Pastoral appraisal of grass-tree relationships has established throughout the fodder production and quality of sahelian range forages in North Senegal. At the scale of analysis, the efficient tree cover is 32 %. The tree efficiency is a fodder production increase by 12 to 50 % in the different rangelands types. In the associated flora to this herbaceous production, the number and contribution of productive species are too improved. Also, graminea have showed an important contribution in the herbaceous cover. These favoured elements by tree have a positive effect on the herbages quality. Fodders are of excel quality, all at less during the rainy season, but they become fast mediocre to the state of straw. The pastoral value of fodders became as weak, by reason of the strong contribution of Phorbes. The tree modifies however of meaningful way the energizing value of fodders. Values in MAD and reports nutrititive are improven distinctly. Ca-Mg and K-Na ratios have low values. Then, the diet balance must be supplemented in these nutrients. On the methodological plan in short, this survey has showed that the previous works led in Sahelian zone, that only carried the open grazing, underestimated the pastoral balance, as well in quantity that in quality.