The Study On Am Fungi Diversity And Its Distribution Impact Factors In Moderate-Temperate Steppes Of Inner Mongolia

Symbiosis of arbuscular mycorrhizal fungi (AMF) and plant root generally exists in nature; this symbiosis relationship plays a role of nutrients regulatory between plant roots and soil. AM fungal hyphae and the glomalin it formed can produce and stabilize soil aggregates, thereby increasing the water stability of soil aggregates and increasing soil carbon content. Mycorrhizal symbiosis plays an important role in maintaining plant diversity, improving soil quality and stabilizing the ecosystem function. Inner Mongolia steppe is an important part of the Eurasian steppe, forest steppe, typical steppe and desert steppe distributes in it. Due to natural and man-made factors, grassland degradation and desertification became more serious, and biodiversity was also affected.In this study, we chose different vegetation communities in moderate-temperate steppes in Inner Mongolia as experimental plots, AM fungal diversity and distribution, AM mycorrhizal symbiosis characteristics, glomalin content, external hyphae length and density, soil nutrients, soil microbial factors, and their correlation were studied.The main results are:1. By spore morphological identification, in desert and typical steppe communities,16species of AM fungi belonging to6genera, and21species of AM fungi belonging to8genera were found, respectively. Funneliformis geosporu, Glomus microaggregatum and Septoglomus constrictum were the dominant species.16species of AM fungi belonging to8genera were found in forest steppe communities, F. geosporus, G. microaggregatum, G. pansihalos and Scutellospora calospora were the dominant species of forest steppe communities. Entrophospora sp1, F. caledonius, F. geosporus, G. aggregatum, G. microaggregatum, G. tenerum, Scut, calospora, Scut, pellucida and S. constrictum were the common species in the study area; and G. microaggregatum had higher relative abundance. The dominant species in rhizosphere soils of plant were basically same to the soils in the field of different steppe communities.2. There were difference of AM fungi diversity between study areas, The average AMF spore density of meadow steppe communities was significantly higher than desert steppe communities and typical steppe communities (P<0.05), The AMF species richness of forest steppe communities was significantly higher than other steppe communities (P<0.05). The AMF evenness index of meadow steppe communities was significantly higher than other steppe communities (P<0.05).3. The AM colonization rates of common plants were different, it was expressed as the average rates of arbuscular colonization and vesicle colonization of common plants in desert steppe communities were significantly lower than other steppe communities (P<0.05); while the average rates of AM fungi internal mycelium root colonization and total colonization of common plants in desert steppe communities were significantly higher than other steppe communities (P<0.05). In the soils of the study area, the extra-radical hyphal length density of AM fungi, the contents of easily extractable glomalin and total glomalin were significantly different (P<0.05). It showed the forest steppe communities had the highest values, followed by meadows and typical steppe communities, desert steppe communities had the lowest values. The extra-radical hyphal length density of AMF was significantly correlated with the contents of easily extractable glomalin and total glomalin.4. The results of correlation analysis showed that, in different grassland vegetation and plant communities, the correlation levels of the AM fungi diversity index (spore density, richness, Shannon Wiener index and evenness index) and soil factors were different. However, the contents of easily extractable glomalin and total glomalin in soils were positivly correlated with fungi, microbial biomass carbon and nitrogen content, total phosphorus, organic carbon, root biomass at defferent levels.5. We did18SrDNA phylogenetic analysis to the root of a wild AM plant belongning to genus Allium in typical steppe communities,16sequences were all clustered in Glomeraceae in phylogenetic analysis, a part of sequences had high similarity with sequences from genus Rhizophagus, Glomus, Funneliformis, Sphaerocreas and Sclerocystis. According to the sequences analysis, the symbiotic AM fungi in the root of Allium were obviously different in different plots with different vegetation type.6. This study showed the AM fungi diversity and the distribution characters in moderate-temperate steppes of Inner Mongolia, explored the interaction between grassland ecosystems biodiversity and soil factors at the AM fungi communities level, in order to provide theoretical basis for health evaluation and protection of grassland ecosystem.