3. PLANT COMMUNITIES AND MAJOR VEGETATION
3.1. PLANT COMMUNITY
A group of populations of different species living in the same local areas and interacting with one another is called ecological community. So, the group or association of plants growing together in a particular habitat is called plant community.
The plant community of a given habitat consists of two or more different species. It has two basic characteristics
1. Plants are ecologically related and can live and grow together in a particular habitat, and
2. The Plant community is well organised i.e., it has well developed composition and structure which is the result of continuous interactions between the different species and with their environment.
Vegetation is assemblages of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers to species composition. In other words, all the plants which grow together in any area form its vegetation, the character of which depends not just on the different species present but on the relative proportions in which their members are represented. It is by far the most abundant biotic element of the biosphere.
Two habitats may have similar floras but their vegetation may vary from one another and two habitats having different floras may have similar vegetation.
For instance, if there are two similar habitats wherein both have grasses and sal trees but there is overwhelming dominance of grasses and sparse distribution of sal trees in the first habitat whereas the second habitat is characterized by dense sal trees and sparse distribution of grasses, the vegetation of the first habitat will be grasses whereas the vegetation of the second habitat will be sal forest.
3.2.1. VERTICAL STRATIFICATION OF PLANT COMMUNITIES
The development of different species of plant community of a given region takes place through the processes of adaptation, competition and natural selection.
Different species of plants are evolved in a habitat having favourable environmental conditions wherein different species of plant community grow together having different life-forms. This results in the development of various strata or layers between the soil surface or ground surface and the tree canopy.
This vertical layering pattern or vertical stratification of plants is the result of competition among various species of plant community to get sunlight.
On an average, there are four vertical strata of plant community in a given region mainly in the deciduous
forests of the temperate regions-
1. Dominant layer represents the topmost layer of the plant community which is determined by the canopy of the largest trees. This uppermost stratum is also called crown or canopy which represents the highest limit of plant community in a given region. A secondary layer very often called as co-dominant layer is formed just below the crown or dominant layer by those large trees which are relatively shorter than the largest trees.
2. Second layer is located below the dominant or crown layer and is represented by plants of shrub by life-form. This is also called as shrub layer.
3. Third layer is formed by the herbaceous plants and is also called as herb layer.
4. Fourth layer represents mosses on the ground surface and is also called as moss, layer or ground layer.
3.3. NATURAL VEGETATION IN INDIA
Vegetation type is primarily dependent upon the rainfall and temperature of a place. Other factors like soil type, topography, presence of rivers and mountains, primitive vegetation, animal species etc. also influence the type of vegetation in an area. It adapts to the constraints of natural environment in size, structure and requirements.
The natural vegetation in India ranges from the one that is found in the tropical region to that found in the Arctic region. On the basis of certain common features such as predominant vegetation type and climatic regions, Indian forests can be divided into the following groups: (Total 12 Types by Forest Survey)
1. Tropical Forests – 6 types
2. Subtropical forests – 1 type, can be further divided into 3 classes
3. Temperate – 3 types
4. Alpine – 1 type
5. Littoral and swamp vegetation
1. Tropical Evergreen
Conditions for growth:
Tropical Evergreen and Semi Evergreen Forests are found mainly in the areas where the annual rainfall is more than 250 cm, with a short dry season. The average annual temperature should be above 22 °C.
Characteristics: Lofty, very dense, multi-layered forest with mesophytic evergreen, 45m or more in height, with large number of species, numerous epiphytes, and few climbers; Due to dense growth of trees, the sunlight cannot reach the ground. Thus, the undergrowth mainly consists of canes, bamboos, ferns, climbers, etc.
Location: The true evergreen forests are mostly found along the western slopes of Western Ghats, in the hills of north-eastern states and in the Andaman and Nicobar Islands.
Trees: Important trees of these forests are rosewood, ebony, mahogany, rubber, cinchona, bamboo, coconut, palms, canes, lianas, etc.
Utility: Not commercially exploitable. However, the timber from the tropical evergreen and semi- evergreen a forest is hard, durable, fine-grained and of high economic value.
2. Tropical Semi-Evergreen
These forests are found along the western coasts, eastern Orissa and upper Assam where annual rainfall is between 200 and 250 cm.
They are characterised by giant and luxuriantly growing intermixed deciduous and evergreen species of trees and shrubs. The under-growing climbers provide an evergreen character to these forests.
The important plants in these forests are the species of white cedar, hollock, kail, etc. Orchids, ferns, some grasses and several other herbs are also common.
These forests are less dense and can be easily exploited.
3. Tropical Dry Evergreen
These forests are found in the areas where rainfall is in plenty but dry season is comparatively longer. The trees are dense, evergreen and short (about 10 to 15 metres high). These forests are found in eastern part of Tamil Nadu.
The common plant species are much the same as in Tropical moist evergreen forests. Species of Maba, Calotropis, Pabatta, Feronia, Canthium, Zizyphus, Randia etc. are most common. Bamboos are absent but grasses are common.
4. Tropical Moist Deciduous
These cover an extensive area of the country receiving sufficiently high rainfall (150 to 200 cm) spread over most of the year. The dry periods are of short duration. Many plants of such forests show leaf-fall in hot summer. It is the representative species of the Monsoon climate.
The forests are found along the wet western side of the Deccan plateau, i.e. Mumbai, N-E Andhra, Gangetic plains, Orissa and in some Himalayan tracts extending from Punjab in west to Assam valley in the east.
Teak, Sal, Sheesham, Hurra, Mahua, Amla, Semul, Kusum, Sandalwood etc. are the main species of these forests. These forests produce some of the most important timbers of India..
