Effect Of Three Invasion Composite Plants On The Structure And Function Of The Soil Microbial Community

The exotic species often affected the structure and diversity of soil microbial community and then influence the diversity of plant communities, so soil microbial play the key roles on the invasion of exotic species. In order to explore the effects of invasive composite plants on the soil microbial, we analyzed and compared the effects of the invasion of Flaveria bidentis(L.) Kuntze, Bidens pilisa L. and Ambrosia artemisiifolia L. on soil microbial community structure and function in a common garden with the methods of phospholipid fatty acid(PLFA) and Biolog. The result showed that:(1) The consentration and the structure of soil microbial were changed when the three exotic plants invasived. The change of the structure of soil microbial varied with growth period, invaded degree and the kinds of plant species. The total PLFAs in Augest was significant higher than that in October. The total PLFAs in 5-yearinvaded plots were significantly higher than that in 4-year-invaded plots. Growth period had no effect on the specific PLFAs in all the treatment of F. bidentis, while the invaded degree had greatly effect on the kinds and concentrations of PLFAs. Three kinds of alien Compositae plant species gathered the different kinds of microbial species. PLFAs 12:0, 16:1ω5c, i15:0, a15:0, 16:0 and 18:1ω9c were clustered in the rhizosphere soil of F. bidentis, PLFAs a15:0、i16:0、10Me18:0 clustered in the rhizosphere soil of B. pilisa, and PFLAs 14:0、i15:0、i16:0 gathered in the rhizosphere soil of A. artemisiifolia. The gathering ability of soil microbial for B. pilisa was bigger than those of F. bidentis and A. artemisiifolia.(2) The metabolic activity of soil microbial was increased in the invaded plots. The diversity index of the soil microbial and carbon utilization in 5-year-invaded plots was higher than that in 4-year-invaded plots. The order of Shannon-Wiener index and Simpson index were A. artemisiifolia> B. pilisa > F. bidentis, while the order of the Mc Intosh index was exactly opposite. There are differences in the utilization of carbon sources for three invasive plant species. The soil microbial in F. bidentis invaded plots significantly increased the use of amino acids and lipids. The soil microbial in B. pilisa invaded plots significantly increased the use of lipids and the soil microbial in A. artemisiifolia invaded plots significantly increased the use of amino acids.(3) CCA analysis results showed that the PLFAs that utilized amino acids, lipids and carbohydrate were gathered in the invasive area of F. bidentis. 12:0, i14:0, 13:0 2 OH and 16:0 were tightly related with carbohydrate utilization, i18:0 and a19:0 with lipids utilization and 16:1ω5c with amino acids. The PLFAs 20:4w6,9,12,15 c and 16:1ω5c that utilized lipids was gathered in the B. pilisa invaded area. The PLFAs 18:1ω9c, 18:0 and 16:0 related amino acids utilization was gathered in the A. artemisiifolia invaded area. Because of different plant species gathered different PLFAs the soil microbial utilize different carbon.