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ECOSYSTEM
An ecosystem is a community of organisms that interact with each other and non living components for sustainable development and adaptation to changing conditions. There are different type of ecosystems around us which involves living organisms and non living organisms. If we combine all the ecosystems present on earth, it is called Biosphere. The term ecosystem was first proposed by A.G.Tansley (1935) who defined ecosystem as follows: “Ecosystem is defined as a self-sustained community of plants and animals existing in its own environment.”Odum (1971) defined ecosystem as any unit that includes all the organisms in a given area interacting with the physical environment, so that a flow of energy give rise to a clearly defined tropic structure, biotic diversity and material cycles within the system ”Michael Allaby (1983) defined ecosystem as a community of interdependent organisms together with the environment.
CONCEPT OF ECOSYSTEM
In an ecosystem, the interaction of life with its environment takes place at many levels. A single bacteria in the soil interacts with water, air around it within a small space while a fish in a river interacts with water and other animals, rivals in a large space.
Considering the operational point of view; the biotic and abiotic components of an ecosystem are so interlinked such that their separation from each other is practically difficult. So, in an ecosystem both organisms (biotic communities) and abiotic environment (rainfall, temperature, humidity) each influence the properties with other for maintenance of life.
STRUCTURE OF ECOSYSTEM
A structure of Ecosystem comprise of
- The Composition of biological community including, species number, biomass, life history, and distribution in space.
- The quantity and distribution of non-living material, such as nutrient water, etc.
- The rage of condition of existence such as temperature, light.
FUNCTION OF ECOSYSTEM
- The rate of biological energy flow i.e. production & respiration rates of the community.
- The rate of material or nutrient cycles
- Biological or ecological regulation including both regulation of organism by environment and regulation of environment by the organisms.
COMPONENTS OF AN ECOSYSTEM
There are two components of an ecosystem; Living components and non living components.
Non Living Components: (Abiotic)
Non living components are the physical and chemical factors that directly or indirectly affect the living components e.g. air, water, land, rock etc. Non living components are also called Abiotic components.
Physical factors include sunlight, water, fire, soil, air, temperature etc.
Chemical factors include moisture, salinity of water, soil nutrients, oxygen dissolved in water etc.
Living Components : (Biotic)
Living components in an ecosystem are either producers or consumers. They are also called biotic components. Producers can produce organic components e.g. plants can produce starch, carbohydrates, cellulose from a process called photosynthesis. Consumers are the components that are dependent on producers for their food e.g. human beings and animals
Classification of Biotic Components
Biotic Components are further classified into 3 main groups -
- Producers
- Consumers
- Decomposers or Reducers
1. Producer (Autotrophs): The green plants have chlorophyll with the help of which they trap solar energy and change it into chemical energy of carbohydrates using simple inorganic compound namely, water and carbon dioxide. This process is known as photosynthesis. The chemical energy stored by the producers is utilized partly by the producers for their own growth and survival and the remaining is stored in the plants for their future use. They are classified into two categories based on their source of food.
a) Photoautotrophs: An organism capable of synthesizing its own food from inorganic substances using light as an energy source. Green plants and photosynthetic bacteria are photoautotrophs.
b) Chemotrophs: Organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs).
2. Consumers (Heterotrophs): The animals lack chlorophyll and are unable to synthesis their own food therefore they depend on the producers for their food. They are known as heterotrophs (i.e. heteros= others, trophs= feeder).The Consumers are of 4 types:
(a) Primary Consumer: ( Herbivores) i.e. Animal feeding on plants, e.g. Rabbit, deer, goat etc.
(b) Secondary Consumers: The animal feeding on Herbivores are called as secondary Consumer or primary carnivores. e.g. Cats, foxes, snakes.
(c) Tertiary Consumers: These are large carnivores which feed on secondary consumers. e.g. Wolves
(d) Quaternary Consumers: They are also called omnivores these are largest carnivores. Which feed on tertiary consumers and are not eaten up by any other animals. e.g. lion and Tiger.
3. Decomposers or Detrivores: Bacteria & fungi belong to this category. They break down the dead organic matter of producers & consumers for their food and release to the environment the simple inorganic and organic substance. These simple substances are reused by the producers resulting in a cyclic exchange of material between biotic & abiotic environment. Eg: Bacteria, Earth worms, Beetles etc.
BIODIVERSITY
The word biodiversity is a combination of two words: “biological and diversity” and refers to the variety of life on the Earth. Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems.
The term biological diversity was used first by wildlife scientist and conservationist Raymond F. Dasmann in the 1968.
The term's contracted form biodiversity may have been coined by W.G. Rosen in 1985.
Levels of Biodiversity
Biodiversity is usually considered at three different levels:
The following are different types of biodiversity -
1. Genetic diversity: variety in the genetic makeup among individuals within a species
2. Species diversity: variety among the species or distinct types of living organisms found in different habitats of the planet
3. Ecosystem or ecological diversity: variety of forests, deserts, grasslands, streams, lakes, oceans, coral reefs, wetlands and other biological communities
4. Functional diversity: biological and chemical processes of functions such as energy flow an matter cycling needed for the survival of species and biological communities
1. Genetic Diversity
Genetic diversity is the “raw material” that permits species to adjust to a changing world whether these changes are due to natural factors or are caused by human factors. It refers to the variation at the level of individual genes and provides a mechanism for populations to adapt to their ever-changing environment. Eg: Human beings
2. Species Diversity
Species diversity refers to the different types of living organisms on Earth. This includes the many types of birds, insects, plants, bacteria, fungi, mammals, and more. Many differing species often live together in communities depending on each other to provide their needs. A species can be defined as a group or population of similar organisms that reproduce by interbreeding within the group. Members of a species do not normally reproduce with members of any other species. Members of a specific species possess common characteristics that distinguish them from other species and this remains constant regardless of geographic location.
3. Ecosystem Diversity
Ecological diversity or ecosystem diversity is the variety of biological communities, such as forests, deserts, grasslands and streams that interact with one another and with their physical and chemical (nonliving) environments. It relates to the different forms of life which are present in any one particular area or site, in more precise terms, it concerns the different species of a particular genus which are present in an ecological community.