5. Tropical Dry Deciduous
These forests are distributed in the areas where annual rainfall is usually low, ranging between 70 and 100 cm, such as, Punjab, U.P., and Bihar, Orissa, M.P. and large part of Indian peninsula.
The largest area of the country’s forest land is occupied by Tropical dry deciduous forests. The dry season is long and most of the trees remain leafless during that season.
The forest trees are not dense, 10 to 15 m in height, and undergrowth is abundant. In north, the forests are dominated by sal and in south by teak. Tendu, palas, amaltas, bel, kair, axlewood, etc. are the common trees.
Utility: The tropical deciduous forests are commercially most important as they yield valuable timber and a variety of other forest products. They are commercially most exploited. Large tracts of these forests have been cleared to provide more land for agricultural purposes and have also suffered from severe biotic factors, such as over-cutting, overgrazing, fires, etc.
6. Tropical Thorny Vegetation
These forests occur in the areas where annual rainfall is less than 50 cm; dry season is hot and very long. They are found in South-west Punjab, Rajasthan, Gujarat, MP and UP. The vegetation is open stunted forest, breaking down into xerophytic bush and further to the northwest grading into deserts. Most of the vegetation is confined to areas along seasonal rivers. The land away from the rivers and devoid of irrigation is mostly sandy and devoid of trees. The vegetation is of open type consisting of small trees (8 to 10 m high) and thorny or spiny shrubs of stunted growth. The forests remain leafless for most part of the year and are sometimes called thorn scrub or scrub jungles. There is luxuriant growth of ephemeral herbs and grasses during the rainy season.
Important species found are babool, ber, khejri, date palm, khair, neem, palas, acacia etc. Tussocky grass grows up to height of two metres as undergrowth.
Utility: These trees are important in checking the increasing desertification in north-western India.
7. Sub-Tropical Vegetation
Sub-tropical wet hills forests occur at 1000-1200m altitude. In eastern Himalayas, oak chestnut, ash, birch, pine are common species. In Western Himalayas, Chir is most important, while oak occurs in wetter areas. In drier areas of Kashmir (RF 50-100cm) wild olives are common with a variety of scrub.
8. Himalayan Dry Temperate Vegetation
It is found in the inner dry ranges of western Himalayas where precipitation is below 10cm. It is predominantly a coniferous forest with xerophytic shrubs. Epiphytes and climbers are rare. Important species are chilgoza, deodar, oak, maple, ash, celtis, olives, etc.
9. Himalayan Moist Temperate Vegetation
In the western Himalayas, between 1500-3000m, forests of deodar, spruce, maple, walnut, poplar, cedar, chestnut, birch, oak, etc. occur. These are 30-50m in height and undergrowth is mostly evergreen. Mosses and ferns grow on the trees.
10.Himalayan Wet Temperate Vegetation
In the eastern Himalayas, evergreen wet temperate forests occur between 1800-2700m altitude. Oak, poplar, elm, laurel, maple, birch, magnolina are common species. Rainfall is high, temperature is moderate in summers and winters are cold. Rate of evaporation is not high and trees do not shed their leaves. Nilgiris, Anamalai and the Palani hills of south India have this kind of forest above 1500m altitude. The trees are shorter there with abundant undergrowth and epiphytes.
11.Sub-Alpine and Alpine Vegetation
It occurs above 2700m in eastern Himalayas and above 3000m in western Himalayas and extends upto the snowline. It is a dense scruby forest of silver firs, junipers, pine, birch and rhododendrons.
In the Himalaya Mountains, one can notice a succession of natural vegetation belts, as we see in the tropical to the tundra region.
Between the height of 1000 m and 2000 m, the evergreen broad-leaf trees such as oak and chestnut predominate.
Between the height of 1500 m and 3000 m, the coniferous trees, such as pine, deodar, silver fir, spruce and cedar are found.
The coniferous forests cover the southern slopes of Himalayas and parts of northeast India. At higher elevations (about 3600 m above sea level) temperate grasslands are common.
At attitudes above 3600 m, coniferous forests and grasslands give way to the alpine vegetation. Silver firs, junipers, pines and birches are common varieties of trees.
Ultimately these forests merge into alpine grasslands, through the shrubs and scrubs.
The southern slopes of the Himalaya Mountains have denser forests than the north facing areas. This is due to relatively higher precipitation.
At higher altitudes, mosses and lichens form part of vegetation.
In the peninsular India, the mountain forests are found in the three district areas—the Western Ghats, the Vindhyas and the Nilgiris.
As they are closer to the tropics, and only 1,500 m above the sea level, vegetation is temperate in the higher regions and subtropical on the lower regions of the Western Ghats, especially in Kerala, Tamil Nadu and Karnataka.
The temperate forests are called Sholas in the Nilgiris, Annamalai and Palani hills.
Utility: Alpine grasslands are extensively used by the nomadic tribes like the Gujjars and the Bakarwals for grazing livestock.
12. Littoral and Swamp
They can be further divided into (i) Beach forests, (ii) Mangroves, and (iii) Fresh water swamps.
The tidal deltas of Ganga, Mahanadi, Godavari and Krishna are all flush with such evergreen vegetation. The soil is sandy having large amount of lime and salts but poor in nitrogen and other mineral nutrients. Ground water is brackish, water table is only a few metres deep and rainfall varies from 75 cm to 500 cm depending upon the area.
The plants are typical halophytes which are characterised by presence of prop roots with well-developed knees for support and pneumatophores and viviparous germination of seeds. Important species are sundari, bruguiera, sonneratia, agarm bhendi, keora, etc.
Sholas are patches of stunted evergreen tropical and sub tropical moist broad leaf forest found in valleys separated by grassland in the higher mountain regions of South India
The word 'shola' is probably derived from the Tamil language word ‘colai’ meaning grove.
