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Those who wish to adopt the textbooks are required to send a request to NCERT, upon which soft copies of the books are received. The material is press-ready and may be printed by paying a 5% royalty, and by acknowledging NCERT. [11] The textbooks are in color-print and are among the least expensive books in Indian book stores. [11]
An ecosystem (or ecological system) is a system formed by organisms in interaction with their environment. [2]: 458 The biotic and abiotic components are linked together through nutrient cycles and energy flows. Ecosystems are controlled by external and internal factors.
Ecosystems may be habitats within biomes that form an integrated whole and a dynamically responsive system having both physical and biological complexes. Ecosystem ecology is the science of determining the fluxes of materials (e.g. carbon, phosphorus) between different pools (e.g., tree biomass, soil organic material).
The global ocean covers more than 70% of the Earth's surface and is remarkably heterogeneous. Marine productive areas, and coastal ecosystems comprise a minor fraction of the ocean in terms of surface area, yet have an enormous impact on global biogeochemical cycles carried out by microbial communities, which represent 90% of the ocean's ...
In 1969, Eugene Odum published The Strategy of Ecosystem Development, a paper that was highly influential to conservation and environmental restoration. Odum argued that ecological succession was an orderly progression toward a climax state where “maximum biomass and symbiotic function between organisms are maintained per unit energy flow."
While an ecosystem often has no clear boundary, as a working model it is practical to consider the functional community where the bulk of matter and energy transfer occurs. [89] Nutrient cycling occurs in ecosystems that participate in the "larger biogeochemical cycles of the earth through a system of inputs and outputs." [89]: 425
Ecosystem complexity was once thought to reduce stability by enabling the effects of disturbances, such as species loss or species invasion, to spread and amplify through the network. However, other characteristics of network structure have been identified that reduce the spread of indirect effects and thus enhance ecosystem stability. [24]
The relationships between primary production and environmental conditions have helped account for variation within ecosystem types, allowing ecologists to demonstrate that energy flows more efficiently through aquatic ecosystems than terrestrial ecosystems due to the various bottom-up and top-down controls in play. [23]