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Application of Satellite Based Remote Sensing for Monitoring and Mapping of India’s Forest and Tree Cover
J. K. Rawat
Director, Forest Survey of India
Alok Saxena
Joint Director, Forest Survey of India
Saibal Dasgupta
Joint Director, Forest Survey of India
Abstract
Forest goods and services are available both from forests as well as plantations and tree lands existing outside conventional forest areas (termed as “Trees Outside Forests” or TOF by FAO). Due to their role in combating green house gases, serving as carbon sink, in conservation of biodiversity, production of water, etc. the conventional forests have gained an important place in international political scenario. Lately, contribution of TOF has been found to be significant in livelihood of local population, in addition to their role in conservation of natural forest areas and in maintaining ecological balance. Accurate and periodic information about forest resources, inside and outside forest areas, is a pre-requisite for planning and their proper management.Considering the crucial role forests play in a country’s ecological stability and economic development, the current National Forest Policy (1988) of India aims at maintaining a minimum of 33 percent of country’s geographical area under forest and tree cover. This requires periodic monitoring of the forest and tree cover of the country for effective planning and sustainable development. Consequently, Forest Survey of India (FSI), an organisation under the Ministry of Environment & Forests (Government of India), has been mandated to carry out assessment of forest cover in the country on a biennial basis. This is done by using satellite based remote sensing data and the findings are published in the State of Forest Report (SFR) every two years. Its first assessment of forest cover was published as SFR 1987 and the latest i.e., the eighth one as SFR 2001. With the improvement in satellite data resolution and adoption of digital image processing by FSI, it has been possible to assess forest cover at 1:50,000 scale enabling it to delineate tree canopy patches as small as 1 ha. The latest assessment which is based on digital interpretation of satellite data (IRS 1C/1D- LISS III) shows that forest cover of the country is 675,538 km2 constituting 20.55% of the country’s geographic area.
However, a substantial part of TOF is less than 1 ha in extent and cannot be captured by satellite sensors used for forest cover assessment. These include small patches of tree plantations and woodlands, or scattered trees on farms, homesteads and urban areas, or trees along linear features such as roads, canals, bunds etc. FSI estimated such tree cover using a stratified sampling and field inventory methods. The corresponding tree cover was thus estimated to be 81,472 km2 or 2.48% of the country’s geographical area. Now, FSI has developed a methodology based on remote sensing data from LISS III sensor (resolution 23.5 m) as well as from PAN sensor (resolution 5.8 m) for assessment of TOF. It has been demonstrated that this methodology provides better estimates of TOF resources than the one generated through field survey alone.In the present paper, methodologies of forest cover assessment and tree cover assessments in urban and rural areas outside forests, as used by the FSI, have been presented.
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