The Effects Of Soil Microorganisms On The Survival And Growth Of Eupatorium Adenophorum Seedlings

Invasive plants commonly show strong competition over the native ones. In introduced ranges, invasive plants can damage ecological system, decrease biodiversity and cause severe environmental and economical problems. Therefore, it is important to understand the invasive mechanism for taking control measures for spread of invasive plant. In recent years, many reports have demonstrated that soil microorganisms can play an important role in the invasive process of exotic plants and therefore have been becoming the research focus in the field of invasive biology.Eupatorium adenophorum is one of the most invasive plants in southwest areas of China. Previous reports demonstrated significant changes in microbial communities in the heavily invaded soils of E. adenophorum. However, rare report has focused on the ecological effects of soil microbial community on the establishment and growth of E. adenophorum population.In this study, two plots in Xishan forest park, Kunming, were selected to carry out feedback experiments of soil microbial community on the growth of E. adenophorum. One is an agricultural field which has never been invaded by E. adenophorum and another is an area which already has been heavily invaded for more than 4 years by E. adenophorum. Three pesticides were applied to inhibit or kill the soil microbes and the growths of E. adenophorum were observed. Together with the greenhouse experiments, several conclusions were made.1. Soil microbes in both of agricultural field and the area invaded heavily by E. adenophorum had positive feedback effects on the survival and growth of E. adenophorum seedlings but negative feedback effects on the growth of other plant species. 2. The positive feedback effects of soil microbes on the survival of E. adenophorum seedlings are independent on the intra-species competition of other plants;3. Bacterial community plays more important role both in stimulation of the growth of E. adenophorum and inhibition of the growth of the other plants than fungal community;4. The changes in soil microbes, especially in bacterial community, also cause significant changes in several key enzyme activities and soil characteristics physically and chemically;In conclusion, the results showed the soil microbes in agricultural field can increase the survival and growth of E. adenophorum and inhibit the growth of other plants. Meanwhile, the soils microbes associated with the E. adenophorum in the heavily invaded area also affect positively the growth of E. adenophorum. These double ecological effects may be one of the reasons for the broadly spread of E. adenophorum. Our data provided a new clue for exploring the invasive mechanism of E. adenophorum.