Table_4_Small-Scale Soil Microbial Community Heterogeneity Linked to Landform Historical Events on King George Island, Maritime Antarctica.XLSX

Although research on microbial biogeography has made great progress in the past decade, distributions of terrestrial microbial communities in extreme environments such as Antarctica are not well understood. In addition, knowledge of whether and how historical contingencies affect microbial distributions at small spatial scales is lacking. Here, we analyzed soil-borne microbial (bacterial, archaeal, and fungal) communities in 12 quadrat plots around the Fildes Region of King George Island, maritime Antarctica, and the communities were divided into two groups according to the soil elemental compositions and environmental attributes of Holocene raised beach and Tertiary volcanic stratigraphy. Prokaryotic communities of the two groups were well separated; the prokaryotic data were primarily correlated with soil elemental compositions and were secondly correlated with environmental attributes (e.g., soil pH, total organic carbon, NO3-, and vegetation coverage; Pearson test, r = 0.59 vs. 0.52, both P < 0.01). The relatively high abundance of P, S, Cl, and Br in Group 1 (Holocene raised beach site) was likely due to landform uplift. Lithophile-elements (Si, Al, Ca, Sr, Ti, V, and Fe) correlated with prokaryotic communities in Group 2 may have originated from weathering of Tertiary volcanic rock. No significant correlations were found between the fungal community distribution and both the soil elemental composition and environmental attributes in this study; however, Monte Carlo tests revealed that elements Sr and Ti, soil pH, sampling altitude, and moss and lichen species numbers had significant impacts on fungal communities. The elements and nutrients accumulated during the formation of different landforms influenced the development of soils, plant growth, and microbial communities, and this resulted in small-scale spatially heterogeneous biological distributions. These findings provide new evidence that geological evolutionary processes in the Fildes Region were crucial to its microbial community development, and the results highlight that microbial distribution patterns are the legacies of historical events at this small spatial scale. Based on this study, the ice-free regions in maritime Antarctica represent suitable research sites for studying the influence of geomorphological features on microbial distributions, and we envision the possibility of a site-specific landform assignment through the analysis of the soil prokaryotic community structure.

尽管近十年来微生物生物地理学（microbial biogeography）研究取得了长足进展，但人们对南极等极端环境中的陆地微生物群落分布特征仍缺乏充分认知。此外，学界尚不清楚历史偶然性是否以及如何在小空间尺度上影响微生物的分布格局。本研究针对南极海洋性区域乔治王岛菲尔德斯地区周边12个土壤样方中的土壤源微生物（细菌、古菌与真菌）群落开展分析，并依据全新世抬升海滩与第三纪火山地层的土壤元素组成及环境属性，将群落划分为两组。两组的原核生物群落（Prokaryotic communities）呈现出显著分离；原核生物群落数据主要与土壤元素组成相关，其次与土壤pH、总有机碳、硝酸盐（NO3-）、植被覆盖率等环境属性相关（皮尔逊检验：r=0.59 vs 0.52，均P<0.01）。第1组（全新世抬升海滩样点）中磷（P）、硫（S）、氯（Cl）、溴（Br）的相对丰度较高，这一现象可能源于地貌抬升作用。第2组中与原核生物群落相关的亲石元素（Lithophile-elements，包括硅Si、铝Al、钙Ca、锶Sr、钛Ti、钒V与铁Fe），其来源或为第三纪火山岩的风化作用。本研究未发现真菌群落分布与土壤元素组成及环境属性存在显著关联；但蒙特卡洛检验（Monte Carlo tests）显示，锶（Sr）、钛（Ti）元素、土壤pH值、采样海拔以及苔藓与地衣物种数对真菌群落具有显著影响。不同地貌形成过程中积累的元素与营养物质，会影响土壤发育、植物生长及微生物群落结构，进而造成小尺度空间异质性的生物分布格局。本研究结果为菲尔德斯地区的地质演化过程对其微生物群落发育的关键作用提供了新证据，同时表明该小空间尺度下的微生物分布模式是历史事件的遗留效应。基于本研究，南极海洋性区域的无冰区可作为研究地貌特征对微生物分布影响的理想样地；我们展望可通过分析土壤原核生物群落结构，实现针对特定地点的地貌归类。