WHAT ARE NATURAL ECOSYSTEMS
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NATURAL ECOSYSTEMS notes UPSC and state PSC By home academy
A natural ecosystem is an assemblage of plants and animals which functions as a unit and is capable of maintaining its identity such as forest, grassland, an estuary, human intervention is an example of a natural ecosystem. Natural ecosystem is totally dependent on solar energy.
There are two main categories of ecosystems.
(1) Terrestrial ecosystem: Ecosystems found on land e.g. forest, grasslands, deserts,
tundra.
(2) Aquatic ecosystem: Plants and animal community found in water bodies. These can
be further classified into two sub groups.
(i) Fresh water ecosystems, such as rivers, lakes and ponds.
(ii) Marine ecosystems, such as oceans, estuary
tundra.
(2) Aquatic ecosystem: Plants and animal community found in water bodies. These can
be further classified into two sub groups.
(i) Fresh water ecosystems, such as rivers, lakes and ponds.
(ii) Marine ecosystems, such as oceans, estuary
TERRESTRIAL ECOSYSTEMS
Terrestrial ecosystems are (a) forests (b) grasslands, (c) deserts and (d) tundra
(a) Forests
Forests are large areas supporting rich growth of trees. Depending on the climate and type of trees they are generally grouped into:
(i) Tropical rain forests
(ii) Temperate deciduous forests
(iii) Boreal or north coniferous forests
(a) Forests
Forests are large areas supporting rich growth of trees. Depending on the climate and type of trees they are generally grouped into:
(i) Tropical rain forests
(ii) Temperate deciduous forests
(iii) Boreal or north coniferous forests
(i) Tropical rain forest
• Distribution: These are found in the high rain fall areas on either side of the equator.
Such forests are found in the western coast of India, scattered in south east Asia, some
parts of Africa and south America.
• Flora and fauna:Tropical rainforests occur in areas by having high temperature and
high humidity and receives above 200 cm of rainfall per year. Soil is rich in humus.
• Distribution: These are found in the high rain fall areas on either side of the equator.
Such forests are found in the western coast of India, scattered in south east Asia, some
parts of Africa and south America.
• Flora and fauna:Tropical rainforests occur in areas by having high temperature and
high humidity and receives above 200 cm of rainfall per year. Soil is rich in humus.
These forests have a very rich biodiversity e.g. Brazilian tropical rain forests have
more than 300 species of trees in an area of 200 square kilometer. Trees are tall
growing upto 50 to 60 m. These forests also support epiphytes, like vines, creepers,
woody creepers and orchid etc. These forests are rich in tree dwelling animals such as
monkeys, flying squirrels, snails, centipedes, millipedes, and many insect species are
common on the forest floor.
more than 300 species of trees in an area of 200 square kilometer. Trees are tall
growing upto 50 to 60 m. These forests also support epiphytes, like vines, creepers,
woody creepers and orchid etc. These forests are rich in tree dwelling animals such as
monkeys, flying squirrels, snails, centipedes, millipedes, and many insect species are
common on the forest floor.
Temperate deciduous forests
Distribution: They occur mostly in northwest, central and eastern Europe, eastern
northAmerica, north China, Korea, Japan, far eastern Russia and Australia. Trees of
deciduous forests shed their leaves in autumn and a new foliage grows in spring.
• Climate: These forests occur in the areas of moderate climatic conditions such as
temperature ranging but 10 to 20oC with a 6 month long winter and an annual rainfall
between 75 to 150 cm. They have its brown soils which are rich in nutrients.
• Flora and fauna: Common trees are oak, beach, heath, chest nut, birch, pine. These
forests also show stratification and have a under storey of saplings shrubs and tall
herbs. Prominent grazers include deer, bison and rodents. Rodents play a very important role in these forests. They feed on seeds, fruits and tree leaves. Black bear, raccoons, wild cat, wolves, fox and skunks are the omnivores found in these forests. Hibernation or winter sleep during winter is a common feature of animals found in these forests.
Invertebrate fauna comprises green flies, aphids, certain moths and butterflies.
deciduous forests shed their leaves in autumn and a new foliage grows in spring.
• Climate: These forests occur in the areas of moderate climatic conditions such as
temperature ranging but 10 to 20oC with a 6 month long winter and an annual rainfall
between 75 to 150 cm. They have its brown soils which are rich in nutrients.
• Flora and fauna: Common trees are oak, beach, heath, chest nut, birch, pine. These
forests also show stratification and have a under storey of saplings shrubs and tall
herbs. Prominent grazers include deer, bison and rodents. Rodents play a very important role in these forests. They feed on seeds, fruits and tree leaves. Black bear, raccoons, wild cat, wolves, fox and skunks are the omnivores found in these forests. Hibernation or winter sleep during winter is a common feature of animals found in these forests.
