Effect of Ageratina adenophora (Spreng.) and Flaveria bidentis (Linn.) invasion on soil microbial community and Oryza sativa L. growth

This study analyzed the differences in soil micro-ecology between alien invasive weeds and local plants to understand impacts of alien invasive plant on soil ecosystem. Two invasive plant species perennial Ageratina adenophora (Sprengel) and annual Flaveria bidentis plants and two native plant species (Digitaria sanguinalis and Salsola collina) were planted in a common garden, in which the same soil from a non-invaded farmland was used to eliminate the effect of different soil minerals on the variations in the four plant species. Then a greenhouse experiment was conducted to verify any effects of rhizospheric soil microbial communities of two invasive plants on the performance of native plants. In the field experiment, soil nutrient, soil microbial community after three months of plants growth were examined. Based on the common garden experiment, differences were noted in the effects of invasive and native plants on soil micro-ecology. A. adenophora drastically increased soil available N (39.80 mg·kg^-1), P (48.52 mg·kg^-1) and K. In particular, PLFA (phospholipids fatty acids) fingerprint spectrum suggested a higher increase in actinomycete contend in the exotic plants soils than in the native plants soils. The increase in bacteria and fungi count was highest in A. adenophora invading soils. Pot feedback experiment showed that alien weed invaded soils inhibited the growth of Oryza sativa. O. sativa plant height increased by 113% and 17% in ste-rilized F. bidentis and A. adenophora invaded soils compared with no-sterilized soils, respectively. The above results suggested that F. bidentis and A. adenophora destroyed micro-habitats of invaded soils and created new micro-ecology environment suitable for the growth of invasive plants by altering soil microbial communities.