Study On The Response Of Autotrophic Bacterial Community And Microbial Carbon Sequestration To Soil Erosion Under Different Soil Types

Soil erosion is one of the most important factors for soil degradation,and has a great impact on the ecological environment and soil quality.In china,soil erosion mainly distribute around the Loess Plateau and the southern red soil hilly region,which significantly affects the process of soil carbon cycle,especially carbon sequestration.Soil autotrophic microorganisms can directly participate in and affect carbon sequestration.There are discrepancy in soil types which bring about the differences of soil biological and abiotic characteristics,and soil autotrophic microbial carbon sequestration may respond to the disturbances.However,the influential mechanism of soil types on soil autotrophic microbial carbon fixation in eroded watersheds is still unclear.In order to explore the difference of soil autotrophic microbial response to soil erosion under different soil types,the eroding slope of the Loess Plateau and the red soil hilly area were selected as the research object.¹³C stable isotope labelling technology and molecular biotechnology such as Real-time quantitative PCR and high-throughput sequencing were employed in our study.The study analyzed the distinction of soil biotic and abiotic properties and the rate of autotrophic microbial carbon fixation among different soil types,and explained the relationship between soil carbon sequestration rate,soil autotrophic microbial characteristics and soil physical and chemical factors.Further explore the mechanism of soil autotrophic microbial carbon sequestration response to soil erosion.The main conclusions of this study are as follows:?1?There are significant differences in soil physical and chemical properties with different soil types.The moisture,soil organic carbon?SOC?and dissolved organic carbon?DOC?in the Loess were significantly lower than those in the red soil,and the pH and bulk density were significantly higher than those in the red soil area.Furthermore,the response pattern of soil physical and chemical properties to soil erosion was also different.Soil organic carbon and its light components in the eroding sites were higher than the depositional sites in Loess,and TN content was similar between the two groups;in the red soil region,the concentration of soil carbon and nitrogen in the depositional sites are significantly higher than the eroding sites.?2?The differences in soil types significantly effects the characteristics of soil autotrophic microorganisms.The overall abundance and diversity of autotrophic microorganisms in red soil were significantly lower than that in Loess.Moreover,the abundance and diversity of soil autotrophic microorganisms responded differently to soil erosion:the microbial abundance and diversity of the depositional sites in Loess were lower than that of the eroding sites;while the microbial abundance in the depositional sites was higher than that in the eroding sites in red soil,and there is no difference in microbial diversity.Furthermore,the structure of autotrophic microbial community has also changed.Although Proteobacteria was the most dominant phylogenetic bacteria,the relative abundance of obligate autotrophs in loess with low organic matter content was significantly higher than that of red soil with high organic matter content.At the same time,compared with other soil abiotic factors,the structure of autotrophic microbial community were primarily influenced by pH under different soil types.?3?The rate of carbon sequestration in the Loess with lower organic matter content was higher than that in the red soil with higher organic matter content.Compared with soil microbial properties and other selected physical and chemical properties,pH is the most important factor for regulating soil autotrophic microbial carbon sequestration by effecting the proportion of obligate autotrophs and facultative autotrophs under different soil types.However,when there is no difference in soil type,liable organic matter rather than pH plays a more critical role in the change of soil autotrophic microbial carbon sequestration caused by erosion...