Ecosystem

What does mean by ecosystem?

Meaning: the living community of plants and animals in any area together with the non-living components of the environment such as soil, air and water is called ecosystem.

Ecosystems have been formed on land and in the sea by evolution that has created species to live together in a specific region. Thus ecosystems have both non-living and living components that are typical to an area giving its own special characteristic that are easily observed. Natural ecosystem includes forests, grasslands, deserts, and aquatic ecosystem such as ponds, rivers, lakes and the sea. Man modified ecosystem includes agricultural land and urban or industrial land.

Ecosystem and man – every region of our earth has different ecosystem based on its climatic conditions and geographical feature. Ecosystems are divided into terrestrial or land based ecosystems and aquatic ecosystems in water. These form the two major habitat conditions for the Earth’s living organism. All the living organism in an area live in communities of plants and animals. They interact with their non-living environment and with each other at different points in time for a large number of reasons. Life can exist only in small proportion of the earth’s land, water and its atmosphere. Ecosystems are the basis of life itself: the natural ecosystems in the wilderness provide a variety of products without which human civilization would not be able to exist.

Producers, Consumers and Decomposers

Every living organism is in some way dependent on other organism. Plants are food for herbivorous animals that are in turn food for carnivorous animals. Thus there are different trophic levels in the ecosystem. Some organism such as fungi lives only on dead material and inorganic matter.

Plants are the ‘producers’ in the ecosystem as they manufacture their food by using energy from the sun. In the forest, these form communities of plant life.

The herbivorous animals are primary consumer as they live on the producers. In a forest, these are the insects, reptiles, and birds. The herbivorous animals include for example deer and elephants that live on plants life. They gaze on grass of feed on the foliage (trees leaves) from trees. In grass lands, there are herbivorous such as the blackbuck that feed on grass. In the sea, there are small fish that live on algae and other plants.

There are carnivorous animals, or secondary consumers, which live on herbivorous animals. In our forests, the carnivorous animals are tiger, leopards, foxes and small wild cats. In the sea, carnivorous fish live on other fish.

Decomposers are a group of organism consisting of small animals like worms, insects, bacteria and fungi, which break down dead organic material into smaller particles and finally into simpler substances that are used by plants as nutrition. Decomposition thus is a vital function in nature, as without this, all the nutrients would be tied up in dead matter and no new life could be produced.

Every ecosystem has several interrelated mechanisms that affect human life. These are the water cycle, the carbon cycle, the oxygen cycle, the nitrogen cycle and the energy cycle. While every ecosystem is controlled by these cycles, in each ecosystem its abiotic and biotic features are distinct from each other. All the functions of the ecosystem are in some way related to the growth and regeneration of its plant and animals species. These linked processes can be depicted as the various cycles. These processes depend on energy from sunlight. The water cycle depends on the rainfall, which is necessary for plants and animals to live. The energy cycles recycles nutrients into the soil on which plant life grows. Our own lives are closely linked to the proper functioning of these cycles of life. If human activities o on altering them, humanity cannot survive on the earth.

Food chains, Food webs and Ecological pyramids

            The transfer of energy from the source in plants through a series of organism by eating and being eaten constitutes food chains. These food chains are not isolated sequences, but are interconnected with each other. This interlocking pattern is known as the food webs. Each step of the food web is called a trophic level. Green plants occupy the first level, herbivorous the second level, and carnivorous the third level. This trophic level together forms the ecological pyramids.

Food chain: The most obvious aspect of nature is that energy must pass from one living organism to another. When herbivorous animals feed on plants, energy is transferred from plants to animals. In an ecosystem, some of the animals feed on other living organism, while some feed on dead organic matter. So, this is the connection of food. At each linkage in the chain, a major part of the energy from the food is lost for daily activities.

The food web: In an ecosystem there are very large numbers of interlinked chains. This forms food webs. If the linkages in the chains that make up the web of life are disrupted due to human activities that lead to the loss or extinction of species, the web breaks down.

The ecological pyramids: In an ecosystem, green plants-the producers are called ‘first trophic level’ of the food pyramids. The herbivorous animals that eat plants are ‘second trophic level’ and are also called primary consumers. The predators (carnivorous) that feed on them form the ‘third trophic level’ and are known as secondary consumers. This is how energy is used by living creatures and flows through the ecosystem from its base to the top. Much of the energy is used up in activities of each living organism.