The shola-forest and grassland complex has been described as a climatic climax vegetation.
Some of the other trees of this forest of economic significance include magnolia, laurel, cinchona and wattle.
They are home to a host of endemic and endangered plants and animals.
They are also vitally important in keeping water cycles alive. They retain most of the rain they get over the monsoons, and release it slowly through the year via a network of streams and rivers that eventually serve the needs of a huge number of human settlements across south India.
In the recent years exotic species that were planted a few years ago had invaded marshes, shola forests and grasslands.
Important Terms related to vegetation
Canopy: The cover of branches and Foliage formed by the crown of trees is called Canopy.
Canopy Density: The percentage area of land covered by the canopy of trees is called Canopy density.
Carbon Stock: It is defined as the amount of carbon stored in the ecosystem of the forest especially in living biomass and soil.
Very Dense Forest: All lands with tree canopy density of 70% and above.
Moderately Dense Forest: All lands with tree canopy density of 40% and more but less than 70%.
Open Forest: All lands with tree canopy density of 10% and more but less than 40%.
Scrub: Degraded forest land with canopy density less than 10%.
Non-Forest: Lands not included in any of the above classes.
Endemic plants: The original natural vegetation, which are purely native are called the endemic plants.
Exotic plants: Those which have come from outside are called the exotic plants.
3.4. FOREST COVER IN INDIA
The total forest cover of the country, as per India State of Forest Report 2015 is 701,673 sq km which constitutes 21.34 percent of the geographical area of the country. In terms of density classes, area covered by Very Dense Forest (VDF) is 85,904 sq km, that with Moderately Dense Forest (MDF) is 315,374 sq km and Open Forest (OF) is 300,395 sq km. The VDF class constitutes 2.61 percent, the MDF class constitutes 9.59 percent and the OF class constitutes 9.14 percent of total forest cover of the total geographical area of the country.
15 StateS/UTS have above 33 percent of the geographical area under forest cover. Out of these states and UTs, seven states have more than 75 percent forest cover while eight states have forest cover between 33 percent and 75 percent.
3.4.1. INDIA STATE OF FOREST REPORT 2015
"India State of Forest Report (ISFR)", a biennial report of FSI is published by Forest Survey of India(FSI) since 1987.
Regular assessment of forest cover is being done by FSI using remote sensing satellite data.
So far thirteen reports have been published by FSI. The latest report i.e. ISFR 2015 is 14th assessment in this series. The findings are:
India’s forest and tree cover has increased by 5,081 sq km.
Forest cover of the country as per this assessment is 701,673 sq. km which is 21.34 percent of the geographical area of the country.
The tree cover of the country is estimated to be 92,572 sq. kmwhich is 2.82 percent of the geographical area.
The total forest and tree cover of the country as per this assessment is 794,245 sq. km which is 24.16 percent of the geographical area of the
The North Eastern states of India account for one fourth of the country’s forest cover.
Mangroves cover has increase by 112 sq. km as compare to the previous assessment.
Sunderbans which accounts for half of the total mangrove area in India, has seen a marginal.42% rise in its mangrove cover in the last two
years despite several plantation drives taken up by the state there.
Difference between forest area and forest cover
The term 'Forest Area' (or recorded forest area) generally refers to all the geographic areas recorded as forest in government records. Recorded forest areas largely comprise Reserved Forests (RF) and Protected Forests (PF), which have been constituted under the provisions of Indian Forest Act, 1927. Besides RFs and PFs, the recorded forest area may include all such areas, which have been recorded as forests in the revenue records or have been constituted so under any State Act or local laws.
On the other hand, the term 'Forest Cover' as used in the 'SFR' refers to all lands more than one hectare in area, having a tree canopy density of more than 10%. Thus the term 'forest area' denotes the legal status of the land as per the government records, whereas the term 'forest cover' indicates presence of trees over any land.
On the basis of the percentage of the actual forest cover, the states can be grouped into four regions:
The Region and Percentage Cover of the Forest
(i) The region of high concentration > 40
Mizoram (88.93%), Lakshadweep (84.56%), A & N Islands (81.84%), Arunachal Pradesh (80.3%), Nagaland (78.21%), Meghalaya (76.76%), Manipur (76.11%),Tripura (74.49%), Goa (60.08%), Sikkim (47.31%), Uttarakhand (45.32%), Kerala (49.5%), Dadra & Nagar Haveli (41.96%), Chhattisgarh (41.12%)
(ii) The region of medium concentration 20-40
Assam (35.22%), Orissa (32.34%), Jharkhand (29.45%), Himachal Pradesh (26.40%), Madhya Pradesh (25.13%), Tamil Nadu (20.26%)
(iii) The region of low concentration 10-20
Karnataka (18.99%), Telengana (18.80%), Andhra Pradesh (15.25%), Maharashtra (16.45%), Daman & Diu (17.51%), Chandigarh(19.32%),West Bengal (18.96%), Delhi (12.73%), Puducherry (11.54%), Jammu & Kashmir (10.34%)
(iv)The region of very low concentration < 10
Gujarat (7.48 %), Bihar (7.74%), Uttar Pradesh (6%), Rajasthan (4.73%), Haryana (3.58%), Punjab (3.52%)
3.4.2. OTHER CLASSIFICATIONS OF FORESTS
1. Constitutional Basis
According to the Constitution of India the forests in India have been classified under the following three categories for the sake of their ownership, administration and management:
State forests: These are under the full control of the government (state/central) and include almost all the important forest areas of the country. More than 90 per cent of the country’s forest area belongs to this category.
