Page 7 - Lesson note-Ecosytem

Nutrient Cycling

The movement of nutrients elements through the various components of an ecosystem is
called nutrient cycling. It is also called as biogeochemical cycles. There are two types of

nutrient cycles-

· Gaseous – exist in atmosphere.

· Sedimentary- exists in earth crust.

Environmental factors like soil, moisture, pH, temperature regulate the rate of release of
nutrients into the atmosphere. The function of reservoir is to meet with the deficit which

occurs due to imbalance in the rate fo influx and efflux.

Carbon Cycle

Carbon cycling occurs through atmosphere, ocean and through living and dead organisms.

Most of carbon is fixed by plants during the process of photosynthesis and returns to
atmosphere in form of CO2 during respiration. Burning of wood, forest fire and combustion

of organic matter, fossil fuel, and volcanic activity are other sources of releasing CO2 in the

atmosphere.

Phosphorus Cycle

The natural reservoir of phosphorus is rock which contains phosphorus in the form of

phosphates. On weathering, minute amount of phosphates dissolve in soil solution and
absorbed by the roots of the plants. The waste products of dead organisms are decomposed

by bacteria to release phosphorus. Gaseous exchange between organism and environment is
negligible as compared to carbon.

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