Ecology is a science that studies the ecosystems at several levels: the population (individuals of the same species), the biotic community (or communities of species), ecotones and ecosystems of different habitats (marine, freshwater, land, ect .) and the biosphere. The Earth, an environmental perspective, includes multiple systems, the hydrosphere (or sphere of water), lithosphere (or sphere soil) and the atmosphere (or sphere of air).The biosphere is part of the terrestrial systems, it is the living part of the planet, the portion which houses the biological life that develops. It is a localized superficial dimension, which goes down to 11 000 feet deep and rising to 15 000 meters altitude above sea level The majority of living species live in area of -100 meters to 100 meters.
Life was first developed in the hydrosphere, at shallow depths in the photic zone. Multicellular beings then appeared and were also colonized benthic zones. Living Earth has developed more slowly after that has formed the ozone layer protecting living beings rays Ultraviolet. The terrestrial species are more diversified than the continents will be fragmented, or otherwise meet. Biosphere and biodiversity are inseparable characteristics of the planet Earth. We define the biosphere as the sphere of living, while biodiversity is the diversity. The sphere is the container, whereas diversity is its content. This diversity is expressed both at the ecological level (ecosystem), population (intraspecific diversity) and species (species diversity).
The biosphere contains great quantities of elements such as carbon, the nitrogen and the oxygen. Other elements such as phosphorus, the calcium, the potassium is also essential for life. In terms of ecosystems and the biosphere, there is a permanent recycling of all these elements, which alternate between the state mineral and the organic state (biogeochemical cycles).
Indeed, the functioning of ecosystems is mainly based on the conversion of the solar energy into chemical energy by organisms autotrophic, through photosynthesis (there is also a chemosynthesis without the use of solar energy). This leads to the production of sugar and release of oxygen. The latter is used by all agencies – as autotrophs heterotrophs – to break down sugars in the cell respiration, freeing the water from carbon dioxide and energy required to operate them. Thus, the activity of living beings is the source of the composition of the atmosphere, the gas flow being provided by large air currents.
The oceans are large tanks that store the exchange of water, ensure thermal and climatic stability, and transport of chemical elements thanks to large oceanic currents.
Similarly, the composition of soils is the result of the composition of the bedrock of the geological and the cumulative effects of living beings. To better understand the functioning of the biosphere, energy balance and dysfunctions related to human activity, American scientists have achieved under glass, a model of the biosphere, called Biosphere II.