Chapter 8: Natural Vegetation
Set out from the western slope of the Western Ghats, the hill wall that runs down India’s western coast, and walk east. For the first few kilometres you are in near darkness at midday. Trees stand more than 60 m tall, and their crowns lock into a canopy so dense that almost no sunlight reaches the floor. Nothing grows down there. The rain here measures more than 200 cm a year and the air stays above 77 per cent humidity. Keep walking. The trees thin and shorten. Somewhere behind you the rainfall dropped to between 100 cm and 200 cm, and the forest changed its habit: for six to eight weeks in spring and early summer it stands bare, because the water in the sub-soil will not support its leaves. Keep walking, into central and eastern Rajasthan. Rainfall is now less than 50 cm. The trees are stunted and thorny, scattered among patches of coarse grass, and the acacia beside you has pushed a tap root far underground to reach water no shallow plant can find. You have crossed no border, climbed no hill. Only the rain has changed — and with it, everything that grows.
Diagram
Fig. 8.A1 Caption: As rainfall falls from over 200 cm to under 50 cm, the forest changes height, density and habit. Brief: A west-to-east side profile in three panels — tall multi-layered evergreen forest, shorter deciduous forest shown leafless, low thorny scrub with grass; a single falling rainfall bar runs beneath all three, labelled ‘more than 200 cm’, ‘100 cm to 200 cm’, ‘less than 50 cm’.
8.1 What Natural Vegetation Means
Natural vegetation is the plant community of an area that has grown by itself, without any human assistance, and has been left undisturbed over a long time. The long stretch of time is part of the definition, not a detail. It is what allows each species to adjust itself fully to the climate and the soil of the place where it stands.
Grasses, shrubs and trees that come up on their own, with no human interference, therefore make up the natural vegetation of an area. A ploughed and watered field is not natural vegetation, however green it looks, because a human hand decided what grows there. Neither is a lawn.
Flora, Vegetation And Forest
In ordinary speech these three words are used as if they meant the same thing. In Geography they do not, and the difference is worth getting right before the rest of the chapter is read.
Flora refers to the plants of a particular region or period, listed as species and considered as a group. Flora is essentially an inventory — a list of what grows there. The Eastern Himalayas, the eastern stretch of the great Himalayan range, have about 4000 species of plants, and these vary with increasing altitude from tropical to temperate and alpine, that is, from the plant kinds of the hot lowlands, through those of cooler middle heights, to the hardy plants of the cold zone near the top.
Vegetation refers to the assemblage of plant species living in association with each other in a given environmental set-up. This is not a list but a living arrangement — species growing together, in one place, under one set of conditions. Redwood forests, coastal mangroves, roadside weed patches, cultivated gardens and lawns are all covered by the word vegetation. Notice that planted and tended cover is included, which is why vegetation is a wider word than natural vegetation.
The major vegetation types of the world are grouped into four kinds. (a) Forests, where trees dominate and shrubs and herbs grow beneath them. (b) Grasslands, where grasses hold the ground and trees are few and scattered. (c) Scrubs, where the cover is low, hardy and bushy. (d) Tundra, the low cover of mosses and lichens that survives in the coldest regions.
Forest refers to a large tract of land covered with trees and an accompanying undergrowth of shrubs and herbs, sustaining thousands of life forms, which include both plants and animals. A forest is therefore one kind of vegetation — the densest and the most crowded with life. All three words can be sorted by asking a short series of questions about any patch of green in front of you.
Flowchart
Fig. 8.A2 Caption: The same patch of green can be described by all three words, but only one of them tests how it got there. Nodes: a stretch of plant cover → has it grown without human assistance? no → it is vegetation, but not natural vegetation (gardens, lawns, roadside weed patches); yes → has it been left undisturbed long enough for its species to adjust to the climate and soil? no → it is vegetation only; yes → it is natural vegetation → is it a large tract of trees with undergrowth of shrubs and herbs? yes → forest; no → grassland, scrub or tundra → in every one of these cases, the species present, listed as a group, are the flora
The Meaning The Law Uses
The law works with a different test. In legal terminology, a forest is any land with its vegetative cover that has been so declared under a legal provision. What settles the question is the declaration, not the trees.
The two meanings can therefore disagree with each other. Land carrying very little tree cover can still be a forest in law if it has been declared one, and thickly wooded land can fall outside the legal category because no such declaration was ever made. This matters later in the chapter, because protection follows the legal meaning.
Forests As National Wealth
The Supreme Court has asserted in a judgment that forests in India are a national asset and a major contributor to the nation’s financial wealth. The court observed that a country with excess forest cover would be in a position to sell its excess carbon credit to a country in deficit, and that this underlines the significance of forests in contributing to the financial wealth of a country.
A carbon credit is a unit standing for carbon dioxide kept out of the atmosphere, which a country holding more than it needs can sell to one that has released more than its share. The court’s point is a hard-headed one. A forest is not only a living system; it is also an asset that can be counted, valued and traded, and a country that lets its forests go is giving up wealth as surely as if it had sold land.
8.2 Importance Of Forests
A forest is easy to value wrongly, because most of what it does is invisible. The timber can be counted and sold; the water it holds in the soil, the oxygen it releases and the carbon it locks away cannot be seen at all. The chapter groups the work a forest does into five kinds of function.
Productive Functions
The productive functions are the goods a forest hands over directly. (a) Trees give food, in the form of fruits, leaves, roots and tubers of plants. (b) Wood is cut into timber and made into furniture, both for houses and for industrial units. (c) Wood and bamboo pulp are broken down and pressed into paper and paper boards. (d) Wood is used indiscriminately as a source of energy for cooking and for providing warmth. (e) Besides timber and firewood, forests yield fibres, essential oils, oil seeds and edible plants. (f) Bamboos are a means of livelihood for the tribals, who make mats, baskets and ropes from them, and bamboo also goes into the manufacture of rayon, the yarn and artificial silk fibre.
Protective Functions
The protective functions are the ones that guard the ground itself. Forests control the water cycle, and the thick layer of humus — the dark, spongy material formed by the decay of forest litter — is central to how they do it. That layer prevents evaporation of water from the surface below it.
