Abstract: Making use of native vegetation to inhibit spread of invasive species is a potential biological measure to control invasion of alien plant species. Solidago canadensis is one of the alien plant species that have been very invasive in recent years in the coastal area of Southeast China. To investigate capabilities of various native herbosa inhibiting spread of the invasive S. Canadensis, three native dominant grass species, i.e. Imperata cylindrical, Phragmites communis and Miscanthus sacchariflorus, that have the same succession stages were selected as subjects in the study.With patch of S. canadensis dominated community as control, density and growth (plant height and basal diameter) of S. Canadensis in the three native plant communities were surveyed and relationships of density and growth of S. canadensis in the native grass communities with illumination level and soil fertility were analyzed. Results show that (1) S. canadensis in the native grass communities was much lower in plant density, and even reduced growth in the I. cylindrical community (P<0.05); (2) the native grass communities reduced illumination level for S. canadensis .Photosynthetically active irradiation (PAR) in the middle of the canopy layer was lower in the native communities than in the S.canadensis community; I. cylindrical and M. sacchariflorus communities had much higher canopy coverage than P. communis and S.canadensis communities (P<0.05); in terms of canopy height, the four communities followed a decreasing order of M. sacchariflorus > P. communis > S.canadensis > I. cylindrical; S.canadensis was significantly and positively related to its neighboring native plants in plant height (P<0.05), and was also lower than M. sacchariflorus and P. communis. (3) soil fertility was lower in the native plant communities than in the S. canadensis community (P < 0.05), especially in the I. cylindrical community, which was the lowest in soil fertility, but not much different from the M. sacchariflorus and P. communis communities in most soil fertility indices (P>0.05). The findings suggest that shading of S.canadensis by native plants is the major mechanism of the latter inhibiting the former, meanwhile, it is very likely that lower soil fertility joining in synergy with light competition intensifies the inhibition of S. canadensis. It is, therefore, advisable to screen and cultivate native plants that may lower illumination level and soil fertility of the community simultaneously to effectively inhibit invasion of S.canadensis.

Key words: grass vegetation, Solidago canadensis, invasive plant species