Shifts in microbial trophic strategy explain different temperature sensitivity of CO2 flux under constant and diurnally varying temperature regimes
Shifts in microbial trophic strategy explain different temperature sensitivity of CO2 flux under constant and diurnally varying temperature regimes
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微生物营养策略的变化解释了在恒定和昼夜变化的温度条件下二氧化碳通量的不同温度敏感性
DOI：
10.1093/femsec/fix063
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发表时间：
2017-05-01
影响因子：
4.2
通讯作者：
Liang, Chao
中科院分区：
文献类型：
--
作者：
Bai, Zhen;Xie, Hongtu;Liang, Chao
了解土壤CO2通量的温度敏感性（Q（10））对于预测生态系统对气候变化的响应至关重要。然而，在目前的地球系统模型下，变暖对微生物CO2呼吸的影响仍然知之甚少，部分原因是有机物分解的热驯化。以4种不同林分、不同土层的森林土壤为材料，进行了恒温和日变温培养117 d的试验。我们的研究结果表明，Q（10）是更大的变化比恒定的温度制度。这种区别最有可能是由于恒定的高和不同的高温处理之间的可用碳消耗的差异，导致显着较高的异养呼吸率在不同的高温制度。基于使用Illumina的16S rRNA基因测序数据，与恒定高处理相比，不同的高温制度具有更高的原核生物α多样性，更受共生策略者的支配，并维持了独特的群落组成。我们发现Q（10）和微生物营养功能团之间存在紧密的耦合关系：共生原核生物对高Q（10）值有积极的响应，而寡养生物则表现出消极的响应。植被和土壤层的影响一致支持的CO2通量的温度敏感性决定的共生与贫营养策略。我们的观察表明，将原核生物的功能性状，如互养和寡养之间的转变，是我们的理解微生物介导的土壤有机碳循环的热驯化的基础。包括微生物功能的变化可能会提供潜在的，以提高我们的预测在森林生态系统中的微生物群落和CO2排放的变化环境的反应。
Understanding soil CO2 flux temperature sensitivity (Q(10)) is critical for predicting ecosystem-level responses to climate change. Yet, the effects of warming on microbial CO2 respiration still remain poorly understood under current Earth system models, partly as a result of thermal acclimation of organic matter decomposition. We conducted a 117-day incubation experiment under constant and diurnally varying temperature treatments based on four forest soils varying in vegetation stand and soil horizon. Our results showed that Q(10) was greater under varying than constant temperature regimes. This distinction was most likely attributed to differences in the depletion of available carbon between constant high and varying high-temperature treatments, resulting in significantly higher rates of heterotrophic respiration in the varying high-temperature regime. Based on 16S rRNA gene sequencing data using Illumina, the varying high-temperature regime harbored higher prokaryotic alpha-diversity, was more dominated by the copiotrophic strategists and sustained a distinct community composition, in comparison to the constant-high treatment. We found a tightly coupled relationship between Q(10) and microbial trophic guilds: the copiotrophic prokaryotes responded positively with high Q(10) values, while the oligotrophs showed a negative response. Effects of vegetation stand and soil horizon consistently supported that the copiotrophic vs oligotrophic strategists determine the thermal sensitivity of CO2 flux. Our observations suggest that incorporating prokaryotic functional traits, such as shifts between copiotrophy and oligotrophy, is fundamental to our understanding of thermal acclimation of microbially mediated soil organic carbon cycling. Inclusion of microbial functional shifts may provide the potential to improve our projections of responses in microbial community and CO2 efflux to a changing environment in forest ecosystems.