Types of Ecosystems

Ecosystems can range from small water bodies to an ocean, similarly on land from a patch of woods to a forest. Ecosystems can be natural or anthropogenic (human-created like farmlands). Broadly Ecosystem is classified into terrestrial and aquatic ecosystems, which are further classified into several kinds.

Types of Ecosystems

Terrestrial Ecosystems

Diverse kinds of terrestrial ecosystems are present on the earth. Both climate and relative contribution of general plant life-forms (trees, shrubs, and grasses) contributes to the diversity.

1. Forest Ecosystem

Forest ecosystem mainly consists of community of plants, animals and microorganism and their non-living environment functioning collectively to exchange material and energy, where trees, shrubs, climbers and ground cover forms the main component. Due to the expansion of human settlements and industrial areas since the last century, the pristine forest is only left in protected areas like National Parks and Wildlife Sanctuaries. The appearance of different types of forest differs greatly from each other. Each forest type forms a habitat for a community of animals that are specifically adapted to live in it.

Forest ecosystem also consists of abiotic or non-living component which includes factors like temperature, rainfall, topography, soil properties, etc. Due to the variation of these abiotic factors biotic or living components of the forest also vary in different types of forest. Forests also differ in their plant communities in response to the type of soil.

2. Tundra Ecosystem

Tundra ecosystems (arctic tundra) are found in extreme northern latitudes where snow melts seasonally. On the other hand, the alpine tundra is found in the higher elevation of mountains, specifically above the tree line. Winters in arctic tundra are long and severe on the other hand, summers or growing season is short. Precipitation is also poor in the tundra ecosystem and mostly occurs in summers. Tundra ecosystems are characterized by low species richness and low primary productivity. The dominant vegetation is tundra include mosses, lichens, grasses and grass-like sedges. Only dwarf willows, dwarf birches and other dwarf trees found in the tundra. Some of the animals found in tundra includes lemmings, voles, weasels, arctic foxes and snowy owls. Oil and natural gas exploration and military use is harming the tundra ecosystem. In addition to this, climate change is posing a serious threat to the tundra ecosystem. As the temperature is rising, causing the permafrost to melt resulting in replacement of tundra vegetation by coniferous trees.

3. Grasslands

A wide variety of landscapes where the predominant vegetation is grasses and small annual plants present in various climatic conditions are called grasslands. Grasslands have been given different names in different continents like prairies in U.S. Midwest, pampas in South America, steppes in central Eurasia and savannas in Africa. Grasslands are found in regions where rainfall is not adequate to support forest but now as less as to form a desert. Broadly there are two different types of grasslands tropical and temperate.

• Tropical grasslands remain warm throughout the year. They have a dry and a rainy season. One of the examples of tropical grassland is Savanna in Africa. Animals like giraffe, zebra, rhinos, lions, hyenas and elephants are found in these grasslands.
• Temperate grasslands, on the other hand, receive less rainfall in comparison to tropical grasslands. Grasses of short lengths are usually found in these grasslands. These grasslands also have two seasons growing and dormant. Grasslands have seasonal appearance because of flowering in the rainy season and during the winter season, only underground storage organs and thick stem bases remain.

4. Desert Ecosystem

Deserts are the ecosystem which receives less or extremely less (less than 12cm per year) rainfall. Deserts and semi-arid regions in India are found in western India and Deccan Plateau. The climate in these vast tracts is extremely dry. The Thar desert of Rajasthan is the example of a typical desert in India which has sand dunes. Rainfall in these areas is sporadic. Sparse grasses and some shrubs grow in these arid regions. In the adjacent semi-arid regions some species of shrubs and trees like Babool (Acacia nilotica) and khair ( Senegalia catechu) are found.

In addition to the Thar desert, India has two more desert ecosystems. Cold desert is found in Ladakh, which is situated in the high plateau of Himalaya. On the other hand, highly specialized arid regions are found in the Great and Little Rann of Kutch in Gujarat. During the summers these regions have conditions similar to a desert but during the monsoon, these regions get converted into salt marshes because they are low lying areas adjacent to a sea. In terms of bird diversity Greater and lesser flamingos are found in Great Rann of Kutch. Similarly, Little Rann of Kutch is the only region where the wild ass is found in India. highly specialized insects and reptiles are found in the desert and semi-arid regions. These regions are home to several species of rare animals desert cat, desert fox, Indian wolf and birds like the Great Indian Bustard and the Florican.

