Introduction

Fire has been a source of disturbance for thousand of years. Forest and wild land fires have been taking place historically, shaping landscape structure, pattern and ultimately the species composition of ecosystems. The ecological role of fire is to influence several factors such as plant community development, soil nutrient availability and biological diversity. Forest and wild land fire are considered vital natural processes initiating natural exercises of vegetation

* Present address : National Remote Sensing Agency, Hyderabad, 500037, India

Satellite Remote Sensing and GIS Applications in Agricultural Meteorology pp. 361-400

succession. However uncontrolled and misuse of fire can cause tremendous adverse impacts on the environment and the human society.

Forest fire is a major cause of degradation of India's forests. While statistical data on fire loss are weak, it is estimated that the proportion of forest areas prone to forest fires annually ranges from 33% in some states to over 90% in others. About 90% of the forest fires in India are started by humans. Forest fires cause wide ranging adverse ecological, economic and social impacts. In a nutshell, fires cause: indirect effect on agricultural production; and loss of livelihood for the tribals as approximately 65 million people are classified as tribals who directly depend upon collection of non-timber forest products from the forest areas for their livelihood.

A combination of edaphic, climatic and human activities account for the majority of wild land fires. High terrain steepness along with high summer temperature supplemented with high wind velocity and the availability of high flammable material in the forest floor accounts for the major damage and wide wild spread of the forest fire. Figure-1 shows triangle of forest fire. The contribution of natural fires is insignificant in comparison to number of fires started by humans. The vast majority of wild fires are intentional for timber harvesting, land conversion, slash - and- burn agriculture, and socio-economic conflicts over question of property and landuse rights. In recent years extended droughts (prolonged dry weather), together with rapidly expanding exploitation

Edaphic

Figure 1: Triangle of forest fire

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Forest

Figure 1: Triangle of forest fire of tropical forest and the demand for conversion of forest to other land uses, have resulted in significant increase in wild fire size, frequency and related environmental impacts.

Recent wild fires have an immense impact in Indonesia, Brazil, Mexico, Canada, USA, France, Turkey, Greece, India and Italy. Large-scale fires and fire hazards were also reported in eastern parts of the Russian Federation and in China northeastern Mongolia autonomous region. There has been a continuous increase of application of fire in landuse system in forest of South East Asian region. This has resulted in severe environmental problems and impacts on society. Wild fires often escape from landuse fire and take unprecedented shape causing problems of transboundary pollution. The paper analyzes the forest and wild land fires issues with particular reference to South East Asia and emphasizes on development of national and regional fire management plans considering the complexity and diversity of fire. The paper also attempts to assess the current status of application of satellite remote sensing for fire detection, monitoring and assessment. According to a classification of forest fires by type and causes, three types of forest fires are prevalent;

a) Ground fires: Ground fires occur in the humus and peaty layers beneath the litter of un-decomposed portion of forest floor with intense heat but practically no flame. Such fires are relatively rare and have been recorded occasionally at high altitudes in Himalayan fir and spruce forests (Fig. 2).

b) Surface fires: Surface fires occurring on or near the ground in the litter, ground cover, scrub and regeneration, are the most common type in all fire-prone forests of the country (Fig. 3).

c) Crown fires: Crown fires, occurring in the crowns of trees, consuming foliage and usually killing the trees, are met most frequently in low level coniferous forests in the Siwaliks and Himalayas (NCA Report, 1976) (Fig. 4).

Figure 3: Surface fire
Figure 4: Crown fire
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