1.History of ecology .Ecology as a science. Sub-disciplines of ecology. Economics and Ecology. Ecology appeared as a distinct field of science in the second part of the nineteenth century from a diversity of different areas, such as geography, plant physiology, taxonomy, and the theory of evolution. In 1893 two significant events happened. First, the book “Flower Ecology” by L.H. Pammel, was published. Secondly, the Madison Botanical Congress adopted the term "ecology" as denoting a new branch of botany distinct from physiology and morphology. One of the most important contributors in the development of an ecological view on nature was Swedish botanist Carolus Linnaeus. In the book “The Oeconomy of Nature” published in 1749, Linnaeus described his view on nature, which is seemingly chaotic. German scientist Alexander von Humboldt was the main opponent of these views. According to Humboldt’s view, all phenomena in nature were interconnected. English naturalist Charles Darwin's “On the Origin of Species”, published in 1859. Darwin's theory of evolution by natural selection provided a mechanism, not only for understanding how species arose, but also for interpreting patterns in the distribution and abundance of species. Haeckel published “The Morphology of Organisms” in 1866 with the aim of interpreting anatomy in the light of evolution. In this book, Haeckel provided the first definition of ecology: "By ecology we mean the body of knowledge concerning the economy of nature—the total relations of the animal to both to its inorganic and organic environment.“ The term oekologie was coined from the Greek oikos meaning "household" and logos meaning "study"; hence, the "study of the household of nature". E. P. Odum defined ecology as, “the study of the structure and function of nature, which includes the living world”. He referred to ecosystem as the basic fundamental unit of ecology. ecological science, is the scientific study of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment.Subdisciplines: Ecophysiology, Ecomechanics, Population ecology, Community ecology, Ecosystem ecology, Systems ecology, Evolutionary ecology, Political ecology. Ecological economics is the union of economics and ecology, with the economy conceived as a subsystem of the earth ecosystem that is sustained by a metabolic flow or "throughput" from and back to the larger system. 2.Structure of Biosphere (Lithosphere, Hydrosphere and Atmosphere). Earth consists of three components: Lithosphere (or sphere of land), Hydrosphere (or sphere of water) and Atmosphere (or sphere of Air). The life supporting zone of the earth where atmosphere, hydrosphere and lithosphere meet, interact and make life possible, is known as biosphere (or sphere of life). 3. The Concept of an ecosystem. An ecosystem as a structural and functional unit of the biosphere. An ecosystem can be defined as 'a structural and functional unit of biosphere or segment of nature consisting of community of living beings and the physical environment, both interacting and exchanging materials between them'. An ecosystem is a self sustaining structural and functional unit of the biosphere. The ecosystem is composed of two entities, the entirety of life -the biocenosis and the medium that life exists in (the biotope). 4. The structure of ecosystems (biotic and abiotic components). The study of ecosystems mainly consists of the study of certain processes that link the living, or biotic, components to the non-living, or abiotic, components. 5. Classification of ecosystems.
Ecosystems are often classified by reference to the biotopes concerned. The following ecosystems may be defined: Continental ecosystems, such as forest ecosystem , meadow ecosystems, deserts or agro-ecosystems. Ecosystems of inland waters, such as lentic ecosystems (lakes, ponds) or lotic ecosystems (rivers). Oceanic ecosystems (seas,...
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