Heat-wave effects on greenhouse gas emissions from shallow lake mesocosms
Heat-wave effects on greenhouse gas emissions from shallow lake mesocosms
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DOI：
10.1111/fwb.12930
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发表时间：
2017-07-01
影响因子：
2.7
通讯作者：
Davidson, Thomas A.
中科院分区：
文献类型：
--
作者：
Audet, Joachim;Neif, Erika M.;Davidson, Thomas A.
浅水湖泊是全球碳循环的重要组成部分。因此，重要的是要知道浅水湖泊生态系统将如何应对当前的气候变化。全球变暖不仅影响平均气温，还影响热浪的频率。极端事件对生态系统进程的影响，特别是对温室气体排放的影响，是不确定的。利用世界上运行时间最长的浅水湖实验，我们研究了模拟夏季HW对二氧化碳（CO2），甲烷（CH4）和一氧化二氮（N2O）通量的影响。实验围隔在人工HW之前已经暴露于不同的温度处理和营养负荷下11年。在一般情况下，有一个增加的温室气体排放总量在1个月的人工HW，与显着增加的CO2，CH4和N2O被观察到在浅水湖泊中围生态系统。然而，在营养水平较高的中生态系统中，HW对CO2排放量没有显著影响。此外，数据表明，除了在HW期间温度升高对代谢过程的直接影响外，生物相互作用对温室气体排放产生了显着的控制作用。例如，在低营养水平下，CO2排放量增加与大型植物丰度低有关，而在高营养水平下，浮游植物丰度减少与CO2和CH4排放量增加有关。与可观察到的热浪效应相反，在整个夏季，长期温度处理没有明显的一般效应，这可能是因为适度温度升高的潜在效应，作为压力干扰，被生物相互作用所覆盖。这项研究表明，生物相互作用的作用，需要考虑在全球变暖的背景下对生态系统过程。
Shallow lakes are a key component of the global carbon cycle. It is, therefore, important to know how shallow lake ecosystems will respond to the current climate change. Global warming affects not only average temperatures, but also the frequency of heat waves (HW). The impact of extreme events on ecosystems processes, particularly greenhouse gas (GHG) emissions, is uncertain. Using the world's longest-running shallow lake experiment, we studied the effects of a simulated summer HW on the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The experimental mesocosms had been exposed to different temperature treatments and nutrient loading for 11years prior to the artificial HW. In general, there was an increase in total GHG emissions during the 1-month artificial HW, with a significant increase in CO2, CH4 and N2O being observed in the shallow lake mesocosms. No significant effect of the HW on CO2 emissions could be traced, though, in the mesocosms with high nutrient levels. Furthermore, the data suggested that in addition to the direct effect of increased temperature on metabolic processes during the HW, biotic interactions exerted a significant control of GHG emissions. For example, at low nutrient levels, increased CO2 emissions were associated with low macrophyte abundance, whereas at high nutrient levels, decreased phytoplankton abundance was linked to increased emissions of CO2 and CH4. In contrast to the observable heat-wave effect, no clear general effect of the long-term temperature treatments could be discerned over the summer, likely because the potential effects of the moderate temperature increase, applied as a press disturbance, were overridden by biotic interactions. This study demonstrates that the role of biotic interactions needs to be considered within the context of global warming on ecosystem processes.