CUTTING AND RESPROUTING OF DETARIUM-MICROCARPUM AND HERBACEOUS FORAGEAVAILABILITY IN A SEMIARID ENVIRONMENT IN BURKINA-FASO

The tree-shrub savanna 'Foret Classee de Nazinon' (Burkina Faso) is su bmitted to a management of grazing and rotational cutting of Detarium microcarpum. This species resprouts after cutting. In order to investi gate whether this silvopastoral land use system is sustainable, aboveg round herbaceous biomass was measured on subplots under uncut trees (' uncut'), next to the stubs of cut trees ('cut') and on subplots not in fluenced by the (former;, crowns of trees ('open grassland') in four l ots. These lots were cut one, three, six and seven years before the st udy. Vegetation composition of the lots and the composition of the die t of cattle were also determined. Comparisons were made between treatm ents and lots, Herbaceous biomass was lower in the open grassland subp lots than in uncut or cut subplots. We speculate that soil enrichment and more efficient precipitation input in (former) tree crown zones co uld have resulted in this pattern. Cutting and subsequent resprouting of trees did not lead to significant differences in herbaceous biomass between cut and uncut subplots. The most simple explanation for this is that the trees could extend their roots beyond the location of thei r neighbouring trees. Biomass and coverage of perennial grasses, mainl y Andropogon, ascinodis and Andropogon gayanus, did not change in lots cut one, three or six years before the study, but decreased dramatica lly in lots that were cut seven years before the study. When foraging, cattle spent more than 90% of their time feeding on these species. Th is indicates that, as a consequence of tree cutting, forage availabili ty may be reduced to the point where local herdsmen are forced to take their cattle to another region.