An ecosystem is a self - regulating group of biotic communities of species interacting with one another and with their nonliving environment exchanging energy and matter. A pond, Lake, desert, grassland, forest etc . are common example of ecosystem. In simple term, ecology is defined as the study of ecosystem. The term 'Ecosystem' was coined by  A.G. Tansley in  1935.

TYPES OF ECOSYSTEM

1. Terrestrial Ecosystem  2. Aquatic Ecosystem

Terrestrial ecosystems are exclusively land-based ecosystems. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows:

A. Forest Ecosystems

B. Grassland Ecosystems

C. Tundra Ecosystems

D. Desert Ecosystem

A. Forest Ecosystem

A forest ecosystem consists of several plants, animals and microorganisms that live in coordination with the abiotic factors of the environment. Forests

help in maintaining the temperature of the earth and are the major carbon sink. Depending upon the climatic conditions forests can be of different types :

1.  Tropical Rain Forest

2. Tropical Deciduous forests

3. Tropical Scrub Forests

4. Temperate Rain Forests

5. Temperate Deciduous Forests

6. Evergreen Coniferous Forests

B. GRASSLAND ECOSYSTEMS

Grasslands are open areas of land where grasses or grass like plants are the dominant species. Other forms of vegetation such as trees are rare in grasslands because they are not suited to thrive in the grassland dry environment.

Three types of grasslands are found to occur in different climatic regions:

1. TROPICAL GRASSLANDS

2. TEMPERATE GRASSLANDS

3. POLAR GRASSLANDS

C. TUNDRA ECOSYSTEM

These are covered with snow for most of the year all the biomes. Tundra is the coldest of all the biomes.

*Low biotic diversity

*Simple vegetation structure

*Energy and nutrients in the form of dead organic material.

Tundra is separated into two types:

1 . Arctic Tundra

2.  Alpine Tundra

D. DESERT ECOSYSTEM

Deserts are found throughout the world. These are regions with very little rainfall. The days are hot and the nights are cold. About 1⁄3 of our world's land area is covered by deserts. Deserts are of three types based on climatic conditions.

TROPICAL DESERTS: Like Sahara and Namibia in Africa and Thar desert in Rajasthan.

TEMPERATE DESERTS : Like Mojave in Southern California.

COLD DESERTS: Like the Gobi desert in China.

2. AQUATIC ECOSYSTEM

Aquatic ecosystems are ecosystems present in a body of water. These can be further divided into two types, namely

                                                                                           :

1.  Freshwater Ecosystem

2. Marine Ecosystem

1. Freshwater Ecosystem

 The freshwater ecosystem is an aquatic ecosystem that includes lakes, ponds, rivers, streams, and wetlands. These have no salt content in contrast with the marine ecosystem.

2. Marine Ecosystem

The marine ecosystem includes seas and oceans. These have a larger salt content and greater biodiversity in comparison to the freshwater ecosystem.

Characteristics of ecosystems include biodiversity, productivity, resilience, and stability. Biodiversity refers to the variety of species and genetic diversity within an ecosystem. Productivity is the rate of biomass production through photosynthesis and primary production. Resilience is the ability of an ecosystem to withstand and recover from disturbances, while stability refers to the ability to maintain structure and function over time.

Ecosystems also provide various ecosystem services such as air and water purification, climate regulation, nutrient cycling, and provision of food and raw materials.