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Research On Soil Microbial Properties In Larix Principis-rupprechtii Plantation At Taiyue,Shanxi

Posted on:2021-02-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:R WuFull Text:PDF
GTID:1360330611469019Subject:Ecology
Abstract/Summary:PDF Full Text Request
For researching soil microbial community structure and function and the microbial responses to forest management,this paper studied soil microbial properties by using the method of PLFA in Larix principis-rupprechtii plantation in Shanxi Province.Combined with thinning treatment,the soil enzyme activities were regarded as soil microbial community function.The key microbial factors regulating soil microbial community function need to be found to analyze the competition and cooperation of soil microbial community by molecular biology techniques,and to investigate soil microbial function in genetic level.Meanwhile,the controlled experimentation were conducted to explore the microbial regulation mechanisms of soil carbon dynamic.The result showed that:(1)In different stand ages in Larix principis-rupprechtii plantation,soil microbial biomass,soil microbial abundance and soil hydrolase activities were significantly higher in the 15-year-old than in the 45-year-old.The RDA analysis showed that,soil organic carbon and soil water content were the key environmental factors affecting soil microbial community structure,and soil enzyme activities were mainly affected by soil bacterial abundance.By further investigating soil bacterial ecological networks and functional prediction,we found that there were little competition among soil bacterial communities in this area.Proteobacteria,Actinobacteria,and Acidobacteria were the key bacteria in Larix principis-rupprechtii plantation.Soil organic carbon,soil microbial biomass carbon,and soil dissolved carbon were significantly corelated with the abundance of Proteobacteria.Soil bacterial genes related to carbon transformation were higher in the 45-year-old in Larix principis-rupprechtii plantation.Soil bacterial function about replication and repair and energy metabolism were significantly correlated with soil microbial biomass carbon and dissolved carbon.(2)The medium thinning treatment increased soil temperature.Soil microbial biomass,soil microbial abundance,and soil hydrolase activities significantly increased in the medium thinning treatment.The RDA analysis showed that soil p H and soil temperature were the key environmental factors affecting soil microbial community structure,and soil enzyme activities were mainly affected by soil bacterial abundance.By further investigating soil bacterial ecological networks and functional prediction,we found that there were much cooperation among soil bacterial communities,and the competition increased in summer.In spring,the light thinning increased the decomposing of soil organic carbon,while medium and high thinning treatment decreased the genetic function related to soil carbon transformation.In summer,thinning decreased the genetic function related to carbon fixation to improve the decomposing of soil organic carbon.In different thinning treatment,soil phenol oxidase and ?-glucosidase were the key enzymes affecting soil carbon properties.Soil microbial properties had a relative higher effect on soil carbon properties.(3)The litter removal treatments were conducted in different thinning treatment.The results showed that the NL treatment(litter removal)significantly increased soil microbial biomass.In medium thinning treatment,litter removal significantly decreased soil microbial PLFAs and soil microbial abundance.There were an opposite trend in the high thinning treatment.Litter removal weakened the relationships between soil microbial communities and soil hydrolase activities.the NRL treatment(root trench and litter removal)increased the relationship between soil organic carbon and the activity of soil acetyl-?-glucosidase.Meanwhile,the NRL treatment increased the relationship between soil peroxidase and soil microbial biomass carbon and dissolved carbon.After the treatments of litter removal and nitrogen addition,we found that soil microbial biomass and microbial abundance significantly increased after the first year of nitrogen addition,while both of them decreased after the second year of nitrogen addition.The NRL treatment weakened the effect of soil oxidase on soil microbial biomass carbon and soil organic carbon,while the NL treatment increased the effect of soil hydrolase on soil carbon properties.The path analysis showed that the Gram-negative bacteria and saprotrophic fungi indirectly affected soil organic carbon by directly soil peroxidase activity.In conclusion,soil microbial community structure and function were better in 15-yearold plantation than in 45-year-old,and the medium thinning improved soil microbial community structure and function.Soil p H and soil temperature were the key environmental factors affecting soil microbial communities in thinning treatment.Compared with environmental factors,soil microbial factors had a relative higher effect on soil carbon properties.This paper explored the effect of forest management measures on soil microbes from the aspect of carbon and nitrogen input changes,and clarified the microbial mechanisms of regulating soil carbon dynamic.This study laid a theoretical foundation for exploring the correlation between plant and below-ground processes,and increasing carbon sequestration potential in Larix principis-rupprechtii plantation.
Keywords/Search Tags:Soil microbial community structure, Soil enzyme activities, Soil microbial network analysis, Soil microbial functional prediction, Soil carbon properties
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