The humus acts as a natural sponge and helps soak the rain water into the soil. Rain that soaks in is rain that does not run off, and this is the difference between water stored underground and water lost downhill in a rush.
The forest, with its complex root system, binds the soil and thereby prevents soil erosion and the loss of nutrients. The same litter that becomes humus over the years also increases the fertility of the soil as it decays. So the forest is not merely sitting on the soil; it is making it.
Regulatory Functions
The regulatory functions are the cycles the forest keeps turning. Trees utilise carbon dioxide and release oxygen during photosynthesis, and the oxygen released is used by the animal world. In this way trees perpetuate the cycles of oxygen and carbon dioxide in the biosphere.
Trees also regulate the water cycle, and here the mechanism is worth following step by step. The trees absorb water from the ground and release it into the atmosphere during transpiration, the loss of water vapour from the leaves. That vapour helps form clouds and precipitation, which brings the water back into the soil, and the cycle is complete.
Flowchart
Fig. 8.A3 Caption: A forest is one of the engines that keeps water moving between the ground and the air. Nodes: water in the soil → roots absorb it → transpiration from the leaves → water vapour rises into the atmosphere → clouds form → precipitation falls → humus soaks the rain into the soil → back to water in the soil
Accessory Functions
The accessory functions are the ones that serve other living things, including us. Forests provide habitat for wildlife, which is why so much of India’s wildlife is found where its forests are. They also provide aesthetics and recreation to human beings, through National Parks, Wildlife Sanctuaries and Biosphere Reserves — the three kinds of protected area in which forest land is set aside and public access is controlled.
Forests As A Carbon Sink
A carbon sink is anything that takes in more carbon dioxide than it gives out, and so holds carbon away from the atmosphere. The Supreme Court of India quoted from a 2009 report of the Ministry of Environment and Forests titled ‘India’s Forest and Tree Cover: Contribution as a Carbon Sink’, saying that India’s forests serve as a major sink of carbon dioxide. The report then did something unusual: it put a price on that sink.
The number is large, but the more useful thing about it is what it does to an argument. Land under forest usually loses when it is compared with land under a factory or a mine, because the factory’s output has a price and the forest’s does not. A figure like ₹6 lakh crores gives the standing forest a value that can sit in the same column as the mine’s, and the $5 per tonne is described as conservative, which means the true worth is probably higher. It is still an incomplete accounting — the soil the roots hold and the water the humus stores carry no price tag here at all.
8.2.1 Environmental Correlation
Everything above describes what a forest does. The correlation runs the other way as well: the environment decides what kind of vegetation grows in the first place.
Climate Influence
The type of vegetation in a region is primarily determined by the climate, and within climate, particularly by rainfall and temperature. Tropical rainforests thrive in areas of high rainfall, while desert vegetation is adapted instead to arid conditions, that is, to conditions of long-term dryness. This single sentence is the key to the whole of the next section, where five vegetation types are separated mainly by how much rain each of them receives.
Soil And Topography
Soil type and topography — the shape and height of the land surface — also play significant roles. Mangrove forests grow in saline coastal soils, where salt would kill most other plants, while mountain forests vary with altitude, because temperature falls as the land rises.
Biodiversity And Ecological Balance
Natural vegetation supports biodiversity, the variety of living species in a place, by providing habitat for various species. It also maintains ecological balance in three ways at once: by regulating the water cycle, by preventing soil erosion, and by contributing to carbon sequestration, which is the locking away of carbon that the carbon sink performs.
Understanding the correlation between natural vegetation and the environment is crucial for conservation efforts and for sustainable development in India. If climate makes the vegetation, then a change in climate remakes it, and a plan to conserve a forest has to begin with the conditions that put it there.
8.3 Types Of Vegetation
India has a wide variety of forests and natural vegetation, and the reason is that the country itself varies so much — in climatic conditions, in soil types and in relief features, that is, in the shape and height of the land.
Four broad patterns show this at a glance. The Western Ghats, the hill wall along the western coast, and the Andaman and Nicobar Islands in the Bay of Bengal are marked with tropical rain forests. The Himalayas have temperate vegetation. The desert and semi-desert regions of Rajasthan carry a wide variety of bushes and thorny vegetation. The delta regions, where large rivers break up and drop their load before meeting the sea, have tropical forests and mangroves.
On this basis the country can be divided into five major vegetation regions. (a) Tropical Evergreen forests, in the wettest belts. (b) Tropical Deciduous forests, in the belts of moderate rain. (c) Tropical Desert forests, where rainfall is scarce. (d) Littoral forests, on the salty, waterlogged coastal margins. (e) Mountain forests, where height rather than latitude sets the conditions.
The distribution of these five regions is mapped below, and it is worth looking at the map before reading further, because almost every fact in this section is a fact about where something grows.
Map
Map 8.1 Caption: Natural vegetation of India. Brief: Political outline of India showing the full extent of India as officially defined, with the Tropic of Cancer marked; area shading for five classes with a key reading Tropical Evergreen, Tropical Deciduous Forests, Tropical Thorn Forests, Mountain Forests, and Littoral and Swamp Forests; label the Arabian Sea, Bay of Bengal, Indian Ocean, Lakshadweep Sea, Andaman Sea, Lakshadweep and the Andaman and Nicobar Islands; scale 1:24 000 000 with a linear scale bar in km.
Reading across the map from west to east, or from the coast inland, the classes change in a definite order, and that order follows rainfall. The chain below is the skeleton of everything that follows.
Flowchart
Fig. 8.A4 Caption: Rainfall does most of the sorting, and only the coast and the mountains are decided by something else. Nodes: an area of India → is the ground salty, waterlogged and tidal? yes → Littoral or Tidal forest; no → is the land high, so that temperature falls with altitude? yes → Mountain forest; no → how much rain falls in a year? more than 200 cm → Tropical Evergreen forest; 100 cm to 200 cm → Tropical Deciduous forest, moist type; 70 cm to 100 cm → Tropical Deciduous forest, dry type; less than 50 cm → Tropical Desert or Thorn forest
8.3.1 Tropical Evergreen Or Rain Forests
Climatic Conditions
These forests are found in areas where the annual rainfall is more than 200 cm, with only a short dry season. The average annual temperature is between 25°C and 27°C, and the average annual humidity exceeds 77 per cent. Humidity is the amount of water vapour held in the air, and a figure above 77 per cent means the air here is close to saturated for most of the year.
