ECOSYSTEM





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An ecosystem is a community of living organisms in conjunction with the nonliving components   of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers  release carbon back to the atmosphere and facilitate nutrients cycling  by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.
Ecosystems are controlled by external and internal factors. External factors such as climate,parent material  which forms the soil and topography control the overall structure of an ecosystem but are not themselves influenced by the ecosystem. Unlike external factors, internal factors are controlled, for example, decomposition, root competition, shading, disturbance, succession, and the types of species present.
Ecosystems are dynamic entities—they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops.
Resource inputs are generally controlled by external processes like climate and parent material. Resource availability within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Although humans operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.
biodiversity affects ecosystem functioning, as do the processes of disturbances and succession. Ecosystems provide a variety of goods and services  upon which people depend.(READ MORE)

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Threats to Ecosystems

For thousands of years, people have interacted with ecosystems. Many cultures developed around nearby ecosystems. Many Native American tribes of North Americas great planes developed a complex lifestyle based on the native plants and animals of plains ecosystems, for instance. bisons a large grazing animal native to the Great Plains, became the most important biotic factor in many Plains Indians cultures, such as the lakota or kiowa. Bison are sometimes mistakenly called buffalo. These tribes used buffalo hides for shelter and clothing, buffalo meat for food, and buffalo horn for tools. The tallgrass prairie  of the Great Plains supported bison herds which tribes followed throughout the year.


As human populations have grown, however, people have overtaken many ecosystems. The tallgrass prairie of the Great Plains, for instance, became farmland. As the ecosystem shrunk, fewer bison could survive. Today, a few herds survive in protected ecosystems such as Yellowstone National Park.

In the tropical rain forest  ecosystems surrounding the Amazon River in South America, a similar situation is taking place. The Amazon rain forest includes hundreds of ecosystems, including canopies, understories, and forest floors. These ecosystems support vast food web.

Canopies are ecosystems at the top of the rainforest, where tall, thin trees such as figs grow in search of sunlight. canopy ecosystems also include other plants, called epipytes which grow directly on branches. understory ecosystems exist under the canopy. They are darker and more humid than canopies. Animals such as monkeys live in understory ecosystems, eating fruits from trees as well as smaller animals like beetles. Forest floor ecosystems support a wide variety of flowers, which are fed on by insects like butterflies. Butterflies, in turn, provide food for animals such as spiders in forest floor ecosystems.

Human activity threatens all these rain forest ecosystems in the Amazon. Thousands of acres of land are cleared for farmland, housing, and industry. Countries of the Amazon rain forest, such as Brazil, Venezuela, and Ecuador, are underdeveloped. Cutting down trees to make room for crops such as soy and corn benefits many poor farmers. These resources give them a reliable source of income  and food. Children may be able to attend school, and families are able to afford better health care.

However, the destruction of rain forest ecosystems has its costs. Many modern medecines have been developed from rain forest plants. curare, a muscle relaxant, and quinine used to treat malaria, are just two of these medicines. Many scientists worry that destroying the rain forest ecosystem may prevent more medicines from being developed.

The rain forest ecosystems also make poor farmland. Unlike the rich soils of the Great Plains, where people destroyed the tallgrass prairie ecosystem, Amazon rain forest soil is thin and has few nutrients. Only a few seasons of crops may grow before all the nutrients are absorbed. The farmer or agribusiness. must move on to the next patch of land, leaving an empty ecosystem behind.

Rebounding Ecosystems
Ecosystems can recover from destruction, however. The delicate coral reef  ecosystems in the South Pacific are at risk due to rising ocean temperatures and decreased  salinity. Corals bleach, or lose their bright colors, in water that is too warm. They die in water that isnt salty enough. Without the reef structure, the ecosystem collapses. Organisms such as algae, plants such as seagrass, and animals such as fish, snakes, and shrimp disappear.

Most coral reef ecosystems will bounce back from collapse. As ocean temperature cools and retains more salt, the brightly colored corals return. Slowly, they build reefs. Algae, plants, and animals also return.

Individual people, cultures, and governments are working to preserve ecosystems that are important to them. The government  of Ecuador, for instance, recognizes ecosystem rights in the countrys constitusion The so-called Rights of Nature says Nature or pachamama  [Earth], where life is reproduced and exists, has the right to exist,persist,maintain  and regenerate its vital cycles, structure, functions and its processes in evolution Every person, people, community or nationality, will be able to demand the recognitions of rights for nature before the public bodies. Ecuador is home not only to rain forest ecosystems, but also river ecosystems and the remarkable ecosystems on the Galapagos Islands.
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