Forest ecosystem

Forest is formed by a community of plants that is predominantly structurally defined by its trees, and shrubs. The landscapes that make up various types of forests look very different from each other. Their distinctive appearance is a fascinating aspect of nature. Each forest type forms a habitat for a specific community of animals that are adapted to live in it.

What is forest ecosystem?

As the plant and animals species are closely depend on each other, together they form different types of forest communities. Man is also part of this forest ecosystem and the local people depend directly on the forest for several natural resources that act as their life support systems. People who do not live in the forest buy forest products such as wood and paper, which has been extracted from the forest. Thus, they use forest product indirectly from the market.

The forest ecosystem has two parts:

      1.       The non-living or abiotic aspects of the forest

      2.       The living or the biotic aspects of the forest

Forest utilization: Natural forests provide local people with a variety of products if the forest is used carefully. Natural forest ecosystem plays an important role in controlling local climatic and water regimes, as well as preventing soil erosion.

Forest product:  Forest products that are collected by people include food such as fruit, roots, herbs and medical plants. Wood from different species of trees has special uses. These forest products are of great economic value as they are collected, sold and marketed. Forest dwellers and agricultural people use these goods directly. Other people get them indirectly from the market.

Forest services: Forest services include the control of the flow of water in stream and rivers. Forest also reduces runoff of rainwater and allows ground water to be stored. It also prevents erosion of soil. Once soil is lost by erosion, it can take thousands of years to reform. Forest regulates local temperature.

What are the threats to the forest ecosystem?

There are number of trees or plants which more sensitive species of forest and because of climatic changes it cannot survive. Overutilizing forest resources is an unsustainable way of misusing our limited forest resources. We are now creating more and more goods that are manufactured from raw material from the forest. This leads to forest degradation and finally changes the ecosystem into wasteland.    

The increasing use of wood for timber, wood pulp for paper and the extensive use of fuel wood results in continual forest loss. Forests are also lost by mining and building dams. As the forest resources are exploited beyond what they can produce with this also, the ecosystem is degraded and its wildlife is seriously threatened.

How can forest ecosystems be conserved?

• It can conserve only if its resources will use carefully.
• This can be done by using alternate sources of energy instead of fuelwood.
• There is a need to grow more trees than cut down from forests every year for timber.

Desert ecosystem

Desert and semi arid lands are highly specialized and sensitive ecosystem that is easily destroyed by human activities. The species of these dry areas can live only in this specialized habitat.

What is desert ecosystem?

Desert and semi arid areas are located in Western India. The climate in these vast tracts is extremely dry. The most typical desert landscape that is seen in Rajasthan is in the Thar Desert. This has sand dunes. There are also areas covered with spare grasses and a few shrubs, which grow if it rains.

Desert and semi arid regions have a number of highly specialized insects and reptiles. There are animals include the Indian Wolf, desert Cat, and desert Fox and birds such as the Great Indian Bustard.

The Great and Little Rann of Kutch are highly specialized arid ecosystem. The Great Rann is famous, as it is the only known breeding colony of the Greater and Lesser Flamingos in our country. The Little ran is only home of the wild ass in India.

How are desert and semi-arid ecosystems used?

Areas of scanty vegetation with semi-arid scrubland have been used for camel, cattle, sheep and goat grazing in Rajasthan and Gujarat. Areas that have a little moisture, such as along the watercourses, have been used for growing crops such as jowar, and bajra. The natural grasses and local varieties of crops have adapted to growing at very low moisture levels. These can be used for genetic engineering and developing arid land crops for the future.

What are the threats to desert ecosystem?

                Several types of development strategies as well as human population growth have begun to affect the natural ecosystem of the desert and semi arid land. Conversion of these lands through extensive irrigation systems has changed several of natural characteristics of this region. The region becomes highly unproductive as it becomes saline. Pulling excessive groundwater from tube wells lower the water table creating an even drier environment. Thus human activities destroy the naturalness of this unique ecosystem.

How can desert ecosystem be conserved?

Desert ecosystems are extremely sensitive. Their ecological balance that forms a habitat for their pants and animals is easily disrupted. The Indira Gandhi Canal in Rajasthan is destroying this important natural arid ecosystem, as it will convert the region into intensive agriculture. In Kutch, areas of the Little Rann which is only home of the Wild Ass, will be destroyed by the spread of salt works.

