Terrestrial Ecosystem- 2 | Environment for UPSC CSE PDF Download

Deforestation

Deforestation is the permanent removal of trees to make room for something besides the forest. This can include clearing the land for agriculture or grazing or using the timber for fuel, construction or manufacturing. According to the World Wildlife Fund, forests cover more than 30% of the Earth's land surface.

What are the causes?

➤ Shifting cultivation

• In this practice a patch of land is cleared, vegetation is burned, and the ash is mixed with the soil thus adding nutrients to the soil.
• This patch of land is used for raising crops for two to three years, and the yield is modest.
• This area is then abandoned and left to recover its fertility, and the same practice is repeated elsewhere on a fresh piece of land.
• All required for this cultivation method is a set of simple tools, not a high mechanization level.

➤ Development project

• The human population have increased considerably, so with their requirements.
• Development projects like hydroelectric projects, large dams and reservoirs, railway lines, and roads are extremely beneficial, but they are also linked with several environmental problems.
• Many of these projects require immense deforestation.

➤ Fuel Requirements

• The increasing demand for firewood with ever-growing population increases greater pressure on the forests, resulting in increased deforestation intensity.

➤ Raw Material Requirements

• Wood is used as a raw material by various industries for making paper, plywood, furniture, match sticks, boxes, crates, packing cases, etc.
• Industries also obtain their raw materials from plants such as drugs, scents and perfumes, resin, gums, waxes, turpentine, latex and rubber, tannins, alkaloids, beeswax.
• This exerted tremendous pressure on forest ecosystems, and their unrestricted exploitation for various other raw materials is the main cause of the forest ecosystem's degradation.

➤ Other Causes

• Deforestation also results from overgrazing, agriculture, mining, urbanization, flood, fire, pest, diseases, defence and communication activities.

➤ How it affects?

• Closed forests (based on canopy level) have been diminished due to deforestation, leading to increased degraded forests.
• Forests recycle moisture from soil into their immediate atmosphere by transpiration where it again precipitates as rain.
• Deforestation results in an immediate lowering of groundwater level and long-term reduction of precipitation.
• Due to deforestation, this natural reuse cycle is broken, and water is lost through rapid runoff.
• Much of the mining activity in India is being carried out in forest regions. The obvious result is deforestation and soil erosion.
• Underground mining has also significantly denuded forests, as timber is used for supporting the roofs of mine galleries.
• Many abandoned mines are lying in bad shape and are under extensive gully erosion leading to degradation of the habitat.
• Deforestation affects the biota and neighbouring ecosystems, soil erosion, land degradation, alteration of groundwater channels, pollution, and scarcity.

Grassland Ecosystem

• The grasslands are found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert. 
• Typical grasslands are vegetation formations that are generally found in temperate climates. 
• In India, they are found mainly in the high Himalayas. The rest of India's grasslands are mainly composed of steppes and savannas. 
• The major difference between steppes and savannas is that all the steppe forage is provided only during the brief wet season. The savannas forage largely from grasses that grow during the wet season and from the smaller regrowth in the dry season.
• Steppe formations occupy large sandy and saline soil; in western Rajasthan, where the climate is semiarid rainfall is less than 200 mm a year, a dry season of 10 to 11 months large variation in rainfall. 
• The soil is always exposed, sometimes rocky but more often sandy with fixed or mobile dunes. Forage is available only during the brief wet season. The grass layer is sparse and consists mainly of annual grass species.
• In the central and eastern parts of Rajasthan, where the rainfall is about 500 mm per year and the dry season is six to eight months, dry savanna grazing ecosystems have developed. The light shade cast by the sparse population of trees like khetri favours the growth of the grasses.

1. Types of Grasslands

Based on climatic conditions, there are six grasslands found in the different regions of the Indian subcontinent. Four major types of grasslands are discussed here.

➤ Semiarid

• It covers the northern portion of Gujarat, Rajasthan (excluding Aravallis), western Uttar Pradesh, Delhi and Punjab.
• Hill spurs and dunes break up the topography.

➤ Dry sub-humid zone

• It covers the whole of peninsular India (except Nilgiri).

➤ Moist sub-humid zone

• It covers the Ganga alluvial plain in Northern India.
• The topography is level, low lying and ill-drained.

➤ Humid montane regions

• This extends to the humid montane regions and moist sub-humid areas of Assam, Manipur, West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh Jammu and Kashmir.
• The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing.

2. Economic importance of grasslands

• India teems with animals of all shapes and sizes from the buffaloes to sheep's, and there are millions of them.
• The livestock wealth plays a crucial role in Indian life. It is a major source of fuel, draught power, nutrition and raw material for village industries.
• But only about 13 million hectares in the country are classified as permanent grazing lands. On top of it, they exist in a highly degraded state.
• Grassland biomes are important to maintain the population of many domesticated and wild herbivores.
• Indian Grasslands and Fodder Research Institute, Jhansi and Central Arid Zone Research Institute, Jodhpur.