Aquatic Ecosystems

Diverse kinds of aquatic ecosystems are present on the earth. Broadly aquatic ecosystems can be classified as freshwater (ponds and lakes i.e. lentic ecosystems; streams and rivers lotic ecosystems i.e. lotic ecosystems), brackish water (estuaries) and salt water (oceans) ecosystems based on the salinity levels of the water.

1. Pond Ecosystem

Ponds are the smallest and simplest aquatic ecosystems. Many pond ecosystems become dry long after the monsoon is over and terrestrial plants grow on it till the arrival of next monsoon. As the monsoon arrives organisms like algae, zooplanktons, insects, snails and worms come out from the bottom of the pond where they spent the dry phase. Slowly large animals like amphibians, crabs and large fishes
also return to the ponds. In addition to this now, floating weeds and rooted vegetation at the periphery of ponds also start growing. Now a large number of food chains are formed.

2. Lake Ecosystem

Lakes on the other hand function like large permanent ponds as water remains in the lakes throughout the year. Organisms like algae, microscopic animals, both herbivorous and carnivorous fishes form several food chains in the lakes. Fishes like catfish are also found in the lakes which specifically feeds on detritus on the bed of the lakes. These fishes are called bottom feeders. Both ponds and lakes play a crucial role in the conservation of water and biodiversity. Pollution from industries and agricultural field are degrading these ecosystems.

3. Streams and Rivers

Streams and riversare the example of lotic water ecosystems which means running water ecosystem.

A stream is significantly smaller in size than the river. These ecosystems are open systems, exchanging nutrients and energy with larger areas than lentic ecosystems. In these ecosystem currents is an important ecological factor. Two zones can be identified in these ecosystems which are rapid zone and pool zone. In the rapid zone, the current is fast which cleans the silt and other material from the bottom making it firm and hard. On the other hand, in the pool zone speed of the current is slow, water is deep resulting in the deposition of sand and silt. Here the bottom is soft. Different kinds of organisms are adapted to these two zones.

Rivers originate from glaciers on the mountains and carry the sediments enter the plain areas making the soil fertile with sediments before ending into the oceans. Rivers provide water for drinking, domestic purpose, industries and agriculture and power generation to mankind. Pollution originating from the sewage drains (Urban areas), effluent drains (Industries) and agriculture fields are polluting the river ecosystems. In addition to this destruction of floodplains and catchment areas are causing loss of property and life during floods.

4. Estuaries

Estuaries are an example of a brackish water ecosystem where salinity levels are intermediate i.e more than the freshwater ecosystem and less than the saltwater ecosystems. Estuaries, where the rivers enter the ocean. It is a complex ecosystem of high productivity having both salt marshes and mud flat connecting the freshwater communities and oceans. Estuaries have both plankton and detritus-based food webs. Most fisheries are directly or indirectly dependent on this ecosystem.

5. Ocean Ecosystem

Ocean ecosystem consists of several communities like littoral, marine sandy beaches and marine mud flat communities. Estuarine, mangrove and coral reef communities are important both ecologically and economically. In addition to this, Continental shelf (Neritic) Benthos communities, Marine surface Pelagic communities and Deep open benthos communities are also found in oceans. Great diversity of organisms is found in each of these communities.

Indian ocean, Bay of Bengal and Arabian sea are examples of ocean or marine ecosystems in India. Seventy percent of the earth’s surface is covered by oceans. These ecosystems are extremely deep and living organisms occur at all depth even beyond 5000 meters. Although density and diversity of organisms in the ocean in the peripheral zones. All oceans are connected with each other. Oceans have salinity levels much higher (35 parts per 1000 parts of water (by weight) or 3.5%) than the freshwater ecosystems (0.5%). Oceans waters continuously move horizontally by the action of strong winds such as trade winds is called waves. On the other hand, the ocean water also rises and falls by the action of different interactions of gravitational forces exerted between the moon, the Earth and the sun. This vertical movement is called as tides.

6. Deep Open Benthos Communities

These communities are present between the boundary of the continental shelf to the deep oceans. Since light does not reach this region, therefore, only heterotrophic organisms and some bacteria are part of these communities.