Ferrari Belinda C, Bissett Andrew, Snape Ian, van Dorst Josie, Palmer Anne S, Ji Mukan, Siciliano Steven D, Stark Jonathon S, Winsley Tristrom, Brown Mark V
School of Biotechnology and Biomolecular Sciences, UNSW Australia, Randwick, NSW, 2052, Australia.
CSIRO Agriculture Flagship, PO Box 1600, Canberra, ACT, 2601, Australia.
Environ Microbiol. 2016 Jun;18(6):1834-49. doi: 10.1111/1462-2920.13034. Epub 2015 Oct 14.
Landscape heterogeneity impacts community assembly in animals and plants, but it is not clear if this ecological concept extends to microbes. To examine this question, we chose to investigate polar soil environments from the Antarctic and Arctic, where microbes often form the major component of biomass. We examined soil environments that ranged in connectivity from relatively well-connected slopes to patchy, fragmented landforms that comprised isolated frost boils. We found landscape connectedness to have a significant correlation with microbial community structure and connectivity, as measured by co-occurrence networks. Soils from within fragmented landforms appeared to exhibit less local environmental heterogeneity, harboured more similar communities, but fewer biological associations than connected landforms. This effect was observed at both poles, despite the geographical distances and ecological differences between them. We suggest that microbial communities inhabiting well-connected landscape elements respond consistently to regional-scale gradients in biotic and edaphic factors. Conversely, the repeated freeze thaw cycles that characterize fragmented landscapes create barriers within the landscape and act to homogenize the soil environment within individual frost boils and consequently the microbial communities. We propose that lower microbial connectivity in the fragmented landforms is a function of smaller patch size and continual disturbances following soil mixing.
景观异质性影响动植物群落的组装，但尚不清楚这一生态概念是否适用于微生物。为了研究这个问题，我们选择调查南极和北极的极地土壤环境，在这些环境中微生物通常构成生物量的主要组成部分。我们研究了从连接相对良好的斜坡到由孤立的冻融泥流组成的零散、破碎地貌等不同连通性的土壤环境。我们发现，通过共现网络衡量，景观连通性与微生物群落结构和连通性存在显著相关性。与连通地貌相比，破碎地貌中的土壤似乎表现出较低的局部环境异质性，拥有更相似的群落，但生物关联较少。尽管两极之间存在地理距离和生态差异，但在两极均观察到了这种效应。我们认为，栖息在连通良好的景观要素中的微生物群落对生物和土壤因子的区域尺度梯度有一致的响应。相反，破碎景观特有的反复冻融循环在景观中形成了障碍，并使单个冻融泥流内的土壤环境趋于均质化，从而使微生物群落也趋于均质化。我们提出，破碎地貌中微生物连通性较低是斑块尺寸较小以及土壤混合后持续干扰的结果。