Distribution
These forests are chiefly distributed in the heavy rainfall areas of the western slopes of the Western Ghats, the hills of the north-eastern region, and the island groups of Lakshadweep, the Andaman and Nicobar, and the Tamil Nadu coast.
Characteristic Features
Four features follow from the warm, wet conditions. (a) Since the region remains warm and wet throughout the year, it carries a luxuriant vegetation of all kinds — trees, shrubs and creepers — which gives it a multi-layered structure, with plants growing at several heights above one another. (b) Trees reach great heights of more than 60 m, taller than a twenty-storey building, as each one races the others for light. (c) The carpet layer of herbs and grasses cannot grow, because the dense canopy, the continuous roof formed by the crowns of the tallest trees, does not allow enough sunlight to reach the ground. (d) The trees have no fixed time to shed their leaves, to flower or for fruition, because no season forces them to stop. That is why these forests appear green all the year round.
The main variety of trees found in these forests includes rosewood, ebony, mahogany, toon, chaplas, sissoo, gurjan and telsur.
Diagram
Fig. 8.1 Caption: Tropical evergreen forests. Brief: Photograph looking into the interior of a dense evergreen forest — tall straight trunks, closed green canopy overhead, dim light at ground level, climbers looped between trees; caption position below the image.
Economical Value
Tropical Evergreen forests produce various plant species of high economic value, and the timber they yield is hard, durable and fine-grained. Yet these forests have not been fully exploited, for two reasons the chapter gives together: the tangled mass of canes, palms, bamboos, ferns and climbers makes movement inside them difficult, and there is a lack of means of transport to carry timber out.
Environmental Correlation
These forests maintain high biodiversity and play a crucial role in carbon sequestration. The same density that keeps loggers out is what makes them so effective a store of carbon.
8.3.2 Tropical Deciduous Forests
These forests are also known as the monsoon forests, because the rain that sustains them arrives in one season and then stops. They are the most widespread forests in India.
Deciduous means shedding the leaves for part of the year, and it is the whole idea of this class. Based on the availability of water, these forests are further categorised into two types: the moist deciduous forests, and the dry deciduous forests.
8.3.2.1 The Moist Deciduous Forests
The climatic conditions are intermediate. Such forests are found in areas with moderate or low annual rainfall of 100 cm to 200 cm, a mean annual temperature of 24°C and 27°C, and a humidity percentage of 50 to 80.
Their distribution is wide. These forests occur in the north-eastern part of the Peninsula, along the foothills of the Himalayas and on the eastern slopes of the Western Ghats — note that the evergreen forests take the western slopes, which face the rain-bearing winds, and the moist deciduous take the drier eastern side of the same hills. They occupy a sizeable area in Uttar Pradesh, Maharashtra, Karnataka and Tamil Nadu, and cover an area bigger than the Evergreen forests.
Three characteristic features are given. (a) The trees shed their leaves for six to eight weeks during spring and early summer, when the shortage of water is acute, and the sub-soil water is not enough for the trees to keep their leaves all the year around. (b) A particular species can be found spread over a large area, rather than mixed in with dozens of others. (c) They are the commercially most exploited forests of India.
That second feature is what makes the third one possible. A timber merchant wants many trees of one kind standing close together, and moist deciduous forests supply exactly that, where the mixed evergreen forest does not.
The common trees of such forests are sal, teak, arjun, shisham, mahua, mulberry, palas, semul and sandalwood. Their economical value follows from this list: besides providing valuable timber, they provide various other products, and the sandalwood found in these forests is in great demand in India and abroad.
The environmental correlation is a quiet one. These forests shed their leaves during dry seasons, and in doing so help conserve both water and soil nutrients.
8.3.2.2 Dry Deciduous Forests
The climatic conditions are a step drier again. These forests are found in areas having a mean annual temperature of 23°C to 27°C, an annual rainfall between 70 cm and 100 cm, and humidity between 51 and 58 per cent.
They are found in the rainier parts of the Peninsular Plateau, the raised tableland that fills most of southern India, and in the plains of Bihar and Uttar Pradesh.
The characteristic feature of this type is that it is a transition, not a fixed thing. These forests thrive between the moist deciduous forests in the east and the tropical thorn forests in the west. On their wetter margins they pass into moist deciduous forest; on their drier margins they degrade into thorn forest. In the northern Indian plains, and in the areas of higher rainfall in the Peninsular Plateau, these forests have open stretches in which teak and other trees are interspersed with patches of grass. During the dry season the trees shed their leaves completely and give the forest the look of a vast grassland with naked trees.
The common trees of these forests are teak, tendu, sal, rosewood, amaltas, bel, khair and axlewood. Their economical value lies in timber, fruits and other useful products, and large tracts of these forests have been cleared for agricultural activities — open ground with grass between the trees is the easiest forest of all to turn into a field.
By way of environmental correlation, these forests are adapted to dry conditions, and where they still stand they prevent soil erosion and support local wildlife.
8.3.3 Tropical Desert Forests
These are also known as Tropical Thorn Forests.
Climatic Conditions
These forests are found in the areas which receive rainfall of less than 50 cm. The mean annual temperature ranges between 25°C and 27°C, and humidity stays below 47 per cent.
Distribution
These forests are chiefly distributed in south-western Punjab, Haryana, Uttar Pradesh, central and eastern Rajasthan, Madhya Pradesh, Chhattisgarh, Gujarat, and parts of Maharashtra, Karnataka and Andhra Pradesh.
Characteristic Features
Three features are given, and all of them are answers to a shortage of water. (a) These forests have xerophytic vegetation, and due to the paucity of rainfall the trees are stunted, with large patches of coarse grasses between them. (b) The trees that have adapted themselves to survive in drought-like conditions are called xerophytes. The acacia or babool trees, for example, have developed long tap roots that can reach deep, ground water resources, and therefore can survive drought-like conditions. Further, the acacia trees have long thorns and a symbiotic relationship with stinging ants, a partnership in which both sides gain: the ants live in the thorns and feed on the nectar produced by the trees, and when an animal takes a bite of the leaves, the ants attack the animal. (c) In these forests plants remain leafless for most part of the year and look like scrub vegetation.
