秦岭火地塘森林景观土壤微生物空间格局

As one of the most important terrestrial ecosystems, forest contributes to improve the ecological environment, maintain the ecological security, and protect the biodiversity. Forest soil microorganisms, which have high diversity and large individual richness and biomass, are the main decomposers of the litter in forest ecology system and affect soil physicochemical properties, soil fertility, and forest ecosystem health and sustainable development. Therefore, it is important to study the forest soil microorganisms for the scientific management of forest ecosystems and the maintenance of forest ecosystem services. As the representative region in the central region of the southern slope of Qinling Mountain, Huoditang has the typicality in biodiversity, ecosystem service function, and sustainable forest management. Therefore, it is important to study soil microorganisms for managing forest ecosystem in Huoditang. However, the previous studies on forest soil microbes were greatly limited to data size, and rarely carried out the spatial pattern and heterogeneity. Thus, it is important to study spatial heterogeneity and pattern of forest soil microorganisms and formation mechanism of spatial heterogeneity and pattern for the evaluation of forest ecosystem services. Firstly, we will finish the scrub map according to the results of our investigations on the scrub and the previous research findings. Secondly, DEM (Digital Elevation Model) will be generated based on three times radar images using the D-InSAR (Differential Interferometric Synthetic Aperture Radar) technology, which is used to generate slope map and aspect map. Spatial uniform sampling site set is selected based on stacking scrub map, DEM, slope map, aspect map, soil type map, and forest form map with ARCGIS software. Thus, about 350 sample plots (20 m × 20 m) will be selected in this study, which will be divided into grid with 4 m × 4 m. Then, the plum blossom sampling method will be used to collect soil samples in every sample plot. The colony-forming units (CFUs) will be used to determinate the abundance of bacteria, fungi, and actinomycetes. Chloroform fumigation extraction method will be used to measure microbial biomass. High-throughput sequencing technology will be used to analyze soil microorganism community structure. Then, soil microbial characteristics in the same and different forest landscape types are analyzed. Based on the scale transformation principle, the spatial interpolation technique is used to complete the scale transformation of microbial abundance, biomass, and community structure results from point to surface. Based on the results that maps of microbial abundance, biomass, and community structure are overlaid to maps of altitude, slope, aspect, soil type, and forest landscape type, the spatial pattern and heterogeneity of soil microorganism will be analyzed. Some effective management measures and countermeasures will be put forward for Huoditang forest ecosystem according to the above results, which provide supports to study the spatial pattern of soil microorganisms in Mt. Qinling in the future.

土壤微生物是森林生态系统凋落物的最主要分解者，影响森林土壤性质、肥力、生态系统健康等。目前的土壤微生物研究局限于点数据，对空间格局及异质性研究不足，因此加强土壤微生物空间分异规律、空间分布格局及形成机制研究意义重大。火地塘在我国森林生态系统研究中占有十分重要的地位，以其为研究区，使用D-InSAR技术生成DEM及衍生数据并与土壤类型图、林相图等叠加完成样地设置，采用梅花样点法取土样，利用高通量测序等技术测定微生物数量、生物量和群落结构，分析不同森林景观类型土壤微生物数量、生物量和群落结构的差异性和同一森林景观类型土壤微生物数量、生物量和群落结构随海拔、坡度、坡向、土壤类型等的变化特征，探讨运用景观生态学尺度转换原理和空间插值技术实现森林土壤微生物 “点”研究到“面”研究，阐明森林土壤微生物空间格局及异质性，为火地塘森林生态系统提出管理措施和对策，为今后开展秦岭土壤微生物空间格局研究提供支撑

秦岭是我国重要的生态屏障区和生态功能区，研究其森林景观土壤微生物数量及空间异质性对于区域生态系统健康、生态保护和高质量发展具有重要意义。项目通过野外土壤采样、室内分析、高通量测序、空间差值分析等，研究了秦岭火地塘不同森林景观类型土壤微生物数量特征、结构和森林景观土壤微生物空间格局；结果表明, 研究区土壤的AK、TC、AP、TS、TN、可溶性盐总量等指标表现出中等程度的变异，空间分布均具有很强的空间相关性。锐齿栎林、华山松林的土壤真菌共有优势纲有伞菌纲、粪壳菌纲、古根菌纲、盘菌纲、锤舌菌纲和散囊菌纲，锐齿栎林、华山松林特有的纲分别是座囊菌纲和银耳纲、被孢霉纲和酵母菌纲。随着海拔的增加，锐齿栎林土壤伞菌纲的相对丰度增加，盘菌纲的相对丰度降低，海拔影响锐齿栎林土壤真菌群落属的多样性水平且差异显著；土壤pH、SOM和SM对优势真菌类群的相对丰度有显著影响，Shannon多样性指数与土壤pH显著负相关。华山松林真菌α多样性与海拔和SOM含量显著负相关；海拔是影响细菌和真菌群落β多样性的主要因子，而pH是显著影响土壤细菌和真菌群落结构的因子， SOM、海拔和AK亦显著影响土壤真菌群落结构。研究区土壤真菌优势门有子囊菌门、担子菌门、接合菌门等，优势纲有伞菌纲、粪壳菌纲、古根菌纲等，在门水平上，罗兹菌门有最大的斑块，子囊菌门在最高丰度等级上有最多的斑块数，隐真菌门在最低等级丰度上有最多的斑块数；在纲水平上，粪壳菌纲有最大的斑块面积，盘菌纲在最低丰度等级上有最大的斑块；土壤pH、EC、AP和SOM对优势真菌群落影响显著。土壤细菌优势门有变形菌门、放线菌门、酸杆菌门等；在门水平上，变形菌门在最高丰度等级上有最大的斑块，其次是浮霉菌门、酸杆菌门和拉氏杆菌门；厚壁菌门在较低丰度等级上有最大的斑块，其次是放线菌门和拟杆菌门；土壤优势细菌门的分布呈斑块-基质镶嵌空间格局；土壤pH是影响细菌群落最显著的因子，其次是SOM、EC和TN。