Ecosystem:Structure and Function

Ecosystem:Structure and Function is meant for the students of CBSE Class 12 and 10.

1. ECOSYSTEM CLASS - XII Developed By: Dr.U.P.Pani PGT (Biology) JNV Durg (CG)

2. The term ecosystem was first coined by A.G.Tansely . Ecosystem consists of two Words : ECOSYSTEM

3. According to E.P.Odum , an American ecologist, the ecosystem is the basic functional unit of organism and their environment interacting with each other and with their own components. e.g. Grassland, Forest, Aquarium, Pond, Lake, River and Ocean. Ecosystem - Definition Grassland Ecosystem Forest Ecosystem Ocean Ecosystem

4. Types of Ecosystem

5. Structure of Ecosystem

6. From nutrition point of view, the biotic components of ecosystem can be grouped into three categories: Biotic Components

7. The vertical distribution of different species occupying different levels is called stratification. Eg . Trees occupy top vertical strata or layer of a forest, shrubs the second, herbs and grasses occupy the bottom layers. STRATIFICATION

8. The components of the ecosystem are seen to function as a unit when we consider the following aspects: Productivity Decomposition Energy flow Nutrient cycling Function of Ecosystem

9. Productivity - The rate of biomass production is called productivity. Units : g –2 yr –1 or (kcal m –2 ) yr –1 Gross primary productivity - The rate of production of organic matter during photosynthesis is called gross primary productivity. Gross PP (GPP) = total energy fixed Net PP (NPP) = GPP – respiration Secondary productivity – The rate of formation of new organic matter by consumers is called secondary productivity . PRODUCTIVITY

10. Components of Productivity

11. The breakdown of complex organic matter into inorganic substances like carbon dioxide, water and nutrients and the process is called decomposition. DECOMPOSITION

12. Decomposition cycle in a Terrestrial Ecosystem

13. The flow of energy is one way direction from producer to consumers, and ends in decomposition process. However, a part of the energy is lost as heat and agrees with the phenomenon of second law of Thermodynamics. ENERGY FLOW

14. GRAZING FOOD CHAIN

15. Detritus is non-living particulate organic material includes the bodies or fragments of dead organisms as well as fecal material. Decomposers are heterotrophic organisms also called saprotrophs . Eg . Fungi and Bacteria. Detritus Food Chain

16. A food web depicts various feeding connections in an ecological community. Natural interconnected food chains make a food web. FOOD WEB

17. TROPHIC LEVEL The trophic level is the position of an organism it occupies in the community or a food chain.

18. Energy flow in different Trophic Levels

19. An ecological pyramid is a graphical representation of trophic levels in a given ecosystem. ECOLOGICAL PYRAMIDS

20. The pyramid of biomass in sea is also generally inverted because the biomass of fishes far exceeds that of phytoplankton. PYRAMID OF NUMBERS

21. The pyramid of biomass in sea is also generally inverted because the biomass of fishes far exceeds that of phytoplankton. PYRAMID OF BIOMASS

22. Pyramid of energy is always upright. It can never be inverted. PYRAMID OF ENERGY