State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, 100101, China.
Centre for Planetary Health and Food Security and School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia.
Environ Sci Pollut Res Int. 2023 Apr;30(19):55635-55648. doi: 10.1007/s11356-023-26295-9. Epub 2023 Mar 10.
Forests play a crucial role in regulating regional climate and mitigating local air pollution, but little is known about their responding to such changes. This study aimed to examine the potential responses of Pinus tabuliformis, the major coniferous tree species in the Miyun Reservoir Basin (MRB), along an air pollution gradient in Beijing. Tree rings were collected along a transect, and ring width (basal area increment, BAI) and chemical characteristics were determined and related to long-term climatic and environmental records. The results showed that Pinus tabuliformis showed an overall increase in intrinsic water-use efficiency (iWUE) at all sites, but the relationships between iWUE and BAI differed among the sites. The contribution of atmospheric CO concentration (c) to tree growth was significant at the remote sites (> 90%). The study found that air pollution at these sites might have caused further stomatal closure, as evidenced by the higher δC levels (0.5 to 1‰ higher) during heavy pollution periods. The analysis of tree ring δN also revealed the potential of using δN to fingerprint major nitrogen (N) deposition, as shown in the increasing tree ring δN, and major nitrogen losses due to denitrification and leaching, as shown in the higher δN in tree rings during heavy rainfall events. Overall, the gradient analysis indicated the contributions of increasing c, increasing water deficit and elevated air pollution to tree growth and forest development. The different BAI trajectories suggested that Pinus tabuliformis has the ability to adapt to the harsh environment in the MRB.
森林在调节区域气候和减轻当地空气污染方面发挥着关键作用，但人们对它们对这些变化的响应知之甚少。本研究旨在探讨大气污染梯度下北京密云水库流域（MRB）主要针叶树种油松的潜在响应。在沿一条样带采集了树木年轮，并测定了年轮宽度（基面积增量，BAI）和化学特征，并与长期气候和环境记录相关联。结果表明，油松在所有地点的内在水分利用效率（iWUE）总体呈上升趋势，但 iWUE 与 BAI 之间的关系在不同地点有所不同。大气 CO 浓度（c）对树木生长的贡献在偏远地点（>90%）显著。研究发现，这些地点的空气污染可能导致进一步的气孔关闭，这从重污染期间较高的 δC 水平（高 0.5 至 1‰）得到了证明。对树木年轮 δN 的分析还揭示了利用 δN 来识别主要氮（N）沉积的潜力，这体现在树木年轮 δN 的增加以及由于反硝化和淋失而导致的主要氮损失，在强降雨事件中树木年轮 δN 较高。总体而言，梯度分析表明，c 的增加、水分亏缺的增加和空气污染的增加对树木生长和森林发育有贡献。不同的 BAI 轨迹表明，油松有能力适应 MRB 的恶劣环境。