Diagram
Fig. 8.2 Caption: Tropical thorn forests. Brief: Photograph of dry open country — a few stunted, flat-crowned thorny trees widely spaced, dry coarse grass covering the ground between them, hard light and bare soil visible; caption position below the image.
The important trees found here include babool or acacia, date palm, ber, khair, neem, khejri, kanju, cactii and kokko.
Economical Value
The value of these trees lies less in timber than in fruit, bark and oil. (a) Ber fruit is eaten raw or made into pickle or beverages, and its timber is hard, strong, tough and durable, used to make legs for bedsteads, boat ribs, agricultural implements and charcoal. (b) Babool bark and gum have medicinal value. (c) Date palm is eaten raw and is also used as an astringent, and as a decoction, syrup or paste for sore throat, cold and fever. (d) Neem bark and roots have medicinal properties, and neem oil, leaves and extracts are used to manufacture health and beauty products; neem is also used as an insecticide.
Important Trees And Their Uses
The chapter gathers here the uses of the main trees named across all the forest types, not only the desert ones. (a) Rosewood is used for making furniture, floor boards and wagon parts, and as a decorative wood for carving and for making ornamental ply-boards and veneers. (b) Ebony is used for ornamental carving and for decoration, for inlaying, and for making musical instruments, sports goods, piano keys and caskets. (c) Teak wood is moderately hard, durable and easy to work, and is used for construction purposes, shipbuilding and making furniture, railway carriages, sleepers and bridges. (d) Sandalwood is used for making statues and ornamental objects, and also in making aromatic substances and for extracting sandalwood oil. (e) Sal wood is very hard, heavy and tough, and is used for making beams, planking and railing of bridges, doors, window posts of houses and railway sleepers. (f) Palas leaves are used for rearing shellac worms. (g) Ber is a fruit which is eaten raw or made into pickle or beverages, and its timber is hard, strong, tough and durable, used to make legs for bedsteads, boat ribs, agricultural implements and charcoal. (h) Babool’s bark and gum have medicinal value. (i) Neem bark and roots have medicinal properties, and are effective in treating diabetes, allergies, ulcers and several other diseases; neem oil, leaves and neem extracts are used to manufacture health and beauty products, and neem is also used as an insecticide. (j) Deodar is a medium weight durable wood, used for construction work and for making railway sleepers, and also suitable for beams, floor boards, ports, window frames and light furniture. (k) Sundari trees provide hard durable timber for construction purposes and boat making.
Environmental Correlation
These plants are adapted to conserve water and survive extreme conditions, preventing desertification — the process by which dry land loses its plant cover and turns into desert. A stunted thorn forest looks like poor vegetation, but it is the last cover holding that ground together.
8.3.4 Littoral Or Tidal Forests
Littoral or Tidal forests are one of the most specialised tropical natural vegetation types. India has a variety of wetland habitats. Wetlands are lands lying between the terrestrial and the aquatic system, where the water table — the level below which the ground is saturated with water — is usually at or near the surface of the land.
Climatic Conditions
These forests thrive in areas where the temperature remains between 26°C and 29°C and the rainfall is not more than 200 cm.
Distribution
These forests are found in wet marshy areas, in river deltas, in tidal or other swampy areas, and along the sea coasts. They are chiefly distributed in the deltas of large rivers on the eastern coast, and in pockets on the western coast, in the saline swamps of Sunderbans in West Bengal and the coastal areas of Andhra Pradesh and Odisha.
Characteristic Features
Four features follow from living in salt water and soft mud. (a) They have mainly evergreen species of varying density and height, usually associated with wetness. (b) The tree trunks are supported by a number of stilt-like roots, which remain submerged under water during high tide and can be seen during low tide. (c) They have a profuse growth with a tangle of climbers, which is an adaptation for survival in soft and shifting mud. (d) These forests have breathing roots called pneumatophores. Because of waterlogged conditions the roots are deprived of oxygen during high tides, so some mangrove roots extend vertically above the ground. These vertical roots have pores which enable the trees to breathe when the other roots remain submerged under water during high tide.
Diagram
Fig. 8.3 Caption: Exposed stilt roots during low tide. Brief: Photograph of a mangrove stand at low tide — arching stilt roots lifting the trunks clear of dark wet mud, roots exposed down to the mud surface, dense green foliage above; caption position below the image.
The important trees include keora, amur, bhara, rhizophora, screw pines, canes and palms, sundari and agar. Mangrove forests grow along the coasts in the salt marshes, tidal creeks, mud flats and estuaries, where a river’s mouth widens and its fresh water mixes with the sea. They are found in the Andaman and Nicobar Islands and West Bengal, and other areas of significance include the Mahanadi, the Godavari and the Krishna deltas.
These forests have Sundari trees, after the name of which they are known as ‘Sunderbans’ in the Ganga Delta.
Economical Value
Mangrove trees are utilised for fuel, whereas sundari trees provide hard durable timber.
Environmental Correlation
Mangroves protect coastlines from erosion and support marine life. A tangle of stilt roots slows a wave before it reaches the shore, so what looks like an obstacle to a boat is a defence for the land behind it.
The five types can now be set side by side, with their temperature and rainfall ranges, their distribution and their trees.
Read down the rainfall column and the sorting is obvious. Read down the temperature column and only the mountain row stands apart, at 12°C to 13°C against 24°C and above everywhere else. That single row is the subject of the last type, and it is the one place where height, not rainfall, does the work.
8.3.5 Mountain Forests
In the mountain regions temperature decreases with altitude. This has a corresponding effect on the natural vegetation of the mountain regions: climbing a mountain does to the vegetation something like what travelling towards the poles would do.
Climatic Conditions
These forests are found in areas where the annual temperature is 12°C to 13°C, rainfall is between 100 and 300 cm, and annual humidity is between 56 and 65 per cent.
Relief
These forests occur at an altitude between 1000 m and 4000 m.
Distribution
These forests cover the entire Himalayan zone. In the Peninsular region they are found in the Vindhyas, the Nilgiris and the Western Ghats.
