Terrestrial community is naturally quite different from the aquatic community.
The amount of water determines the habitability of a particular landmass.
A comparison of a rain forest with a desert makes this point clear to us. Besides water, the sustaining foundations of all terrestrial life are air, and, directly or indirectly soil. Like air, soil is itself a home for a vast majority of terrestrial organisms. By creating the conditions necessary for the survival of all other terrestrial organisms, soil becomes a major agency, which transforms terrestrial environments into life sustaining habitats.
The physical conditions, e.g., temperature, wind, humidity, sunlight of the terrestrial environments are not as uniform as in the aquatic habitats. Hence, terrestrial habitats often show greater extremes, as of temperature, and sharper discontinuities, as between opposite sides of a mountain range, than are found in the ocean, for example.
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Terrestrial Life Zones:
Since rainfall and temperature vary with geographic latitude and altitude, they divide the soil covered land surface into a number of distinct habitat zones, or biomes. A biome is, therefore, the largest terrestrial ecological unit, which is characterized by interactions of flora, fauna, and abiotic substances.
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The climate is considered to be a part of the abiotic component. A biome gets its name from its climax or dominant plant form. Therefore, the term ‘biome’ may also be defined as one of the major categories of the world’s distinctive plant assemblages. For example, a grass biome is an area in which grasslands predominate; a coniferous biome is an area of cone-bearing evergreen trees.
The various zoogeographic regions contain more than one biome. The Oriental region, for instance, contains a tropical rain forest, a tropical deciduous forest, a tropical scrub forest, temperate deciduous and rain forest, temperate grassland, mountains, and desert. Many of the similar biomes are also found in Australian, Ethiopian, and Neo-tropical regions.