Ecosystem-Quick Revision

1

Lindeman 10% law

• The law states that during transfer of food energy from one trophic level to the other, only about 10% is stored at higher trophic level and the remaining 90% is lost in respiration, decomposition and waste in the form of heat.

2

Stratification

• Vertical distribution of species in an ecosystem is known as stratification.

3

Standing crop

• A standing crop is the total dried biomass of the living organisms present in a given environment.

4

Pioneer Species

1. Species that are first to invade a barren area are called pioneer species.
2. In primary succession, lichens invade the rocks which results into weathering of rocks and soil formation, leading to the growth of small plants like bryophytes.

5

Primary productivity

1. Primary productivity refers to the amount of organic matter, produced at the producer level during a given period of time. It is of two types, gross primary productivity and net primary productivity.
2. The rate at which organic compounds are formed in a green plant or in a population of green plants per unit time and area is known as the gross primary productivity.
3. Building of biomass or storage of energy by green plants or plant in a unit time and area is known as net primary productivity.
4. Gross primary productivity minus respiration losses is the net primary productivity.

6

Secondary productivity

• Secondary productivity refers to the amount of organic matter produced at any of the consumer level during a given period of time.

7

Factors affecting primary productivity

1. The primary productivity of an ecosystem depends upon variety of envionmental factors such as light, temperature, water, precipitation etc.
2. It also depends upon the availability of nutrients and the availability of plants to carry out photosynthesis.

8

Types of ecological succession

1. Primary succession: Occurs in barren, soilless, uninhabited regions.
2. Secondary succession: Takes place in the previously inhabited but somehow disturbed areas.

9

Phosphorous cycle

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10

Carbon cycle

• The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.