Abstract:

Plants' compensatory growth is the common response following grazing/mowing, particularly determined by the damage severity, availability of resources, and plant functional types. Clonal plants exhibit unique clonal functional traits, yet the compensatory growth strategies underlying their responses to clipping intensity in various nitrogen availability levels remain poorly understood. In this study, a pot experiment was conducted to test how the clonal plant species Leymus chinensis responds to clipping and nitrogen (N) enrichment under heterogeneous soil conditions. Moderate clipping significantly enhanced the total biomass of younger ramets by 22% and 12%, under high and low N conditions, respectively, but had no impact on the total biomass of older ramets. The results suggested that L. chinensis exhibited over-compensatory growth characterized by prioritized biomass allocation to younger ramets rather than to older ramets, which facilitated its spatial expansion. However, severe clipping reduced the total biomass of younger ramets by 23%. Furthermore, the older ramets reduced biomass allocation to belowground parts and decreased the rhizome length (–28%), which negatively affected the growth of younger ramets. The younger ramets exhibited adaptation to clipping through the enhancement of antioxidant enzyme activities and the elevation of osmotic regulatory substance concentrations. Nitrogen enrichment did not influence the total biomass of younger ramets or the entire clone. However, under moderate clipping, the biomass of older ramets increased relative to conditions without N enrichment. Our findings indicate that N availability affected the compensatory growth of the L. chinensis clone induced by clipping, thereby promoting the spatial expansion of this species. These results hold significant potential utilization of clonal plants for the restoration of patchy degraded grasslands.

Key words: Clonal plants, Spatial expansion, Leymus chinensis, Biomass allocation, Compensatory growth