Ecosystem Services

Ecological goods include clean air and abundant fresh water. All the natural processes, arising from healthy ecosystems that are beneficial to the living components of the ecosystem are called as ecological services. 

These natural processes involve purification of air and water, maintenance of biodiversity, decomposition of wastes, soil and vegetation generation and renewal, pollination of crops and natural vegetation, groundwater recharge through wetlands, seed dispersal, greenhouse gas mitigation etc. Such benefits are available to all living organisms, including animals and plants, rather than to humans alone.

Carbon fixation

Ø Carbon fixation or carbon assimilation is the process of conversion of inorganic carbon (carbon dioxide) to organic compounds by living organisms. 

Ø It is the incorporation of carbon into organic compounds by living organisms, chiefly by photosynthesis in green plants. The most prominent example is photosynthesis.

Ø Chemosynthesis (is carbon fixation driven by the oxidation of inorganic substances e.g., hydrogen gas or hydrogen sulfide) is also another form of carbon fixation and can take place in the absence of sunlight.

Ø Organisms that help in the fixing of carbon are called autotrophs.

Ø These autotrophs depend on the process of carbon fixation for their own growth.

Ø Autotrophs include photoautotrophs, which synthesize organic compounds using the energy of sunlight, and lithoautotrophs, which synthesize organic compounds using the energy of inorganic compounds. 

Ø Heterotrophs are organisms that depend upon autotrophs for their growth.

Ø The organic compounds produced by autotrophs are used by heterotrophs to produce energy and to build body structures.

Ø “Fixed carbon”, “reduced carbon”, and “organic carbon” are terms used for various organic compounds.

Carbon fixation by green plants

Ø Trees and green plants are essential for the removal of carbon entering the atmosphere by converting inorganic carbon into organic compounds with the release of oxygen.

Ø The main chemical flow between forest and atmosphere is the exchange of CO₂ and O₂.

Oxygen Release

Ø Atmospheric oxygen is required by all terrestrial and aquatic plants and animals for respiration (the breakdown of organic compounds with the release of energy). 

Ø Twenty-one percent of Earth’s atmosphere has oxygen and this is rapidly cycled between plants, animals, and the atmosphere through photosynthesis and respiration.

Photosynthesis: 

Ø During photosynthesis, atmospheric carbon dioxide is converted into glucose inside the leaves of plants.

Ø Oxygen is a by-product of photosynthesis and is released by the plants back into the atmosphere.

Ø The oxygen can also be released through the root system, providing oxygen to the soil.

Ø Submerged aquatic plants and phytoplankton release oxygen produced during photosynthesis into the water.

Ø Both terrestrial and aquatic plants provide oxygen for respiration by other plants and animals.

Respiration: 

Ø Respiration is performed by both plants and animals.

Ø During respiration, molecular oxygen is used to break down organic carbon compounds.

Ø Food prepared by plants during photosynthesis contains organic carbon compounds.

Ø This food is directly or indirectly consumed by animals and humans for their growth and development.

Ø Plants also use the food produced by them during photosynthesis for their growth.

Ø During aerobic respiration (respiration that takes place in the presence of oxygen), the food is burnt and energy is released.

Ø The energy is used by the body for various works.

Ø However, when all of the oxygen in water or saturated soil has been consumed, some microbes undergo anaerobic respiration (respiration that does not require oxygen) and other compounds for oxygen, like iron, manganese, nitrate, and sulfate, are used for respiration by these microbes. 

Ø Anaerobic respiration is common in wetland soils, which are frequently flooded and have lower oxygen concentrations than drier soils.

Ø When oxygen re-enters the soil or water, aerobic respiration starts again.