Ecosystem :-

Organisms living in a particular environment, such as a forest or a coral reef, and the physical parts of the environment that affect them are known as Ecosystem. The term ecosystem was coined in 1935 by the British ecologist Sir Arthur George Tinsley, who described natural systems in “constant interchange” among their living and nonliving parts.
Coral reefs represent the most complex aquatic ecosystem found on Earth. Wetlands are complex ecosystems that provide spawning and nursery grounds for saltwater and freshwater fish, habitat for more than half of the migratory birds in the United States, and plant both exotic and commonplace. In addition to providing plant and animal habitat, wetlands play a crucial role in flood control and water filtration.

The ecosystem concept fits into an ordered view of nature that was developed by scientists to simplify the study of the relationship between organisms and their physical environment, a field known as ecology. At the top of the hierarchy is the planet’s entire living environment, known as the biosphere. Within this biosphere are several large categories of living communities known as biomes that are usually characterized by their dominate vegetation, such as grasslands, tropical forests, or deserts. The biomes are in turn made up of ecosystems. The living, or biotic, parts of an ecosystem, such as the plants, animals, and bacteria found in soil, are known as a community. The physical surroundings, or biotic components, such as the minerals found in the soil, are known as the environment or habitat.

Producers, consumers, decomposers, and a biotic matter form an integrated, functioning whole driven by the Sun’s energy. The living portion of an ecosystem is best described in terms of feeding levels known as tropic levels. Green plants make up the first tropic level and are known as primary producers.

Plants are able to convert energy from the sun into food in a process known as photosynthesis. In the second tropic level, the primary consumers known as herbivores are animals and insects that obtain their energy solely by eating the green plants. Third tropic level is composed of the secondary consumers, flesh-eating or carnivorous animals that feed on herbivores. At the fourth level are the tertiary consumers, carnivores that feed on other carnivores. Finally, the fifth tropic level consists of the decomposers, organisms such as fungi and bacteria that break down dead or dying matter into nutrients that can be used again.

Some or all of these tropic levels combine to form what is known as a food web, the ecosystem’s mechanism for circulating and recycling energy and materials. For example, in an aquatic ecosystem algae and other aquatic plants use sunlight to produce energy in the form of carbohydrates. Primary consumers such as insects and small fish may feed on some of this plant matter, and are in turn eaten by secondary consumers, such as salmon. A brown bear may play the role of the tertiary consumer by catching and eating salmon. Bacteria and fungi may the feed upon and decompose the salmon carcass left behind by the bear, enabling the valuable nonliving components of the ecosystem, such as chemical nutrients, to leach back into the soil and water, where they can be absorbed by the roots of plants. In this way nutrients and the energy that green plants derive from sunlight are efficiently transferred and recycled throughout the ecosystem.

Governments and Some NGOs have begun to restore the proper chain of ecosystem. They have adopted studies and training upon it. Large amount of money and concentration is put in restoring ecosystem management. Ecosystem management often requires special measures to protect threatened or endangered species that ply key roles in the ecosystem.