Topic: Environment, Habitat and Niche

Environment

Environment is the sum of total of all biotic (living) and abiotic (non-living) factors that surround and potentially influence an organism. Some components of the environment serve as resource, while others act as regulatory factor. The different components of the environment are interlinked and interde-pendent. The environment can be understood both at large and small scales. This is reflected in regional and global climate patterns, as well as the local climate conditions, the microclimate.

Spatial and Time Scales of Environment

Most organisms interact with their environment at several spatial and time scales. A single bacterium in soil, for example, interacts with air and water within a fraction of a cubic centimeter space. On the other hand, a tree interacts with a large volume of air, water and soil at a large spatial scale. The environment varies from place to place due to variation in climate, soil type and topography. The activities of organisms influence the hydro-sphere, the lower atmosphere and the near-surface part of the lithosphere, through exchanges of matter and energy. Organism have to cope with the external environment over a range of time scales, varying from few minutes to days, seasons or over a much longer period of geological time scale. For example, phytoplankton populations may change conditions in aquatic systems. On the other hand, the variations in lithosphere occur very slowly over a long period of time.

Climate

The short-term properties of the atmosphere (such as temperature, pressure, humidity, rainfall, sun shine, cloud cover and wind), at a given place and time, are what we call weather. Climate is the average weather of an area, including general patterns of atmospheric conditions, seasonal variations and weather extremes averaged over a long period. Thus, while weather reflects the hourly, daily or weekly changes in the above properties, climate entails longer periods, such as seasons, or years. Temperature and rainfall are the two most important factors which determine the climate of an area. Global variations of temperature and rainfall result from differential input of solar radiation in different regions, and from the redistribution of heat energy by winds and ocean currents. Variations in temperature, rainfall, and humidity in different regions of the globe form global climate patterns, which govern all life on earth.

Climate zones: On the basis of variation in mean temperature along latitude, the main climatic regions are:

• Tropical (0o-20o latitude)

• Subtropical (20o-40o latitude)

• Temperature (40o-60o latitude)

• Arctic and Antarctic (60o-80o latitude)

The mean temperature declines as we move from tropical to arctic region. A similar climatic zonation occurs with increasing altitude in the mountains. A mountain located in a tropical region will successively have tropical, subtropical, temperate and alpine zones with increasing altitude. Similarly, in temperature zone, the high altitudes will have alpine climatic condition. Within each temperature-based climatic zone, the annual precipitation (rainfall and/or snowfall) varies considerably. These two factors, temperature and precipitation, together determine the vegetation and soil types.

Microclimate

The microclimate represents the climate conditions that prevail at a local scale, or in areas of limited size, such as the immediate surroundings of plants and animals. Microclimate generally differs from the prevailing regional climatic conditions. For example, in a forest, dense foliage reduces the amount of light reaching the ground. This also results in a changed air temperature profile. The day-time air temperature inside the forest is lower than outside. Also, the interior of a forest may be more humid than a nearby non-forested area.

Habitat and Niche

The place where an organism light is called its habitat. Habitat are characterised by conspicuous physical features, which may include the dominant forms of plant and animal life. We may also understand that habitat may refer to the place occupied by an entire biological community. For example, a large number of species are found in a forest habitat. Plants and animals, as influenced by the environmental conditions of a particular habitat, indicate some specific traits. For example plants growing on saline soils have several characteristics that are not found in other plants. A habitat can contain many ecological niches and support a variety of species. The ecological niche of an organism represents the range of conditions that it can tolerate, the resources it utilises, and its functional role in the ecological system. Each species has a distinct niche, and no two species are believed to occupy exactly the same niche.

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