Nutrient availability amplifies adaptive transgenerational plasticity in response to grazing in a dominant clonal grass

Abstract Grazing shapes grassland ecosystems through defoliation and altered nutrient dynamics, yet how these factors jointly influence plant adaptation via transgenerational plasticity (TGP) remains poorly understood. A two-phase greenhouse experiment examined TGP in Leymus secalinus, a dominant clonal grass in northern China's semi-arid grasslands. We manipulated clipping intensity (unclipped, light, heavy) and nutrient availability (low, high) across both parental and offspring generations, assessing offspring biomass, clonal propagation, and regrowth capacity under matching and non-matching environmental conditions. Parental clipping increased offspring tiller production, with high nutrients amplifying transgenerational effects. Combined parental clipping and nutrient stress elicited stronger transgenerational effects than single clipping stressors. Specifically, Light clipping with low nutrients enhanced biomass and clonal propagation, reflecting a strategy focused on resource acquisition. Conversely, heavy clipping with low nutrients showed a trade-off between biomass and propagation, indicating a shift toward clonal propagation as a resilience mechanism. Moreover, parental exposure to simultaneous clipping and high nutrient availability substantially increased offspring performance under matched environmental conditions, highlighting nutrient modulation of TGP. These findings emphasize how interactions between defoliation intensity and nutrient availability in parental environments shape the capacity of offspring to adaptively respond to grazing pressures. This study underscores the pivotal role of clonal TGP as a mechanism for grazing tolerance, with nutrient availability serving as a key modulator. In degraded, nutrient-poor ecosystems, strategic nutrient supplementation following heavy grazing may amplify the capacity of populations to develop stress-tolerant phenotypes through TGP. This finding highlights the potential of leveraging TGP mechanisms in grassland restoration and management practices.