Assessment of Fire vulnerability and Firelines designing in rangelands, using remote sensing techniques (Albaja area Western White Nile State)

Abstract

This study was conducted in Albaja area western part of Eldueim town in White Nile State (central Sudan), which in know to be a unique grazing site in term of its richness in rangeland resources. The objectives were to investigate the vulnerability of fire occurrence in rangeland in relation to the fuelload availability. It was also to study layout and designing of firelines based on using remote sensing means and techniques. The study concept based on identifying areas of high fuelload expressed in values of kg/ha of dry matter compared with the existing firelines layout and design. The locations of the existing firelines in Albaja namely “Elburei”, “Elmushroa”, “Elhibeal” and “Elfrianiga”, were marked using G.P.S. In each line. Points were marked nearly 2 KM a part to enable tracing the lines and to locate them in a map later. The dry pre-determent matter weight values <(450 kg/ha) that were obtain from ground readings, and correlated with value of Normalized Different Vegetation Index (NDVI) derived from MODIS, terra 16 days vegetation index image, with spatial resolution of 250m were used as an indicator to detect areas subjected to fire occurrence. The five years (2000, 2001, 2003, 2004, and 2005) were used for this study because the locations of the firelines were nearly in the same places. It was found in Albaja area, that areas with biomass more than 450kg dry matter per ha, are more susceptible to fires than other areas with less values of biomass(less than 450kg dry mater/ha). This was found to be true for the years 2000, 2001, 2003, 2004, and 2005 in Elbaja areas. It was also found that, the amount of biomass and its spatial distribution in the study area exhibited annual variations due to variations in rainfall amount and distribution. It is obvious that, the five years showed varied amount of biomass. In 2000 and 2005, the northern part of the study area exhibited biomass production less than 450 kg dry mater/ha, in most parts of this site. The variations in biomass distribution should be considered in the activities of fire management mainly fire breaks layout, in term of width and lengths. The biomass values and firelines locations for years 2001 and 2003 showed that the biomass values were more than 450kg was highly dominated and nearly with homogenous distribution, indicating that large areas are under fire threat. Such year will require maximum effort in the establishment and maximum possible coverage of firelines. Firelines extended to areas with biomass less than 450kg per ha, indicated efforts excreted in wrong place, because the areas of 30km South of the firelines was requires more protection compared to where the existing lines were located , and could be used in areas more needed. when the biomass were distributed in patches there was a need for short and widely distributed lines, rather than long clustered ones, to cope with such situation. Remotely sensed means have promising potential in range management activities such as firelines establishment due to their continuous improvement and new solution that may come in the near future.