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Components Of Ecosystem – Environment Notes – For W.B.C.S. Examination.
বাস্তুতন্ত্রের উপাদানসমূহ – পরিবেশের নোট – WBCS পরীক্ষা।
An ecosystem is a system formed by the interactions of a variety of individual organisms with each other and with their physical environment. Ecosystems are nearly self-contained so that the exchange of nutrients within the system is much greater than exchange with other system.An ecosystem, thus, is not entirely a biological entity. Any complete description of an ecosystem must include the physical environment as well as the biological components and the interactions between the two. Ecosystems are of diverse types-mostly natural, but there are a few which are man-made or modified by man’s activity.Continue Reading Components Of Ecosystem – Environment Notes – For W.B.C.S. Examination.
An ecosystem is not entirely a biological entity. The biological or biotic components of an ecosystem include both living organisms and products of these organisms. Thus microbes, all categories of plants and animals as well as their waste products are included in the ecosystems.
The non-biological or abiotic components include climatic and edaphic features, in particular climatic components like sunlight, temperature, air and water supply along with soil component such as soil nutrients which are very important contributing factors of ecosystem operation.
The biotic components are broadly categorized as producers, and consumers of different classes viz. herbivores (animals that eat plants), carnivores (animals that eat flesh of other animals), omnivores (animals that consume both plants and animals as available) and lastly scavengers (animals that eat dead plant and animal matters).
In addition there are decomposer classes, which include mostly saprophytic organisms that help in nutrients and element recycling process.
Decomposers:
They are heterotrophic organisms that feed solely on dead organic matter, i.e., saprophytes. The bulk of the saprophytic decomposition is carried out by bacteria, fungi and protozoans. Imagine that a piece of organic Utter falls to the floor of a forest.
In a typical sequence, microscopic bacteria or fungi will excrete chemicals, called enzymes, that break down the complex chemical compounds in the object Some of the breakdown products are absorbed as food, whereas others are left behind.
These serve as a food supply for other organisms that carry the decomposition one step further. Eventually the waste products of the final line of decomposers are energy-poor mineral nutrients that are reabsorbed, and thus recycled, by plants .
During the process of production and consumption, energy is passed along, or flows, from one organism to another. For example, solar energy is converted to chemical energy within the leaves of green plants. The leaves can then be eaten by some herbivore, and the herbivore may, in turn, be eaten by a carnivore.
Consider a hypothetical ecosystem that receives 1,000 Kilocalories of light energy in a given day (Fig. 5.2). Most of this energy is not absorbed at all. Some is simply reflected back into space. Of the energy that is absorbed, most is stored as heat or used for evaporation of water. A small amount is assimilated by plants.The productivity in an ecosystem are of two kinds—primary productivity and secondary productivity. The primary productivity of an ecosystem is the rate at which organic matter is produced during photosynthesis.
Some amount of photosynthetic material is subsequently utilized for respiratory purpose. The initial photosynthetic product which is formed at first is called gross primary productivity which is expressed as Kcal/m2/yr.
Only about half of the gross productivity accumulates as new plant matter, because the rest of the chemical energy is metabolized by the plant’s own respiration and released to the environment as heat. The net gain in plant matter is called the net primary productivity.
Thus the Net primary productivity = Gross primary productivity – Plant respiration
On the whole, productivity depends on a variety of factors such as sunlight, temperature, rainfall and the availability of nutrients. The total quantity of organic matter present at any one time in an ecosystem is called the biomass.
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