A peep into ecology and environment
Hyderabad: Eco system – Elementary Aspects An ecosystem consists of both structural & functional components. The ecosystem components of ecosystem are of two types – Abiotic factors and Biotic factors. Abiotic factors are again of two types – Physical factors and Chemical factors. The physical factors are lights, temperature, soil, pressure etc. The chemical factors […]
Hyderabad:
Eco system – Elementary Aspects
An ecosystem consists of both structural & functional components. The ecosystem components of ecosystem are of two types – Abiotic factors and Biotic factors. Abiotic factors are again of two types – Physical factors and Chemical factors. The physical factors are lights, temperature, soil, pressure etc. The chemical factors are oxygen, carbon dioxide, various mineral nutrients in the soil/water, etc.
These physical and chemical factors affect the life of the organisms present in an ecosystem. Energy transfer and recycling of minerals constitute the functional aspect of an ecosystem.
Light
Since plants produce food through photosynthesis, a process which is possible only when sunlight is available as a source of energy. We can easily understand the importance of light for all living organisms, particularly the autotrophs.
Many species of small plants (herbs and shrubs) growing in forests are adopted to photosynthesis optimally under very low light conditions because they are constantly over shadowed by tall trees with well-spread branches.
Many plants are also dependent on sunlight to meet their photoperiod requirement for flowering.
For many animals light is important in that they use the diurnal and seasonal variations in the intensity and duration (photoperiod) of light, as cues (indicator-s) for timing their foraging (collection of food) reproductive and migratory activities.
The availability of light on land is closely linked with that of temperature since the sun is the source of both.
But, deep in the oceans, the environment is always dark and its inhabitants do not experience light. The spectral quality of solar radiation is also important for life. The UV component of the spectrum is harmful to many organisms. All the colour components of the visible spectrum are not available for marine plants, living at different depths of the seas.
Biological effects of light: Light is an ecological factor that shows its influence on many biological phenomena and activates like pigmentation, movement, vision, metabolism, etc.
Effect of light on pigmentation:
Light influences the colour of the skin
The animals which live in regions of low intensity of light such as caves have less pigmentation than that of the animals exposed to light
For example: – A cave dwelling amphibian, proteus anguinus, has pale coloured skin because of less pigmentation. When it is brought into sunlight the skin colour turns dark over a period of time.
Effect of light on direction and rate of movement: Response shown by an organism to changes in light is called photo response. The major photo responses of motile organisms include:
Phototaxis: Phototaxis is oriented loco motor movement of an organism away from the direction of light as seen in euglenas (positive response)and cockroaches (negative response).
Plotokinesis: Photokinesis is the influence of light on non-directional movement of organisms as seen in the larvae of pinnotheres maculatus-the mussel carb, in which intensity of light influences the velocity of the movement of the organism.
Phototropism: The orientation of light of a non-motile organism such as a plant/plant part is called phototropism.
For example: The growth mediated bending of plants towards sunlight is due to phototropism.
To be continued …
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