G. Tansley, a British ecologist, coined the term "ecosystem" in 1935, combining the words "eco" (environment) and "system" (complex of coordinated units).
• It is a particular category of physical systems, consisting of organisms and inorganic components in a relatively stable equilibrium.
• Its functioning, interacting system composed of one or more living organisms and their effective physical and biological environment.
• It is a system composed of physical, chemical, and biological processes, within a space-time unit of any magnitude.
• An ecosystem is a self-contained natural unit. It is functionally independent unit (of nature) in which living organisms interact with one another and with their physical surroundings.
• It include a region with a distinct and recognizable landscape form, such as a forest, grassland, desert, wetland, or coastal area, is referred to as an ecosystem.
• Climate conditions such as the amount of sunlight, temperature, and rainfall in the region influence. The biotic component of an ecosystem is the living part, while the abiotic component is the non-living part.
There are two types of ecosystems in nature
1. Terrestrial ecosystems: It include forests, deserts, and grasslands.
2. Aquatic ecosystems: It include ponds, lakes, wet lands, and salt water.
Man-made ecosystems include crop lands and aquariums.
CLASSIFICATION OF ECOSYSTEMS
Ecosystems can be identified and classified in a variety of ways, each with its own set of goals and objectives.
BASIS OF HABITATS
• Habitats refer to the physical environmental conditions of a specific biosphere spatial unit.
• The nature and characteristics of biotic communities are determined by these physical conditions, and thus there are spatial variations in biotic communities.
BASIS OF PREMISE THE WORLD ECOSYSTEMS ARE DIVIDED INTO TWO MAJOR CATEGORIES
A. Terrestrial ecosystems
B. Aquatic ecosystem
The terrestrial ecosystems are subdivided into five broad categories:
1. Upland or mountain ecosystems
2. Lowland ecosystems
3. Forest ecosystems
4. Warm desert ecosystems
5. Cold desert ecosystems
The aquatic ecosystems are subdivided into two broad categories:
1. Freshwater (on continents) ecosystems: It divided into river ecosystems, marsh ecosystems, and bog ecosystems,
2. Marine ecosystems: It divided into open ocean ecosystems, coastal estuarine ecosystems, coral reef ecosystems, or ocean surface ecosystems and ocean bottom ecosystems.
ON THE BASIS OF SPATIAL SCALES
• Ecosystems are classified into various orders based on the spatial dimensions required for specific purposes.
• From a continent to a single biotic life, spatial scales can be reduced (plant or animal).
• Ellenberg stated in 1973 that the world can be divided into different ecologies in a hierarchical order (I-II-III-IV)
PART 1: THE BIOSPHERE
Largest and all encompassing ecosystem, the major ecosystem of whole biosphere are divided into
1. Continental ecosystems, an
2. Oceanic or marine ecosystems.
PART 2: RTMEGA-ECOSYSTEMS
• Marine ecosystems, such as oceans and seas, are related to saline water environments.
• Rivers and lakes are examples of freshwater ecosystems.
• Semi-terrestrial ecosystems are those that are based on wet soil and air.
• Forests, grasslands, and deserts are examples of terrestrial ecosystems that are related to aerated soil and air.
• Cities, cropland, and other man-made ecosystems make up urban-industrial ecosystems.
PART 3: MACRO, MESO, AND MICRO ECOSYSTEMS ARE SUBDIVIDED INTO EACH MEGA-ECOSYSTEM.
• The macro division is the forest ecosystem, the meso division is the deciduous broad-leaf forest with its fauna, and the micro division is the mountain deciduous broad-leaf forest.
PART4: NANO-ECOSYSTEMS ARE EVEN SMALLER ECOSYSTEMS THAT EXIST WITHIN LARGER ECOSYSTEMS BUT HAVE DISTINCT CHARACTERISTICS.
ON THE BASIS OF USES
On the basis of harvest methods and net primary production, E.P. Odum (1959) divided the world ecosystems into two broad categories:
1. Cultivated ecosystems: It can be divided into several categories based on the dominant crops cultivated, such as wheat field ecosystems, rice field ecosystems, sugarcane field ecosystems, fodder field ecosystems.
2. Non-cultivated or natural ecosystems: It can be divided into forest ecosystems, tall grass ecosystems, short grass ecosystems, desert ecosystems, see-weeds ecosystems’
ON THE BASIS OF HUMAN INTERFERENCE
• Some ecosystems are relatively resilient and are less affected by human disturbance. Others are extremely vulnerable to human activity and are quickly destroyed.
• Mountain ecosystems are extremely vulnerable, as deforestation causes severe soil erosion and changes in river courses.
• Any form of human activity can easily affect island ecosystems, resulting in the extinction of several of their unique plant and animal species.
• Pollution and changes in surrounding land use can have a significant impact on river and wetland ecosystems.
Ecosystems can also be classified into based on the degree of human interference and the impact of anthropogenic activities.
• Natural Ecosystems, which are self-regulating systems that do not require much human intervention. Ecosystems such as forest, grassland, desert, sea, ocean, estuarine, lake, river, coral reef, and others are included.
• Man-engineered ecosystems, such as urban ecosystems, irrigated croplands, greenhouses, and, more recently, biotic ecosystems — canopied, air-conditioned, vegetative places where scientists live and grow crops and fruits for 2 or 3 months away from the rest of the world.