Characteristic Features
Seven features are given, and the first six of them describe a ladder of belts, one above the other. (a) These forests contain mixed species of broad leafed evergreen trees and conifers, the cone-bearing, needle-leafed trees; they also contain scrubs, creepers and ferns. (b) At the foothills of the Himalayas, deciduous forests are found. (c) At an altitude of 1000 m to 2000 m they are the moist temperate forests. (d) In the hilly areas of West Bengal and Uttarakhand, evergreen broad leafed trees like chestnut and oak are found. (e) Between the altitude of 1500 m and 1750 m, coniferous trees like Chir pine are an important tree, and at an altitude of 2250 m and 3000 m blue pine and spruce are found. (f) At higher altitudes, alpine forests and alpine grass up to the snowline are found, followed by mosses and lichens; beyond the snowline, the level above which snow lies through the year, no vegetation is found. (g) In the Peninsular regions the area is only about 1500 m in height, and vegetation varies from tropical to temperate forests.
Diagram
Fig. 8.A5 Caption: On a Himalayan slope the vegetation changes belt by belt, and the only thing that has changed is height. Brief: Vertical cross-section of a Himalayan slope with an altitude axis in metres up the left side; label the belts in order from the base — deciduous forest at the foothills, moist temperate forest 1000 m to 2000 m, Chir pine 1500 m to 1750 m, blue pine and spruce at 2250 m and 3000 m, alpine forest and alpine grass above, then mosses and lichens, and a snowline above which no vegetation is shown.
That last feature needs unpacking. The Peninsular hills are close to the tropics and stand only about 1500 m above sea level, so the vegetation is temperate in the higher regions and sub tropical on the lower regions of the Western Ghats, especially in Kerala, Tamil Nadu and Karnataka. These temperate forests are called Sholas in the Nilgiris, the Anaimalai and the Palani hills.
Environmental Correlation
These plants are adapted to conserve water and survive extreme conditions, preventing desertification.
The important trees found in these forests include magnolia, laurel, cinchona, wattle and plum.
8.4 Forest Conservation
Forests have been over-exploited to satisfy not only human needs but human greed, and the result has been a decline in the forest cover. The distinction matters, because a forest can survive being used and cannot survive being emptied.
Why The Forest Cover Has Declined
Five pressures are named, and they pull in different directions on the same land. (a) Rapid population growth and the demand for more food have led to forests being cleared and converted into agricultural land. (b) Forests have been converted into pasture land, to make room for expanding dairy farming and cattle ranching. (c) Overgrazing by animals in the forests of the tropical and sub-tropical regions has resulted in large-scale degradation of natural vegetation, because grazing removes the young growth before it can replace the old. (d) The ever increasing demand for timber, driven by industrial expansion and urbanisation, has added to the problem of deforestation, the clearing or thinning of forests by humans. (e) The construction of multi-purpose river valley projects has led to the submergence of land and the destruction of forested riversides.
What The Decline Has Cost
The consequences run well beyond the timber that is no longer there. (a) A decline in the forests has led to a decline in forest productivity, so each remaining hectare yields less than it once did. (b) Forests influence the human environment by moderating climate, regulating water supply, maintaining the fertility of the soil and purifying the air, and all four of these weaken together when the cover goes. (c) Lack of forest cover reduces precipitation and thus causes droughts, because the water trees return to the air by transpiration is part of what forms the clouds that bring rain back. (d) Forests act as a sink for the carbon dioxide that trees use during photosynthesis, so their absence increases the concentration of carbon dioxide in the atmosphere.
The second of those points has a chain inside it that is worth following slowly. The absence of forest cover leads to soil erosion, which increases the load of the rivers — the solid material a river carries along with its water. That increased surface load reduces the water available in the rivers for human use, and the siltation it causes, the settling of that material on the river bed, causes floods which destroy property, crops and living beings.
The fourth point ends in a change that reaches everyone. A rising concentration of carbon dioxide increases the greenhouse effect in the atmosphere, the trapping of heat by certain gases, and this raises the temperature of the earth’s surface and of the atmosphere, leading to global warming and its harmful consequences.
Flowchart
Fig. 8.A6 Caption: Cutting a forest does not only remove trees; it removes the thing that was taking carbon dioxide out of the air. Nodes: trees use carbon dioxide during photosynthesis → the forest acts as a carbon sink → the forest is cleared → the sink is gone → concentration of carbon dioxide in the atmosphere rises → greenhouse effect increases → temperature of the earth’s surface and the atmosphere rises → global warming and its harmful consequences
Hence the conservation of forest is of vital importance for the survival and prosperity of human kind.
8.4.1 Conservation Measures
The aim of conservation is stated in two parts: to arrest deforestation, and to stop the diversion of forest lands to non-forest uses. Four terms are used repeatedly in what follows, and they are easily confused with one another.
The chapter lists nine conservation practices that must be undertaken. (a) Increasing the area under forests: the loss of forests can be remedied by a massive programme of tree plantation, and planting on degraded lands and on land unfit for agriculture both improves the environment and relieves the harvesting pressure on existing forests. (b) Afforestation around industrial units: trees are planted around cities having Iron and Steel Plants, where they act as a barrier for the dust and purify the air. (c) Stopping indiscriminate felling of trees: there should be a strict ban on felling naturally growing trees, and where a tree must be cut, necessary permission has to be obtained. (d) Replacement by planting: saplings should be planted at least in the ratio of 1:10, that is, ten saplings for every one tree that is cut. (e) Establishing corridors between different reserved forests: wide corridors should be opened so that wild animals can migrate between one protected block and another, which also helps numerous species to use them for dispersal and migration. (f) Using alternative sources of energy: since trees are felled for firewood in many parts of the world including India, forests are conserved by shifting to non-conventional or renewable sources such as solar energy, tidal energy and hydel energy. (g) Proper legislation and its implementation: strict laws should be made to check deforestation, and equal care taken to see that those laws are strictly implemented. (h) People’s participation: the participation of the local community is of utmost significance if any plan is to be enforced, since the local inhabitants are the ultimate users, and most programmes now involve local communities in planning, decision-making and implementation. (i) Developing badlands and barren lands into vegetation belts, and taking climate action by reducing carbon footprints to mitigate climate change impacts, while supporting global and national climate initiatives.
