Tracking the fate of fresh carbon in the Arctic tundra: Will shrub expansion alter responses of soil organic matter to warming?
Tracking the fate of fresh carbon in the Arctic tundra: Will shrub expansion alter responses of soil organic matter to warming?
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DOI：
10.1016/j.soilbio.2018.02.002
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发表时间：
2018-05
影响因子：
9.7
通讯作者：
Laurel Lynch;M. Machmuller;M. F. Cotrufo;Eldor A. Paul;M. Wallenstein
中科院分区：
文献类型：
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作者：
Laurel Lynch;M. Machmuller;M. F. Cotrufo;Eldor A. Paul;M. Wallenstein
北极快速的气候变暖可能会破坏数千年来积累的大量土壤碳(C)的稳定，这可能会放大C-气候反馈。然而，气候诱导的灌木扩张可能会抵消这些损失，如果它们的高质量凋落物(较低的C：N)有效地结合到微生物产品中并稳定在土壤中。另外，增加C输入可通过启动机制促进土壤老有机质(SOM)微生物分解。我们研究了低分子碳(LMW-C)的输入是否诱导了土壤中SOM的启动或保留，在Eriophorum ovinata和Betula nana下的土壤中SOM的启动或保留。Eriophorum ovinata是一种普遍存在的形成草丛的莎草，Betula nana是一种优势灌木，正在扩大其在北极的范围和覆盖率。我们没有从任何一种植被类型下的土壤中发现启动的证据，启动的定义是增加本地SOM存量的分解。然而，在E下面的土壤中，新的LMW-C输入的微生物呼吸是前者的两倍。阴道分泌物比B。Nana，而新的LMW-C输入在地下的保留量在B下面的土壤中高出150%。我们的研究结果突出了灌木生长的土壤在地下保留新的碳输入的非凡能力，这可能会减少随着北极气候变暖而导致的土壤碳流失。
Rapid climate warming in the Arctic threatens to destabilize vast stocks of soil carbon (C) that have accumulated over millennia, which could amplify the C-climate feedback. However, climate-induced shrub expansion may counteract these losses if their higher-quality litter (lower C:N) is efficiently incorporated into microbial products and stabilized within the soil. Alternatively, increased C inputs could stimulate microbial decomposition of old soil organic matter (SOM) through priming mechanisms. We investigated whether inputs of low molecular weight carbon (LMW-C) induced SOM priming or retention in soils underlyingEriophorum vaginatum, an ubiquitous tussock-forming sedge, andBetula nana,a dominant shrub that is expanding its range and coverage across the Arctic. We did not find evidence of priming, defined as an increase in the decomposition of native SOM stocks, from soils underlying either vegetation type. However, microbial respiration of new LMW-C inputs was twice as high in soils underlyingE. vaginatumthanB. nana,while belowground retention of new LMW-C inputs was 150% higher in soils underlyingB. nana.Our results highlight the extraordinary capacity of shrub-colonized soils to retain new C inputs belowground, which may mitigate soil C loss as the Arctic climate warms.