Communal forests: These forests are owned and administered by the local bodies (municipal corporation, municipal board, town area, district board, village panchayat etc.) and occupy about 5 per cent of the country’s forest area.
Private forests: These are under the private ownership and cover little more than 1 per cent of the forested area of the country. Many of these forests are degraded and in bad condition and have been converted into waste lands. Such forests are mainly found in Orissa, Meghalaya, Punjab and Himachal Pradesh.
2. Administrative Basis
Indian forests were classified under following three categories during the British rule and they continue to be done today as well:
Reserved forests: These forests are under the direct supervision of the government where no public entry is allowed for collecting timber and grazing of cattle. About half of forest area has been declared as the Reserved Forests by the government. They are regarded as the most valuable as far as conservation of forest and wildlife resources are concerned.
Protected forests: These forests are looked after by the government but here local people are allowed to collect timber/fire wood and graze their cattle without causing serious damage to the forests. Almost one third of total forest area is protected forest as declared by the Forest Department. This forest land is protected from any further depletion.
Unclassified forests: These are unclassified forests where there is no restriction on the cutting of trees and cattle grazing. These are other forests and wasteland belonging to both government and private entities.
Merchantability basis: On the basis of merchantability, Indian forests may be grouped under two categories:
Merchantable: Forests which are accessible. About 82% of forests belong to this group
Non-merchantable: These are inaccessible mostly situated in high hills. About 18% forests, mostly conifers fall under this category.
Based on type of leaves:
Coniferous forests: These are temperate forests found over the Himalayan ranges and occupying 6.43% of total forest area.
Broad leaf forests: About 93.57% of the country's forest area belongs to this category. These are tropical and sub-tropical forests occupying the plains, plateaus and hill slopes and yielding good quantity of timber and forest products
Based on Canopy Density: FSI categorises forests based on the canopy density:
Scrubs: The degraded forest lands which have a Canopy density of less than 10% are called Scrubs.
Open Forests: The Lands with Canopy density of 10-40% are called Open Forests.
Moderately Dense Forest: The Land with forest cover having a canopy density of 40-70% is called the Moderately Dense Forest (MDF).
Very Dense Forests: The Lands with forest cover having a canopy density of 70% and more are called Very Dense Forests (VDF)
3.4.3. NATIONAL FOREST POLICY 1988
India adopted a forest policy in 1952, which was further modified in 1988. According to the new forest policy, the Government will emphasise sustainable forest management in order to conserve and expand forest reserve on the one hand, and to meet the needs of local people on the other.
The forest policy of the Government of India aims at:
i. bringing 33 per cent of the geographical areas under forest cover;
ii. maintaining environmental stability and to restore forests where ecological balance was disturbed;
iii. conserving the natural heritage of the country, its biological diversity and genetic pool;
iv. checks soil erosion, extension of the desert lands and reduction of floods and droughts;
v. increasing the forest cover through social forestry and afforestation on degraded land;
vi. increasing the productivity of forests to make timber, fuel, fodder and food available to rural population dependant on forests, and encourage the substitution of wood;
vii. Creating of a massive people’s movement involving women to encourage planting of trees, stop felling of trees and thus, reduce pressure on the existing forest.
3.5. SOCIAL FORESTRY
Social forestry means the management and protection of forests and afforestation on barren lands with the purpose of helping in the environmental, social and rural development. The National Commission on Agriculture (1976) has classified social forestry into three categories. These are urban forestry, rural forestry and Farm forestry.
Urban forestry pertains to the raising and management of trees on public and privately owned lands in and around urban centres such as green belts, parks, roadside avenues, industrial and commercial green belts, etc.
Rural forestry lays emphasis on promotion of agro-forestry and community-forestry.
Agro-forestry is the raising of trees and agriculture crops on the same land inclusive of the waste patches. It combines forestry with agriculture, thus, altering the simultaneous production of food, fodder, fuel, timber and fruit.
O It involves the raising of trees on public or community land such as the village pasture and temple land, roadside, canal bank, strips along railway lines, and schools etc.
O Community forestry programme aims at providing benefits to the community as a whole.
O Community forestry provides a means under which the people of landless classes can associate themselves in tree raising and thus, get those benefits which otherwise are restricted for landowners.
Farm forestry: It is a term applied to the process under which farmers grow trees for commercial and non-commercial purposes on their farm lands. Forest departments of various states distribute seedlings of trees free of cost to small and medium farmers.
Wetlands – Refer the material on Wetlands provided separately.
What is a biome?
The large natural ecosystem comprised of abiotic (land, air, water and soils of the concerned habitat) and biotic (plants, animals and micro-organisms) components wherein all the biota have minimum common characteristics, and more or less uniform environmental conditions is called biome.
There are five major biomes — forest, desert, grassland aquatic and altitudinal biomes.
Some features of these biomes are given in this Table.
Flora and Fauna
A. Tropical 1. Evergreen 2. Deciduous B. Temperate C. Boreal/ Taiga
A1. 10° N-S A2. 10°-25° N-S
B. Eastern North America, N.E. Asia, Western and Central Europe
C. Broad belt of Eurasia and North America (parts of Siberia, Alaska, Canada and Scandinavia)
A1. Temp. 20-25°C, Rainfall, ave. ann. 2,000mm,evenly distributed A2. Temp. 25-30°C, Rainfall, ave. ann. 1,000mm, seasonal
B. Temp. 20-30° C, Rainfall evenly distributed 750- 1,500mm, Well defined seasons and distinct winter.
C. Short moist moderately warm summers and long cold dry winter; very low temperatures. Precipitation mostly snowfall 400 -1,000mm
A1. Acidic, poor in nutrients A2. Rich in nutrients
B. Fertile, en-riched with decaying litter
C. Acidic and poor in nutrients, thin soil cover
A1. Multi-layered canopy tall and large trees A2. Less dense, trees of medium height; many varieties coexist. Insects, bats, birds and mammals are common species in both
B. Moderately dense broad leaved trees. With less diversity of plant species. Oak, Beach, Maple etc. are some common species. Squirrels, rabbits, skunks, birds, black bears, mountain lions etc.
