Ecological Research On AM Fungi Associated With The Clonal Plants In Mu Us Sandland

In Mu Us sandland, there live some kinds of clonal plants. As pioneer plants, their emergence improved the living conditions for colonization of other plants. Despite their own physiological characters, their endurance capability for the atrocious circumstance also rest with their symbiosis with edaphon, especially the AM fungi. In this research, the spatial and temporal variation and diversity of AM fungi from the rhizosphere of clonal plants, effects of the growth of clonal plant on diversity of AM fungi and arbuscular mycorrhiza, effects of AM fungi on the growth and drought resistance of clonal plant were systemically investigated. Results were showed as follows:An abundant diversity of AM fungi was found in the rhizosphere of clonal plants in Mu Us sandland. Isolation and purification of the mycorrhizal fungi led to the identification of 23 species belonged to four genera:15 to the genus Glomus,5 to Acaulospora,2 to Gigaspora and 1 to Scutellospore.5 uncertain species were identified as unrecorded species. Ecological distribution of the diverse species is different. Scutellospore erythropa only occurred in the rhizosphere of Psammochloa villosa. Glomus hydembadensis, Glomus constrictum and Glomus convolutum only appeared in the rhizosphere of Hedysarum laeve. Glomus dolichosporum, Gigaspora margarita and Acaulospora mellea only occurred in the rhizosphere of Artemisia ordosica. Glomus aggregatum and Glomus dolichosporum were own species in Yanjiuzhan, Glomus hydembadensis and Glomus multicaule were own species in Yulin.Clonal plants can form well symbionts with AM fungi in Mu Us sandland. Psammochloa villosa and Hedysarum laeve form the Arum-type mycorrhizas, Artemisia ordosica has the intermediate type. At the same time, a kind of special structure that is similar with arbuscule was found in the mycorrhiza of Hedysarum laeve.A distinct temporal variation of AM fungi and colonization of arbuscular mycorrhiza from the rhizosphere of clonal plants was found. On the mobile dunes or semifixed dunes where soils are infertile and with better soil air-permeability, the spore density was lower and colonization rate and intensity were higher. There has no significant difference among the 5 soil layers sections. On the fixed dunes where soils are fertile and with wore soil air-permeability, the spore density was higher and colonization rate and intensity were lower, the colonization rate and intensity were significantly higher at 0～30cm sections than 30～ 50cm sections.Seasonal variation of AM fungi and colonization of arbuscular mycorrhiza from the rhizosphere of clonal plants was found also. The spore density was highest and colonization rate of arbuscular mycorrhizal was lowest in spring, the colonization rate of arbuscular mycorrhizal was maximal and the spore density significantly declined in summer, the spore density was lowest and colonization rate of arbuscular mycorrhizal declined in fall.Geographical and environmental factors affect the diversity of AM fungi and colonization rate of arbuscular mycorrhiza. The major factors were the temperature, water and soil components. There is significant correlation between both the spore density and the colonization rate, along with the temperature of the soil and the available N and the organic matter in soil.Effects of the clonal plants inbreaking on the diversity of AM fungi and the forming of arbuscular mycorrhizal are different between plant species and sample sites. (1) After Psammochloa villosa inbreaking, the Shannon-Winer index of AM fungi rised from 0.2690 to 0.5566, the spore density and colonization rate significantly increased in Yanjiuzhan. The Shannon-Winer index of AM fungi rised from 0.7227 to 0.9368, the spore density and colonization rate increased in Yulin. (2) After Hedysarum leave inbreaking, the Shannon-Winer index of AM fungi rised from 0.8377 to 1.0308, the spore density and colonization rate of arbuscule significantly increased, but the colonization rate of vesicle significantly descended in Yanjiuzhan. The Shannon-Winer index of AM fungi descended from 1.0338 to 0.9587, the spore density and colonization rate of arbuscule significantly increased, but the colonization rate of hyphae and vesicle significantly descended.The AM fungi in the rhizosphere of Artemisia ordosica significantly accelerated the growth and enhanced the drought-resistance of Artemisia ordosica. After inoculating AM fungi, the number of branchs, fresh and dry weight significantly increased, the moisture status of leaves were improved, the stability of plasma membrane enhanced, activities of some defense enzymes and soluble agar content increased.The results of this thesis enrich the basic theory of desert restoration ecology and provided the scientific basis and germ plasm resource for the applications of AM biotechnology in vegetation restoration and ecology reconstruction of desert.