Department of Environmental and Biological Sciences, University of Eastern Finland, P. O. Box 1672, 70211, Kuopio, Finland.
Department of Environmental and Biological Sciences, University of Eastern Finland, P. O. Box 1672, 70211, Kuopio, Finland.
Environ Pollut. 2021 Jun 1;278:116830. doi: 10.1016/j.envpol.2021.116830. Epub 2021 Mar 8.
Increased tropospheric ozone (O) concentrations in boreal forests affect the emission of biogenic volatile organic compounds (BVOCs), which play crucial roles in biosphere-atmosphere feedbacks. Although it has been well documented that BVOC emissions are altered in response to elevated O, consequent effects on the carbon budget have been largely unexplored. Here, we studied the effects of elevated O (80 nmol mol) on diurnal variation of BVOC emissions and gas exchange of CO from above- and belowground parts of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) and further investigated effects on the carbon budget. In spring, elevated O decreased BVOC emissions and net photosynthesis rate (Pn) from above-ground parts of both species. As BVOC emissions have a causal relationship with dormancy recovery, O-induced decreases in BVOC emissions indicated the inhibition of dormancy recovery. Contrary to the spring results, in summer BVOC emissions from aboveground parts were increased in response to elevated O in both species. Decreases in Pn indicated O stress. O-induced monoterpene emissions from aboveground were the main volatile defense response. Elevated O had little effect on BVOC emissions from belowground parts of either species in spring or summer. In spring, elevated O decreased the proportion of carbon emitted as BVOCs relative to that assimilated by photosynthesis (the proportion of BVOC-C loss) at the soil-plant system levels in both species. In summer, elevated O resulted in a net CO-C loss at the soil-plant system level of Scots pine. During this process, O-induced BVOC-C loss can represent a significant fraction of carbon exchange between the atmosphere and Scots pine. In Norway spruce, the effects of O were less pronounced. The current results highlight the need for prediction of BVOC emissions and their contributions to the carbon budget in boreal forests under O stress.
大气中臭氧（O）浓度的增加会影响生物挥发性有机化合物（BVOC）的排放，这些化合物在生物圈-大气反馈中起着至关重要的作用。尽管已经有充分的文献证明，BVOC 排放会因 O 升高而发生变化，但对碳预算的后续影响在很大程度上仍未得到探索。在这里，我们研究了 O（80 nmol/mol）升高对挪威云杉（Picea abies）和欧洲赤松（Pinus sylvestris）地上和地下部分 CO 气体交换和 BVOC 排放日变化的影响，并进一步研究了对碳预算的影响。在春季，O 升高会降低两种物种地上部分的 BVOC 排放和净光合速率（Pn）。由于 BVOC 排放与休眠恢复有因果关系，O 诱导的 BVOC 排放减少表明休眠恢复受到抑制。与春季的结果相反，在夏季，两种物种地上部分的 BVOC 排放都因 O 升高而增加。Pn 的降低表明 O 胁迫。O 诱导的单萜从地上部分排放是主要的挥发性防御反应。O 对春季两种物种地下部分的 BVOC 排放几乎没有影响。在春季，O 降低了两种物种土壤-植物系统水平上 BVOC 同化碳的比例（BVOC-C 损失比例）。在夏季，O 导致欧洲赤松土壤-植物系统水平上的净 CO-C 损失。在此过程中，O 诱导的 BVOC-C 损失可能代表大气和欧洲赤松之间碳交换的重要部分。在挪威云杉中，O 的影响不那么明显。目前的结果强调了在 O 胁迫下预测北方森林 BVOC 排放及其对碳预算的贡献的必要性。