C. Evergreen conifers like pine, fur and spruce etc. Wood peckers, hawks, bears, wolves, deer, hares and bats are common animal
A. Hot and Dry desert
B. Semi arid desert
C. Coastal desert
A. S a h a r a , Kalahari, Marusthali, Rub-el-Khali
B. Marginal areas of hot deserts
A. Temp. 20-45°C 35°C.
D. 2 - 25°C
A-D Rainfall is less than 50 mm
Rich in nutrients with little or no organic matter
A-C. Scanty vegetation; few large mammals, insects, reptiles and birds D. Rabbits, rats, antelopes and ground squirrels
D. Tundra climatic regions
A. Tropical Savannah
B. Temperate Steppe
A. Large areas of Africa, Australia, South America and India
B. Parts of Eurasia and North America
A. Warm hot climates, Rainfall 500-1,250 mm
B. Hot summers and cold winter. Rainfall 500 - 900 mm
A. Porous with thin layer of humus. B. Thin flocculated soil, rich in bases
A. Grasses; trees and large shrubs absent; giraffes zebras, buffalos, leopards, hyenas, elephants, mice, moles, snakes and worms etc., are common animals B. Grasses; occasional trees such as cottonwoods, oaks and willows; gazelles, zebras, rhinoceros, wild horses, lions, varieties of birds, worms, snakes etc., are common animals
A. Lakes, streams, rivers and wetlands B. Oceans, coral reefs, lagoons and estuaries
A-B Temperatures vary widely with cooler air temperatures and high humidity
A. Water, swamps and marshes B.Water, tidal swamps and marshes
Algal and other aquatic and marine plant communities with varieties of water dwelling animals
Slopes of high mountain ranges like the Himalayas, the Andes and the Rockies
Temperature and precipitation vary depending upon latitudinal zone
Regolith over slopes
Deciduous to Tundra vegetation varying according to altitude
3.6.1. FOREST BIOME
Forest is the ultimate vegetation type which results from the process of succession on land areas, unless local conditions such as climate, soil or biotic factors arrest development. Trees can be divided into the two main types: evergreen, which always have leaves, and deciduous, which have no leaves at all at some stage, usually in the winter or dry season. Many naturalists have devised differing classifications of forests in relation to climatic zones, but there is general agreement in distinguishing boreal, temperate deciduous and tropical rain forests.
184.108.40.206. The tropical rain-forests
Location: It occupies low-altitude areas near the equator in South America, Central and West Africa, and in the Indo-Malay peninsula and New Guinea regions.
Climate: The Temperature is high throughout the year and the average range is 20-25°C while the average
annual rainfall is 2,000mm and evenly distributed.
Flora: It is a broad-leaved evergreen forest of dense, prolific growth and an extremely diverse fauna and flora.
The hot, wet tropical climate is highly conducive to plant growth and there is very little seasonality which means that the growing period extends throughout the year.
In these conditions there will be severe competition for survival, leading to specialisation of roles and the predominance of narrow ecological niches.
All green plants strive to reach the light so that they either become very tall, or adopt a climbing habit like many climbers or live as epiphytes (plants living on other plants but not deriving food from them).
Beneath the tree canopy, which may itself consist of two layers, there is usually a well-developed layering of understorey vegetation which is so dense that hardly any light reaches ground level.
The leaves possess thick cuticles for protection against the strong sunlight, anddrip tips whose probable function is to shed water rapidly, thereby aiding transpiration.
Fauna: The heterotrophs also show similarities in their general characteristics.
Some animals have developed the ability to glide in the air like fox, tree frogs, squirrels, tree snakes etc. Some mammals have large and sturdy bodies to push plants away like chimpanzee, gorilla, bison, African Elephant etc.
Many snakes and mammals are adapted to live in the trees because this is where the bulk of the foliage exists.
220.127.116.11. Temperate Deciduous Forest
This type of forest is dominated by broad-leaved deciduous trees.
The trees have deciduous character where they shed their leaves seasonally
Location: It covers most of the temperate areas of Europe, eastern North America, eastern Asia and small parts of South America and Australia.
Climate: There is a longer growing season, higher light intensity and a moderate amount of precipitation of between 500 and 1500 mm per annum.
The temperature regime is also
characterised by lack of extremes but there is still a marked cold season which plants and animals must endure.
Flora: There are at least sixty dominant species, notably several sorts of chestnut, maple and hemlock.
The deciduous habit and the lighter shade cast by these trees, allows sufficient light to reach beneath the canopy so that understorey vegetation can develop.
Fauna: The animal range from very small animals to large bodied animals like elephants, hippopotamus, lions, rhinos etc.
Soils: The soils associated with the temperate deciduous forest are varied but on the whole they are brown earths.
The temperate deciduous forest has probably been more modified by human activity than any other type of
18.104.22.168. Boreal Forest or Taiga
The boreal forest formation is a vast expanse of coniferous, evergreen forest.
Location: It extends across North America and Eurasia on the southern margins of the tundra zone.
Climate: The growing season is only of three or four months' duration and even during this time; the energy input from solar radiation is small because of the
Temperatures are low throughout the year, although the average temperature of the warmest month of the year is higher than 10° C.
In the winter the temperatures fall to many degrees below freezing and permafrost frequently extends into the northern edge of the forest.
