Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Weijin Road 94, Tianjin 300071, PR China.
School of Environmental Science and Engineering, Tiangong University, Binshui West Road 399, Tianjin 300387, PR China.
Sci Total Environ. 2024 Nov 1;949:175070. doi: 10.1016/j.scitotenv.2024.175070. Epub 2024 Jul 29.
Rhizosphere microbial community characteristics and ecosystem multifunctionality (EMF), both affected by topographic factors, are closely correlated. However, more targeted exploration is yet required to fully understand the variations of rhizosphere microbial communities along topographic gradients in different soil layers, as well as whether and how they regulate EMF under specific site conditions. Here, we conducted relevant research on Juglans mandshurica forests at six elevation gradients and two slope positions ranging from 310 to 750 m in Tianjin Baxian Mountain. Results demonstrated that rhizosphere soil physicochemical properties and enzyme activities of both layers (0-20 cm and 20-40 cm) varied significantly with elevation, while only at top layer did slope position have significant impacts on most indicators. Bacterial richness and diversity were higher in the top layer at slope bottom and middle-high elevation, the difference in fungi was not as noticeable. Both topographic factors and soil depth significantly impacted microbial community structure, with Candidatus_Udaeobacter of bacteria, Mortierella, Sebacina, and Hygrocybe of fungi mainly contributing to the dissimilarity between communities. EMF rose with increasing elevation, bacteria were more critical drivers of this process than fungi, and topographic factors could affect EMF by altering bacterial diversity and dominant taxa abundance. For evaluating EMF, the aggregate structure of sub layer and the carbon cycle-related indicators of top layer were of higher importance. Our results revealed the depth-dependent characteristics of the rhizosphere microbial community along topographic gradients in studied stands, as well as the pivotal regulatory role of bacteria on EMF, while also highlighting depth as an important variable for analyzing soil properties and EMF. This work helps us better understand the response of individuals and communities of J. mandshurica to changing environmental conditions, further providing a scientific reference for the management and protection of secondary forests locally and in North China.
根际微生物群落特征和生态系统多功能性（EMF）均受地形因素影响，二者密切相关。然而，为了充分了解不同土壤层沿地形梯度的根际微生物群落的变化，以及它们在特定地点条件下是否以及如何调节 EMF，还需要更有针对性的探索。在这里，我们对天津八仙山 6 个海拔梯度和 2 个坡位（310-750m）的麻栎林进行了相关研究。结果表明，根际土壤理化性质和两层（0-20cm 和 20-40cm）的酶活性均随海拔显著变化，而只有在表层，坡位对大多数指标才有显著影响。在坡底和中高海拔的顶层，细菌丰富度和多样性较高，真菌的差异则不明显。地形因素和土壤深度均显著影响微生物群落结构，细菌中的 Candidatus_Udaeobacter、真菌中的 Mortierella、Sebacina 和 Hygrocybe 是群落差异的主要贡献者。EMF 随海拔升高而升高，细菌对这一过程的影响大于真菌，地形因素可以通过改变细菌多样性和优势类群丰度来影响 EMF。在评估 EMF 时，亚层的团聚结构和顶层的碳循环相关指标更为重要。本研究结果揭示了研究林分中沿地形梯度的根际微生物群落的深度依赖性特征，以及细菌对 EMF 的关键调节作用，同时强调了深度是分析土壤性质和 EMF 的一个重要变量。这项工作有助于我们更好地了解麻栎个体和群落对环境变化的响应，为本地和华北地区次生林的管理和保护提供了科学参考。
