土壤真菌群落对五台山亚高山草甸退化的响应

草地退化已经成为了一个世界性的生态问题.尽管土壤微生物作为草地退化过程的主要参与者,在维持生态系统功能和提高土壤生产力中扮演着关键角色,但目前对草地退化引起的微生物群落变化及其与土壤性质和植物群落的关系知之甚少.本文利用Illumina MiSeq测序技术,对五台山亚高山草甸4个不同退化阶段[未退化(ND)、轻度退化(LD)、中度退化(MD)和重度退化(HD)]土壤真菌群落特征进行了分析.结果表明,子囊菌门、担子菌门和接合菌门是亚高山草甸土壤真菌的优势门. LEfSe分析显示不同退化程度草甸富集了不同的生物标志物,MD和HD富集了更多的病原真菌.与ND相比,HD土壤真菌群落丰富度和香农指数显著降低(P<0.05).非度量多维尺度分析(NMDS)和相似性分析(ANOSIM)结果表明,真菌群落组成和结构在退化梯度上存在显著的差异(P<0.05).冗余分析(RDA)发现土壤含水量、总氮、植物丰富度和铵态氮是真菌群落组成和结构变化的主要驱动因子.植物与真菌群落之间的α多样性和β多样性均存在显著相关性(P<0.05),具有强耦合性.本研究结果为研究亚高山草甸不同退化阶段下土壤真...     

Sulfur cycle in the typical meadow Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain, Northeast China

The sulfur cycle and its compartmental distribution within an atmosphere-plant-soil system was studied using a compartment model in the typical meadow Calamagrostis angustifolia wetland in the Sanjiang Plain Northeast China. The results showed that in the typical meadow C. angustifolia wetland ecosystem, soil was the main storage compartment and current hinge of sulfur in which 98.4% sulfur was accumulated, while only 1.6% sulfur was accumulated in the plant compartment. In the plant subsystem, roots and litters were the main storage compartment of sulfur and they remained 83.5% of the total plant sulfur. The calculations of sulfur turnover through the compartments of the typical meadow C. angustifolia wetland ecosystem demonstrated that the above-ground component took up 0.99 gS/m2 from the root, of which 0.16 gS/m2 was translocated to the roots and 0.83 gS/m2 to the litter. The roots took in 1.05 gS/m2 from the soil, subsequent translocation back to the soil accounted for 1.31 gS/m2, while there was 1.84 gS/m2 in the litter and the net transfer of sulfur to the soil was more than 0.44 gS/(m2·a). The emission of H2S from the typical meadow C. angustifolia wetland ecosystem to the atmosphere was 1.83 mgS/(m2·a), while carbonyl sulfide (COS) was absorbed by the typical meadow C. angustifolia wetland ecosystem from the atmosphere at the rate of 1.76 mgS/(m2·a). The input of sulfur by the rainfall to the ecosystem was 4.85 mgS/m2 during the growing season. The difference between input and output was 4.78 mgS/m2, which indicated that sulfur was accumulated in the ecosystem and may cause wetland acidify in the future.     

高寒草甸不同土地利用格局土壤CO2的释放量

分析高寒草甸不同土地利用格局下土壤CO₂的释放量大小表明,在植物生长季的5～9月,土壤CO₂释放量大小排序为:金露梅灌丛草甸(1871.40g/m²)＞矮嵩草草甸(1769.63g/m²)＞退化金露梅灌丛草甸(1495.60g/m²)＞退化矮嵩草草甸(1191.26g/m²);而在植物非生长季的10月到翌年4月,其土壤CO₂释放量大小与植物生长季略有差异,表现出矮嵩草草甸(661.46g/m²)＞金露梅灌丛草甸(550.90g/m²)＞退化矮嵩草草甸(502.50g/m²)＞退化金露梅灌丛草甸(384.50g/m²)的特点;全年内表现为矮嵩草草甸(2431.09g/m²)＞金露梅灌丛草甸(2422.30g/m²)＞退化金露梅灌丛草甸(1880.10g/m²)＞退化矮嵩草草甸(1694.06g/m²).高寒草甸地区不同土地利用格局土壤CO₂释放数量的差异及季节变化,不仅与各利用格局的土壤生物活性及土壤物理化学性状有关,而且与气象条件(特别是温度)及其土壤冬季冻结期长短关系极为密切.     

青海高寒草甸草地退化的遥感技术调查分析

应用遥感技术探讨了巴颜喀拉山北坡,青海省达日县段退化高寒草甸草地的成因、分布、面积和遥感判译标志,将研究区内高寒草地划分为５个类,２个亚类和３个退化草地型．重点分析了高山草甸草地退化的主要原因和遥感影像特征