Response Of Microorganisms Mediating Shrub Soil Carbon Transformation To Rainfall Changes

Global warming is an environmental issue of great concern to all countries in the world.It can cause global redistribution of precipitation,melting of glaciers and permafrost,rising sea levels and other problems,as well as induce extreme weather and climate events,including mega-droughts,strong cold waves,persistent heavy precipitation,regional heat waves,super typhoons and other climate disasters,which not only endanger the balance of natural ecosystems,but also affect human health and even threaten They also affect human health and even threaten the survival of the human race.The amount and intensity of precipitation and the seasonal distribution of precipitation in local areas will also be significantly affected,and the frequency and magnitude of events such as extreme precipitation,drought and persistent heavy precipitation will change.This means that soils,particularly top soils,will experience more dramatic changes in soil moisture.In turn,soil moisture affects organic matter degradation and soil greenhouse gas emissions by altering soil microbial activity,thereby altering soil carbon transformation processes and influencing ecosystem structure and function.Soil organic carbon transformation is primarily determined by the rate of decomposition by soil microorganisms.In the context of changing rainfall patterns,soil moisture is an important factor influencing soil microbial activity and organic carbon transformation.In this study,an ecosystem-level rainfall control experiment was conducted in a constructed artificially simulated rainfall increase and decrease sample plot in a typical vegetation of wattle scrub in the low hills of Taihang Mountains.Soil physical and chemical properties,soil greenhouse gas emissions,soil microbial bacteria and fungi were measured under different rainfall conditions,and the changes in soil carbon content,soil greenhouse gas emission rates and the evolution of bacteria and fungi under different rainfall conditions were analysed.It helps to reveal the response of soil physicochemical properties,greenhouse gas emission rates and microbial diversity to changes in precipitation associated with the carbon transformation process in scrub soils.（1）Changes in precipitation significantly influenced soil water content,with the rainfall increase treatment significantly increasing soil water content and the rainfall reduction treatment significantly decreasing soil water content.The rainfall increase and decrease treatments did not significantly affect p H and total nitrogen on 30 July 2021and 29 July 2022.Incremental and decremental rainfall treatments had a significant effect on soil ammonium nitrogen,with moisture being an important influence on soil ammonium nitrogen.Soil depth had a significant effect on soil water content,p H,total nitrogen,ammonium nitrogen and nitrate nitrogen,and there were significant differences in the physicochemical properties of 0-10cm and 10-20cm soils.（2）Increasing and decreasing rainfall treatments had significant effects on greenhouse gas emission rates.The 30%water reduction treatment significantly promoted soil N₂O emission rates,and the 30%rainfall reduction treatment promoted soil N₂O emission rates,but excessive moisture content also suppressed soil N₂O emission rates,and the 60%rainfall reduction treatment sampled on the same day had lower N₂O emission rates than the 30%rainfall reduction treatment.Between June 2022and August 2022,soil CO₂ emission rates were higher in the 30%rainfall reduction treatment than in the other treatments,and the reduction in precipitation during periods of high precipitation could contribute to soil CO₂ emission rates.Soil CH₄ emission rates were lower in the 60%rainfall reduction treatment than in the other treatments,and moisture also had a limiting effect on them.（3）Increasing and decreasing rainfall treatments had significant effects on species composition at the bacterial and fungal phylum levels and species composition at the genus level.Soil depth was the main factor affecting differences in soil bacterial communities,and the relative abundance of species composition at the bacterial and fungal phylum levels was significantly different between 0-10 cm soil and 10-20 cm soil.The treatment of increasing and decreasing rainfall had a significant effect on species composition at the bacterial and fungal phylum levels and species composition at the genus level,soil depth was the main factor influencing differences in soil bacterial communities,and the relative abundance of species composition at the bacterial and fungal phylum levels differed significantly between 0-10cm soil and 10-20cm soil.The species diversity within the community was significantly higher in the three treatments of 60%water reduction,30%water reduction and 30%water increase than in the control.on 29 July 2022,the shannon index was significantly higher in the 60%water reduction treatment 0-10cm soil than in the 10-20cm soil,and the species diversity within the community was significantly higher in the 60%water reduction treatment 0-10cm soil than in the 10-20cm soil.