Precipitation ranges from 400 to 1000 mm per annum, mostly falling as snow.
Despite the climate, coniferous trees form a dense canopy which intercepts a great amount of light and precipitation so that conditions beneath are dark and dry.
Consequently there is little opportunity for undergrowth to develop and very few other plants are associated with the coniferous trees.
Flora: The trees themselves show very little variety across the formation; species of pine, fir and spruce tend to be dominant throughout.
The trees grow needles instead of leaves, and cones instead of flowers. The needle-like leaves have a waxy outer coat which prevents water loss in freezing weather and the branches are soft and flexible and usually point downwards, so that snow slides off them.
Conifers tend to be evergreen, that is, they bear needles all year long.
Fauna: At the herbivore level the invertebrates are predominant, the vertebrate herbivores only becoming numerous in areas where foliage is thicker.
Carnivores, such as the wolf and lynx, and the large omnivores, such as the black and grizzly bears, which need a lot of food to maintain themselves, are scarce.
Soils: Characteristically the boreal forest is found growing on podzols which tend to become highly acidic
3.6.2. DESERTS BIOME
Location: This biome is mainly found in the hot arid zones of the world, such as the Sahara and Australian deserts. Some cooler deserts—for example, those of the Gobi and Patagonia—are also found.
Hot deserts occur in the subtropical dry zone of the global atmospheric circulation system
Flora: Up to 60 per cent of desert floras are made up of annual or ephemeral species which evade the drought by completing their life cycles within a few weeks of the onset of any rain.
One of the most important ways of avoiding water loss is to close the leaf stomata, particularly during the hottest period of the day, yet the stomata need to be kept at least partly open to maintain transpiration and cool the leaves. Some plants only open their stomata at night.
Succulents, such as cacti, combat the water problem with the aid of well-developed water storage organs and small surface area to volume ratios.
An evasion of the worst effects of high salt concentrations in the saline ground conditions may be achieved by the synchronisation of life cycles with rain periods sufficiently wet to leach temporarily the upper soil layers. Thus besides their xerophytic characteristics, many plants need also to be halophytic.
The most noticeable visual characteristic of areas of desert vegetation is the discontinuous cover and the even spacing of individuals. This appears to be the result of extensive root development and competition.
Vegetation is more discontinuous than in the tundra, but on the other hand it is more diverse in composition and form.
Related to varying degrees of aridity, desert vegetation includes low woody scrub formations, cacti communities, intermittent swards of perennial grass tufts, ephemeral or seasonal herbaceous vegetation, and 'accidental' vegetation in areas where rainfall may occur only once in several years
In the particularly harsh conditions of the coastal deserts where the sole source of moisture is the sea mist, only halophytes or succulent epiphytes, absorbing moisture directly from the atmosphere, can survive.
Fauna: As in the tundra, the animal species of deserts are fewer but more specialised than in humid environments. Morphological protection may be given by such features as an impermeable body covering, a small number of sweat glands and a light colouring. Camels and donkeys have in addition a physiological tolerance of high water losses and can survive a water reduction equal to more than 25 per cent of body weight.
In smaller animals the burrowing habit is widely developed, especially among insects. Nocturnal activity and summer dormancy are also common features.
The close interrelationship between the lack of vegetation cover and the unstable geomorphological environment gives deserts a character of delicate instability in which they are particularly susceptible to disruption by man.
Location: The tundra includes all types of vegetation found in high latitudes between the limits of tree growth and the polar ice-caps
Permafrost is common over large areas.
Climate: In broad terms, climates range from a continental type of extremely cold winters and little snow precipitation, as in Siberia and northern Canada, to the raw maritime conditions of southern Greenland, northern Norway and Alaska.
Flora: Plants in the tundra adapt to these
unfavourable conditions in several ways, so that in some species cellular ice does not form until temperatures drop below — 30°C. Other plants, such as lichens, never freeze and can adjust to rapid and extreme temperature changes.
Where undisturbed, the southern parts of the tundra are characterised by stands of dwarf willow, birch and alder, sometimes up to two metres in height. Further north, these give way to heaths of cowberry or crowberry.
Fauna: Animals in the tundra are limited in number and variety by the lack of plant food and the intense cold. Warm-blooded animals must either be protected from the surface cold by such adaptations as woolly coats and low surface area to body volume ratios, as in the polar bear, or they must migrate.
Cold-blooded animals, of which the insects are by far the most numerous, can survive in larval form throughout the winter.
The main herbivores include caribou, reindeer, musk ox, lemmings and the Arctic hare; predators, both carnivores and omnivores, include the Arctic fox, the wolf and bears
3.6.4. GRASSLANDS BIOME
22.214.171.124. Temperate Grasslands
Location: These include the prairies of North America, the steppes of Eurasia, the pampas of South America, and the veldt of South Africa, downs of Australia and Canterbury grasslands of New Zealand.
Climate: The temperate grasslands of northern hemisphere are characterized by continental climate wherein extremes of summer and winter temperatures are well marked but the temperate grasslands of the southern hemisphere are characterized by more moderate climate.
Precipitation in these areas ranges from 500 to 900 mm per annum, and the grasslands extend over a wide range of soil conditions.
Flora: Trees only occur on steep slopes or near water.
The geographical isolation of these areas from each other has led to some species differentiation, but most other features are similar.
Fauna: Grasslands are dominated by few species of large mammals like buffalo and pronghorn antelope in North American Prairies; wild horse and saiga antelope in the Eurasian steppes; antelopes in the South African velds and guanaco in the South American pampas.
Soils: Soils within the prairie belt include deep and fertile chernozems, prairie soils and chestnut soils.
