Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China; Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China; Guangxi Industrial Technology Research Institute for Karst Rocky Desertification Control, Nanning 530001, China; Guangxi Key Laboratory of Karst Ecological Processes and Services, Huanjiang 547100, China.
Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China; Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, China; Guangxi Industrial Technology Research Institute for Karst Rocky Desertification Control, Nanning 530001, China; Guangxi Key Laboratory of Karst Ecological Processes and Services, Huanjiang 547100, China.
J Environ Manage. 2024 Mar;355:120468. doi: 10.1016/j.jenvman.2024.120468. Epub 2024 Mar 2.
Soil depth plays a crucial role in shaping the interactions between soil microbes and nutrient availability. However, there is limited understanding of how bacterial, fungal, and protistan communities respond to different soil depths, particularly in the unique geological context and soil properties of karst regions. Organic matter, total nitrogen, and phosphorus, ammonium, nitrate, and plant root biomass, as well as bacterial and fungal abundances, bacterial and protistan diversity were higher in the 0-20 cm soil layer than those in the 20-40 cm and soil-rock mixing layers. In contrast, soil pH was higher in the 20-40 cm and soil-rock mixing layers than that in the 0-20 cm soil layer. The soil exchange of calcium, nitrate, and root biomass were identified as the primary factors regulating microbial assemblages across the depth transect. Moreover, co-occurrence network analysis revealed a greater degree of connectivity between protistan taxa and fungal taxa in the 0-20 cm soil layer than those in the 20-40 cm and soil-rock mixing layers. In contrast, the number of association links between protist-bacteria and bacteria-bacteria was higher in the soil-rock mixing layers compared to the 0-20 cm soil layer. Actinobacteria, Ascomycota, and unclassified protistan taxa were identified as keystones, displaying the highest number of connections with other microbial taxa. Collectively, these results suggested that the increased plant root biomass, coupled with sufficient available nutrient inputs in the upper 0-20 cm soil layer, facilitates strong interactions among fungal and protistan taxa, which play crucial roles in the topsoil. However, as nutrients become less available with increasing depth, competition among bacterial taxa and the predation between bacterial and protistan taxa intensify. Therefore, these findings indicate the interactions among keystone taxa at different soil depths has the potential to generate ecological implications during vegetation restoration in fragile ecosystems.
土壤深度在塑造土壤微生物与养分可利用性之间的相互作用方面起着至关重要的作用。然而，对于细菌、真菌和原生动物群落如何响应不同的土壤深度，特别是在喀斯特地区独特的地质背景和土壤特性方面，我们的了解有限。有机物质、总氮和磷、铵、硝酸盐和植物根生物量以及细菌和真菌丰度、细菌和原生动物多样性在 0-20 cm 土壤层中高于 20-40 cm 和土壤-岩石混合层。相比之下，土壤 pH 值在 20-40 cm 和土壤-岩石混合层中高于 0-20 cm 土壤层。钙、硝酸盐和根生物量的土壤交换被确定为调节整个深度横截面上微生物组合的主要因素。此外，共生网络分析显示，在 0-20 cm 土壤层中，原生动物类群与真菌类群之间的连接程度大于 20-40 cm 和土壤-岩石混合层。相比之下，在土壤-岩石混合层中，原生动物-细菌和细菌-细菌之间的关联数量高于 0-20 cm 土壤层。放线菌门、子囊菌门和未分类的原生动物类群被确定为关键种，与其他微生物类群的连接数量最多。总的来说，这些结果表明，增加的植物根生物量，加上上层 0-20 cm 土壤中充足的可用养分输入，促进了真菌和原生动物类群之间的强烈相互作用，这些相互作用在表土中起着至关重要的作用。然而，随着深度的增加养分变得不那么可用，细菌类群之间的竞争和细菌与原生动物类群之间的捕食加剧。因此，这些发现表明，在脆弱生态系统的植被恢复过程中，不同土壤深度的关键种之间的相互作用有可能产生生态影响。
