Desert Ecosystem Desertification Grassland Ecosystem
- Deserts are formed in regions with less than 25 cm of annual rainfall.
- At high altitudes and at a greater distance from the equator the deserts are cold and near the equator and at low altitudes in tropics they are hot.
- The perennial plant species like bush, cactus, fetrocactus are scattered throughout the desert biomes.
- Where soils are suitable, irrigation can convert deserts into some of the most productive agricultural lands.
- As the large volume of water passes through the irrigation system, salts may be left behind that will gradually accumulate over the years until they become limiting.
Desert plants conserve water by following methods
- They are mostly shrubs.
- They have deep roots. Root system
- spread over large area.
- Their epidermal layers are made up of
- thick cuticle.
- Leaves are absent or reduced in size.
- In some plants leaves are modified into thorns or spines that can carry out photosynthesis.
- Leaves and stem are succulent (having thick fleshy leaves or stems adapted to storing water) and water storing.
- In some plants even the stem contains chlorophyll for photosynthesis.
- The seeds germinate only during the short rainy season.
- They are fast runners.
- They are nocturnal in habit to avoid the
- sun’s heat during day time.
- They conserve water by excreting
- concentrated urine.
- Animals and birds usually have long
- legs to keep the body away from the hot ground.
- Lizards are mostly insectivorous and can live without drinking water for several days.
- Herbivorous animals get sufficient water from the seeds which they eat.
- A few species of nocturnal rodents can live in the desert without drinking water.
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 into the region.
- The cold season starts from about the middle of November to the middle of March.
- This season is characterized by extreme variations of temperature 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 effect.
- The relative humidity of the atmosphere is always low.
- The climate is hostile to all vegetation, only plants and animals possessing special adaptations being able to establish themselves.
- The proper desert plants may be divided into two main groups.
- Depending directly upon on rain and
- Those depending on the presence of subterranean water.The first group consists of two types:
- The ‘ephemerals’ and
- The ‘rain perennials’
- The ‘ephemerals’ and
- 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 an incredibly 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.
- It is home to some of India’s most magnificent grasslands and sanctuary for a charismatic bird, theGreat Indian Bustard.
- Among the mammal fauna, 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 ofGreat Rann, Gujarat.
- It is the migration flyway used by cranes and flamingos.
Indian Cold Desert/Temperate Desert
- Cold desert of India includes areas of 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 rainshadow of the Himalayan mountain systems.
- Characterized by extreme cold weather and denuded terrain they are not suitable for plant growth.
- Isolated, scattered and over grazed herbaceous shrubs are found. Grazing period is less than 3-4 months.
- The flora and fauna is unique to the area. Oak, pine, deodar, birch and rhododendron are the important trees and bushes found there. Major animal includes yaks, dwarf cows, and goats.
- Severe arid conditions – Dry Atmosphere
- Temperature less than 0 degrees C for most of the period, drops to -50 degrees C during winter.
- Mean annual rainfall less than 40 cm.
- 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 aforesaid extreme cold conditions, growth of vegetation is slow and of stunted nature.
- A 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 alpine mesophytes [a plant needing only a moderate amount of water] and desert vegetation.
- It is the destruction of the biological potential of the land which can ultimately lead to desert-like conditions.
- In arid and semiarid regions, the restoration of the fragile ecosystem is very slow, and issues like deforestation, mining enhances the desertification.
- Desertification is the main problem faced by desert adjoining areas, which stretches across parts of Rajasthan, Gujarat, Punjab and Haryana.
- The cause of this process is not climatic changes, droughts, etc. but human actions.
- Increase in population and lack of alternative employment opportunities have left the people living in the Thar desert with no choice but to continue grazing cattle even in its inhospitable conditions.
- India as a signatory to United Nations Convention to Combat Desertification (UNCCD) has submitted National Reports to UNCCD since 2000.
- The National Action Programme for Combating Desertification was prepared in 2001 to take appropriate action in addressing the problems of desertification.
- Some of the major programmes currently implemented that address issues related to land degradation and desertification are
1. Integrated Watershed Management Programme (IWMP),
2. National Afforestation Programme (NAP),
3. National Mission for Green India (GIM),
4. The Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGS),
5. Soil Conservation in the Catchment of River Valley Project and Flood Prone River,
6. National Watershed Development Project for Rained Areas (NWDPRA),
7. Desert Development Programme (DDP)
8. Fodder and Feed Development Scheme-component of Grassland Development including Grass Reserves
9. Command Area Development and Water Management (CADWM) programme etc.
Grassland Ecosystem in India
- The grasslands are found where rainfall is about 25-75 cm per year.
- Grasslands are generally found in temperate climates [Steppe Grasslands – tree less]. In India, they are found mainly in the high Himalayas.
- The rest of India’s grasslands are mainly composed of savannas [Tropical grasslands – trees like Khatri, acacias, shrubs, cacti intersperse (scatter among or between other things) here and there].
- The major difference between Indian steppes and savannas is that all the forage (food for horses and cattle) in the steppe is provided only during the brief wet season whereas in the savannas forage is largely from grasses that not only grow during the wet season but also from the smaller amount of regrowth in the dry season.
Types of Grasslands in India
- It covers the northern portion of Gujarat, Rajasthan (excluding Aravallis), western Uttar Pradesh, Delhi and Punjab.
- The topography is broken up by hill spurs and sand dunes.
Dry sub-humid zone
- It covers the whole of peninsular India (except Nilgiri)
- It covers the Ganga alluvial plain in Northern India.
- The topography is level, low lying and ill-trained.
- The common trees and shrubs are Acacia arabica.
- This extends to the humid montane regions and moist sub-humid areas of Assam, Manipur, West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh and Jammu and Kashmir.
- It is derived from the humid forests on account of shifting cultivation and sheep grazing.
The economic importance of grasslands
- 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.
- Grassland biomes are important to maintain the population of livestock such as horse, mule, ass, cow, pig, sheep, goat, buffalo, camel, deer, zebra, etc.
- This huge mass of livestock needs fodder for sustenance but there is not enough of it. Only about 13 million hectares in the country are classified as permanent grazing lands. But they exist in a highly degraded state.
Indian Grasslands and Fodder Research Institute is at Jhansi
Central Arid Zone Research Institute is at Jodhpur.
Impact of grazing
- Due to heavy grazing, the mulch cover of the soil reduces and the soil is readily invaded by xerophytic plants.
- Increased areas of bare soil create a new habitat for burrowing animals such as mice, jack-rabbits, gophers, prairie dogs, locusts etc., which render large areas of forage lands sterile.
- The soil surface is heavily trampled by cattle leading to pulverized (reduce to fine particles) top soil which is easily washed away by rain.
- Soil trampled by cattle in wet season creates puddling which reduces the percolation of water. This leads to quick water runoff and the rate of soil erosion increases.
- Reduced percolation also lowers the groundwater table leading to water scarcity and drought in the dry season.
- Wind erosion becomes intense due to bare soil and this slowly leads to desertification of grasslands.
- These changes contribute to the reduction of energy flow and the disruption of the periodicity of the primary producers.
- It results in a breakdown of the biogeochemical cycles of water, carbon and nitrogen.
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 fire is often necessary to maintain grasslands against the invasion of desert shrubs. Burning increases, the forage yields (burning of grasses and shrubs adds a lot of nutrients to the soil).
Desert Ecosystem, Desertification, Grassland Ecosystem