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Here is an essay on ‘Biomes’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Biomes’ especially written for school and college students.
Essay on Biomes
Essay on Biome # 1. Tundra:
The word Tundra means north of the timber line (Tree line). It extends across Asia, Europe and North America generally above 60°N latitude and lies between the Arctic Ocean and the coniferous forests. There is no Tundra biome in Southern Hemisphere. It covers about 8 × 106 sq. km. area.
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The characteristics of tundra are:
(a) Plains are characterized by, snow, ice and frozen soil most of the year (permafrost).
(b) Light is very poor and temperature is very low (- 30°C to – 40°C in winter). Summer temperature is about 10°C but summer is only of 60 days.
(c) Annual precipitation is below 25 cm (mostly as snow).
(d) Productivity of Tundra biome is only 200 kcal/m2/year. Vegetation in the North Tundra is so sparse that it is also called arctic desert. It has low species diversity.
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(e) The biome is virtually without trees. It consists mainly of lichens (Cladonia-Reindeei moss), mosses (Sphagnum-Peat moss), sedges, and grasses, dwarf birches (Betula) and dwarf willow trees (Salix). The plants are mostly shallow rooted.
(f) Fauna of Tundra biome includes insects like biting flies, mosquitoes, etc.; birds like snow-owl, snow-grouse (ptarmigan) and migratory birds like water fowls in the summer; and mammals like musk ox, reindeer, caribou, arctic hare, arctic fox, polar bear (hibernating in winter) and weasles. No amphibians and reptiles are found m this biome. Caribou and reindeer are migratory mammals.
Essay on Biome #
2. Northern Coniferous (Taiga):
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These forests are also known as the north woods. They are very common in Siberia. It covers about 10% of the land mass. Taiga extends as an east-west band across North America, Europe and Asia just south of the Tundra (between 45° and 75° N latitudes).
In southern hemisphere, Taiga is found in South island of New Zealand. In India, such forests are found m Himalayas over 1700 to 3000 metres altitude. Productivity of Taiga biome is 2000 kcal/m2/year.
The main characteristics of this biome are listed below:
(a) The temperature is low in winter (average 6°C). Winters are long and snowy. Summers are very brief (Average temp. 15°C).
(b) The duration of growing period of plants is 60- 150 days.
(c) Rainfall ranges from 10-35 cm in dry areas but may be up to 100 cm. in wet areas.
(d) Many lakes and bogs are associated with these forests.
(e) The soils are thin, acidic and poorly drained. Forest floor is covered by a thick zone of fallen needles (due to poor growth of decomposers by long winters) so soil is poor in humus.
(f) The climax vegetation consists of needle-leaved evergreen trees. These include highly economically useful gymnospermous trees like Finns wallichiana (pine), Cedrus deodara (deodar), Cupressus torulosa (cypress) and Abies pindrow (silver fir). These are about 30-35 metres tall and generally possess a cone-shaped canopy which always remains green.
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(g) Forest is stratified into four layers—an evergreen tree stratum (30-35 m. high); a short shrub stratum (2- 4 ft high); a layer of low herbaceous plants; and finally a very low moss and lichen layer.
(h) Animals of this biome include mammals like mouse deer, musk rat, pine mouse, porcupine, elks, deer, rabbits, squirrels, lynx, pumas; insectivorous birds like grouse, jay crossbill etc.; lizards and snakes among the reptiles and many species of insects. It also has reindeer and caribou migrated from Tundra biome during winter months.
Essay on Biome #
3. Temperate Deciduous Forests:
These forests are found in temperate regions of North Central Europe, Eastern Asia and the Eastern United States covering an area of 18 x 106 sq. km. hi southern hemisphere, such forests are found in Australia and New Zealand. In India, these occur in western Himalayas between 1500 and 2400 m. altitude. Productivity of this biome is 3000 kcal/m2/year.
Main characteristics are listed below:
(a) The annual precipitation is abundant which ranges from 75 cm to 150 cm and is evenly distributed throughout the year.
(b) Temperature remains moderate (maximum 20-27°C and – 12°C in winter) and shows distinct seasonal patterns.
(c) The dominant vegetation consists of broad-leaved deciduous trees of about 25-30 m. height. These are dominated by several species of Quercus (oak) trees and are rich in epiphytic flora. Oak species include Q. leucotrichophora (banj oak), Q. seme-carpifolia (khrsn oak), Q.floribanda (tilonej oak) Q. lanu-ginose (rianj oak).
Other trees found in these forests are Elmus (elms), Acer (maples), Betula (birch), Fagus (beech), Salix (willow), etc. In autumn, these trees shed their leaves so are leafless in winter. The trees occur in two storeys; canopy and understorey. Grasses are generally absent.
(d) The fauna (animals) is rich in vertebrates and invertebrates. Vertebrate fauna is represented by salamanders, frogs, toads, turtles, snakes, lizards, rabbits, bears, foxes and song birds. Invertebrate fauna is represented by earthworms, snails, millipedes, insects etc.
