Modeling the effects of livestock rotation frequency on forage production and soil carbon using a spatially explicit grazing distribution

Livestock grazing strongly influences terrestrial ecosystems and carbon (C) dynamics, but outcomes depend on grazing management. High-frequency rotation (HFR) grazing may reduce the uneven grazing distribution commonly associated with low-frequency rotation (LFR), which can alter forage production and soil organic carbon (SOC). However, most ecosystem models do not explicitly represent uneven grazing distribution, limiting their ability to evaluate management effects. We enhanced the MEMS ecosystem model by incorporating discrete spatial units to simulate grazing distribution driven by key environmental drivers, including forage availability and quality, and distance to water. Using remote sensing-derived enhanced vegetation index (EVI), we verified the simulated grazing distribution at an experimental rangeland site in Oklahoma. We tested the model’s sensitivity to rotation frequency under different management (stocking rate, timing, and duration) and weather (typical, dry, and wet) scenarios. Simulated light and moderate grazing generally sustained forage production and SOC regardless of rotation frequency. However, under heavy grazing, the 30-year projection showed HFR reduced localized overgrazing and sustained higher pasture average forage productivity and SOC stocks than LFR. Long-term experimental data are needed to validate these results. Our study offers guidance for designing grazing management experiments to address this critical knowledge gap and advance C management strategies.