Compensatory growth of plant in Trifolium repens and Lolium perenne grassland under different stubble heights

The compensatory growth of plant, which can be affected by the grazing and clipping directly, is an important character to maintain stability of grassland. Clipping is one of the main ways to use grassland in Southern China and clipping intensity (stubble height) on compensatory growth of grassland has become the core matter in grassland management to achieve the sustainable development of grassland. In this study, clipping treatments (with stubble height of 6, 9, 12 cm and unclipping) on the compensatory growth of the whole community, component functional groups and dominant species was carried out in the typical degraded grasslands dominated by Trifolium repens and Lolium perenne. At the community level, the results showed that clipping increased the aboveground biomass and over-compensatory growth was found in both high and low stubble clipping treatments, probably owning to the advantageous precipitation and temperature in grassland of Southern China. At the functional group level, grass and forbs can achieve over-compensation even under clipping with middle and low stubble. Over-compensation of Fabaceae was only found in clipping with high and middle stubble, indicating that Fabacea species were sensitive to clipping intensity and proper clipping intensity should be adopted in grassland management to improve their production. However, clipping affected the aboveground biomass of Asteraceae negatively and the compensation index ranged from 0.31 to 0.48. The relationship between the aboveground and root biomass showed that the aboveground over-compensation of grass was achieved probably by sacrificing its root biomass, while the aboveground compensatory growth of forbs and Asteraceae were not related to their root biomass. The aboveground compensatory growth patterns of dominant species were mainly obtained without reducing their root biomass. The compensatory growth patterns of community and functional groups were determined by the compensatory pattern of component species essentially. The result in this study can serve as guidelines in explaining and predicting the dynamic change of vegetation composition, the allocation of biomass and compensatory growth after clipping in the management of grassland, dominated by T. repens and L. perenne.