Research On The Distribution Patten Of Desert Soil Microbial Diversity In Arid Inland River Basin

The Shiyang River,the Heihe River and the Shule River,which originated from the Qilian Mountains,formed three independent inland river basins in the arid region of Northwest China.They were pregnant with rich soil microbial resources.These microorganisms could not only regulate the material cycle and energy flow in the arid desert region,but also serve as an important driving force for subsurface biodiversity and above-ground plant diversity.Therefore,the analysis of desert soil microbial distribution pattern can reflect the health status of arid ecosystem.In this study,a fixed transect was set up to investigate the physical and chemical characteristics of the typical desert soil in the inland river basin of the Hexi Corridor in arid northwest China.High-throughput sequencing technology was used to systematically analyze the composition,structure and diversity of soil bacterial and fungal communities,and to explore the distribution pattern of soil microbial communities in the three inland river basins of Shiyang River,Heihe River and Shule River.The differences in species diversity at catchment scale were compared.By redundancy analysis(RDA)and Spearman correlation analysis,the relationship between soil microbial community diversity and 13 habitat soil factors,including Gravel,Sand,Silt,Clay,soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),total potassium(TK),available nitrogen(AN),available phosphorus(AP),available potassium(AK),p H,and soil water content(SWC),in inland river basin was explored.This study is of great significance to stabilize the biodiversity of the arid region ecosystem and maintain the sustainable development of soil productivity.The main research results and conclusions are as follows:(1)The relative abundance of soil microbial was analyzed by Heat Map and unweighted group mean method(UPGMA).The bacterial community structure was similar in Heihe River Basin and Shiyang River Basin.The fungal community structure of Shiyang River basin and Shule River basin is similar.The analysis of α-diversity index of desert soil microorganisms showed that the bacterial richness index(Ace,Chao1)in Shiyang River Basin was significantly higher than that in Heihe River basin and Shule River basin(P<0.001).The bacterial diversity index(Shannon,Simpson)of Shiyang River Basin and Shule River Basin was the highest,and there was no significant difference between them,but both were significantly higher than that of Heihe River Basin(P<0.001).For the fungal community,there was no significant difference in the diversity index(Shannon,Simpson)among the three basins.The fungal richness indices(Ace,Chao1)of Shule River basin and Shiyang River basin were higher and the difference was not significant,but both were significantly higher than that of Heihe River Basin(P<0.001).(2)The results of habitat soil factors showed that in Shiyang River basin,Sand has a significant negative correlation with Gravel,Silt and Clay(P<0.01),it has a significant negative correlation with SWC and SOC(P<0.05),and TP has significant positive correlation with TK and SOC(P<0.05).Silt in the Heihe River Basin has a highly significant negative correlation with Clay(P<0.01)and a significant negative correlation with TN(P<0.05),SOC has a significant positive correlation with AP and TN(P<0.05),and TN has a significant positive correlation with AP(P<0.05).Gravel and AK were significantly positively correlated in the Shule River basin(P<0.05).The results showed that there were different correlations among habitat soil factors in inland river basin,and soil nutrient content was affected by different soil particle size composition.(3)The RDA analysis of dominant bacteria and habitat soil factors showed that AP and TK significantly affected the distribution of bacterial community(P<0.05),while TK and SWC significantly affected the distribution of fungal community in Shiyang River Basin.Silt and AN significantly affected the distribution of bacterial community in Heihe River Basin,while AK,TK and SOC significantly affected the distribution of fungal community.p H and AN significantly affect the distribution of bacterial community,while Gravel,TN and AN significantly affected the distribution of fungal community in Shule River basin.Spearman correlation analysis showed that bacterial diversity(Simpson)was negatively correlated with AK in Shiyang River Basin.In the Heihe River Basin,the fungal richness(Ace)was positively correlated with TN,(Chao1)with Sand,and the fungal diversity(Shannon and Simpson)was negatively correlated with SOC and AP.In the Shule River basin,bacterial richness(Ace,Chao1)was positively correlated with TK(P<0.01).Fungal richness(Ace,Chao1)has a significant positive correlation with Gravel and AK,while fungal diversity(Ace,Chao1)has a significant negative correlation with AN.This study analyzed the distribution characteristics and diversity patterns of soil microbial communities in the Shiyang River,Heihe River and Shule River basins,explained the distribution characteristics and survival adaptation mechanism of dominant bacteria in arid ecosystems,and identified the main effects of habitat soil factors on microbial survival.This will provide theoretical reference for soil and water conservation and sustainable development of ecological environment in arid area.