Species-specific prediction models to estimate browse production of seven shrub and tree species based on semi-destructive methods in savannah

Browse shrubs and trees, in spite of their significant role in livestock production in arid and semi-arid zones, are often omitted from pasture potential assessments because of the lack of methodology, the difficulty in calculation or method application and because it is usually a long and tedious task. For an accurate estimation of the carrying capacity of rangelands the shrub and tree fodder component has to be taken into account in order to avoid under estimation of the potential phytomass available for browsing. In this study, a semi-destructive method was used to develop fodder prediction equations of seven shrub and tree species based on multiple explanatory variables at four different locations in Burkina Faso (Taffogo, Safané, Nobéré, Dano and Sokouraba). The physical characteristics (explanatory variables) and the leaf weight (response variable) of the plants were measured or calculated and the non collinear explanatory variables correlated with the response variable. More than 50 % of the observed variation in fodder was explained by the basal area and/or the crown cover for all the target species except Ficus sur at Sokouraba and both Acacia seyal and Balanites aegyptiaca at Safané. The prediction equations were species-specific and equations developed for the same species in different sites were different. These results suggest that many local species-specific fodder prediction equations have to be developed to get an accurate fodder prediction in a large scale, and practitioners of rangelands management may be cautious about applying general species-specific prediction equation tables.