Study On Plant And Microorganism Diversity Of Pisha Sandstone Area In Ordos

Pisha Sandstone is commonly known as fluvial sedimentary debris forming in the Triassic,Jurassic and Cretaceous periods,which has loose structure,low organic content,poor water stability and really low erosion resistance.It is the most vivid description of Pisha Sandstone that with water,pisha sandstone described as that “As solid as rock without water,as loose as mud with water,as weathering as Erosion with wind''.This study takes Ordos Pisha Sandstone area as the research object.Four gullies(A Da highway,HuoJitu,Haragou and Shigetai)were selected to investigate their plant communities and soil physical and chemical properties.The variation of AM fungi in soil was examined in morphological method.The mechanism affecting AM fungi diversity was analyzed to provide theoretical basis for vegetation construction and ecological restoration in Pisha Sandstone area.The main results are as follows:1.14 families,24 genera and 30 species of angiosperms were isolated in the study area,of which Compositae and Gramineae are the most abundant,accounting for 43.75% of the total species.The results of plant diversity index showed that:except for HLG sample area,the other areas showed slope crest > bottom of gully >middle of gully slope,and there was no significant difference between Negative side and Sunny side in top of slope and gully slope.2.In order to investigate the soil nutrient and enzyme activity in Pisha sandstone area,we determined the physicochemical properties of the soil in the research area,the results showed that the soil was alkaline,and the nutrient indexes was in the third-sixth grade standard of the second national soil nutrient census classification,which belonged to low nutrient soil.The results of enzymatic activity investigation:showed that the activity of in soil were low,especially the activity of phosphatase in soil was lower.3.Number of culturable microbial colonies in the soil of the study area: number of bacterial colonies >number of actinomycete colony > number of fungal colony.It was positively correlated with plant diversity.There was no significant correlation between the number of bacterial colonies and the soil physicochemical properties,but there was a significant positive correlation between the number of actinomycetes and soil pH,and no significant correlation with other factors.The number of culturable bacteria was positively correlated with neutral phosphatase.4.36 species of AM fungi which belong to 9 genera of 6 families were isolated from the soil in the research area,among them,Acaulospora and Glomus were the most abundant,with 9 species.The variation trend of spore density was as follows:ADX and HJT sample areas all showed: slope crest > middle of gully slope and bottom of gully,but the difference was not significant.HLG and SGT sample areas showed as follows: slope crest > middle of gully and sunny slope > bottom ofgully.Spore Simpson index showed that ADX and HJT trench slopes were in the middle of the slope > slope crest > the bottom of the trench.Except for the balcony top of Shigetai,there was no significant difference in Shannon-Weiner index among the other plots.5.The spore density of soil AM fungi was negatively correlated with pH,total carbon,total calcium,actinomycetes;positively correlated with water content.AM fungal richness was negatively correlated with available phosphorus,actinomycete quantity,pH and total carbon.,and positively correlated with catalase.Simpson index of spores of AM fungi was negatively correlated with available phosphorus and total carbon,positively correlated with soil aggregate size 0.106 mm < D < 0.250 mm,and Shannon-Wiener index was positively correlated with available phosphorus,available potassium,total nitrogen,alkaline phosphatase,invertase and urease,and negatively correlated with the number of bacteria in soil.