The objective of this study is to have a real knowledge by locality of dynamics and the propagation mode of the bush fires in time in space. To achieve our goal a methodological approach was adopted by a use on the one hand satellite images and software of SIG for the image processing and on the other hand cards of investigations for the talks, the GPS for the localization of the CVD (Village Committee of Development), of the mowings for the collection of herbaceous biomass and of the compasses for the determination of the transect. This work was supplemented by investigations into the ground and that made it possible to determine on average 10000 hectares which burn each season is to say October to May with reduction (controlled fire) for the period from October at November. The study highlighted on the one hand that late fires intervene in second half of the dry season to reach significant proportions in February and Mars and on the other hand that the occurrences of fire are observed in the South of the district where is the classified field.The estimate of the vegetable biomass is obtained starting from a correlation of the data to the level satelitte to extract the Index from Vegetation by the Standardized Difference (NDVI) of the channels red and near infra-red to the imagery of the year corresponding and the data of ground for the determination of the herbaceous and woody production to the level of the sites of control on the ground. Each more than 60% of the total production of the vegetable biomass disappears under the action of fires.