Invertebrate fauna comprises green flies, aphids, certain moths and butterflies.
Boreal or north coniferous forests:
Distribution: Coniferous forests are also known as ‘Taiga’.They extend as a continuous
belt across north America and north Eurasia below the arctic tundra. There is no
counterpart of these forests in southern hemisphere as there is no land at this latitude.
Climate is cold with long, harsh winter, with mean annual temperature below 00C.The
soils are acidic and poor in nutrients.
• Flora and fauna:Coniferous forests are characterized by evergreen, drought resistant
and woody. Conifers (gymnosprerms) e.g. spruce, fir and pine trees which bear naked
seeds in cones. The animals found in these forests, are red squirrel, deer, goat, mule,
moose etc. The carnivores which feed upon them are timber wolves, lynxes, bear.
Some common birds are crossbill, thrushes, warblers, flycatchers, robin and sparrow.
counterpart of these forests in southern hemisphere as there is no land at this latitude.
Climate is cold with long, harsh winter, with mean annual temperature below 00C.The
soils are acidic and poor in nutrients.
• Flora and fauna:Coniferous forests are characterized by evergreen, drought resistant
and woody. Conifers (gymnosprerms) e.g. spruce, fir and pine trees which bear naked
seeds in cones. The animals found in these forests, are red squirrel, deer, goat, mule,
moose etc. The carnivores which feed upon them are timber wolves, lynxes, bear.
Some common birds are crossbill, thrushes, warblers, flycatchers, robin and sparrow.
Grasslands
Distribution: Grasslands are areas dominated by grasses. They occupy about 20%
of the land on the earth surface. Grasslands occur in both in tropical and temperate
regions where rainfall is not enough to support the growth of trees. Grasslands are
known by various names in different parts of the world.
regions where rainfall is not enough to support the growth of trees. Grasslands are
known by various names in different parts of the world.
| Place | Name of the grassland |
| NorthAmerica | Prairies |
| Eurasia (Europe andAsia) | Steppes |
| Africa | Savanna |
| SouthAmerica | Pampas |
| India | Grassland, Savanna |
Tropical grasslands are commonly called Savannas. They occur in eastern Africa, South America, Australia and India. Savannas form a complex ecosystem with scattered medium size trees in grass lands.
Deserts
Distribution: Deserts are hot and low rain areas suffering from water shortage and
high wind velocity. They show extremes of temperature. Globally deserts occupy about
1/7thof the earth’s surface.
• Flora and fauna: Cacti, Acacia, Euphorbia and prickly pears are some of the
common desert plants. Desert animals include shrew, fox, wood rats, rabbits, camels
and goat are common mammals in desert. Other prominent desert animals are, reptiles, and burrowing rodents insects.
• Adaptations: Desert plants are hot and dry conditions.
1/7thof the earth’s surface.
• Flora and fauna: Cacti, Acacia, Euphorbia and prickly pears are some of the
common desert plants. Desert animals include shrew, fox, wood rats, rabbits, camels
and goat are common mammals in desert. Other prominent desert animals are, reptiles, and burrowing rodents insects.
• Adaptations: Desert plants are hot and dry conditions.
Tundra
The word tundra means a “barren land” since they are found in those regions of the world where environmental conditions are very severe. 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 occupies the northern fringe of
Canada,Alaska, European Russia, Siberia and island group of arctic ocean. On the
south pole Anatarctica tundra in the south pole is very small since most of it is
covered by ocean . Alpine tundra occurs at high mountains above the tree line. Since mountains are found at all latitudes therefore alpine tundra shows day and night temperature variations.
• Flora and fauna: Typical vegetation of arctic tundra is cotton grass, sedges, dwarf
heath, willows, birches and lichens. Animals of tundra are reindeer, musk ox, arctic
hare, caribous, lemmings and squirrel.
and above the tree line in the northern hemisphere. It occupies the northern fringe of
Canada,Alaska, European Russia, Siberia and island group of arctic ocean. On the
south pole Anatarctica tundra in the south pole is very small since most of it is
covered by ocean . Alpine tundra occurs at high mountains above the tree line. Since mountains are found at all latitudes therefore alpine tundra shows day and night temperature variations.
• Flora and fauna: Typical vegetation of arctic tundra is cotton grass, sedges, dwarf
heath, willows, birches and lichens. Animals of tundra are reindeer, musk ox, arctic
hare, caribous, lemmings and squirrel.
Most of them have long life e.g. Salix arctica that is arctic willow has a life span of 150 to 300 years. They are protected from chill by the presence of thick cuticle and epidermal hair. Mammals of the tundra region have large body size and small tail and ear to avoid the loss of heat from the surface. The body is covered with fur for insulation. Insects have short life cycles which are completed during favourable period of the year.