Temperature and water controls on vegetation emergence, microbial dynamics, and soil carbon and nitrogen fluxes in a high Arctic tundra ecosystem
Temperature and water controls on vegetation emergence, microbial dynamics, and soil carbon and nitrogen fluxes in a high Arctic tundra ecosystem
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DOI：
10.1111/j.1365-2435.2012.02056.x
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发表时间：
2012-12-01
影响因子：
5.2
通讯作者：
Jones, Davey L.
中科院分区：
文献类型：
--
作者：
Glanville, Helen C.;Hill, Paul W.;Jones, Davey L.
1.北极苔原生态系统含有全球土壤碳（C）储量的14%，这些碳（C）储量正变得容易分解。北极土壤有机质（SOM）含有大量的古老的、不稳定的、高分子量（MW）的C化合物，这些化合物在土壤保持冻结状态时不会分解。气候变化改变了北极地区的土壤温度和水分状况，然而，这些变化对碳分解和储存的影响尚不清楚.我们调查了植被的出现，微生物动态和营养物质通量在高北极斯瓦尔巴群岛上的积雪融化的现场和实验室研究。使用细菌和古细菌的遗传物质（16 S rRNA）和氨氧化基因，微生物群落进行了量化的横断面在整个活跃的融雪锋。利用C-14标记的低分子量和高分子量化合物测定了土壤温度和含水量对土壤有机质分解速率的影响.植被和地下微生物群落，在该领域，迅速作出反应，在72小时内观察到的融雪养分供应和土壤呼吸峰值。温度强烈驱动北极早期生长季节C动态。我们认为，融雪后的营养高峰，加上雪下区较高水平的DNA，是由于前几年细菌和古细菌的分解。我们表明，在实验室中，当土壤解冻，矿化的柠檬酸C（高分子量）化合物是敏感的土壤水分，但不增加温度。相反，低分子量化合物表现出对温度和土壤水分的敏感性。我们认为，如果未来土壤含水量在气候变化下增加，高分子量化合物可能会变得更容易分解，向大气中释放更多的C。
1. Arctic tundra ecosystems contain 14% of the global soil carbon (C) store which is becoming vulnerable to decomposition. Arctic soil organic matter (SOM) contains large amounts of old, recalcitrant, high molecular weight (MW) C compounds which are protected from decomposition whilst soils remain frozen. Climatic change alters soil temperature and water regimes in the Arctic, however, the impact of these changes on C decomposition and storage is poorly understood.2. We investigated vegetation emergence, microbial dynamics and nutrient fluxes in response to snow melt on the high Arctic Svalbard archipelago using field and laboratory studies. Using bacterial and archaeal genetic material (16S rRNA) and ammonia-oxidising genes, microbial communities were quantified in transects across the active snow melt front. The effects of soil temperature and water content on SOM decomposition rates were measured using C-14-labelled low and high MW compounds.3. Vegetation and below-ground microbial communities, in the field, responded rapidly with peaks in nutrient availability and soil respiration observed within 72 h of snowmelt. Temperature strongly drives early growing season C dynamics in the Arctic. We suggest the nutrient peaks following snowmelt, coupled with higher levels of DNA in the subniveal zone are due to the decomposition of bacteria and archaea from previous years.4. We show, in the laboratory, when soils thaw, mineralisation of recalcitrant C (high MW) compounds was sensitive to soil water but not to increasing temperatures. In contrast, low MW compounds exhibited sensitivity to both temperature and soil water. We suggest that if future soil water content increases under climate change, high MW compounds could become more susceptible to decomposition, releasing more C to the atmosphere.