• Organism needs constant supply of nutrients to grow, reproduce, and regulate various body functions.
  • Standing state: the amount nutrients such as carbon, nitrogen, phosphorus, calcium etc. present in soil at any given time.
  • Nutrient cycling: The movement of nutrient elements through the various component of an ecosystem is called nutrient cycling.
  • Another name of nutrient cycling is biogeochemical cycle.
  • Nutrient cycles are of two types:
    • Gaseous cycle
    • Sedimentary cycle.
  • The reservoir for gaseous type of nutrient cycle (nitrogen, carbon) exists in the atmosphere.
  • The reservoir for sedimentary cycle (sulphur, phosphorus) is Earth’s crust.
  • Environmental factors like soil, moisture, pH temperature regulate the rate of release of nutrient into the atmosphere.
  • The function of the reservoir is to meet the deficit which occurs due to imbalance in the rate of influx and efflux.

Ecosystem – Carbon cycle:

  • Carbon constitutes 49 percent of dry weight of organism.
  •  Out of total global carbon:
    • 71 percent carbon found dissolved in ocean.
    • About 1 percent in the atmosphere.
  • 4 X 1013 kg of carbon is fixed in the biosphere by photosynthesis, annually.
  • Large amount of carbon returned to the atmosphere as CO2 through respiration of producers and consumers.
  • Decomposers also return CO2 to reservoir during decomposition process.
  • Some amount of Carbon is lost to sediments and removed from circulation.
  • Burning wood, forest fire, combustion of organic matter, fossil fuel, volcanic activities are additional sources for releasing CO2 to atmosphere.


Influence of human activity on Carbon cycling.

  • Rapid deforestation.
  • Massive burning of fossil fuel for energy and transport
  • Increased the rate of release of CO2 into the atmosphere.

Ecosystem Phosphorus cycle:

  • Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer system(ATP)
  • Animals need phosphorus to make shell, bones and teeth.
  • Reservoir pool of phosphorus is the rock, which contain phosphorus in the form of phosphates.
  • During weathering of rock small amount of phosphates dissolved in soil solution and are absorbed by the roots of the plants.
  • Herbivore and other animals obtain organic form of phosphorus from plants.
  • The waste product and dead organisms are decomposed by phosphate-solubilising bacteria releasing phosphorus.

How phosphorus cycle differs from carbon cycle?

  • There is no respiratory release of phosphorus into atmosphere.
  • Atmospheric inputs of phosphorus through rainfall are much smaller.
  • Gaseous exchange of phosphorus between organism and environment are negligible.


  • The products of ecosystem processes are named as ecosystem services.
  • Healthy forest ecosystems purify air and water.
  • Mitigate droughts and flood.
  • Cycle nutrients.
  • Generates fertile soil.
  • Provide wildlife habitat.
  • Maintain biodiversity.
  • Pollinate crops.
  • Provide storage site for carbon
  • Provides aesthetic, cultural and spiritual values

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