Biotic interactions mediate soil microbial feedbacks to climate change
Biotic interactions mediate soil microbial feedbacks to climate change
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DOI：
10.1073/pnas.1502956112
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发表时间：
2015-06-02
影响因子：
11.1
通讯作者：
Bradford, Mark A.
中科院分区：
文献类型：
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作者：
Crowther, Thomas W.;Thomas, Stephen M.;Bradford, Mark A.
土壤微生物对有机物质的分解每年产生50-75pg的碳排放到大气中，相当于全球人为排放量的7.5-9倍。这一过程对全球变化因素很敏感，全球变化因素可能会推动碳循环-气候反馈，并有可能加剧大气变暖。虽然相互作用的全球变化因素对土壤微生物活性的影响一直是一个广泛的生态学焦点，但在气候反馈研究中很少考虑种间相互作用的调节效应。我们在一项长期的、基于现场的全球变化研究中，探索了土壤动物调节微生物对气候变暖和氮素增加的反应的潜力。全球变化因素的组合缓解了自下而上对真菌生长的限制，在没有土壤动物的情况下刺激了酶的产生和分解速度。然而，真菌生物量的增加也刺激了土壤无脊椎动物的消耗速率，使微生物过程速率恢复到环境条件下观察到的水平。我们的结果支持了当代的理论，即土壤食物网中的自上而下控制只有在没有自下而上限制的情况下才是明显的。因此，当全球变化因素缓解了对微生物活动的自下而上的限制时，自上而下的控制成为一种越来越重要的监管力量，有能力抑制正碳循环-气候反馈的强度。
Decomposition of organic material by soil microbes generates an annual global release of 50-75 Pg carbon to the atmosphere, similar to 7.5-9 times that of anthropogenic emissions worldwide. This process is sensitive to global change factors, which can drive carbon cycle-climate feedbacks with the potential to enhance atmospheric warming. Although the effects of interacting global change factors on soil microbial activity have been a widespread ecological focus, the regulatory effects of interspecific interactions are rarely considered in climate feedback studies. We explore the potential of soil animals to mediate microbial responses to warming and nitrogen enrichment within a long-term, field-based global change study. The combination of global change factors alleviated the bottom-up limitations on fungal growth, stimulating enzyme production and decomposition rates in the absence of soil animals. However, increased fungal biomass also stimulated consumption rates by soil invertebrates, restoring microbial process rates to levels observed under ambient conditions. Our results support the contemporary theory that top-down control in soil food webs is apparent only in the absence of bottom-up limitation. As such, when global change factors alleviate the bottom-up limitations on microbial activity, top-down control becomes an increasingly important regulatory force with the capacity to dampen the strength of positive carbon cycle-climate feedbacks.