Description of Ecosystem and Ecology background of Environmental studies

 

Ecology

Ernst Haeckel (1866)

Ecology “as the body of knowledge concerning the economy of nature-the investigation of the total relations of animal to its inorganic and organic environment.

Taylor (1936)

Ecology as “the science of the relations of all organisms to all their environments.”

ECOSYSTEM :

Ecosystem where meaning as ‘eco’ implies the environment, and ‘system’ implies an interacting, inter-dependent complex.

All living organisms and their non-living environment particles are inseparably interrelated and interact with each other. Furtherly, A.G. Tansley ,in 1935 defined the Eco-system as

‘The system resulting from the integrations of all the loving and non-living actors of the environment’.

Meaning of Structure

By structure of an eco-system we mean as under.

(i) The composition of biological community including species, numbers, biomass, life history and distribution in space etc.

(ii) The quantity and distribution of the non-living materials, such as nutrients, water etc.

(iii) Structure of an ecosystem the range, or gradient of conditions of existence, such as temperature.

From some literature such parallel terms of ecosystems ideations are

1. Biocoenosis - "community of living", Microcosm- "miniature", Geobiocoenosis- "Biotic + Abiotic = Total ecosystem" , Hlocoen- impact of environment, Biosystem- "system of living organism" , Bioenert body- "ones do not initiate a response to biological" and ecosom- "different interactions between living and non-living" etc these are  used for such ecological systems.

Eco-system is an integrated unit, consisting of interacting plants and animals whose survival depends upon the maintenance of abiotic i.e. physicochemical environment and gradients such as moisture, wind and solar radiation with its concomitants of light and heat, as well as biotic structures and functions.

Biotic or Biological Factors

The biological (biotic) factors of ecosystem include all the living organisms-plants, animals,

bacteria and viruses. Each kind of living organism found in an ecosystem is given the name

a species. A species includes individuals which have the following features:

1. They are genetically alike.

2. They are capable of freely inter-breeding and producing fertile offsprings.

Biotic aspects of ecosystems

The eco-system can be defined as any spatial or organizational unit including living organisms and non-living substances interacting to produce an exchange of materials between the living and non-living parts. The eco-system can be studied from either structural or functional aspects.

1. Structural Aspect

The structural aspects of ecosystem include a description of the arrangement, types and

numbers of species and their life histories, along with a description of the physical features

of the environment.

2. Functional

The functional aspects of the ecosystem include the flow of energy and the cycling of

nutrients.

Abiotic Factors

Among the main abiotic factors of the ecosystem are included the follwing:

(1) The climatic factors as solar radiation, temperature, wind, water currents, rainfall.

(2) The physical factors as light, fire, pressure, geomagnetism,

(3) Chemical factors as acidity, salinity and the availability of inorganic nutrients

needed by plants.

Division of Ecosystem

The ecosystem can be divided, from the energetic view point into three types of organisms:

producers, consumers, and reducers. These can be explained as under:

(1) Producer

Photosynthetic algae, plants and bacteria are the producers of the ecosystem; all other

organisms depend upon them directly or indirectly for food.

(2) Consumers

Consumers are herbivorous, carnivorous, and omnivorous animals; they eat the organic

matter produced by other organisms.

(3) Reducers

Reducers are heterotrophic organisms like animals; they are fungi and bacterial that

decompose dead organic matter.

FOOD CHAINS OF FOOD WEB

Species are related by their feeding behaviour in food chains or food webs. There are

two basic types of food chains as under:

• The consumer food chain includes the sequence of energy flow from

producer+herbivore+carnivore+reducer;

• The detritus food chain pypasses the consumers, going from producer+reducer.

GENERAL CHARACTERISTICS OF AN ECO-SYSTEM

According to Smith following are the general characteristics of eco-system.

(1) The ecosystem is a major structural and functional unit of ecology.

(2) The structure of an eco-system is related to its species diversity; as such the more complex ecosystem has high species diversity.

(3) The relative amount of energy required to maintain an ecosystem depends on its structure. The more complex the structure, the lesser the energy it requires to maintain itself.

(4) The function of the ecosystem is related to energy flow in material cycling through and within the system.

(5) Ecosystems mature by passing from less complex to more complex states. Early stages of such succession have an excess of potential energy. Later (mature) stages have less energy accumulation.

(6) Both the environment and the energy fixation in any given ecosystem are limited. They cannot be exceeded in any way without causing serious undesirable effect.

(7) Alterations in the environments represent selective pressures upon the population to which it must adjust. Organisms, which fail to adjust to the changed environment, must vanish.

ECOLOGICAL PYRAMIDS

The main characteristic of each type of Ecosystem in Trophic structure, i.e. the interaction of food chain and the size metabolism relationship between the linearly arranged various biotic components of an ecosystem. We can show the trophic structure and function at successive trophic levels, as under:-

It may be known by means of ecological pyramids. In this pyramid the first or producer

level constitutes the base of the pyramid. The successive levels, the three make the apex.

Ecological pyramids are of three general types as under:

(i) Pyramid of numbers: It shows the number of individual organisms at each level,

(ii) Pyramid of energy: It shows the rate of energy flow and/or productivity at successive trophic levels.

(iii) Pyramid of energy: It shows the rate of energy flow and/or productivity at

successive trophic levels.

DECOMPOSERS

In the ecosystem the decomposition takes major role which is helpful to sustain the environment health.

In this world all living organisms require a constant supply of nutrients for growth. Also from the death and decomposition of plants and animals, with release of nutrients constitutes an essential link in the maintenance of nutrient cycles. When an organism dies, an initial period of rapid leaching takes place and populations of macromolecules. Enzymic action breaks down the disintegrating parts. Animals invade and either eat the rapidly recolonized by micro- organisms, and the litter biomass decreases. It becomes simpler in structure and chemical composition.

Process of Decomposition

The process of decomposition involves three interrelated components, viz.

(i) Leaching (ii) Catabolism, (iii) Comminution.

1. Leaching

Leaching is a physical phenomenon operating soon-after litter fall. Soluble matter is removed from detritus by the action of water. Sometime over 20% of the total nitrogen content of litter maybe leached off.

2. Catabolism

The process in a plant or animal by which living tissue is changed into waste products.

3. Comminution

Comminution to make small to reduce to power or minute particles. Comminution means the reduction in particle size of detritus. During the course of feeding, the decomposer animals community detritus physically. And utilize the energy and nutrients for their own growth (secondary production). In due course, the decomposers themselves die and contribute to the detritus.