Intra-annual productivity of rangelands in the Sahelian zone of Burkina Faso, West Africa

Abstract

This study aimed to assess the seasonal dynamics of herbaceous pastures in the Sahelian zone of Burkina Faso. To estimate the biomass of the herbaceous layer, two operations of biomass cutting, spaced an interval of fifteen days were carried out each month in ten permanent plots of 100 m² as well as phytosociological surveys in order to distinguish the different types of pasture. The evolution of the biomass showed distinct phases. The first phase (June July) had a slow growth. This was the installation phase of the vegetation following the humidity conditions favored by the first rains. The second phase ran from August to when the production was at its peak. This was the maturation phase of herbaceous plants. The peak of production in each of the pastures was observed in this period when the soil humidity reserve was high. The fourth phase (October November) reflected the decrease in the production of the herbaceous layer. The daily growth rate of the biomass of the herbaceous layer was irregular. The growth of the herbaceous layer began just after the first rains. The high values (from 7.8 to 19 grams/day) were found in the months of July until the beginning of September, corresponding to the months when the useful soil reserve was at its maximum. The average monthly biomass productivity varied according to the pastures. Piliostigma reticulatum and Justicia insularis pasture was the most productive with 0.91 ± 0.97 t of dry matter per hectare. Carrying capacities varied from 0.02 to 0.7 TLU/ha/month and called out the need to moderate pasture and enrich Sahelian rangelands.