Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2022 Jan 15;804:150032. doi: 10.1016/j.scitotenv.2021.150032. Epub 2021 Sep 1.
Mountainous alpine ecosystems are sensitive to global change, where soil nutrient content would potentially vary under current climate change background, and thus possibly influence the activity of nitrifiers and denitrifiers, as well as NO emissions. However, within mountainous alpine ecosystems, the potential variation of soil nutrients under current global change and the consequence to NO emission from nitrification and denitrification are still unclarified, hampering a comprehensive understanding of the feedback mechanisms between the nitrogen cycle and climate change. In order to fill this knowledge gap, we selected alpine grasslands at three different elevations and investigated the distribution and environmental drivers of nitrifiers and denitrifiers. The results showed that the lowest elevation site tended to have higher total phosphorus (TP) accumulation within the topsoil. The abundance of functional groups, emission of CO and NO, and the NO/CO ratio showed a decreasing trend along elevation. TP was the greatest influence on denitrifier composition (nosZ/narG and nirS/nirK ratios) and considerably influenced nitrifier composition (AOA/AOB ratio), and was significantly correlated to the NO/CO ratio. In microcosms of soils from the highest elevation site, TP addition decreased the ratios of nosZ/narG, nirS/nirK, and AOA/AOB, and increased NO/CO ratio and NO emission, thus contributing to positive climate change feedback. This study indicates the potential for change within the nitrifier and denitrifier communities under current climate change, and highlights the role TP plays in governing nitrification and denitrification in mountainous alpine ecosystems.
高山生态系统对全球变化敏感，在当前气候变化背景下，土壤养分含量可能会发生变化，从而可能影响硝化和反硝化作用以及 NO 排放。然而，在高山生态系统中，当前全球变化下土壤养分的潜在变化及其对硝化和反硝化作用产生的 NO 排放的后果仍不清楚，这阻碍了对氮循环与气候变化之间反馈机制的全面理解。为了填补这一知识空白，我们选择了三个不同海拔高度的高山草原，研究了硝化和反硝化作用的功能类群分布及其环境驱动因子。结果表明，最低海拔处的表层土壤中总磷（TP）的积累量较高。功能群的丰度、CO 和 NO 的排放以及 NO/CO 比值随海拔升高呈下降趋势。TP 对反硝化菌组成（nosZ/narG 和 nirS/nirK 比值）的影响最大，对硝化菌组成（AOA/AOB 比值）的影响也较大，与 NO/CO 比值显著相关。在来自高海拔处的土壤微宇宙中，TP 的添加降低了 nosZ/narG、nirS/nirK 和 AOA/AOB 的比值，增加了 NO/CO 比值和 NO 排放，从而有助于产生积极的气候变化反馈。本研究表明，在当前气候变化下，硝化和反硝化作用的功能类群可能会发生变化，并强调了 TP 在控制高山生态系统中硝化和反硝化作用中的作用。
