Microbial-driven Mechanism Of Soil Organic Carbon Turnover In Different Ways Of Returning Farmland To Forest

Loess Plateau is characterized by dry climate,sparse vegetation and severe soil erosion.Due to concentrated rainfall and indiscriminate reclamation,it has caused serious ecological damage.Ecological restoration,ie vegetation restoration and reconstruction,is the main measure to control the degraded ecosystems.It is also an important measure to alleviate atmospheric CO₂ and promote soil carbon and nitrogen recovery.Since the 1950s,ecological restoration of returning farmland to forest has been carried out in the Loess Plateau.To explore the effect of different ecological restoration on soil organic matter turnover and mechanism can provide theoretical guidance for ecosystem restoration in the Loess Plateau.In this paper,we studied the ecological restoration effect of different returning farmland to forest in Zhifanggou drainage area of Loess Plateau.Soil organic carbon content and activity were determined.Soil ecoenzymatic activity and stoichiometry were analyzed.The diversity ofβ-glucosidase-encoding microbes were performed by high-throughput sequencing technology.The main results were as follows:1.Different ways of returning farmland to forests significantly affect soil organic carbon content and activity.Restoration time and vegetation type have the greatest impact on soil organic carbon and components.Compared with orchard,Robinia pseudoacacia Linn.and Caragana Korshinskii Kom significantly increased soil organic carbon and lalibe organic carbon content.2.Different ways of returning farmland to forests significantly affect the characteristics of soil ecoenzymatic activity and stoichiometry.The enzyme activity in rhizosphere soil than that in bulk soil.C:N:P stoichiometry of soil microbes and ecoenzymatic activity is nutrient dependent,rather homeostatic.The growth of soil microbes are limited by P availability,and it is co-limited by C and P in orchard soil.3.Different ways of returning farmland to forests significantly affected the diversity of microbial communities encodingβ-glucosidase.The microorganisms encoding GH1-Bacteria gene are mainly Actinobacteria,Proteobacteria and Bacteroidetes.The microorganisms encoding GH3-Bacteria gene are mainly Proteobacteria,Bacteroidetes and Ignavibacteriae.The microorganisms encoding GH3-Fungi gene are mainly Ascomycota.Vegetation type has greater impact on the specific OTU abundance in microbial communities.The abundance of Proteobacteria and Ascomycota in orchard are the great.