Although the boundaries of the prairies seem to have fluctuated in the geologicalpast, one of the most interesting features is the sharpness of the prairie edge, and the lack of an ecotone or transitional area with adjacent forests.
The factors which have created this situation are difficult to isolate, but most would include grazing and fire.
126.96.36.199. Tropical Grasslands (Savannas)
The savanna lands of Africa, South America and Australia are essentially open, and ecologically dominated by a herbaceous stratum in which grasses and sedges are the principal components.
Location: They are found in large areas of Africa, Australia, South America and India
The climate is characterized by distinct wet and dry seasons and means high temperature throughout the year
All types experience a climate of marked seasonal
Flora: Greater diversity of tropical as opposed to temperate grasslands is often a function of the added variety afforded by wooded plants. In some cases the tree cover may be as much as 50 per cent; in others it may be nil.
Many of the plants, grasses and woody species, exhibit xerophytic features.
Marked contrasts exist in the appearance of the savanna during the year: the brown and withered short grasses of the dry season give way rapidly to tall lush growth with the arrival of the summer rains.
Fauna: The African Savanna accounts for the largest number and greatest variety of grazing vertebrate mammals in the world. African buffalo, zebra, giraffe, elephants, many types of antelopes, hippopotamus are some examples.
South American and Australian Savanna do not have large number of grazing animals like African Savanna but great variety of birds. Australian Savanna is dominated by marsupials (mammals having pouch in their bodies to keep and feed their offsprings).
Soils: The ferralsolic soils of savanna areas frequently include near-surface lateritic crusts, creating an impermeable surface soil layer in which nutrients, especially phosphates and nitrates, are markedly lacking.
As in the case of prairies, tropical grasslands tend to show little ecotone development, especially on margins adjacent to tropical rain-forest.
Factors of soil, fire and grazing are important in maintaining the character of tropical grasslands.
Many of the tree species appear to be fire-resistant.
There is a great variety of herbivores and carnivores in this biome.
3.6.5. THE AQUATIC BIOME
Life forms in these waters depend on the abiotic factors such as sunlight entering the waters, temperature, pressure, salt content and so on. Water biomes with lots of light tend to have more flora (plant) diversity and the growth of algae and plankton is more. Small water bodies that freeze during the cold seasons, or dry out in the dry and hot seasons tend to have less diversity. Aquatic biomes are very important because apart from being home to millions of water animals, they also form the basis of the water cycle and help with atmospheric moisture, cloud formation and precipitation. One example of a marine biome is the Great Barrier Reef (a coral reef system) of Australia.
188.8.131.52. Freshwater Biome
Freshwater is defined as having a low salt concentration — usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean).
There are 3 different types of freshwater regions:
o Ponds and Lakes
o Streams and Rivers
o Wetlands (sometimes considered brackish water)
184.108.40.206. Marine Biome
Marine regions cover about three-fourths of the Earth's surface and include oceans, coral reefs, and estuaries. Marine algae supply much of the world's oxygen supply and take in a huge amount of atmospheric carbon dioxide. The evaporation of the seawater provides rainwater for the land. Oceans cover 70 per cent of the surface area of the world, they are habitable throughout and support a total biomass probably as much as ten times that on land.
Types: Oceans, Corals reefs, Estuaries
The ocean regions are separated into separate zones: intertidal, pelagic, abyssal, and benthic. All four zones have a great diversity of species.
The intertidal zone is where the ocean meets the land — sometimes it is submerged and at other times exposed, as waves and tides come in and out. Because of this, the communities are constantly changing. On rocky coasts, the zone is stratified vertically. In areas where only the highest tides reach, there are only a few species of algae and molluscs; in areas usually submerged during high tide, there is a more diverse array of algae and small animals. At the bottom of the intertidal zone, which is only exposed during the lowest tides, many invertebrates, fishes, and seaweed can be found.
The pelagic zone includes those waters further from the land, basically the open ocean. The pelagic zone is generally cold though it is hard to give a general temperature range since, just like ponds and lakes; there is thermal stratification with a constant mixing of warm and cold ocean currents. The flora in the pelagic zone includes surface seaweeds. The fauna include many species of fish and some mammals, such as whales and dolphins. Many feed on the abundant plankton.
The benthic zone is the area below the pelagic zone, but does not include the very deepest parts of the ocean (see abyssal zone below). The bottom of the zone consists of sand, slit, and/or dead organisms. Here temperature decreases as depth increases toward the abyssal zone, since light cannot penetrate through the deeper water. Flora are represented primarily by seaweed while the fauna, since it is very nutrient-rich, include all sorts of bacteria, fungi, sponges, sea anemones, worms, sea stars, and fishes.
The deep ocean is the abyssal zone. The water in this region is very cold (around 3° C), highly pressured, high in oxygen content, but low in nutritional content. The abyssal zone supports many species of invertebrates and fishes. Mid-ocean ridges (spreading zones between tectonic plates), often with hydrothermal vents, are found in the abyssal zones along the ocean floors. Chemosynthetic bacteria thrive near these vents because of the large amounts of hydrogen sulfide and other minerals they emit. These bacteria are thus the start of the food web as they are eaten by invertebrates and fishes
3.7. ECO SENSITIVE ZONES
What are Eco Sensitive Zones?
o The National Wildlife Action Plan (2002–2016) of the Ministry of Environment, Forest and Climate Change (MoEFCC) stipulated that state governments should declare land falling within 10 km of the boundaries of national parks and wildlife sanctuaries as eco fragile zones or ESZs under section 3 (v) of the Environmental (Protection) Act, 1986.
o The purpose of the ESZ was to provide more protection to the parks by acting as a shock absorber or transition zone.
o Transition zones around protected forest areas would minimise forest depletion and man-animal conflict.
o The protected areas are based on the core and buffer model of management. The core area has the legal status of being a national park. The buffer area, however, does not have legal status of being a national park and could be a reserved forest, wildlife sanctuary or tiger reserve.
o This will help in protecting endangered species.
o This will also promote eco-tourism.
