Invasion of Robinia pseudoacacia and impacts on native vegetation.

Investigations were carried out to study the diffusion and invasion of Robinia pseudoacacia into native vegetation by line plot and small plot methods in Mount Tai of Shandong Province in 2005.Results show that R.pseudoacacia invades the plantations of Pinus tabulaeformis and Platycladus orientalis by vegetative reproduction and the expanding extent is related to cutting or root injury.It is found that R.pseudoacacia is not dominant and is remained as an associated tree species in the stands with high density and even distribution.But it grows up quickly and becomes dominant in the upper layer within the stands and the invaded pure stands of native tree species subsequently become mixed stands.The capability of invading shrub indicates the high tolerance of R.pseudoacacia to soil infertility.Six native woody plant species can naturally regenerate under the canopy of R.pseudoacacia and grow well.R.pseudoacacia establishes mixed stands with native species instead of replacing and the mixed forests are finally replaced by native communities during the long process of succession due to their short life span.It is a pioneer tree for barren hills and produce no harm to native plant community with rational design of species composition and plantation management.The results provide a theoretical basis for R.pseudoacacia cultivation and management.