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Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of")[A] is the branch of biology which studies the interactions among organisms and their environment. Objects of study include interactions of organisms with each other and with abiotic components of their environment. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits. Biodiversity means the varieties of species, genes, and ecosystems, enhances certain ecosystem services.

Ecology is not synonymous with environmentalism, natural history, or environmental science. It overlaps with the closely related sciences of evolutionary biology, genetics, and ethology. An important focus for ecologists is to improve the understanding of how biodiversity affects ecological function. Ecologists seek to explain:

  • Life processes, interactions, and adaptations
  • The movement of materials and energy through living communities
  • The successional development of ecosystems
  • The abundance and distribution of organisms and biodiversity in the context of the environment.

Ecology has practical applications in conservation biology, wetland management, natural resource management (agroecology, agriculture, forestry, agroforestry, fisheries), city planning (urban ecology), community health, economics, basic and applied science, and human social interaction (human ecology). For example, the Circles of Sustainability approach treats ecology as more than the environment 'out there'. It is not treated as separate from humans. Organisms (including humans) and resources compose ecosystems which, in turn, maintain biophysical feedback mechanisms that moderate processes acting on living (biotic) and non-living (abiotic) components of the planet. Ecosystems sustain life-supporting functions and produce natural capital like biomass production (food, fuel, fiber, and medicine), the regulation of climate, global biogeochemical cycles, water filtration, soil formation, erosion control, flood protection, and many other natural features of scientific, historical, economic, or intrinsic value.

The word "ecology" ("Ökologie") was coined in 1866 by the German scientist Ernst Haeckel. Ecological thought is derivative of established currents in philosophy, particularly from ethics and politics. Ancient Greek philosophers such as Hippocrates and Aristotle laid the foundations of ecology in their studies on natural history. Modern ecology became a much more rigorous science in the late 19th century. Evolutionary concepts relating to adaptation and natural selection became the cornerstones of modern ecological theory.

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An estuary mouth and coastal waters, part of an aquatic ecosystem
Pictured left: An estuary mouth and coastal waters, part of an aquatic ecosystem

An aquatic ecosystem is an ecosystem located in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.

Marine ecosystems cover approximately 71% of the Earth's surface and contain approximately 97% of the planet's water. They generate 32% of the world's net primary production. They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, in the water. Approximately 85% of the dissolved materials in seawater are sodium and chlorine. Seawater has an average salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems. Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, and sharks. Fish caught in marine ecosystems are the biggest source of commercial foods obtained from wild populations.

Freshwater ecosystems cover 0.80% of the Earth's surface and inhabit 0.009% of its total water. They generate nearly 3% of its net primary production. Freshwater ecosystems contain 41% of the world's known fish species. There are three basic types of freshwater ecosystems:

Wetlands are dominated by vascular plants that have adapted to saturated soil. Wetlands are the most productive natural ecosystems because of the proximity of water and soil. Due to their productivity, wetlands are often converted into dry land with dykes and drains and used for agricultural purposes. Their closeness to lakes and rivers means that they are often developed for human settlement.

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Lightnings sequence 2 animation-wcag.gif
Credit: Sebastien D'ARCO

Lightning is an atmospheric electrostatic discharge (spark) accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms. The study of the atmosphere and atmospheric variables that affect various ecoregions and ecosystems is a significant part of the discipline of Ecology.

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Ernst Heinrich Philipp August Haeckel (February 16, 1834 – August 9, 1919), also written von Haeckel, was an eminent German biologist and philosopher. He promoted Charles Darwin's work in Germany and developed the theory that the organism's biological development, or ontogeny, parallels its species' evolutionary development, or phylogeny.

The published artwork of Haeckel includes over 100 detailed, multi-color illustrations of animals and sea creatures (see: Kunstformen der Natur, "Art Forms of Nature"). As a philosopher, Ernst Haeckel wrote Die Welträtsel (1895–1899, in English, The Riddle of the Universe, 1901), the genesis for the term "world riddle" (Welträtsel); and Freedom in Science and Teaching to support the teaching of evolution.

Did you know...

...that in 2006, the United Nations estimated humanity's total ecological footprint to be 1.4 planet Earths? In other words, humanity uses ecological services 1.4 times as fast as Earth can renew them?[1]
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Since natural resources are finite, increased consumption must inevitably lead to depletion and scarcity.
— Paul Ehrlich

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Le Naturaliste Canadien is a Canadian French-language peer-reviewed scientific journal published semiannually by the Société Léon-Provancher d'Histoire Naturelle du Canada. The journal publishes articles on all topics of natural sciences with a specific focus on ecology and conservation biology in Quebec. The journal also acts as the official publication of the society. The journal is the oldest scientific publication in French in North America and one of the oldest scientific journals still in publication in Canada.

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  1. ^ "Data Sources". Global Footprint Network. 2010-02-05. Retrieved 2010-02-05.