坝上地区退耕还林还草措施对土壤细菌的影响

Effects of Returning Farmland to Forest and Grassland on Soil Bacteria:A Case Study in Bashang Area,China

以河北坝上地区实施退耕还林还草18年后的耕地、林地、灌丛和草地为研究对象,通过测定土壤理化性质并结合氯仿熏蒸浸提法和高通量测序技术,分析了坝上地区退耕还林还草措施对土壤微生物生物量、细菌多样性和群落结构特征的影响。结果发现:林地的土壤含水量有微弱下降趋势,但不同植被恢复类型下土壤中的碳、氮、磷、钾等元素含量无显著差异。耕地中的土壤微生物生物量碳、氮均显著低于其他植被恢复类型。不同退耕措施下的土壤细菌群落组成均以酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和绿弯菌门(Chloroflexi)为主。与耕地相比,林地、灌丛和草地土壤中细菌OTU多样性、群落丰富度和多样性呈下降趋势,但土壤细菌的群落结构组成尚未发生明显改变。研究结果表明在坝上地区实施退耕还林还草措施显著提高土壤微生物生物量,但对土壤细菌丰富度和多样性的影响不大。

In this study we investigated soil bacteria of farmland,woodland,shrubland and grassland in Bashang area of Hebei Province to clarify the effects of the Returning Farmland to Forest Program(RFFP)on soil microbial biomass and diversity after carrying out RFFP for 18 years.Here,we determined soil physicochemical properties and analyzed the changes of soil microbial biomass,soil bacterial community structure and diversity via chloroform fumigation and high throughput sequencing techniques.Our results showed a weak downward trend in soil water content of woodland,while no significant difference in the contents of carbon,nitrogen,phosphorus,potassium and other elements in soils under different vegetation restorations.Moreover,microbial biomass carbon and nitrogen were lower in the farmland than vegetation restorations.The common dominant phyla of soil bacteria were Acidobacteria,Actinobacteria,Proteobacteria and Chloroflexi.Compared with farmland,soil bacterial community composition changed insignificantly under different vegetation restorations,yet the operational taxonomic unit(OTU),soil bacterial abundance and diversity weakly decreased.Our results indicate that restoring vegetation in Bashang area has significantly improved soil microbial biomass but with little effect on bacterial abundance and diversity.