Microbial dynamics in a High Arctic glacier forefield: a combined field, laboratory, and modelling approach
Microbial dynamics in a High Arctic glacier forefield: a combined field, laboratory, and modelling approach
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DOI：
10.5194/bg-13-5677-2016
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发表时间：
2016-10-13
期刊：
影响因子：
4.9
通讯作者：
Anesio, Alexandre M.
中科院分区：
文献类型：
--
作者：
Bradley, James A.;Arndt, Sandra;Anesio, Alexandre M.
为了评估微生物和地球化学过程如何相互作用并塑造土壤发育以应对冰川退缩，有必要对冰川前田的土壤发育进行建模。此外，此类模型可以帮助我们预测微生物的生长以及北极土壤在日益无冰的未来的命运。在这里，我们首次将现场采样与实验室分析和数值模型结合起来，研究斯瓦尔巴群岛贫营养前冰期土壤中的微生物群落动态。我们测量了较低的细菌生长率和生长效率（相对于高山冰川前场的估计）以及细菌生长率对土壤温度的高敏感性（相对于温带土壤）。我们利用这些实验室测量结果为新数值模型中的参数值提供信息，并对大约 120 年期间土壤发育的微生物和生物地球化学动力学进行了显着改进的预测。该模型预测了观察到的自养和异养生物量的积累。基因组数据表明，最初的微生物群落以来自冰川环境的细菌为主，而较古老的土壤则存在自养和异养细菌的混合群落。这一发现通过数值模型进行了模拟，表明活跃的微生物群落在固定和回收碳和养分方面发挥着关键作用。我们还证明了外来碳和微生物坏死物在维持有机物质库中的作用，尽管旧土壤中存在高度异养活性。这种结合现场、实验室和建模的方法证明了综合模型数据研究对于理解和量化新兴高北极土壤生态系统中微生物群落功能的价值。
Modelling the development of soils in glacier forefields is necessary in order to assess how microbial and geochemical processes interact and shape soil development in response to glacier retreat. Furthermore, such models can help us predict microbial growth and the fate of Arctic soils in an increasingly ice-free future. Here, for the first time, we combined field sampling with laboratory analyses and numerical modelling to investigate microbial community dynamics in oligotrophic proglacial soils in Svalbard. We measured low bacterial growth rates and growth efficiencies (relative to estimates from Alpine glacier forefields) and high sensitivity of bacterial growth rates to soil temperature (relative to temperate soils). We used these laboratory measurements to inform parameter values in a new numerical model and significantly refined predictions of microbial and biogeochemical dynamics of soil development over a period of roughly 120 years. The model predicted the observed accumulation of autotrophic and heterotrophic biomass. Genomic data indicated that initial microbial communities were dominated by bacteria derived from the glacial environment, whereas older soils hosted a mixed community of autotrophic and heterotrophic bacteria. This finding was simulated by the numerical model, which showed that active microbial communities play key roles in fixing and recycling carbon and nutrients. We also demonstrated the role of allochthonous carbon and microbial necromass in sustaining a pool of organic material, despite high heterotrophic activity in older soils. This combined field, laboratory, and modelling approach demonstrates the value of integrated model-data studies to understand and quantify the functioning of the microbial community in an emerging High Arctic soil ecosystem.