Why Trees Are Planted Around Steel Plants
The second measure deserves its own explanation, because it is the one that treats a forest as a piece of equipment. The level of pollution is much higher in areas where industries are located, and cities having Iron and Steel Plants generate more pollutants than other cities.
During the manufacture of steel, air emissions from the manufacturing plants release particulate matter — fine solid particles small enough to stay suspended in air — along with sulphur oxides, nitrogen oxides, hydrocarbons and hydrogen fluoride, all of which pollute the air. Besides this, these steel plants emit significant dust levels of about 20 kilograms per metric ton of steel produced.
The last two measures widen the frame considerably. Corridors and community participation both accept that a forest cannot be protected as an island — animals move across boundaries, and so do the people who depend on the land. Protecting natural vegetation is crucial for maintaining biodiversity, preventing soil erosion and ensuring ecological balance, and none of those three stops at a fence line.
8.5 Forest Restoration
Conservation protects a forest that is still standing. Restoration is the harder task of putting one back, and the chapter sets out several ways of doing it, from planting bare ground to reorganising how a village and its trees live together.
Flowchart
Fig. 8.A7 Caption: The approaches differ in what the land was before the planting started, and in who the planting is for. Nodes: putting trees back on the land → was the land forest within the last fifty years? no, it was farmland or built-up land → afforestation → the Miyawaki method is one technique for doing it quickly; yes, forest was removed by fire, logging or clearing → reforestation → seeding, hand planting or aerial reforestation → planting organised around people rather than around timber → social forestry → combined with crops and animals on the same land → agro-forestry
8.5.1 Afforestation
Afforestation refers to planting trees in an area that was not a forest 50 years ago. Such lands had been used for agriculture or for urban development for a long time, so the trees are going in where no forest has stood within living memory.
The gains listed are several. Trees planted to forest an area reduce soil erosion, improve soil quality, absorb carbon and provide habitat for wildlife. They help in mitigating climate change and in increasing biodiversity. Besides this, they provide forest products like timber to local communities, improving their standard of living. Afforestation therefore helps control the level of soil degradation; in fact it improves soil health.
When Planting Trees Goes Wrong
Afforestation might be dangerous, and the chapter gives the clearest example India has. The non-native ‘Vilayati kikar’ (prosopis juliflora) is an invasive Mexican tree species, introduced by the British in the Aravalis of Delhi around the 1890s. Over time it spread aggressively across Delhi’s ridges, completely changing the native forest landscape.
Unlike the diverse local forests, Vilayati Kikar lacks biodiversity and any cultural connection for local communities. Its thick leaf litter blocks sunlight and reduces soil nutrients, making it hard for the seeds of native plants even to germinate. Its roots can grow over 50 metres deep, depleting groundwater, and its leaves contain toxic chemicals which prevent them from undergoing microbial degradation, so the litter does not rot down into humus the way forest litter should.
The social cost followed from the ecological one. Entire stretches of community-used forest land, the common grazing resource zones, turned into inaccessible and non-productive patches.
Diagram
Fig. 8.4 Caption: Vilayati kikar, an introduced species that spread across Delhi’s ridges. Brief: Photograph of a prosopis juliflora branch in flower — fine bipinnate leaves and pale cylindrical flower spikes, thorny stems visible, dry scrub background; caption position below the image.
Where the right trees are planted, the benefit is real: the forests benefit the urban area by restoring its green cover as well as its biodiversity, and by enabling it to combat climate change. The lesson of the kikar is not that planting is wrong, but that the choice of species decides whether a plantation becomes a forest or a problem.
8.5.2 Reforestation
Reforestation refers to planting trees to restore damaged or destroyed forests, in areas affected by natural disasters like wildfires, or in areas that have been logged or cleared. The purpose of reforestation is to restore the ecological function of the original forest.
The two words are easy to mix up, and the difference lies entirely in the history of the ground. Afforestation puts trees where there was no forest for fifty years, so it creates cover that was not there; reforestation puts trees back where a forest recently stood and was removed, so it repairs cover that was lost. Both end with trees on the ground, but only reforestation has an original forest to aim at.
8.5.2.1 Characteristics
Four characteristics are given for reforestation. (a) It can be carried out in urban areas as well as rural areas to increase tree cover. (b) Trees may be planted by seeding, by hand planting or by aerial reforestation, in which seed is released from the air, and aerial reforestation is preferred in the case of rainforests, where the ground is hard to reach. (c) Native trees are preferred for successful forest development. (d) It helps in preserving biodiversity hotspots.
8.5.3 Miyawaki Method
The Miyawaki method is a technique for creating dense native forests in a short period. It is named after its developer Akira Miyawaki, a Japanese botanist, and has been successfully implemented in urban areas all over the world.
The key features are four. (a) Native trees are planted very close to each other, so that they compete for light and grow upward fast. (b) Only indigenous species are used, divided into four layers — shrub, sub-tree, tree and canopy — and all non-native species are removed. (c) The soil is enriched with organic matter before planting. (d) The forest becomes self-sustaining in three years, with growth rates up to ten times faster than the conventional method.
Notice that the four layers are the multi-layered structure of a natural evergreen forest, built deliberately instead of waiting for it. That is what the method is really doing — copying the arrangement a mature forest arrives at on its own, and letting competition do the rest.
8.5.5 Agro-Forestry
Agro-forestry is a part of social forestry and represents the intermediate stage between forestry and agriculture. It refers to the sustainable system of managing a piece of land through the combined production of agricultural crops and forest crops together with animal rearing, to ensure the most efficient land use under a management system that is in accordance with the socio-cultural practices of the local people.
Its aim is to provide conservation of the land while achieving a combined produce of forest and agricultural crops. One field, in other words, is asked to yield two kinds of harvest without being exhausted by either.
8.5.5.1 Objectives Of Agro-Forestry
Four objectives are listed. (a) To reduce pressure on natural forests for obtaining timber as well as non-timber forest produce. (b) To check soil erosion and to maintain the natural fertility of the soil. (c) To maintain ecological balance along with the proper utilisation of farm resources. (d) To make the best use of all the available resources, such as land, manpower, livestock and ecological factors, so as to obtain food, fuel, fodder, livestock, recreation and a variety of forest products sustainably from the same land.
