance (external shocks) triggers a completely different system behavior.〔Scheffer, M., et al. (2001) Catastrophic shifts in ecosystems. ''Nature'' 413, 591–596〕〔Scheffer, M., and Carpenter, S. (2003) Catastrophic regime shifts in ecosystems: linking theory to observation. ''Trends Ecol. Evol.'' 18, 648–656〕〔Folke, C., et al. (2004) Regime Shifts, Resilience, and Biodiversity in Ecosystem Management. ''Annu. Rev. Ecol. Evol. Syst.'' 35, 557–581〕〔Beisner, B., et al. (2003) Alternative stable states in ecology. ''Front. Ecol. Environ.'' 1, 376–382〕 Although such non-linear changes have been widely studied in different disciplines ranging from atoms to climate dynamics,〔Feudel, U. (2008) Complex dynamics in multistable systems. ''Int J Bifurcat Chaos'' 18, 1607–1626〕 regime shifts have gained importance in ecology because they can substantially affect the flow of ecosystem services that societies rely upon,〔Biggs, R., et al. (2009) Turning back from the brink: Detecting an impending regime shift in time to avert it. ''P Natl Acad Sci Usa'' 106, 826–831〕〔Millennium Ecosystem Assessment (2005) Ecosystems and human well-being: biodiversity synthesis. 87〕 such as provision of food, clean water or climate regulation. Moreover, regime shift occurrence is expected to increase as human influence on the planet increases – the Anthropocene〔Steffen, W., et al. (2007) The Anthropocene: Are humans now overwhelming the great forces of nature. ''Ambio'' 36, 614–621〕 – including current trends on human induced climate change and biodiversity loss.〔Rockström, J., et al. (2009) A safe operating space for humanity. ''Nature'' 461, 472–475〕 ==History of the concept== Scholars have been interested in systems exhibiting non-linear change for a long time. Since the early 20th century, mathematicians have developed a body of concepts and theory for the study of such phenomena based on the study of non-linear system dynamics. This research led to the development of concepts such as catastrophe theory; a branch of bifurcation theory in dynamical systems. In ecology the idea of systems with multiple regimes, domains of attraction called alternative stable states, only arose in the late '60s based upon the first reflections on the meaning of stability in ecosystems by Richard Lewontin〔Lewontin, R. (1969) Meaning of Stability. ''Brookhaven Sym Biol'', 13〕 and Crawford “Buzz” Holling.〔Holling, C.S. (1973) Resilience and stability of ecological systems. ''Annual review of ecology and systematics'' 4, 1–23〕 The first work on regime shifts in ecosystems was done in a diversity of ecosystems and included important work by Noy-Meir (1975) in grazing systems;〔Noymeir, I. (1975) Stability of Grazing Systems - Application of Predator-Prey Graphs. ''Journal of Ecology'' 63, 459–481〕 May (1977) in grazing systems, harvesting systems, insect pests and host-parasitoid systems;〔May, R.M. (1977) Thresholds and Breakpoints in Ecosystems with a Multiplicity of Stable States. ''Nature'' 269, 471–477〕 Jones and Walters (1976) with fisheries systems;〔Jones, D.D., and Walters, C.J. (1976) Catastrophe Theory and Fisheries Regulation. ''Journal of the Fisheries Research Board of Canada'' 33, 2829–2833〕 and Ludwig et al. (1978) with insect outbreaks.〔Ludwig, D., et al. (1978) Qualitative-Analysis of Insect Outbreak Systems - Spruce Budworm and Forest. ''J. Anim. Ecol.'' 47, 315–332〕 These early efforts to understand regime shifts were criticized for the difficulty of demonstrating bi-stability, their reliance on simulation models, and lack of high quality long-term data.〔Collie, J., et al. (2004) Regime shifts: can ecological theory illuminate the mechanisms? ''Prog. Oceanogr.'' 60, 281–302〕 However, by the 1990s more substantial evidence of regime shifts was collected for kelp forest, coral reefs, drylands and shallow lakes. This work led to revitalization of research on ecological reorganization and the conceptual clarification that resulted in the regime shift conceptual framework in the early 2000s.〔Scheffer, M., et al. (2001) Catastrophic shifts in ecosystems. ''Nature'' 413, 591–596〕〔Scheffer, M., and Carpenter, S. (2003) Catastrophic regime shifts in ecosystems: linking theory to observation. ''Trends Ecol. Evol.'' 18, 648–656〕〔Folke, C., et al. (2004) Regime Shifts, Resilience, and Biodiversity in Ecosystem Management. ''Annu. Rev. Ecol. Evol. Syst.'' 35, 557–581〕〔Beisner, B., et al. (2003) Alternative stable states in ecology. ''Front. Ecol. Environ.'' 1, 376–382〕 Outside of ecology, similar concepts of non-linear change have been developed in other academic disciplines. One example is historical institutionalism in political science, sociology and economics, where concepts like path dependency and critical junctures are used to explain phenomena where the output of a system is determined by its history, or the initial conditions, and where its domains of attraction are reinforced by feedbacks. Concept such as international institutional regimes, socio-technical transitions and increasing returns have an epistemological basis similar to regime shifts, and utilize similar mathematical models. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「regime shift」の詳細全文を読む スポンサード リンク
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