TERRESTRIAL ECOSYSTEM
Environment
Natural Ecosystem
A natural ecosystem is an assemblage of plants and animals which functions as a unit and is capable of maintaining its identity. For example, forest, grassland etc. There are the following two main categories of ecosystems:
Terrestrial ecosystem: Ecosystems found on the land e.g. forest, grasslands, deserts, tundra, etc.
Aquatic ecosystem: Plants and animal community found in water bodies. These can be further classified into two sub groups.
- Freshwater ecosystems: Rivers, Lakes, Ponds, etc.
- Marine ecosystems: Oceans, Estuary, etc.
Terrestrial Ecosystem
The interrelations between organisms and environment on the land constitute "Terrestrial Ecology". The most important determining factors are:
- Moisture
- Temperature
Terrestrial ecosystems can be classified into different biomes as:
- Tundra Biome
- Forests Biome
- Grasslands Biome
- Deserts Biome
Tundra Biome
- The word tundra means a “barren land” (treeless plain) since they are found in those regions of the world where environmental conditions are very severe. Tundra is the coldest of all the biomes.
- It is known for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons.
- There are two types of tundra- Arctic and Alpine.
Distribution:
- Arctic tundra extends as a continuous belt below the polar ice cap and above the tree line in the northern hemisphere. It predominantly occupies the northern fringe of Canada, Alaska, European Russia, Siberia, and the island group of Arctic Ocean.
- On the south pole, tundra is very small since most of the parts are covered by the ocean. Alpine tundra occurs at high mountains above the treeline.
Flora and Fauna:
- Typical vegetation consists of cotton grass, sedges, dwarf heath, willows, birches, and lichens.
- Insects have short life cycles which are completed during favourable period of the year.
- Animals of tundra are the arctic hare, caribous, lemmings, reindeer, musk ox, and squirrel. They are protected from the extreme cold by the presence of thick cuticle and epidermal hair. The body is covered with fur for insulation.
- Mammals of the tundra region have large body size and small tail and ear, mainly to avoid the loss of heat from the surface.
Forest Biome
Forests may be either evergreen or deciduous. They are distinguished on the basis of the leaf into broad-leafed or needle-leaved coniferous forests in the case of temperate areas.
Coniferous forest (Boreal forest)
- Coniferous forests are also known as ‘Taiga’. They extend as a continuous belt across the North America and northern Eurasia below the arctic tundra.
- Climate is cold with high rainfall, strong seasonal climates with long winters and short summers.
- Soils of Boreal forest are acidic and mineral deficient. They are characterized by thin podzols and are poor.
- Coniferous forests are characterized by evergreen, drought resistant, and woody vegetation e.g. spruce, fir and pine trees.
- Animals found here include the red fox, porcupine, lynx, wolf, bear, squirrel, and amphibians like Hyla, Rana etc.
Temperate deciduous forest
- Moderate climate and broad-leaved deciduous trees.
- Trees of deciduous forests shed their leaves in autumn and new foliage grows in spring.
- Precipitation is fairly uniform throughout the year. Soils are podzolic and fairly deep.
Temperate rain forests
- Rainfall is high and fog may be very heavy.
- Biodiversity is higher than temperate forests but lower than tropical rainforests.
- Common trees: oak, beach, chestnut, birch, pine.
- Animals: deer, bison, rodents. Hibernation is common.
Tropical rain forests
- Found in high rainfall areas: Western Ghats, Southeast Asia, Africa, South America.
- Most diverse ecosystems.
- Rainfall above 200 cm, uniform temperature and humidity.
- Dense canopy, epiphytes, lianas common.
- Animals: monkeys, flying squirrels, snails, centipedes.
- Soils are red latosols.
Subtropical rainforests:
- Broad-leaved evergreen trees.
- Found in high rainfall regions with small temperature variation.
Grassland Biome
- Found in tropical and temperate regions with insufficient rainfall for forests.
- Short trees and tall grasses dominate.
Tropical grasslands (Savannah)
- Extensive in Africa; found also in India, Australia, South America.
- Scattered trees and fire-resistant shrubs.
- Fauna includes zebras, antelopes, buffaloes, elephants, rhinos; carnivores include hyena, lion, cheetah.
Temperate Grassland (Steppes, Prairies)
- Low temperature, low rainfall.
- Vegetation dominated by grasses.
- Animals: bison, antelope, cattle, prairie dog, wolves.
- Steppes provide forage only during wet season; savannas provide some forage even in dry season.
Desert Biome
- Hot or cold regions with less than 25 cm annual rainfall.
- Deserts in temperate regions lie in rain shadows.
- Vegetation: Cacti, Acacia, Euphorbia, prickly pears.
- Adaptations: reduced leaves, succulent stems, extensive roots.
- Animals: shrew, fox, woodrats, rabbits, camels, goats.
- Adaptations: nocturnal habits, long legs, concentrated urine.
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Subject: Environment
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