Positive microbial legacy and short-term clonal plasticity aid grazing tolerance of a widespread grass species

Aims Legacy effects arising from grazing may alter the effect of plant-soil feedback (PSF), plant-phyllosphere feedback (PPF) and/or transgenerational plasticity on plant performance. Understanding how effects from these mechanisms are influenced by grazing can help predict grassland production and ecosystem dynamics. Methods Plant clonal buds and shoot materials of Leymus chinensis (a clonal grass species widely distributed across the eastern Eurasian Steppes), sterilised and non-sterilised soils were collected from sites subjected to long-term grazing or no grazing. We then conducted a series of studies to determine the presence and context-dependency of (1) PSF, (2) PPF and (3) clonal transgenerational plasticity mechanisms on long-term grazing by measuring plant above/belowground biomass, height and density. Results Inoculation with soil biota conditioned by L. chinensis from grazed sites increased root growth by 83.99% (positive PSF), but not inoculum from ungrazed sites (neutral PSF). Shoot inocula from grazed and ungrazed sites had similar positive effects on plant growth (positive PPF). Clonal offspring from grazed sites showed transgenerational trait plasticity in terms of herbivory-avoidance (21.24% height reduction and 84.62% tiller density increase), but aboveground production was unaffected. Additionally, grazed field plots with a year of grazing exclusion showed similar plant heights and aboveground biomass as ungrazed plots, which indicated short-term transgenerational trait plasticity. Conclusions Positive PSF and short-term clonal transgenerational plasticity of L. chinensis depended on past grazing activity, and together with positive PPF, can aid their recovery and fitness in subsequent growing seasons. Our findings highlighted context-dependent plant-microorganism interactions and trans-generational feedback of plants in response to grazing.

Automated summary

Legacy effects arising from grazing can influence the plant-soil feedback, plant-phyllosphere feedback and transgenerational plasticity, which are important for predicting grassland production and ecosystem dynamics.