Abstract:

Since introduced into the Chongming Dongtan Nature Reserve in 1995,Spartina alterniflora has rapidly expanded and seriously threatened the biodiversity there.During 2005 and 2006, a field experiment of physical controls, including digging tillage, breaking rhizome, cutting, and biological substitute,on S.alterniflora was conducted to search effective measures for controlling this invasive plant.The growth parameters of density, coverage and aboveground biomass were used to evaluate the efficiency of different treatments.The results showed that for the digging tillage treatments, the density, coverage and aboveground biomass were significantly lower than that of the control and there were no significant difference among the different depth treatments.In the end of the second growing season, there were no significant differences among the treatments and the control.The treatments of breaking rhizome significantly inhibited the growth of S.alterniflora in the first growing season and inhibition increased with the depth of treatments.However, the inhibition of growth disappeared after two growing seasons and there were no significant differences among the treatments and the control.The treatments of cutting significantly inhibited the growth of S.alterniflora in the first growing season.In the end of the second growing season, the growth of S.alterniflora recovered in some extent, only the treatments of JUN, JUL, AUG and SEP significantly inhibited its growth.In the biological substitute treatment, the transplanted Phragmites australis kept a relatively high survival in the first growing season.The survival rate maintained at the level of 54.2% and both the plant height and fruiting increased considerably in the second growing season.The results demonstrated that it is necessary to take into account of frequency, intensity and season of these measures to achieve a high efficiency for controlling the invasion of S.alterniflora.

Key words: biological invasions, physical control, biological substitute, Chongming Dongtan, Spartina alterniflora, biological invasions, physical control, biological substitute, Chongming Dongtan