Monteiro Maria R, Marshall Alexis J, Hawes Ian, Lee Charles K, McDonald Ian R, Cary Stephen Craig
International Centre for Terrestrial Antarctic Research, University of Waikato, Hamilton, New Zealand.
Te Aka Matuatua-School of Science, University of Waikato, Hamilton, New Zealand.
Front Microbiol. 2022 Jan 31;12:783767. doi: 10.3389/fmicb.2021.783767. eCollection 2021.
The space-for-time substitution approach provides a valuable empirical assessment to infer temporal effects of disturbance from spatial gradients. Applied to predict the response of different ecosystems under current climate change scenarios, it remains poorly tested in microbial ecology studies, partly due to the trophic complexity of the ecosystems typically studied. The McMurdo Dry Valleys (MDV) of Antarctica represent a trophically simple polar desert projected to experience drastic changes in water availability under current climate change scenarios. We used this ideal model system to develop and validate a microbial space-for-time sampling approach, using the variation of geochemical profiles that follow alterations in water availability and reflect past changes in the system. Our framework measured soil electrical conductivity, pH, and water activity to geochemically define 17 space-for-time transects from the shores of four dynamic and two static Dry Valley lakes. We identified microbial taxa that are consistently responsive to changes in wetness in the soils and reliably associated with long-term dry or wet edaphic conditions. Comparisons between transects defined at static (open-basin) and dynamic (closed-basin) lakes highlighted the capacity for geochemically defined space-for-time gradients to identify lasting deterministic impacts of historical changes in water presence on the structure and diversity of extant microbial communities. We highlight the potential for geochemically defined space-for-time transects to resolve legacy impacts of environmental change when used in conjunction with static and dynamic scenarios, and to inform future environmental scenarios through changes in the microbial community structure, composition, and diversity.
时空替代方法为从空间梯度推断干扰的时间效应提供了有价值的实证评估。应用于预测当前气候变化情景下不同生态系统的响应时，它在微生物生态学研究中仍未得到充分检验，部分原因是通常研究的生态系统营养复杂性较高。南极洲的麦克默多干谷（MDV）代表了一个营养简单的极地沙漠，预计在当前气候变化情景下其可用水量将发生剧烈变化。我们利用这个理想的模型系统，通过地球化学剖面的变化来开发和验证一种微生物时空采样方法，这些剖面随可用水量的变化而变化，并反映了系统过去的变化。我们的框架测量了土壤电导率、pH值和水分活度，以地球化学方式定义了来自四个动态和两个静态干谷湖泊岸边的17个时空样带。我们确定了对土壤湿度变化持续有反应并与长期干旱或湿润土壤条件可靠相关联的微生物类群。在静态（开阔盆地）和动态（封闭盆地）湖泊定义的样带之间的比较突出了地球化学定义的时空梯度识别水的存在历史变化对现存微生物群落结构和多样性持久确定性影响的能力。我们强调，地球化学定义的时空样带在与静态和动态情景结合使用时，有潜力解决环境变化的遗留影响，并通过微生物群落结构、组成和多样性的变化为未来环境情景提供信息。
