土壤微生物生物地理学:国内进展与国际前沿

土壤微生物生物地理学是研究土壤中微生物空间分布格局及其随时间变化的一门科学,是土壤微生物学和微生物生态学等领域的研究前沿。近年来,尽管土壤微生物生物地理学研究取得了巨大进展,目前仍面临诸多难题与挑战。本文简要回顾了土壤微生物生物地理学的发展历程,重点介绍近年来我国在森林、草地和农田生态系统中土壤微生物生物地理学研究的主要进展。同时进一步阐述了目前土壤微生物生物地理学研究的国际前沿方向,包括微生物群落空间分布及其驱动机制、群落构建过程与共存网络、微生物地理分布与生态系统功能的关联以及预测微生物群落对全球变化的响应。最后,对土壤微生物生物地理学未来的研究方向进行了展望,强调了清晰的微生物物种定义、微生物群落的时间动态、多组学与合成生物学技术以及高精度的预测模型在土壤微生物生物地理学研究中的重要性。

Distribution Patterns of Soil Microorganisms under Different Vegetation Types along the Riparian Wetland of the Ulson River and Its Influencing Factors

Wetlands are important for maintaining global ecosystem functions,mitigating global climate change,and regulating regional climate change.Ecological problems caused by global climate change have had serious impacts on plant distribution patterns in the wetlands of riparian zones,as well as on microbial community habitats in the soil.This study was based on a field sampling survey of the distribution characteristics of plant communities in the Ulson River,combined with remote sensing to obtain the spatial distribution pattern of vegetation in the riparian wetland.High-throughput sequencing technology combined with the characteristics of soil physicochemical factors were then used to explore the distribution characteristics of the community structures of soil bacteria and fungi under different vegetation types in the Ulson River Basin,in order to reveal the pattern of changes of soil microbial microorganisms under the different vegetation types in the wetlands of the riparian area and the factors driving those changes.The results showed an obvious banding phenomenon of wetland vegetation in the Ulson River Basin.Proteobacteria ranked first in relative abundance in all the sample plots and were the dominant bacteria in the study area.Ascomycota and Basidiomycota were the dominant fungi in the study area.In swamp areas,degenerate swamp soils,soil moisture content,and soil bulk density affected the microbial richness directly or indirectly by controlling soil nutrients.Plant aboveground biomass was the most significant factor influencing microbial diversity in a typical wet meadow sample.In salinized meadows and swamped meadows,electrical conductivity affected microbial richness and soil bulk density was the main factor influencing microbial diversity.The findings of this study can provide a theoretical basis for the ecological restoration of degraded riparian wetlands and further clarification of soil ecosystem functions in riparian wetlands.

Distribution of microbial fatty acids and fatty alcohols in soils from an altitude transect of Mt. Jianfengling in Hainan, China: Implication for paleoaltimetry and paleotemperature reconstruction

The temperature gradient along the altitude transect of Mt. Jianfengling provides a good opportunity to establish and evaluate the microbial lipid-based environmental proxies. The soils collected from 14 different altitudes of Mt. Jianfengling contain abundant microbial fatty acids and fatty alcohols, including iso/anteiso fatty acids （i/aC12：0-i[aCl9：0）, 10-Me-C16：0 fatty acid, iso/anteiso fatty alcohols （i/aC13-iC26）, 10-Me-C16：0 fatty alcohol and unsaturated fatty alcohols, which can indicate a strong microbial activity in the Jianfengling soils. The branched and unsaturated fatty alcohols can be only detected when saponifica- tion is performed, implying that these lipids are present as the constituents of bacterial wax esters in the soils. The ratio of aC15/iC15 fatty acids is positively correlated with altitude, suggesting that the decrease in temperature can induce the increase in the relative abundance of anteiso C^5 fatty acid. In contrast, the ratio of aCJiC15 fatty alcohols and of aCjs/nC15 fatty alco- hols both decrease with increased altitude or decreased temperature. Similarly, the ratio of nC18：l/nCi8：0 fatty alcohols also de- creases with decreased temperature, which is opposite to the previous observation that unsaturation of fatty acids in microor- ganism increases in response to decreased temperature. Besides, the average chain length （ACL） of long chain fatty alcohols （C22-C30） from leaf waxes and carbon preference index （CPI） of all n-fatty alcohols are also significantly correlated with alti- tude or mean annual temperature, demonstrating their potential for paleoclimate reconstruction. The correlation of microbial fatty acids and alcohols as well as ACL and CPI of plant wax-derived fatty alcohols with altitude may provide novel ways to reconstruct paleotemperature and paleoaltimetry.