Explore topic-wise InterviewSolutions in .

Primary productivity varies from ecosystem to ecosystem because it depends on the plant species inhabiting the area and their photosynthetic activity. It also depends on various environmental factors, which vary in different ecosystems.

The rate of assimilation and formation of new organic matter by consumers is called secondary productivity. 

The factors which affect productivity in an aquatic ecosystem are:

i. Nitrogen in marine ecosystem. 

ii. Light, which decreases with increasing depth of water.

• Pyramid of number in a tiee ecosystem.
• Pyramid of biomass in an aquatic ecosystem.

Food web is given to the inter connected food chain.

1. Grazing food chain 

2. Detritus food chain

(b) Energy transformation results in reduction of free energy.

Food and feeding relation among organisms makes a chain like structure is called food chain.

Ex : Grass → Deer → Lion 

Photosynthetically Active Radiation. 2-10%.

The part of incident solar radiation that can be absorbed and used by plants autotrophs for photosynthesis, is called photosynthetically active radiation (PAR)

It is the rate of energy stored or biomass accumulated by the producers. It depends up on rate of photosynthesis as well as respiration.

Pond, crop fields

An ecosystem is a functional unit of nature, where living organisms (biotic) interact among themselves and also with the abiotic factors or their physical environment.

Sedimentary Biogeochemical cycle:-

It is circulation of a biogeochemical between biotic and abiotic compound of an ecosystem is a nongaseous being lithosphere or sediments of the earth. Sedimentary cycles occur in case of phosphorus, calcium, magnesium, zinc, copper etc. Important feature:

(i) Input of Nutrients:-

Nutrients enter the nutrient pool through weathering of rocks. In sites soil formation also occur through weathering of rocks. Nutrients present in the soil become available to plants. Wind carries nutrients from mining areas and industrial area and deposited over the soil.

(ii) Internal nutrient cycling:-

It is cycling or circulation of nutrients with in the ecosystem. Plants absorb nutrients from soil and incorporate them into organic matter. In the form of organic matter the nutrients pass from producers to herbivores and herbivores to carnivores. The process is called transfer. All trophic level pass a part of organic matter as detritus.

Detritus acted up on by decomposers and release the nutrients back into cycling pool. In stable ecosystems, over 80% of nutrient requirement of the biotic is met through internal nutrient cycling.

(iii) Out put of Nutrients:-

It is a movement of nutrients out of an ecosystem. Out put reduces the availability of nutrients in the cycling pool. It occurs through soil erosion, run off water and economic out put like harvesting of crops or removal of wood from forest. Crop fields are always under negative nutrient budget.

The process of physical and chemical breakdown of complex organic remains into inorganic raw materials (CO₂, H₂O, minerals) for recycling is called decomposition. It is carried out by organism remain are called detritus.

There are types decomposition process occurs.

(a) Fragmentation

(b) leaching

(c) Catabolism

(a) Fragmentation of Detritus:-

Small invertebrates animals called detritivores comes out in highly pulverised state in their faeces.

(b) Leaching:-

Part of soluble substances present in the fragmented and decomposing detritus get leached to upper layers of soil by percolating water.

(c) Catabolism:- 

It is carried out by saprotrophic bacteria. They secrete digestive enzymes over the fragmented detritus. The enzymes change the complex organic compounds into Simple compounds.

Catabolic action forms two types of products-

humus and inorganic the process involved in formation of these products are respectively called humification and mineralisation.

Breakdown of complex organic matter by decomposers.

Process :

(i) fragmentation 

(ii) leaching 

(iii) catabolism. 

Humification and mineralization –humification leads to accumulation of dark colour substance called humus. Mineralisation result in release of inorganic substances.