Essay on Biome #
4. Tropical Rain (Evergreen) Forests:
This biome is located in the equatorial regions where annual rainfall exceeds 140 cm. It occurs between the Tropics of Cancer and Capricorn covering an area of 20 × 106 sq. km. These are found on the eastern coast of Mexico, South America (Amazon and Orinoco river basins), Congo River basin of Africa, South-east Asia etc.
These cover about 1/12th of the earth’s surface but have over half of the world’s flora and fauna. In India, tropical rain forests are found in Westerrn Ghats, Andamans and North-East Himalayas (Assam).
These have maximum bio-diversity. These are also most productive forests (12000 kcal/m2/year). These forests have highest standing crop biomass among all the biomes.
These are characterized by:
(a) The temperature is relatively high and uniform throughout the year. Mean annual temperature is 23-27°C.
(b) Rainfall is abundant, between 200 to 1000 cm/year and is generally distributed throughout the year.
(c) Climate is warm and humid which supports broad-leaved evergreen plants.
Soil is very rich in minerals and humus (due to abundance of decomposers) but is highly leached.
(d) The plants show distinct stratification into 4 or 5 strata formed by different species of plants.
(e) The vegetation is comprised of broad-leaved evergreen tall trees (about 30-40 m high), below which are present shade tolerant plants such as bamboos, ferns, shrubs etc. Epiphytes (air plants like orchids) and woody vines (Lianas) are also abundant. These forests are very dense (called jungles) and almost impermeable.
Important trees of this biome are Rosewood, Mahogany, Rubber trees. Figs, Nutmeg, etc. In Indian rain forests of western ghats, Dipterocarpus (rose wood) and Hopea are most common species of trees. Many tree species show butteresses (swollen leaf bases), large leaves with drip tips to drain excess of water and round the year leaf-fall.
(f) The fauna include monkeys, lemurs, sloths, snakes, ant-eaters, tropical birds, bats, and large carnivorous animals like leopards. Jaguars, etc. Upper storeys are dominated by brilliantly coloured birds like parakeets, toucans, birds of paradise, etc. About 71-80% of the world’s insect species and 80-85% of bird species are found in these forests.
Essay on Biome #
5. Tropical Deciduous or Monsoon Forests:
These occur in the northern and southern parts of India in plain and low hilly areas. In south India, these are abundant in the tropical islands of the Indian Ocean. These are also found in West Indies, Brazil and Northern Australia.
These are characterized by:
(a) Climate is with distinct alternating wet and dry season. Mean annual temperature is 22°-32°C.
(b) Annual rainfall is 900-1600 mm but mostly occurs in the monsoon period, so called moonson forests.
(c) Soil is rich in minerals and humus as the environment favours the growth of decomposers but there is lesser leaching.
(d) Vegetation is dominated by broad-leaved trees and shows distinct stratification in 3 to 4 strata. The average height of trees is of 10-20 m so are of short stature. Dominating trees of these forests are Shorea robusta (sal) and Tectona grandis (teak).
Other useful species of trees are Diospyros melanoxylon (tendu), Buchanania lanzan (chiraimji) and Acacia catechu (khair). The epiphytes are absent though seasonal climbers may be present. The trees shed their leaves just before the summer months so become nearly leaf-less while these are lush green during rainy season.
(e) Mean net primary productivity of these forests is 2500 kcal/m2/year.
(f) Animal fauna of these forests is similar to that of tropical rain forests but is less varied.
Essay on Biome # 6.
Chaparral:
This biome is also known as Mediterranean scrub forest. It extends along the Mediterranean, Pacific coast of North America, Chile, South Africa and South Australia.
Main characteristics are:
(a) Rainfall is limited and occurs in winter, summers are long, hot and dry.
(b) Temperature is moderate under the influence of cool, moist air of the oceans.
(c) Vegetation consist of hard, thick, broad-leaved evergreen plants which are fire resistant e.g. sage, oak, etc. Fires are very common in this biome. Fire acts as a decomposer to release the mineral nutrients from old accumulated litter. So fires increase the productivity.
(d) The fauna consist of drought resistant animals. These are reptiles (lizards and snakes), birds and mammals (rat, ground squirrel, rabbits, deer, tiger, etc.).
Essay on Biome #
7. Tropical Savannah:
They are located primarily in South America, Africa and northern Australia covering an area of 15 x 106 sq. km. Mean net primary productivity is 900 gm/m2/year while its range is 200-2000 gm/m2/year. It is also called tropical grassland.
Main characteristics of this biome are:
(a) They are warm climate plains having coarse grass with scattered trees on the margins of tropics.
(b) Average total rainfall is 100-150 cm.
(c) Wet seasons alternate with prolonged dry seasons.
(d) Plants and animals are drought-tolerant and do not show much diversity. The dominant vegetation is of coarse grass. Most abundant grass species in Indian savaimah are Dichanthium, Sehima, Phragmites, Saccharum, Cenchrus, Imperata and Losturus. Most of these grass species showiC4– photosynthetic cycle. Productivity of tropical savartna is 3000 kcal/m2/year. Scatterly grown trees include Prosopis, Zizyphus, Capparis, Acacia, Butea, Phoenix and Eucalyptus.
