岩溶区土壤硝化过程对土地利用的多尺度响应机制研究

中国西南喀斯特岩溶地区土壤有很强的氮淋溶风险。本研究着眼于从分子生物尺度到原位样地尺度探究广西岩溶地区多种林地利用类型的土壤硝化过程。通过采集岩溶地区具代表性的林地类型（自然林及人工林）的土壤，并与非岩溶的酸性土壤作对比，采用分子生物学方法、实验室培养测定硝化酶活性技术、原位15N 同位素示踪法和常规土壤理化性质测定分析方法等技术手段，测定典型岩溶和非岩溶林地土壤的自养及异养硝化过程，分析氨氧化菌AOA 和AOB 的群落特征及酶活性表达的差异性，探讨土壤理化性质与微生物群落结构如何从不同尺度上决定林地土壤的硝化过程，揭示岩溶和非岩溶林地土壤中硝化过程对于各自氮循环的影响、季节变化规律及其驱动机制。以期在此基础上评估两种林地生态系统的NO3-产生和累积过程对于林地土壤肥力的影响和淋溶的环境风险，为岩溶区林地石漠化的潜在风险评价和植物多样性恢复提供理论依据。

Karst soil from Southwest China has the potential of high nitrogen leaching risk. This study focused on studying the soil nitrification process of typical land use types of woods in the karst region of Guangxi province from the molecular scale to in-situ forest plot scale. The soils of various wood types (natural forests and plantations) in karst areas were collected and compared with non-karst acidic soils. By combining the molecular approaches, laboratory incubation as well as in situ 15N labeling techiniques, we are aiming at 1) determining the the autotrophic and heterotrophic nitrification processes of typical karst and non-karst wood soils; 2) analyzing the differences of community characteristics and enzymatic activity of AOA and AOB; 3) exploring how soil physicochemical properties and microbial community structure determine the nitrification process of forest soils from different scales, and 4) evaluating the effects of nitrification process on the nitrogen cycle in karst and non-karst forests, their seasonal variation and driving mechanisms. based on this study, we will be able to evaluate the impact of NO3- producation and accumulation processes on soil fertility and leaching environmental risk of the karst and non-karst ecosystems and to provide a theoretical basis for potential risk assessment of forest rocky desertification and for the restoration of forest plant diversity in karst areas.