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Regime Shift
Regime shifts are large, abrupt, persistent changes in the structure and function of ecosystems, the climate, financial systems or other complex systems.Lewontin, R. (1969) Meaning of Stability. ''Brookhaven Sym Biol'', 13Holling, C.S. (1973) Resilience and stability of ecological systems. ''Annual Review of Ecology and Systematics'' 4, 1–23Biggs, 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, 591–596Scheffer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes. Ecosystems are controlled by external and internal factors. External factors such as climate, parent material which forms the soil and topography, control the overall structure of an ecosystem but are not themselves influenced by the ecosystem. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvesting
Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-intensive activity of the growing season. On large mechanized farms, harvesting uses the most expensive and sophisticated farm machinery, such as the combine harvester. Process automation has increased the efficiency of both the seeding and harvesting processes. Specialized harvesting equipment utilizing conveyor belts to mimic gentle gripping and mass-transport replaces the manual task of removing each seedling by hand. The term "harvesting" in general usage may include immediate postharvest handling, including cleaning, sorting, packing, and cooling. The completion of harvesting marks the end of the growing season, or the growing cycle for a particular crop, and the social importance of this event makes it the focus of seasonal celebratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Regime
An international regime is the set of principles, norms, rules and procedures that international actors converge around. Sometimes, when formally organized, it can transform into an intergovernmental organization. Definition and types Stephen D. Krasner defines international regimes as "sets of implicit or explicit principles, norms, rules, and decision-making procedures around which actors' expectations converge in a given area of international relations". Regimes "are more specialized arrangements that pertain to well-defined activities, resources, or geographical areas and often involve only some subset of the members of international society", according to Oran R. Young. Types of regimes include International Conventions such as the Basel Convention, the Mediterranean Action Plan and well-known regimes like the Bretton Woods System of monetary management. International Regimes might also include international organizations in a broader sense. Formation International regime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Path Dependency
Path dependence is a concept in economics and the social sciences, referring to processes where past events or decisions constrain later events or decisions. It can be used to refer to outcomes at a single point in time or to long-run equilibria of a process. Path dependence has been used to describe institutions, technical standards, patterns of economic or social development, organizational behavior, and more. In common usage, the phrase can imply two types of claims. The first is the broad concept that "history matters", often articulated to challenge explanations that pay insufficient attention to historical factors. This claim can be formulated simply as "the future development of an economic system is affected by the path it has traced out in the past" or "particular events in the past can have crucial effects in the future." The second is a more specific claim about how past events or decisions affect future events or decisions in significant or disproportionate ways, throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Economics
Economics () is the social science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services. Economics focuses on the behaviour and interactions of Agent (economics), economic agents and how economy, economies work. Microeconomics analyzes what's viewed as basic elements in the economy, including individual agents and market (economics), markets, their interactions, and the outcomes of interactions. Individual agents may include, for example, households, firms, buyers, and sellers. Macroeconomics analyzes the economy as a system where production, consumption, saving, and investment interact, and factors affecting it: employment of the resources of labour, capital, and land, currency inflation, economic growth, and public policies that have impact on glossary of economics, these elements. Other broad distinctions within economics include those between positive economics, desc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sociology
Sociology is a social science that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. It uses various methods of Empirical research, empirical investigation and critical analysis to develop a body of knowledge about social order and social change. While some sociologists conduct research that may be applied directly to social policy and welfare, others focus primarily on refining the Theory, theoretical understanding of social processes and phenomenology (sociology), phenomenological method. Subject matter can range from Microsociology, micro-level analyses of society (i.e. of individual interaction and agency (sociology), agency) to Macrosociology, macro-level analyses (i.e. of social systems and social structure). Traditional focuses of sociology include social stratification, social class, social mobility, sociology of religion, religion, secularization, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Political Science
Political science is the scientific study of politics. It is a social science dealing with systems of governance and power, and the analysis of political activities, political thought, political behavior, and associated constitutions and laws. Modern political science can generally be divided into the three subdisciplines of comparative politics, international relations, and political theory. Other notable subdisciplines are public policy and administration, domestic politics and government, political economy, and political methodology. Furthermore, political science is related to, and draws upon, the fields of economics, law, sociology, history, philosophy, human geography, political anthropology, and psychology. Political science is methodologically diverse and appropriates many methods originating in psychology, social research, and political philosophy. Approaches include positivism, interpretivism, rational choice theory, behaviouralism, structuralism, post-struct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Historical Institutionalism
Historical institutionalism (HI) is a new institutionalist social science approach that emphasizes how timing, sequences and path dependence affect institutions, and shape social, political, economic behavior and change. Unlike functionalist theories and some rational choice approaches, historical institutionalism tends to emphasize that many outcomes are possible, small events and flukes can have large consequences, actions are hard to reverse once they take place, and that outcomes may be inefficient. A critical juncture may set in motion events that are hard to reverse, because of issues related to path dependency. Historical institutionalists tend to focus on history (longer temporal horizons) to understand why specific events happen. The term "Historical Institutionalism" began appearing in publications in the early 1990s, although it had been used in the late 1980s. The most widely cited historical institutionalist scholars are Peter Hall, Paul Pierson, Theda Skocpol, Doug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drylands
Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical and temperate areas with an aridity index of less than 0.65."Millennium Ecosystem Assessment, 2005. Drylands Systems". Chapter 22 in: ''Ecosystems and Human Wellbeing: Current State and Trends'', Volume 1. Island Press. One can classify drylands into four sub-types: * Dry sub-humid lands * Demi-arid lands * Arid lands * Hyper-arid lands Some authorities regard hyper-arid lands as deserts (United Nations Convention to Combat Desertification - UNCCD) although a number of the world's deserts include both hyper-arid and arid climate zones. The UNCCD excludes hyper-arid zones from its definition of drylands. Drylands cover 41.3% of the earth's land surface, including 15% of Latin America, 66% of Africa, 40% of Asia, and 24% of Europe. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral Reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian. Sometimes called ''rainforests of the sea'', shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France, yet they provide a home for at least 25% of all marine species, including fish, mollusks, worms, crustaceans, echinoderms, sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelp Forest
Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Earth.Mann, K.H. 1973. Seaweeds: their productivity and strategy for growth. Science 182: 975-981. Although algal kelp forest combined with coral reefs only cover 0.1% of Earth's total surface, they account for 0.9% of global Primary production, primary productivity. Kelp forests occur worldwide throughout temperate and polar region, polar coastal oceans. In 2007, kelp forests were also discovered in tropical waters near Ecuador.Graham, M.H., B.P. Kinlan, L.D. Druehl, L.E. Garske, and S. Banks. 2007. Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity. Proceedings of the National Academy of Sciences 104: 16576-16580. Physically formed by brown macroalgae, kelp forests provide a unique habitat for m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Exponential Growth
Biological exponential growth is the unrestricted growth of a population of organisms, occurring when resources in its habitat are unlimited. Most commonly apparent in species that reproduce quickly and asexually, like bacteria, exponential growth is intuitive from the fact that each organism can divide and produce two copies of itself. Each descendent bacterium can itself divide, again doubling the population size. The bacterium Escherichia coli, under optimal conditions, may divide as often as twice per hour. Left unrestricted, a colony would cover the Earth's surface in less than a day. If, in a hypothetical population of size ''N'', the birth rates (per capita) are represented as ''b'' and death rates (per capita) as ''d'', then the increase or decrease in ''N'' during a time period ''t'' will be \frac=(b-d)N (b-d) is called the 'intrinsic rate of natural increase' and is a very important parameter chosen for assessing the impacts of any biotic or abiotic factor on population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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