Eco-Sensitive Zone Guidelines
o The guidelines proposed that the boundary had to be site specific, decided in consultation with a field based team comprising representatives from the forest department, revenue department and Panchayati Raj institution.
o Though ESZ does not affect the ownership rights of people on land resources, it restricts land-use change. Activities such as widening of roads, construction or expansion of buildings, change of the agriculture system and erection of electric cables will also be regulated by a monitoring committee, mostly comprising of government officials, as per the master plan of the ESZ.
o It mentioned that the ESZs are not anti-people and do not intend to hamper their everyday activities.
Concerns of local people
o Locals claim that it is against their livelihood.
o There is no compensation for damage to crops by animals.
o Man-animal conflict may increase.
o Local people will be treated as encroachers.
o There are no policies to regulate tourism. Hotels and mega resorts, dominate the area and locals are restricted to low paying jobs. The locals are not enthusiastic in the ecotourism business as mass tourism gives them tough competition.
o Worried about how the process would hit development and apparently under pressure from mining and industry lobbies, the states have excluded several ecologically important areas around wildlife parks and sanctuaries from being protected.
o The presence of minerals and resources near Protected Areas has disrupted the identification of ESZs in many states too.
o The communities around eco-sensitive areas are also in uproar because they have been excluded from the process of identifying and governing the eco-sensitive zones (ESZs).
o Also the ESZ guidelines do not restrict the current tourism practices or put any restriction on the vehicular pollution in the area.
Western Ghats and various committees
o Western Ghats Ecology Expert Panel (WGEEP) headed by Madhav Gadgil was formed by MoEF in 2010.
o It’s recommendations were:
Make entire Western Ghats region ecologically-sensitive area. This would be divided into two parts: The protected areas which will be the national parks and wildlife sanctuaries; three Ecological Sensitive Zones (ESZ) viz. ESZ-1, ESZ-2 and ESZ-3, with different degrees of protection.
Highest protection in ESZ-1 and ESZ-2 categories. It recommended that the government should put an indefinite moratorium on new environmental clearances for mining in ESZ-1 and ESZ-2 and phasing out of mining from ESZ-1 by 2015. The continuation of existing mining in ESZ-2 under strict regulation with an effective system of social audit.
It also recommended that no new dams based on large-scale storage be permitted in ESZ-1.
The demarcation of the ESZs should be based on participation from local communities and local bodies
It also recommended constitution of a Western Ghats Ecology Authority (WGEA), as a statutory authority under the Ministry of Environment and Forests to focus on local participation and sustainability. o There was a lot of controversy and criticism of the recommendations as states felt that it would hamper energy and development projects. The ban on dams adversely impacted power sector. Locals also were against the report as the perception was that it would adversely impact livelihood. Then, the Kasturirangan committee was constituted to examine the WGEEP report. o It is called HLWG, meaning 10 member high-level working group (HLWG), headed by Kasturirangan.
o The recommendations were:
Instead of the total area of Western Ghats, only 37% (i.e. 60,000 sq. km.) of the total area be brought under ESA under Kasturirangan report.
Complete ban on mining, quarrying and sand mining in ESA. Distinguished between cultural (58% occupied in Western Ghats by it like human settlements, agricultural fields and plantations) and natural landscape (90% of it should come under ESA according to committee).
Current mining areas in the ESA should be phased out within the next five years, or at the time of expiry of mining lease, whichever is earlier.
No thermal power should be allowed and hydropower projects be allowed only after detailed study. o There were criticisms of these recommendations as it used aerial survey methods and remote sensing techniques for demarcation without examining ground realities. Also, there was no power to gram sabhas.
o The Minister of State (Independent Charge),Environment, Forest & Climate Change Javadekar said as per the Kasturirangan Committee report, commercial mining and polluting industries would be strictly banned in areas identified as eco sensitive zones in Western Ghats.
o He also said that every State will be given full opportunity for development works and the Union Ministry is currently going through the proposals submitted by State Ministers. o Since more than 4,000 villages fell in the proposed eco-sensitive zones, consultation with local population was on to seek their recommendation on the plan of action and the process would be completed by month-end.
o The need for conservation of vrgetation and wildlife cannot be doubted and ESZ’s are steps towards the same.
o However, there is a need for rethinking on the impacts of the environmental policies at the local level, the type and prospects of local participation and most importantly the prospects of alternate income generating opportunities for successful conservation initiatives.
3.8. PREVIOUS YEAR UPSC QUESTIONS
1. Discuss the wetlands and their role in ecological conservation in India. (UPSC 2009/15 Marks)
2. Mention the area of Shola forests in India. (UPSC 2003/2 Marks)
3. What are mangroves and in what way are they useful to us? (UPSC 2001/10 Marks)
4. What is waste land? Write a note on prospects of waste land development in India. (UPSC 2000/10 Marks)
5. Why has there been opposition from the North-Eastern States to the Supreme Court ban on all activities inside forests? (UPSC 1997/10 Marks)
6. Where do mangrove forests occur in India? Describe their main characteristics. (UPSC 1996/15 Marks)
7. Which parts of India are described as ‘arid zones’? Comment on the characteristics and economic activities prevalent in these regions? (UPSC 1993/15 Marks)
8. Where do we find large desert areas in India? What steps have been taken by the Government for their development? (UPSC 1985/20 Marks)
9. Which is the largest expanse of tidal forests in India and in which State is it located? (UPSC 1981/3 Marks)