3. Impact of grazing

• Due to heavy grazing pressure, the quality of grasslands deteriorates rapidly. The soil's mulch cover reduces, microclimate becomes drier and is readily invaded by xerophytic plants and borrowing animals.
• Due to absence of humus cover, the mineral soil surface is heavily trampled, when wet it produces puddling of the surface layer. It reduces the infiltration of water into the soil and accelerates runoff, resulting in soft erosion.
• These changes contribute to the reduction of energy flow, and the disruption of the stratification and periodicity of the primary producers. It results in a breakdown of the biogeochemical cycles of water, carbon and nitrogen.
• Water and wind erosion completely deteriorates dry grassland microclimate.

4. Role of fire

• Fire plays an important role in the management of grasslands.
• Under moist conditions fire favours grass over trees, whereas in dry conditions the fire is often necessary to maintain grasslands against the invasion of desert shrubs.
• Burning increases the forage yields.

Desert Ecosystem

• Deserts are formed in regions with less than 25 cm of annual rainfall, or sometimes in hot regions where there is more rainfall, but unevenly distributed in the annual cycle.
• Lack of rain in the mid-latitude is often due to stable high-pressure zones; deserts in temperate regions often lie in "rain shadows", where high mountains block off moisture from the seas.
• The climate of these biomes is modified by altitude and latitude. At high altitudes and a greater distance from the equator, the deserts are cold and hot near equator and tropics.
• The perennial plant like creosote bush, cactus are scattered throughout the desert biomes.
• In shallow depressed areas with salt deposits geese-wood, seep-wood and salt grasses are common.

1. Adaptations

Desert plants are under hot and dry conditions.

• These plants conserve water by following methods
  (i) They are mostly shrubs.
  (ii) Leaves are absent or reduced in size.
  (iii) Leaves and stem are succulent and water storing.
  (iv) In some plants, even the stem contains chlorophyll for photosynthesis.
  (v) Root system is well developed and spread over a large area.

The annuals wherever present germinates, bloom and reproduce only during the short rainy season, not in summer and winter. This is an adaption to desert condition.

• The animals are physiologically and behaviorally adapted to desert conditions.
  (i) They are fast runners.
  (ii) They are nocturnal in habit to avoid the sun's heat during day time.
  (iii) They conserve water by excreting concentrated urine.
  (iv) Animals and birds usually have long legs to keep the body away from the hot ground.
  (v) Lizards are mostly insectivorous and can live without drinking water for several days.
  (vi) Herbivorous animals get sufficient water from the seeds which they eat.
  (vii) Camel is known as the ship of the desert as it can travel long distances without drinking water for several days.
  (viii) Mammals are poorly adapted to deserts, but some species have become secondarily adapted. A few species of nocturnal rodents can live in the desert without drinking water.

2. Indian Desert – Thar desert (hot)

• The climate of this region is characterized by excessive drought, the rainfall being scanty and irregular.
• The winter rains of northern India rarely penetrate the region.
• Extreme variations of temperature characterize November to March, and the temperature is frequently below freezing point at night.
• During April to June the heat are intense, frequent scorching winds prevail with great desiccating.
• The relative humidity of the atmosphere is always low.
• The climate is hostile to all vegetation, only plants and animals possessing special adaptations to establish themselves.

➤ Flora

• The proper desert plants may be divided into two main groups.
  (i) depending directly upon on rain and
  (ii) those depending on the presence of subterranean water.

➤ The first group consists of two types

• depending directly upon on the rain is two types - the 'ephemeral' and the rain perennials'.
• The ephemerals are delicate annuals, apparently free from any xerophilous adaptations, having slender stems and root-systems and often large flowers. They appear almost immediately after rain, develop flowers and fruits in a short time, and die as soon as the surface layer of the soil dries up.
• The rain perennials are visible above the ground only during the rainy season but have a perennial underground stem.
• The second group - depending on the presence of subterranean water
• By far the largest number of indigenous plants can absorb water from deep below the surface of the ground through a well-developed root system, the main part of which generally consists of a slender, woody taproot of extraordinary length.
• Generally, various other xerophilous adaptations are resorted to reduced leaves, thick hairy growth, succulence, coatings of wax, thick cuticle, protected stomata, etc., all having for their object of reduction of transpiration.

➤ Fauna

• It is home to some of India's most magnificent grasslands and sanctuary for the Great Indian Bustard.
• Among the mammal, the blackbuck, wild ass, chinkara, caracal, Sandgrouse and desert fox inhabit the open plains, grasslands, and saline depressions.
• The nesting ground of Flamingoes and the only known population of Asiatic wild Ass lies in the remote part of Great Rann, Gujarat.
• It is the migration flyway used by cranes and flamingos.

3. Cold Desert/ Temperate Desert

Cold desert of India includes Ladakh, Leh and Kargil of Kashmir and Spiti valley of Himachal Pradesh and some parts of northern Uttaranchal and Sikkim. These arid areas are not affected by the Indian monsoons because they lie in the Himalayan mountain systems' rain-shadow. Characterized by extreme cold weather and denuded terrain, they are not suitable for plant growth. Isolated, scattered and overgrazed herbaceous shrubs are found. Grazing period is less than 3-4 months.

