Soil characteristics vary across land uses, and soil microbial communities are likely to respond to such variations. However, such responses are not well understood. In this study, we examined how specific changes in soil organic matter (SOM) and geochemical characteristics influenced the bacterial and fungal community composition and structure across land uses. Soil samples were collected from grazing, sugarcane, forest and banana land uses in the Johnstone River catchment (wet tropics), northeastern Australia. High-throughput sequencing of 16S rRNA gene and ITS amplicons were employed to characterise soil bacterial and fungal communities, respectively. Bacterial and fungal α-diversity did not differ across land uses, whereas strong shifts in their community composition and structure were evident. Patterns in microbial community composition were strongly (p < 0.01) associated with changes in soil total organic carbon and nitrogen (TOC and TN), TOC:TN ratio, hot-water extractable organic carbon (HWEOC) and soil geochemical characteristics (e.g., pH, Co, Mn, K, Mg and P contents). Distinct bacterial community composition was observed in forest soils, while fungal communities were similar in banana and forest soils compared with sugarcane and grazing. Overall, our results showed that SOM characteristics were the major driver on structuring soil microbial communities across land uses, while soil bacterial communities were more sensitive to variations in SOM and geochemical characteristics compared with fungi. Results from this study have implications for developing more targeted management practices across different land uses to improve soil health and ecosystem function in a wet tropical area.

中文翻译：

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土壤有机质和地球化学特征塑造了澳大利亚潮湿热带集水区不同土地利用的微生物群落组成和结构

土壤特性因土地用途而异，土壤微生物群落可能会对这些变化作出反应。然而，这样的反应并没有得到很好的理解。在这项研究中，我们研究了土壤有机质 (SOM) 和地球化学特征的具体变化如何影响土地利用中的细菌和真菌群落组成和结构。土壤样本是从澳大利亚东北部约翰斯通河流域（湿热带地区）的放牧、甘蔗、森林和香蕉土地用途收集的。16S rRNA 基因和 ITS 扩增子的高通量测序分别用于表征土壤细菌和真菌群落。细菌和真菌的 α-多样性在土地利用方面没有差异，而其群落组成和结构的强烈变化是显而易见的。p < 0.01) 与土壤总有机碳和氮（TOC 和 TN）、TOC:TN 比、热水可提取有机碳 (HWEOC) 和土壤地球化学特征（例如，pH、Co、Mn、K、Mg 和P 内容）。在森林土壤中观察到不同的细菌群落组成，而与甘蔗和放牧相比，香蕉和森林土壤中的真菌群落相似。总体而言，我们的研究结果表明，SOM 特征是跨土地利用构建土壤微生物群落的主要驱动力，而与真菌相比，土壤细菌群落对 SOM 和地球化学特征的变化更敏感。这项研究的结果对于在不同的土地用途中开发更有针对性的管理实践以改善潮湿热带地区的土壤健康和生态系统功能具有重要意义。