(e) Hoofed herbivore species including zebra, rhinoceros, giraffe, elephant, several kinds of antelope etc. are common in this biome. These herbivores are preyed upon by carnivores like fox, wolf, tiger, lion etc. Kangaroos are found in the Savannah of Australia.
Essay on Biome #
8. Temperate Grassland:
The principal temperate grasslands of world include Steppes of Europe and Asia, Prairies of Canada and North America, the Pampas of South America, Tussocks of New Zealand and the Veldts of Africa. The largest continuous grassland is the Steppe of Russia and Siberia. It covers about 9 x 106 sq. km. area. Its annual productivity is 2500 kcal/m2/year.
Main characteristic features of temperate grassland are:
(a) Annual rainfall is between 25 to 75 cm. which is not enough to support the forest vegetation.
(b) Winter blizzards and summer drought can be severe with periodic fire devastations. Burning of common ‘doob’ grass increases the forage yield.
(c) Soil is rich in humus due to rapid decomposition.
(d) The dominant plant species comprise short and tall grasses (Andropogon, Panicum etc.) belonging to family Poaceae. These grasses have extensive root system. These also have leguminous dicots which help in nitrogen fixation.
(e) Shoot biomass of grassland biomes varies from about 50 to 1000 gm/m2.
(f) The height of grassland vegetation varies from a few centimeters in arid region to more than a meter in moist region.
(g) Animal species include the grazing mammals (e.g. bison, elk, antelope, zebra, bighorn sheep and deer) and burrowing animals (e.g. rodents, rabbit, prairie dogs, ground squirrel, etc.) These herbivores are preyed upon by carnivores like wolf, coyote and predatory birds.
Temperate grasslands are of tremendous economic importance to mankind because these are mainly grain- growing and cattle-raising areas as these provide fodder for livestock.
Essay on Biome # 9.
Desert:
Deserts occupy approximately l/5th (20%) of earth’s surface. The great deserts of the world occur on all the continents except Europe and Antarctica. The deserts of the world are primarily located in the South-Western USA (Great Western Desert – Death Valley), Mexico, Chile, Peru, North Africa (Sahara and Kalahari), Asia (Tibet, Gobi, Thar), Atacama desert of S. America and Central-Western Australia.
Deserts are located around the tropic of Cancer and tropic of Capricorn between 15° abd 35° latitudes and are characterized by following main features:
(a) Rainfall is extremely low, varying from 5-25 cm a year. So there is scarcity of water.
(b) Days are extremely hot (temperature about 50-60°C) and nights are cold. So evaporation from soil exceeds rainfalls by 7 to 50 times.
(c) Dust storms are of common occurrence as soil is generally sandy. Such deserts are called hot deserts (e.g. Thar, Sahara) while Gobi desert is a cold desert.
(d) Deserts have very scanty flora and fauna.
(e) The organisms in deserts have specialized structural, physiological and behavioural adaptations to withstand extremes of temperature and arid conditions.
(f) Desert plants include different types of acacias, cacti, euphorbias, hardy grasses and several types of succulents. The shurbs and small trees are less in number and widely spaced. These include Acacia, Prosopis, Tamarix etc. and have deep root system. Some plants are short-lived (Ephemerals) and occur only during rainy season e.g.
Boerhaavia repens (life span of 10-14 days only) of Sahara desert. Some are with xerophytic adaptations against water loss e.g. hardy grasses, Echinops, etc. Some are succulents and open their stomata only at night e.g. cacti, euphorbias. The most common grass in the desert biome is Cenchrus.
(g) Animals include ants, locusts, wasps, scorpions, spiders, lizards like horned lizard, Gila monster, collard lizard; snakes like coral snake, rattle snake; insect eating birds, burrowing owls, Gambel’s quail, doves, kangaroo rats, rabbits, camel, white-tailed deer, ground squirrel, skunk, badger foxes, jackals and desert cats.
Some of these animals are beautifully adapted to face desert’s extreme conditions e.g. Kangaroo rats feeds on dry seeds and depends upon only metabolic water, while camel can withstand a loss up to 40% of water from its body cells.
Altitudinal Biomes and Latitudinal Biomes: Correlation
The climate varies not only latitudinally but also with altitude. The series of biomes mentioned above can also be noted along the slopes of high mountains like Himalayas in Asia, Andes in South America and the Rockies in North America. In the mountain ranges the change in the type of biome is due to change in the altitude. On the mountain slopes, the horizontal sequence of four types of biomes extending over thousands of kilometres latitudinally are compacted altitudinally into a few thousand metres.
Temperature and precipitation rate are the most important factors which determine the type of altitudinal biome. In the tropical mountains the sequence of four types of biomes from the base of the mountain to the snow line are- Tropical or Terai forest. Deciduous forest. Coniferous forest and Tundra. The basal region of the tropical mountain range is called Terai in India while the Tundra on a mountain is called alpine tundra. But in the temperate areas.
Taiga-like forests occur in the terai region while the Terai region of hills of India has mixed forests having both conifers like Pinus, Cedrus, Abies, etc. and broad-leaved trees like Quercus, Betula, Acer, Ulmus, Rhododendron, etc.