Ecosystem

• Aquatic


  Relating to or living in water
• Components of an aquatic ecosystem

  • Phytoplankton
  • ZooPlankton
  • Small fish
  • Large fish
• Components of a terrestrial ecosystem

  • Tree
  • Insect
  • Bird
• Interaction of biotic and abiotic components result in a physical structure that is characteristic for each type of ecosystem
• Species composition


  Identification and enumeration of plant and animal species of an ecosystem
• Stratification


  Vertical distribution of different species occupying different levels
• Components of an ecosystem

  • Productivity
  • Decomposition
  • Energy flow
  • Nutrient cycling
• A pond is a shallow water body in which all the above mentioned four basic components of an ecosystem are well exhibited
• Abiotic components of a pond

  • Water with dissolved inorganic and organic substances
  • Rich soil deposit at the bottom
• Autotrophic components of a pond

  • Phytoplankton
  • Algae
  • Floating plants
  • Submerged plants
  • Marginal plants
• Consumers in a pond


  • Zooplankton
  • Free swimming
• Decomposers in a pond

  • Fungi
  • Bacteria
  • Flagellates
• The pond system performs all the functions of any ecosystem and of the biosphere as a whole
• Functions of an ecosystem

  1. Conversion of inorganic into organic material with the help of the radiant energy of the sun by the autotrophs

  2. Consumption of the autotrophs by heterotrophs

  3. Decomposition and mineralisation of the dead matter to release them back for reuse by the autotrophs
• There is unidirectional movement of energy towards the higher trophic levels and its dissipation and loss as heat to the environment
• Productivity


  The rate of biomass production, expressed in terms of gm 2 yr or (kcal m²) yr to compare the productivity of different ecosystems
• Gross primary productivity (GPP)


  The rate of production of organic matter during photosynthesis
• Net primary productivity (NPP)

  Gross primary productivity minus respiration losses (R)
• Secondary productivity


  The rate of formation of new organic matter by consumers
• Factors affecting primary productivity

  • Plant species inhabiting a particular area
  • Availability of nutrients
  • Photosynthetic capacity of plants
• The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of organic matter
• The productivity of the oceans is only 55 billion tons, despite occupying about 70 per cent of the surface
• The rest of the net primary productivity is on land
• A constant input of solar energy is the basic requirement for any ecosystem to function and sustain
• Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis
• A considerable amount of GPP is utilised by plants in respiration
• Net primary productivity is the available biomass for the consumption to heterotrophs (herbiviores and decomposers)