Microbial and Biogeochemical Dynamics in Glacier Forefields Are Sensitive to Century-Scale Climate and Anthropogenic Change
Microbial and Biogeochemical Dynamics in Glacier Forefields Are Sensitive to Century-Scale Climate and Anthropogenic Change
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DOI：
10.3389/feart.2017.00026
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发表时间：
2017-04-03
影响因子：
2.9
通讯作者：
Arndt, Sandra
中科院分区：
文献类型：
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作者：
Bradley, James A.;Anesio, Alexandre M.;Arndt, Sandra
由于全球变暖，最近冰川和冰盖的退缩暴露了微生物迅速定居的前田土壤。这些生态系统在高纬度的碳和养分循环中占主导地位，因为微生物活动推动了这些新暴露土壤中的生物地球化学转化。尽管如此，人们对这些新兴生态系统和相关生物地球化学循环对人类影响引起的环境因素预计变化的反应知之甚少。在这里，我们应用模型SHIMMER定量探索的敏感性，在前场的Midtre Lovenbreen，斯瓦尔巴群岛，未来的气候变化和人为强迫，包括土壤温度，积雪，营养和有机基质沉积。模型结果表明，北极的快速变暖以及有机碳和营养物质沉积的增加可能会影响北极土壤中的主要微生物定居者。变暖和无雪条件的增加导致了细菌产量的增加和生物量的积累，这种积累在整个200年的土壤发育中得以维持。氮沉降刺激生长在第一个50年的土壤发育暴露后。增加沉积的有机碳维持较高的细菌生产率和异养呼吸，导致减少净生态系统生产，从而净CO2从土壤中流出。先锋微生物群落特别容易受到未来变化的影响。由于有机物的异养降解增强，所有未来的气候模拟都鼓励从以外来物为主的年轻土壤（< 40年）转向以微生物为主的老年土壤。至关重要的是，这推动了土壤的矿化，增加了养分的可用性。总的来说，我们表明，人类活动，特别是化石燃料的燃烧和氮和有机碳的沉积增强，有可能大大影响最近暴露的北极土壤在今天和未来几个世纪的生态地球化学发展。当试图准确预测目前大片冰雪覆盖地区暴露的北极土壤的未来命运时，必须承认这些影响。
The recent retreat of glaciers and ice sheets as a result of global warming exposes forefield soils that are rapidly colonized by microbes. These ecosystems are dominant in high-latitude carbon and nutrient cycles as microbial activity drives biogeochemical transformations within these newly exposed soils. Despite this, little is known about the response of these emerging ecosystems and associated biogeochemical cycles to projected changes in environmental factors due to human impacts. Here, we applied the model SHIMMER to quantitatively explore the sensitivity of biogeochemical dynamics in the forefield of Midtre Lovenbreen, Svalbard, to future changes in climate and anthropogenic forcings including soil temperature, snow cover, and nutrient and organic substrate deposition. Model results indicated that the rapid warming of the Arctic, as well as an increased deposition of organic carbon and nutrients, may impact primary microbial colonizers in Arctic soils. Warming and increased snow-free conditions resulted in enhanced bacterial production and an accumulation of biomass that was sustained throughout 200 years of soil development. Nitrogen deposition stimulated growth during the first 50 years of soil development following exposure. Increased deposition of organic carbon sustained higher rates of bacterial production and heterotrophic respiration leading to decreases in net ecosystem production and thus net CO2 efflux from soils. Pioneer microbial communities were particularly susceptible to future changes. All future climate simulations encouraged a switch from allochthonously-dominated young soils (< 40 years) to microbially-dominated older soils, due to enhanced heterotrophic degradation of organicmatter. Critically, this drove remineralisation and increased nutrient availability. Overall, we show that human activity, especially the burning of fossil fuels and the enhanced deposition of nitrogen and organic carbon, has the potential to considerably affect the biogeochemical development of recently exposed Arctic soils in the present day and for centuries into the future. These effects must be acknowledged when attempting to make accurate predictions of the future fate of Arctic soils that are exposed over large expanses of presently ice-covered regions.