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Abstract
Assessment of Grassland Status using Remote Sensing and GIS to Workout Fodder Requirement - A Case Study in Talala Taluka, Dist. Junagadhs
K. L. N. SASTRY
Scientist
Forestry and Environment Division (FED)
FLPG/RESIPA
Space Applications Centre (SAC)
Jodpur Tekra
Ambawadi Vistar PO, Ahmedabad - 380 015
Phone: 079-6914026 (O), 079-7485271 (H)
e-mail : klnsastry@sac.isro.org, klnsastry@hotmail.com
P.S. Thakker and Ravi Jadhav
Forestry and Environment Division (FED)
Space Applications Centre (ISRO), Ahmedabad
Abstract
One fifth of the Earth's land surface is covered by grassland, a biome found on every continent except Antarctica. In many parts of the world, grasslands are among the most ecologically productive lands on Earth with high levels of soil nutrients. Consequently, many of the grasslands around the globe have been replaced by agriculture. It is estimated that before the dawn of civilization natural grasslands covered about 30-40 per cent of the land. Researchers working with International Geosphere-Biosphere Programme are now actively investigating the climatological consequences of replacing these grasslands with agriculture. Tropical forests have attracted considerable attention with respect to `global greenhouse effect' as they store about 19 % of the total carbon sequestered by terrestrial communities each year. On the other hand tropical and semi-tropical grasslands store about 26 % of the carbon sequestered by terrestrial communities. The grasslands thus have a greater role to play in global greenhouse effect. In the face of global warming, the health of planet Earth may depend on grasslands because they are superior carbon sinks compared to forests with similar environmental characteristics (Seastedt and Knapp 1993).
Generally speaking, grassland have few, scattered, small sized trees to break the drying winds. Most of these areas go through periodic drought conditions. As a result, majority of plants of these regions lives more " in " the soil than above it. Just under the surface there is a tangled map of roots and rhizomes. Some grassroots grow down to the depths of a meter into the soil, while the tap roots of other soft stemmed plants may penetrate to five meter in their search for water and nourishment.
Deterioration or even extinction of grasslands can happen due to overgrazing. Such overgrazing affects the composition and structure of grasslands. Palatable and productive species decrease in abundance whereas less desirable species increase in quantity. Normal grasslands have close canopy cover which is lost due to `invaders' Grazing has been found to affect grasslands converting them to less desirable shrublands. Overgrazing also leads to soil erosion. Soil formation is a slow, continuous process and it takes 100-1000 years to form a 2.5 cm layer of soil depending on climate, vegetation and other living organism, topography and the nature of the soil's parent material (Sampson, 1981).
More than 70% of our population dwell in rural areas and hence the socio-economic development in India is closely related to the increase in livestock productivity. India is having 12.47 m.ha of grasslands which is about 4.1% of total geographical area of the country. The huge livestock population of 420 million with a grazing intensity is far below the healthy sustenance of cattle population.
The grassland extents presently available is purely based on earlier estimates and suffer for want of spatial distribution and true extent on the degradation/increase aspects for precise grassland/grazing land resource planning and management. Grasslands, close to urban areas, are often subjected to urbanization or industrialization. Of course, grasslands are more often converted to agricultural lands. Other connected activities can be construction of roads, railway lines, canals etc. However, no information is available on the impact of such activities on the grasslands. In Saurashtra a more recent threat is the invasion by Prosopis Julifera.
Keeping this in mind a pilot study was taken-up in Talala Taluka of Junagadh Dist. of Gujarat. 1998 post monsoon Remote Sensing Satellite Data was interpreted and Grass land area both open grassland and Grassland under tree cover were computed. Various statistical figures for Grass production/ ha., consumption rate of domestic cattle and latest cattle population data were obtained from Dist. authorities. Subsequently grassland map of Talala Taluka was prepared using 1998 IRS LISS-III data. This map was checked on ground and accuracy was fond to be 90% at 90% confidence limits.
It was shocking to observe that Grass land area derived from Satellite data can sustain only 589 cattle where as cattle population of Talala is 49737. Thus 84 times more land is required to sustain the cattle in this taluka. These shocking figures indicate high degree of pressure on Agriculture and Forest areas. This would ultimately result in biodiverisity loss and degradation of forest.
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