Effects Of Three Invasive Composite Plants On The Diversity Of Arbuscular Mycorrhizal Fungiand Soil Factors

Arbuscular Mycorrhizal Fungi(AMF) can form mycorrhizal symbiosis with 80%-90% plants. Most of the invasive plants are mycorrhizal plants, which can establish a symbiotic relationship with AMF in the soil. Lots of invasive plant species belong to the Asteraceae in China. Hebei province is the major invasion area of the Flaveria bidentis(L.) Kuntze, Bidens pilosa L. and Ambrosia artemisiifolia L.. The universal rule of invasion composite plants on AMF was carried out in the common garden, the invasive plant species F. bidentis, B. Pilosa, and A. artemisiifolia were selected to the experiment. We determined the morphological classification of AMF and the soil properties in each treatment to study the effects of three invasive composite plants on the diversity of AMF, and then to explore the relationship between AMF and soil nutrient. We also studied the effects of the native plants and seasonal variation on the diversity of AMF. Our study provided an important theoretical basis for the further revealing the invasion mechanism of the composite plant invasion. The results were as following:1 The competition between the invasion plants and Setaria viridis(L.) Beauv, Melilotus suaveolens Ledeb. increased AMF species, while the species decreased after forming dominant community. The spore density decreased when three invasion plants competed with Chenopodium album L.. The abundance of AMF species increased when they competed with M. suaveolens. The AMF species in mixed cultivation(except for F. bidentis and C. album mixed planting) were higher than that of invasive plants in monoculture.2 The competition between three kinds of invasion plants and S. viridis improved the activity of urease and the utilization of available potassium and ammonium nitrogen. The activity of phosphatase and invertase were reduced, while the utilization of available potassium and soil organic carbon content increased when they competed with C. album. The content of available potassium increased when they competed with M. suaveolens.3 The activity of acid phosphatase of F. bidentis in monoculture was higher than that in the mixed cultivation between F. bidentis and native species, respectively. Soil pH, the activity of alkaline phosphatase and urease in mixed cultivation of B. pilosa and native plants were lower than those in monoculture of B. pilosa. Compared with A. artemisiifolia in monoculture the urease activity decreased, while the content of available phosphorus and available potassium content increased when A. artemisiifolia competed with three native plant species.4 Compared with those in August, the diversity of AMF spores of invasive plants increased in October; the activity of alkaline phosphatase and acid phosphatase decreased, pH and the content of ammonium nitrogen increased in the three monocultures of invasive plants; the activity of acid phosphatase decreased, and the content of ammonium nitrogen increased in mixed planting site in October.