Clonal integration differentially impacts grassland plants under simulated homogeneous and heterogeneous grazing

Abstract The frequency and intensity of grazing may play different roles in plant growth. This potential uncoupling of frequency and intensity may be intensified by the complexities of grass demography, such as their ability for clonal integration, and the foraging behaviour of livestock, which can range from heterogeneous to homogeneous grazing regimes. We examined the effects of clonal integration and grazing regimes (homogeneous and heterogeneous grazing) on the biomass of Leymus chinensis, a dominant plant and important forage resource in Inner-Mongolian grasslands, influenced by variation in grazing frequency (leaf removal once or twice) and intensity (control, 50%, 100%). Whilst holding grazing intensity constant, a single event of heavy grazing was more detrimental to the growth of L. chinensis than two events of moderate grazing. Furthermore, under a single heterogeneous heavy grazing event, clonal integration improved stem biomass of distal ramets by 66.38% (estimate = 0.14, 95% CI: 0.02 to 0.27), and total biomass of distal ramets by 56.67% (estimate = 0.47, 95% CI: −0.01 to 0.95). However, the positive effects of clonal integration on biomass were only observed under simulated heterogeneous grazing, not homogeneous grazing. Our findings indicated that distributing grazing across multiple time points, instead of being concentrated in a single grazing event, can alleviate the negative effects on L. chinensis growth under controlled conditions. Furthermore, raising livestock with a selective heterogeneous grazing may reduce damage to grasslands dominated by clonal plants, highlighting a potential management strategy for sustaining clonal plant populations under grazing pressure.