Agro-forestry differs from traditional forestry in that it is not vulnerable to population stresses. It is created in accordance with the socio-cultural practices of the population, and in fact it co-ordinates with the local population and reduces the pressure of population on traditional forestry. Traditional forestry keeps people and trees apart and is strained whenever the number of people rises; agro-forestry puts them on the same land and is not.
8.5.5.2 Sustainable Agro-Forestry To Combat Hunger In India
One Tree Planted, a non-profit tree planting charity that plants trees in countries around the world, has partnered with Sustainable Green Initiative (SGI), a local organisation with one objective: to plant mostly fruit trees, in order to fight hunger, poverty and climate change.
Under this model, fruit tree saplings are distributed for 1 to 3 years in community lands, in the homesteads of marginal farmers, and on government school campuses, orphanages and old age homes. The trees planted include lemon, guava, custard apple, gooseberry, pomegranate, jack fruit, wood apple and tamarind. These native trees produce a high yield of fruit, either seasonally or year round, and as they mature and bear, they ensure food for local people during difficult times.
To date, over 6,500 farmers have benefited, mostly in regions reeling under severe drought. Planting trees in this way also helps foster environmental consciousness and sustainability in rural communities. The design is worth noticing: a fruit tree pays the household every season, so the household has its own reason to keep it alive, which no plantation of pure timber can offer as quickly.
8.5.6 Van Mahotsav
Van Mahotsav, literally meaning ‘Forest Festival’, is an annual tree-planting festival celebrated during the first week of July. The first tree plantation week was organised by M.S. Randhawa, a botanist from Punjab, in 1947, from July 20 to 27 in Delhi. Prominent leaders like Jawaharlal Nehru and Dr. Rajendra Prasad attended this event.
Dr. K.M. Munshi, the Union Minister for Agriculture and Food, officially launched Van Mahotsav as a national event. He moved the celebration to the first week of July, to coincide with the monsoon season, which is ideal for planting trees. Van Mahotsav has since grown into a significant environmental campaign, with millions of trees planted across India each year.
Diagram
Fig. 8.5 Caption: Tree plantation. Brief: Photograph of schoolchildren kneeling on open grass, together settling a sapling into a freshly dug pit with their hands, straw mulch and green surroundings behind them; caption position below the image.
The objectives of this festival include seven things. (a) Raising awareness about the importance of trees. (b) An increase in fruit production. (c) The creation of shelter-belts across agricultural fields, that is, lines of trees planted to break the force of the wind. (d) Providing fodder for cattle. (e) Prevention of soil infertility. (f) Encouraging soil conservation. (g) Enabling the supply of timber for various uses.
8.6 Summary
- Natural vegetation is the plant community of an area that has grown without human assistance and has been left undisturbed long enough for its species to adjust fully to the climate and the soil.
- Three words that are used loosely in speech mean different things in Geography.
- Flora is the list of plant species of a particular region or period, considered as a group; the Eastern Himalayas have about 4000 species.
- Vegetation is the assemblage of species living in association in a given environmental set-up, and it includes planted cover such as gardens and lawns.
- Forest is a large tract of land covered with trees and undergrowth of shrubs and herbs, sustaining thousands of life forms.
- In legal terminology a forest is any land with its vegetative cover that has been so declared under a legal provision, so the declaration decides the matter and not the tree cover.
- The Supreme Court has held that forests in India are a national asset and a major contributor to the nation’s financial wealth, since a country with excess forest cover can sell its excess carbon credit to a country in deficit.
- Forests perform five kinds of function.
- Productive — fruits, timber, paper pulp, firewood, fibres, essential oils, oil seeds, edible plants and bamboo for mats, baskets, ropes and rayon.
- Protective — humus prevents evaporation and soaks rain into the soil, while the root system binds it against erosion.
- Regulatory — trees perpetuate the oxygen and carbon dioxide cycles and return water to the air by transpiration.
- Accessory — habitat for wildlife, and recreation through National Parks, Wildlife Sanctuaries and Biosphere Reserves.
- Carbon sink — the 2009 Ministry report values about 24,000 million tonnes of carbon dioxide locked in India’s forests at $120 billion, or ₹6 lakh crores.
- The type of vegetation in a region is primarily determined by climate, particularly rainfall and temperature, with soil type and topography also playing significant roles.
- India is divided into five major vegetation regions, sorted mainly by rainfall.
- Tropical Evergreen, above 200 cm of rain, 25°C to 27°C, multi-layered, trees over 60 m, green all year because no season forces leaf fall.
- Tropical Deciduous or monsoon forests, the most widespread in India, shedding leaves when water runs short.
- Tropical Desert or Thorn forests, under 50 cm of rain, with stunted xerophytes such as acacia that send long tap roots to deep ground water.
- Littoral or Tidal forests, on saline waterlogged coasts, with stilt roots and breathing roots called pneumatophores.
- Mountain forests, at 1000 m to 4000 m, where temperature falls with altitude and the vegetation changes belt by belt up to the snowline.
- Tropical Deciduous forests are further divided by the availability of water.
- Moist deciduous, with 100 cm to 200 cm of rain, one species over large areas, and commercially the most exploited forests of India.
- Dry deciduous, with 70 cm to 100 cm of rain, a transition belt that passes into moist deciduous on its wetter margins and degrades into thorn forest on its drier ones.
- Forest cover has declined because of clearing for agriculture and pasture, overgrazing, rising demand for timber from industry and urbanisation, and submergence under multi-purpose river valley projects.
- The decline has consequences that reach far beyond timber.
- Soil erosion raises the load of the rivers, leaving less water fit for human use, and siltation causes floods that destroy property, crops and living beings.
- Lack of forest cover reduces precipitation and causes droughts.
- Losing the carbon sink raises the concentration of carbon dioxide, increasing the greenhouse effect and leading to global warming.
- Conservation measures include increasing the area under forests, afforestation around industrial units, a strict ban on indiscriminate felling with replacement in the ratio of 1:10, corridors between reserved forests, alternative sources of energy, proper legislation and its implementation, people’s participation, developing badlands into vegetation belts, and climate action.