Aquatic ecosystem (Fresh water & Marine ecosystem)

The aquatic ecosystems constitute the marine environment of the seas and the fresh water systems in lakes, rivers and ponds. These ecosystems provide human beings with a wealth of natural resources. They provide goods that people collect for food such as fish and marine salt water. If aquatic ecosystems are misused or over utilized, their ability to provide resources suffers in the long term. Over-fishing leads to a fall in the fish catch. River courses that are changed by dams to provide electricity affect thousands of people who do not get a continuous supply of water downstream for their daily use. Water is an important factor in all our ecosystems. Several ecosystems exist in freshwater and marine salt water. There is very little fresh water on earth, which is a key resource for people all over the world.

What is an aquatic ecosystem?

In aquatic ecosystems, plants and animals live in water. These species are adapted to live in different types of aquatic habitats. Aquatic ecosystems may be classified as being stagnant ecosystems, or running water ecosystems. The special abiotic features are its physical aspects such as the quality of the water, which includes its clarity, salinity, oxygen content and rate of flow. The aquatic ecosystems are also classified into freshwater, brackish and marine ecosystems, which are based on the salinity levels.

The fresh water ecosystems that have running water are streams and rivers. Ponds and lakes are ecosystems where water does not flow. Marine ecosystems are highly saline, while brackish areas have less saline water such as in river deltas. Brackish water ecosystems in river deltas are covered by mangrove forests and are among the world’s most productive ecosystems in terms of biomass production.

Pond & Lake ecosystem: Pond is temporary and has water only in the monsoon but lakes are seen throughout the year. When a pond begins to fill during the rains, its life forms such as the algae and microscopic animals, aquatic insects, snails and worms. After that a large number of food chains are formed. Algae are eaten by eaten by small fish on which larger carnivorous fish depend. These are in turn eaten by birds such as kingfisher, herons. Aquatic insects, worms and snails feed on the waste material by the dead or decaying plant. A lake ecosystem functions like a giant permanent pond. A large amount of its plant material is the algae, which derives energy from the sun. This is transferred to the microscopic animals, which feed on the algae. There are fish that are herbivorous and are dependent on algae and aquatic weeds. The small animals such as snails are used as food by small carnivorous fish, which in turn are eaten by larger carnivorous fish.

Stream and River ecosystems: Streams and rivers are flowing water ecosystems in which all the living forms are specially adapted to different rates of flow. The community of flora and fauna of stream and river depend on the clarity, flow and oxygen content. The stream and river have their different plants and animals. As deforestation occurs in the hills the water in the streams that once flowed throughout the year become seasonal. This leads to flash floods in the rains and a shortage of water once the streams dry up after the monsoon.

Marine ecosystems: In the coastal area the sea is shallow while further away, it is deep. Both these are different ecosystems. There are many different types of coastal ecosystems which are highly dependent on the tide. The marine ecosystem is used by coastal fisherfolk for fishing which forms their livelihood. In the past, fishing was done at a sustainable level. The marine ecosystem continued to maintain its abundant supply of fish over many generations.

Now with intensive fishing by using giant nets and mechanized boats, fish catch in the Indian Ocean has dropped significantly. Several different species of fish are caught by fishermen. In many areas the fish catch has decreased during the last decade.

How are aquatic ecosystem used?

Man uses aquatic ecosystems for the clean freshwater on which his life is completely dependent. We need clean water to drink and for other domestic uses. Water is essential for agriculture. Fisherfolk use the aquatic ecosystems to earn a livelihood. People catch fish and crabs. They also collect edible plants. This is used locally as food or for sale in the market. Over fishing leads to a serious decline in the catch and a long-term loss of income for fisherfolk. Modern man impounds water in dams to be able to store it throughout the year. Agriculture and industry are highly dependent on large quantities of water. Dams are built across rivers to generate electricity. A large proportion of this energy is used by urban people, by agriculturists in irrigated farmlands and in enormous quantities for industry.

What are the threats to aquatic ecosystems?

Water pollution occurs from sewage and poorly managed solid waste in urban areas when it enters the aquatic ecosystem of lakes and rivers, which destroy life in the water. In rural areas the excessive use of fertilizers and pesticides increase nutrients but kills aquatic and pollute water.

How can aquatic ecosystems be conserved?

For sustainable use of an aquatic ecosystem, water pollution must be prevented. Changing the nature of the aquatic ecosystem from a flowing water ecosystem to a static ecosystem destroys its natural biological diversity. Thus dams across rivers decrease the population of species that require running water, while favoring those that need standing water.