Abstract
Dryland pastoral systems across Africa are routinely characterised as ecologically fragile and economically marginal, yet the herding communities that inhabit them have, over centuries, developed detailed, place-calibrated knowledge of how rainfall pulses translate into forage. In Richtersveld National Park (RNP), South Africa's Northern Cape, the Nama people's annual transhumance between Succulent Karoo uplands and the Orange River riparian zone is one such system. Drawing on stratified vegetation surveys, allometric browse measurements, satellite-derived productivity data, and soil nutrient profiling conducted across five vegetation types between 2006 and 2008, this study examines the ecological mechanisms underlying this pastoral system. Annual plant biomass was most strongly predicted by rainfall (R² = 0.69, 95% CI: 0.56–0.79; F(1,58) = 36.90, p < 0.01), with grazing pressure and landform accounting for far less variance. Shrub biomass in the Succulent Karoo peaked at 962.8 g/m², nearly twelve times the 81.6 g/m² recorded in the Desert Biome. Riparian grass under low-discharge conditions reached 600–700 g/m² during months when all upland vegetation was dormant. MODIS-derived fPAR values tracked ground-measured biomass closely (R² = 0.89). The results provide quantitative evidence that year-round forage availability is maintained under the existing management regime; whether this translates into sustained livestock body condition or reproductive performance under future climate conditions requires dedicated herd-monitoring data that were beyond the scope of this study. Taken together, the results provide a quantitative ecological rationale for practices that policy has historically dismissed as traditional rather than adaptive.
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