In Niger, the cumulative effects of successive years of drought and anthropic pressures have resulted in significant declines in the quality and quantity of natural resources. The present study aims to characterize the woody vegetation of the 527261.75ha Dosso Partial Wildlife Reserve. To this end, the analysis highlighted a characterization along the rainfall gradient. Data were collected by radial transect sampling, using floristic surveys and diameter measurements at 1.30 m for trees in 200 plots measuring 50 x 50 m in agrosystems and 50 x 30 m in contracted formations. Diversity indice were calculated on the basis of specific frequencies. The results revealed a woody stand characterized by a floristic richness ranging from 42 to 73 species, with an index varying from 3.86 to 4.74bits. The most dominant families in the sectors are fabaceae (32.87±35.71%) and combretaceae (10.95±19.04%). Microphanerophytes are more abundant (50.7±52.4%), reflecting the shrubby character of this stand. Dendrometric parameters indicate a low stand density (135.8±25.3ft/ha), but with a mean diameter (36.7±9.4cm) and a dominant mean height (11.67m). In the Sudanian and Sahelian domain, the dominant species in terms of importance value index are established. The diametric structure of the individuals fits the Weibull distribution and shows a predominance of young individuals. However, the low proportion of mature individuals suggests, among other things, the existence of anthropic pressures and difficult soil and climatic conditions that prevent individuals from reaching large dimensions. These results provide additional information on the state of the population in the study area, and can be used as a basis for management.