- An increase in the average temperature of Earth’s near surface air and oceans since the mid-20th century
- 4th assessment report of IPCC: global temperature increased 74+0.18 degree C during the 20th century.
- Caused by greenhouse gases
- Water vapour, Co2, Methane, Nitrous Oxide, Ozone, CFCs (in order of abundance)
- Since the industrial revolution, the burning of fossil fuels has increased the levels of Co2 in the atmosphere from 280 ppm to 390 ppm.
Environment
Aquatic Zones
Aquatic systems are not called biomes,
The major differences between the various aquatic zones are due to salinity, levels of dissolved nutrients; water temperature, depth of sunlight penetration.
- Fresh Water Ecosystem-Fresh water ecosystem are classified as lotic
(moving water) or lentic (still or stagnant water).
- Marine Ecosystem-
- Estuaries-Coastal bays, river mouths and tidal marshes form the
estuaries. In estuaries, fresh water from rivers meet ocean water and the two are mixed by action of tides.
Estuaries are highly productive as compared to the adjacent river or sea
GRASSLAND ECOSYTEM
found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert.
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 aremainly composed of steppes and savannas.
Steppe formations occupy large areas of sandy and saline soil; in western Rajasthan, where the climate is semi-arid,
The major difference between steppes and savannas is that all the forage 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
- semi-arid zone (The Sehima-dichanthium type)
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.
senegal, Calotropis gigantia, Cassia auriculata, Prosopis cineraria, Salvadora oloides and zizyphus Nummularia which make the savanna rangeland look like scrub.
- dry sub humid zone (The Dichanthium- cenchrus-lasitrrus type)
It covers the whole of peninsular India (except Nilgiri).
The thorny bushes are Acacia catechu, Mimosa, Zizyphus (ber) and sometimes fleshy Euphorbia, along with low trees of Anogeissus latifolia, Soymida febrifuga and other deciduous species.
Sehima (grass)is more prevalent on gravel and the cover maybe 27%. Dichanthium (grass) flourishes on level soils and may cover 80% of the
ground.3) moist subhumid zone(The Phragmities- sacchrum-imperata type)
It covers the Ganga alluvial plain
in Northern India.The topography is level, low lying and ill-drained.
Bothriochloa pertusa, Cypodon dactylon and Dichanthium annulatum are found in transition zones.
The common trees and shrubs are Acacia arabica, hogeissus, latifolia, Butea monosperma,
Phoenic sylvestris and Zizyphus nummularia.
Some of these are replaced by Borassus sp in the palm savannas especially near Sunderbans.
4) The Themeda – Arundinella type
This extends to the humid montane regions and moist sub-humid axeas of Assam, Manipur,West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh and. Jammu and Kashmir.
The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing.
Indian Grasslands and Fodder Research Institute, Jhansi and Central Arid Zone Research institute, Jodhpur
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, e.g. Cynodon daotylon
GRASSLAND ECOSYTEM
found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert.
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.
Steppe formations occupy large areas of sandy and saline soil; in western Rajasthan, where the climate is semi-arid,
The major difference between steppes and savannas is that all the forage 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
- semi-arid zone (The Sehima-dichanthium type)
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.
senegal, Calotropis gigantia, Cassia auriculata, Prosopis cineraria, Salvadora oloides and zizyphus Nummularia which make the savanna rangeland look like scrub.
- dry sub humid zone (The Dichanthium- cenchrus-lasitrrus type)
It covers the whole of peninsular India (except Nilgiri).
The thorny bushes are Acacia catechu, Mimosa, Zizyphus (ber) and sometimes fleshy Euphorbia, along with low trees of
Anogeissus latifolia, Soymida febrifuga and other deciduous species.Sehima (grass)is more prevalent on gravel and the cover maybe 27%. Dichanthium (grass) flourishes on level soils and may cover 80% of the ground.
3) moist subhumid zone(The Phragmities- sacchrum-imperata type)
It covers the Ganga alluvial plain in Northern India.
The topography is level, low lying and ill-drained.
Bothriochloa pertusa, Cypodon dactylon
and Dichanthium annulatum are found in transition zones.The common trees and shrubs are Acacia arabica, hogeissus, latifolia, Butea monosperma,
Phoenic sylvestris and Zizyphus nummularia.
Some of these are replaced by Borassus sp in the palm savannas especially near Sunderbans.
4) The Themeda – Arundinella type
This extends to the humid montane regions and moist sub-humid axeas of Assam, Manipur,West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh and. Jammu and Kashmir.
The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing.
Indian Grasslands and Fodder Research Institute, Jhansi and Central Arid Zone Research institute, Jodhpur
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, e.g. Cynodon daotylon
