Ecosystem CH – 12
1. Functional unit of Nature Ecosystem
2. Biosphere Global ecosystem
3. Terrestrial Ecosystem Forest, Desert, Grassland
4. Aquatic Ecosystem Ponds, River, Lake, Wetland
5. Man made Ecosystem Crop fields and Aquarium
6. species composition of Ecosystem is given by Identification and Enumeration of plant and animal species
7. Vertical distribution of different species occupying different levels Stratification
Example Trees > Shrubs > Herbs > Grasses
8. Pond contains all 4 basic components of ecosystem (Productivity, Decomposition, Energy flow, Nutrient cycle)
Autotrophic component Phytoplankton’s, Algae, submerged and marginal plants
Consumers are represented as Zooplankton’s
Decomposers Fungi, Bacteria, Flagellates (abundant at bottom of pond)
These above system performs all function of ecosystem and of Biosphere as whole
9. Productivity The rate of biomass production, It is expressed as gm–2yr –1 or (kcal m–2)yr –1
10. Primary production amount of biomass or organic matter produced per unit area over a time period by plants
during photosynthesis
It is expressed as weight (gm–2 ) or energy (kcal m–2)
11. Secondary productivity rate of formation of new organic matter by consumers
12. Gross primary productivity the rate of production of organic matter during photosynthesis
A considerable amount of GPP is utilised by plants in respiration
Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP). GPP – R = NPP
13. Net primary productivity available biomass for the consumption to heterotrophs
(herbivores and decomposers).
14. Factors affecting Primary Productivity:
a. plant species inhabiting a particular area
b. environmental factors
c. availability of nutrients
d. photosynthetic capacity of plants
e. it varies in different types of ecosystems
15. The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of
organic matter.
16. productivity of the oceans are only 55 billion tons
17. Decomposition decomposers break down complex organic matter into inorganic substances like carbon
dioxide, water and nutrients and the process is called decomposition
18. Detritus raw material for decomposition
Example Dead plant remains such as leaves, bark, flowers and dead remain of animals, including faecal matter
19. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and
mineralisation
fragmentation Detritivores (e.g., earthworm) break down detritus into smaller particles
leaching water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts
catabolism Bacterial and fungal enzymes degrade detritus into simpler inorganic substances
1. Functional unit of Nature Ecosystem
2. Biosphere Global ecosystem
3. Terrestrial Ecosystem Forest, Desert, Grassland
4. Aquatic Ecosystem Ponds, River, Lake, Wetland
5. Man made Ecosystem Crop fields and Aquarium
6. species composition of Ecosystem is given by Identification and Enumeration of plant and animal species
7. Vertical distribution of different species occupying different levels Stratification
Example Trees > Shrubs > Herbs > Grasses
8. Pond contains all 4 basic components of ecosystem (Productivity, Decomposition, Energy flow, Nutrient cycle)
Autotrophic component Phytoplankton’s, Algae, submerged and marginal plants
Consumers are represented as Zooplankton’s
Decomposers Fungi, Bacteria, Flagellates (abundant at bottom of pond)
These above system performs all function of ecosystem and of Biosphere as whole
9. Productivity The rate of biomass production, It is expressed as gm–2yr –1 or (kcal m–2)yr –1
10. Primary production amount of biomass or organic matter produced per unit area over a time period by plants
during photosynthesis
It is expressed as weight (gm–2 ) or energy (kcal m–2)
11. Secondary productivity rate of formation of new organic matter by consumers
12. Gross primary productivity the rate of production of organic matter during photosynthesis
A considerable amount of GPP is utilised by plants in respiration
Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP). GPP – R = NPP
13. Net primary productivity available biomass for the consumption to heterotrophs
(herbivores and decomposers).
14. Factors affecting Primary Productivity:
a. plant species inhabiting a particular area
b. environmental factors
c. availability of nutrients
d. photosynthetic capacity of plants
e. it varies in different types of ecosystems
15. The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of
organic matter.
16. productivity of the oceans are only 55 billion tons
17. Decomposition decomposers break down complex organic matter into inorganic substances like carbon
dioxide, water and nutrients and the process is called decomposition
18. Detritus raw material for decomposition
Example Dead plant remains such as leaves, bark, flowers and dead remain of animals, including faecal matter
19. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and
mineralisation
fragmentation Detritivores (e.g., earthworm) break down detritus into smaller particles
leaching water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts
catabolism Bacterial and fungal enzymes degrade detritus into simpler inorganic substances