- Restoration is distinguished by the history of the ground: afforestation plants where there was no forest 50 years ago, while reforestation replants where a forest was recently destroyed or removed.
- Planting can fail if the species is wrong — Vilayati kikar, introduced in the Aravalis of Delhi around the 1890s, blocks light with its litter, depletes groundwater with roots over 50 metres deep, and turned common grazing land into non-productive patches.
- Several people-centred approaches now carry much of the work.
- The Miyawaki method builds a dense native forest in four layers, self-sustaining in three years and growing up to ten times faster than the conventional method.
- Social forestry manages and protects forests on uncultivated and barren land for environmental, social and rural development.
- Agro-forestry, the intermediate stage between forestry and agriculture, takes crops, trees and animals from the same land.
- Van Mahotsav, held in the first week of July to meet the monsoon, has grown into a national tree-planting campaign.
Flowchart
Fig. 8.A8 Caption: The whole chapter in one line of reasoning — conditions make the vegetation, use wears it down, and restoration tries to put it back. Nodes: climate, soil and relief set the conditions → natural vegetation grows and adjusts over long undisturbed time → five vegetation regions of India: evergreen, deciduous, desert, littoral, mountain → forests do productive, protective, regulatory, accessory and carbon-sink work → demand for cropland, pasture, fuel and timber takes more than the forest can replace → forest cover declines → soil erosion, siltation and floods; less precipitation; more carbon dioxide and global warming → conservation measures protect what still stands → restoration replants through afforestation, reforestation, social forestry, agro-forestry and Van Mahotsav → cover returns, though a planted forest is not yet the natural vegetation it replaced
What This Chapter Cannot Tell You
The five vegetation types are classes drawn at the scale of the whole country, and Map 8.1 at 1:24 000 000 can only show broad belts. Inside any one belt there will be patches that belong to a different class altogether, and the map has no way of showing them.
The temperature, rainfall and humidity figures in Table 8.1 are annual ranges. They say nothing about how the rain was spread through the year, and it is the length of the dry spell, not the annual total, that decides whether a tree can hold its leaves.
The chapter also describes what grows where, not how much of it is still standing. A forest type shown on the map may survive as a fraction of the area it once covered, and nothing in these pages tells you which fraction. ## 8.7 Check Your Concepts
- Using Table 8.1, arrange Tropical Evergreen, Tropical Deciduous and Tropical Desert forests in decreasing order of the rainfall each one needs. Then explain why the Littoral row of the same table cannot be placed anywhere in that order.
- Write out, step by step and in the correct order, the chain of events by which the removal of forest cover from a slope ends in a flood that destroys crops downstream.
- The western slopes of the Western Ghats carry tropical evergreen forest, while the eastern slopes of the same hills carry moist deciduous forest. Explain why one range of hills has two different forest types on its two sides.
- Fig. 8.A5 shows the belts of vegetation on a Himalayan slope, which rises to 4000 m. The hills of the Peninsular region rise only to about 1500 m. Explain what difference this makes to the vegetation found on them, and name the temperate forests of the Nilgiris.
- Give two points of difference between Tropical Evergreen and Tropical Deciduous forests.
- Why do the trees of the tropical desert forests remain stunted?
- How does the environment determine the natural vegetation of a place?
- Give a geographical reason for each of the following.
- The Nilgiri region has a variety of vegetation types.
- Sundari trees are used for boat making and for construction purposes.
- Littoral forest is also called tidal forest.
- On an outline map of India, mark the areas having the following.
- Tropical Evergreen forests.
- Tropical Deciduous forests.
- Tropical Desert vegetation.
- Mountain forests.
- Littoral vegetation.
8.8 Case-Based Questions
- The Desertification and Land Degradation Atlas of India, published by ISRO’s Satellite Application Centre, reports that water erosion is the single largest process of degradation, affecting 11.01% of India’s land, followed by vegetation degradation at 9.15% and wind erosion at 5.46%. These processes are made worse by deforestation, poor agricultural practices and climate change, and are most widespread in the semi-arid and dry sub-humid regions of the country. Describe the methods of protecting forests under the following heads.
- Afforestation.
- Reforestation.
8.5.4 Social Forestry
Social forestry refers to the management and protection of forests, and to afforestation on barren lands, with the purpose of helping in environmental, social and rural development. It is people-oriented and value based, a joint management of forests whose major objective is satisfying the needs, wants and aspirations of both the people and the government.
It embraces almost a limitless range of activities on uncultivated land, and in doing so reduces the pressure on the nation’s forest resources. Social Forestry is also known as extension forestry, mined forestry, urban forestry, tree farming, Van Mahotsav, recreation forestry and livestock forestry. Most of these names indicate the utility of the forest features of Social Forestry — each name is really a use.
Social forestry is forestry for community development, and it consists of three things. (a) The restoration, reallocation and reorganisation of existing forest lands, for the total development of the land and of the people living on it. (b) The joint management of the forest and of its production processes. (c) Developing the socio-economic structure that makes the first two possible.
Who Gains When Common Land Is Planted? The rural household: social forestry on uncultivated land supplies fuel wood, fodder for cattle, timber and minor forest products, and brings employment. The family that grazed there: the same open land was a common grazing resource zone, and this chapter’s kikar case shows such stretches can end up inaccessible and non-productive. Both agree: the land is not empty, and whatever is planted will decide what it can be used for next. What would you need to know to decide? Whether the species chosen is native, and whether the people who used the land were part of the planning and decision-making.
8.5.4.1 Objectives Of Social Forestry
The main objectives of Social Forestry, as recommended by the National Commission on Agriculture, include the following. (a) Providing fuel wood, fodder for cattle, timber and minor forest products to rural people. (b) Utilising the available land according to its productive capacity. (c) Developing local cottage industries by providing them with raw materials. (d) Providing efficient conservation of soil and water. (e) Providing employment opportunities to the rural people. (f) Increasing agricultural production by using cow dung as manure. (g) Fulfilling the recreational needs of the people. (h) Improving the aesthetic scene of the area. (i) Achieving all-round rural development as a part of the integrated rural development programme.