Timing of Firelines Establishment in Rangelands Using Remote Sensing Techniques

Abstract

The rangelands areas in Sudan are estimated as 117 million hectare. The vegetation composition and distribution over the predominant ecological zones are entirely attributed to the actions and interactions of the prevailing environmental factors such as climate, soil, topography and the common human and animal activities Wildfires are among the main reasons that cause great loss of rangelands annually, especially when incidences increase as a result of human related factors. Fire contributed to loss of about 30-60% of plants annually in the low rainfall savanna, while limited efforts are taken in this respect. This situation requires an effective means of protection mainly firelines establishment. Determination of optimum timing for firelines establishment is very important because it contributes to minimize the incidence of fire occurrence and hence reduces damage to vegetation and seed bank. This study was conducted in Albaja area western Eldueim town in White Nile State, the main objective of it was to investigate the use of remote sensing tools for determination of optimum timing for firelines establishment. Sampling carried out on eight sites, in each site four (1m ×1m) quadrates were located 50 m apart and perpendicular to the 5th central quadrate. The biomass at each quadrate clipped, and oven dried inorder to determine the moisture content. 16 readings were taken within the period from 13/9/2007 to 22/10/2007. MODIS NDVI images 250mX250m spatial resolution were used inorder to make correlation between NDVI and moisture content and between NDVI and dry biomass weight. The minimum values of fuelload expressed in biomass and maximum moisture content values (at one day before fire occurrence) for areas burned previously were used as critical values to trace areas of maximum vulnerability. When the two factors (areas of equal or less than the maximum moisture content and of equal or more than the minimum fuelload) overlapped indicate fire occurrence because the enough burnable dry fuel is available. The starting of the appearance of areas of overlapping of the two values of fuelload and moisture content indicates the possibility of fire occurrence and hence the time to establish firelines. The study recommended that, remote sensing techniques can be used as an effective mean for determination of timing of firelines establishment and areas more subjected to fires. Also Remote sensing data and other related tools are promising for wildfire monitory and rangeland management hence they are in continuous development.