退耕还湿后土壤细菌群落结构和生物量变化过程

土壤细菌对湿地生态系统功能和健康维持起着重要作用。以菜子湖原始湿地、不同退耕年限湿地(3a、7a、11a和21a)和仍耕作油菜地土壤为研究对象，应用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)、高通量测序和磷脂脂肪酸(PLFAs)方法分析土壤细菌群落组成和生物量，探讨它们在退耕还湿后的变化过程及其影响因素。结果表明，退耕还湿后土壤变形菌门(α-变形菌纲、β-变形菌纲和δ-变形菌纲)、酸杆菌门(酸杆菌纲和全噬菌纲)、Nitrospinae(Nitrospinia纲)和硝化螺旋菌门(硝化螺旋菌纲)相对丰度先增高后降低；这些参与氮循环的土壤细菌对退耕后湿地生态恢复过程中土壤氮素提升起着重要作用。与农业生产活动密切关联的厚壁菌门(芽孢杆菌纲和梭菌纲)和放线菌门(放线菌纲)相对丰度逐渐降低。湿地土壤细菌多样性在退耕初期(3—7a)上升达到最大，退耕中后期逐渐降低。表层土壤各类群细菌生物量逐渐升高，亚表层土壤各类群细菌生物量则先降后升再降。水分条件和容重是与研究区土壤细菌群落结构和多样性密切相关的土壤因子，而全氮是与土壤细菌生物量密切相关的土壤因子。研究从生态过程视角解析了土壤细菌群落较详...

Changes of soil bacterial community structures and biomass in wetlands recovered from farmland

Soil bacteria play an important role in maintaining ecological function and health of wetland ecosystem. Soil samples were collected from natural wetlands, wetlands with different ages (3a, 7a, 11a, and 21a) recovered from farmland and rape fields around Caizi Lake, Anqing City, Anhui Province. Soil bacterial community structures and biomass were analyzed by PCR-DGGE, high-throughput sequencing and phospholipid fatty acid method. The changes and influencing factors of soil bacterial community structures and biomass during wetland ecology restoration were discussed. The results showed that the relative abundance of Proteobacteria (Alphaproteobacteria, Betaproteobacteria and Detaproteobacteria), Acidobacteria (Acidobacteria and Holophagae), Nitrospinae (Nitrospinia) and Nitrospirae (Nitrospira) increased at the initial restoration period and decreased subsequently. These bacteria participating in soil nitrogen cycling played an important role in improving soil nitrogen during the ecology restoration. The relative abundance of Firmicutes (Bacilli and Clostridia) and Actinobacteria (Actinobacteria) related to agricultural activities, decreased gradually during the whole restoration period, indicating the declining impact of historical agricultural activity. Soil bacterial diversity reached the maximum at the early stage of restoration (3-7a) and then decreased gradually. Bacterial biomass tended to increase in the surface soil, and showed decreasing-increasing-decreasing tendency in the subsurface soil during the whole restoration period. Soil bulk density and water condition had close relationship with soil bacterial community structures and diversity index, and soil total nitrogen had close relationship with soil bacterial biomass. In this study, the successions of soil bacterial communities associated with wetland restoration over time, and their ecological function were elucidated in detail, which is helpful to improve the knowledge of restoration process of the degraded wetland ecosystem.