Rafalska Adrianna, Walkiewicz Anna, Osborne Bruce, Klumpp Katja, Bieganowski Andrzej
Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
Sci Total Environ. 2023 May 1;871:162127. doi: 10.1016/j.scitotenv.2023.162127. Epub 2023 Feb 9.
Grassland soils are climate-dependent ecosystems that have a significant greenhouse gas mitigating function through their ability to store large amounts of carbon (C). However, what is often not recognized is that they can also exhibit a high methane (CH) uptake capacity that could be influenced by future increases in atmospheric carbon dioxide (CO) concentration and variations in temperature and water availability. While there is a wealth of information on C sequestration in grasslands there is less consensus on how climate change impacts on CH uptake or the underlying mechanisms involved. To address this, we assessed existing knowledge on the impact of climate change components on CH uptake by grassland soils. Increases in precipitation associated with soils with a high background soil moisture content generally resulted in a reduction in CH uptake or even net emissions, while the effect was opposite in soils with a relatively low background moisture content. Initially wet grasslands subject to the combined effects of warming and water deficits may absorb more CH, mainly due to increased gas diffusivity. However, in the longer-term heat and drought stress may reduce the activity of methanotrophs when the mean soil moisture content is below the optimum for their survival. Enhanced plant productivity and growth under elevated CO, increased soil moisture and changed nutrient concentrations, can differentially affect methanotrophic activity, which is often reduced by increasing N deposition. Our estimations showed that CH uptake in grassland soils can change from -57.7 % to +6.1 % by increased precipitation, from -37.3 % to +85.3 % by elevated temperatures, from +0.87 % to +92.4 % by decreased precipitation, and from -66.7 % to +27.3 % by elevated CO. In conclusion, the analysis suggests that grasslands under the influence of warming and drought may absorb even more CH, mainly because of reduced soil water contents and increased gas diffusivity.
草原土壤是依赖气候的生态系统，通过其储存大量碳（C）的能力，具有显著的温室气体减排功能。然而，人们常常没有认识到的是，它们还可能表现出较高的甲烷（CH₄）吸收能力，这可能会受到未来大气二氧化碳（CO₂）浓度增加以及温度和水分可利用性变化的影响。虽然关于草原碳固存的信息丰富，但对于气候变化如何影响CH₄吸收或所涉及的潜在机制，人们的共识较少。为了解决这个问题，我们评估了关于气候变化因素对草原土壤CH₄吸收影响的现有知识。与背景土壤湿度较高的土壤相关的降水增加通常会导致CH₄吸收减少甚至净排放，而在背景湿度相对较低的土壤中，效果则相反。最初湿润的草原在变暖与水分亏缺的综合影响下可能吸收更多CH₄，主要是由于气体扩散率增加。然而，从长期来看，当平均土壤湿度低于甲烷氧化菌生存的最佳湿度时，高温和干旱胁迫可能会降低甲烷氧化菌的活性。在CO₂浓度升高、土壤湿度增加和养分浓度变化的情况下，植物生产力和生长的增强会对甲烷氧化活性产生不同影响，而增加氮沉降通常会降低甲烷氧化活性。我们的估计表明，草原土壤中的CH₄吸收可能因降水增加而从-57.7%变为+6.1%，因温度升高而从-37.3%变为+85.3%，因降水减少而从+0.87%变为+92.4%，因CO₂浓度升高而从-66.7%变为+27.3%。总之，分析表明，在变暖和干旱影响下的草原可能吸收更多CH₄，主要是因为土壤含水量降低和气体扩散率增加。
