Assessment of African grassland sustainability for livestock use by constructing a carrying capacity alert index

Beyond natural factors, overgrazing is emerging as a critical threat to grassland ecosystems, potentially driving degradation and unsustainable resource utilization. Grassland carrying capacity refers to the maximum number of livestock that can be sustained by available grassland biomass. Accurately assessing its sustainability is critically important, yet challenging without considering long-term trends, especially at the continental scale. Here, we develop a grassland carrying capacity alert index to assess its utilization risk, reflecting whether grassland ecosystems are currently sustainable. Using data from 2001 to 2020, we assess spatiotemporal changes in grassland carrying capacity across Africa. Our results show that increases in aboveground biomass do not keep pace with growing livestock feed demand. Moreover, the utilization level of grassland resources remains highly uneven across the continent. Approximately 51.02% of African grasslands are under high pressure, with livestock numbers exceeding carrying capacity, primarily in northern Africa. In contrast, 26.53% of grasslands, mainly in southern Africa, remain underutilized over the long term. Shifting livestock development focus to Southern Africa, complemented by cross-regional cooperation to utilize southern pastures for alleviating northern overgrazing, may balance economic growth with grassland sustainability across the continent.