4. Characters

• Severe arid conditions - Dry Atmosphere
• Temperature less than 0°C for most of the period, drops to -50°C during winter.
• insignificant monsoon - Mean annual rainfall less than 400mm
• Heavy snowfall occurs between November and March.
• Soil type - sandy to sandy loam
• Soil pH - neutral to slight alkaline.
• Soil nutrient - Poor organic matter content
• Soil has low water retention capacity.
• Wind erosion is more common.
• Narrow growing period, mostly during the summer.
• Due to foresaid extreme cold conditions, vegetation growth is slow and of stunted nature.

Biodiversity

• Cold desert is the home of highly adaptive, rare endangered fauna, such as Asiatic Ibex, Tibetan Argali, Ladakh Uriyal, Bharal, Tibetan Antelope (chiru), Tibetan Gazelle, Wild Yak, Snow Leopard, Brown Bear, Tibetan Wolf, Wild Dog and Tibetan Wild Ass ('Kiang' a close relative of the Indian wild ass), Woolly hare, Black Necked Crane, etc.
• Cold desert comprises of alpine mesophytes and desert vegetation.
• Dry temperature zone: Betula, Salix, Juniperus.
• Alpine zone: Junipers, Birch, Rhododendron with grasses.
• Perpetual snow zone: No vegetation due to permanently frozen soil.
• Oak, pine, deodar, birch and rhododendron are the important trees.

Desertification

• Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid.
• In arid and semiarid, the fragile ecosystem's restoration is prolonged, and issues like deforestation and mining enhance desertification. 
• Desertification is the main problem faced by desert adjoining areas, which stretches across Rajasthan, Gujarat, Punjab and Haryana.

The cause of this process is not climatic changes, droughts, etc. but human actions.

Causes

• Population pressure
• Increase in cattle population, overgrazing
• Increased agriculture
• Development activities
• Deforestation

➤ Desertification in India

• As per the Desertification and Land Degradation Atlas of India, 2007, the country's percentage under drylands is 69.6%. 
• The total area undergoing land degradation in India is 105.48 million hectares, which constitutes 32.07 percentage of India's total land area. 
• 81.45 million hectares area of the country is under desertification (land degradation within drylands).

➤ Control measures

• India is a signatory to the United Nations Convention to Combat Desertification (UNCCD). 
• The National Action Programme for combating desertification was prepared in 2001 to address the problems of desertification.

Some of the major programmes currently implemented that address issues related to land degradation and desertification are

• Integrated Watershed Management Programme
• National Afforestation Programme
• National Mission for Green India
• The Mahatma Gandhi National Rural Employment Guarantee Scheme
• Soil Conservation in the Catchment of River Valley Project and Flood Prone River
• National Watershed Development Project for Rainfed Areas
• Desert Development Programme
• Fodder and Feed Development Scheme-component of Grassland Development including Grass Reserves, Command Area Development and Water Management programme etc.

Afforestation

• The desert regions of Rajasthan, Gujarat, Haryana, Punjab, and Trans-Himalayan regions are scarce.
• People require firewood, timber and fodder for their domestic consumptions and livestock.
• Presence of vegetation prevents soil erosion and modifies the hostile climate.
• Thus, desert Afforestation is inevitable to modify the climate, desertification, and meet the demands of people living in that region.

Indian State of Forest Report, 2017

• State of Forests Report is published by the Forest Survey of India (FSI) on a biennial basis since 1987. 
• The India State of Forest Report 2017 is the 15th report in the series. It is based on interpretation of LISS III sensor data of indigenous Resource sat - II satellite. The satellite data interpretation is followed by extensive and rigorous ground-truthing. 
• The total forest and tree cover is 24.39 per cent of the total geographical area. Forest and Tree Cover of the country has increased by 8,021 sq km (1 %) compared to the assessment of 2015. The very dense forest (VDF) has increased by 1.36 % as compared to the last assessment. VDF absorbs maximum carbon dioxide from the atmosphere. 
• Madhya Pradesh has the largest forest cover in the country, followed by Arunachal Pradesh and Chhattisgarh. 
• With 88.93 percentage of forest cover, Mizoram has the highest forest cover in percentage terms, followed by Lakshadweep with 84.56 per cent. The ISFR 2015 states that 15 States/Union Territories have above 33 per cent of the geographical area under forest cover. 
• Out of these, 7 States/Union Territories - Mizoram, Lakshadweep, Andaman & Nicobar Island, Arunachal Pradesh, Nagaland, Meghalaya and Manipur have more than 75 per cent forest cover, while 8 states - Tripura, Goa, Sikkim, Kerala, Uttarakhand, Dadra & Nagar Haveli, Chhattisgarh and Assam have forest cover is between 33 per cent to 75 per cent. 
• "India is ranked 10th globally in forest cover, with 24.39% of land area under forest and tree cover. 
• As per the FAO report, India is placed 8th in Top Ten nations reporting the greatest annual net gain in the forest area.