- 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 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.
- Steppe formations occupy large areas of sandy and saline soil; in western Rajasthan, where the climate is semi-arid, average rainfall is less than 200 mm a year with a dry season of 10 to 11 months, and a 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 of 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.
Types of Grasslands
Based on climatic conditions there are six types of grasslands found in the different regions of the Indian subcontinent. But we discuss Four major types of grasslands:
- Semi-arid zone
- Dry sub humid zone
- Moist sub humid zone
- Humid montane regions
Semi-arid zone
- 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 Nigiri).
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 and Jammu and Kashmir.
- The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing
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.
Impact of grazing
- Due to heavy grazing pressure, the quality of grasslands deteriorates rapidly, the mulch cover of the soil reduces, microclimate becomes more dry and is readily invaded by xerophytic plants and borrowing animals.
- Due to absence of humus cover, mineral soil surface is heavily trampled, when wet it produces puddling of the surface layer. In turn it reduces the infiltration of water into the soil and accelerates run off, 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.
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.
