Peatland and Soil Ecology Research Group, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland.
Peatland and Soil Ecology Research Group, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland.
Sci Total Environ. 2024 Nov 15;951:175738. doi: 10.1016/j.scitotenv.2024.175738. Epub 2024 Aug 23.
Climate change and the associated increased frequency of extreme weather events are likely to alter the emissions of biogenic volatile organic compounds (BVOCs) from boreal peatlands. Hydrologically sensitive Sphagnum mosses are keystone species in boreal peatland ecosystems that are known to emit various BVOCs. However, it is not known how their emissions respond to seasonal droughts. In this study, we quantified the effect of severe drought, and subsequent recovery, on the BVOC emissions from Sphagnum mosses using mesocosms originating from wet open and naturally drier treed boreal fens and bogs. Here we report the emissions of 30 detected BVOCs, of which isoprene was the most abundant with an average flux rate of 5.6 μg m h (range 0-31.9 μg m h). The experimental 43-day ecohydrological drought reduced total BVOC and isoprene emissions. In addition, in mesocosms originating from bogs, sesquiterpene emissions decreased with the drought, while the emissions of green leaf volatiles were induced. Sesquiterpene emissions remained low even six weeks after rewetting, indicating a long and limited recovery from the drought. Our results further imply that long-term exposure to deep water tables does not decrease sensitivity of Sphagnum to an extreme drought; we did not detect differences in the emission rates or drought responses between Sphagna originating from wet open and naturally drier treed habitats. Yet, the differences between fen and bog originating Sphagna indicate local variability in the BVOC quality changes following drought, potentially altering the climate feedback of boreal peatland BVOC emissions.
气候变化和与之相关的极端天气事件的频率增加，可能会改变北方泥炭地生源挥发性有机化合物（BVOC）的排放。水文敏感的泥炭藓是北方泥炭地生态系统中的关键物种，已知它们会排放各种 BVOC。然而，它们的排放如何应对季节性干旱还不得而知。在这项研究中，我们使用源自湿润开阔和自然干燥的树木繁茂的北方湿地和泥沼的中观模型，量化了严重干旱及其随后的恢复对泥炭藓 BVOC 排放的影响。在这里，我们报告了 30 种检测到的 BVOC 的排放情况，其中异戊二烯的丰度最高，平均通量为 5.6μg m h（范围为 0-31.9μg m h）。为期 43 天的生态水文干旱实验减少了总 BVOC 和异戊二烯的排放。此外，在源自泥沼的中观模型中，随着干旱的进行，倍半萜烯的排放减少，而绿叶挥发性物质的排放则增加。即使在重新润湿六周后，倍半萜烯的排放仍然很低，表明干旱的恢复过程漫长且有限。我们的研究结果进一步表明，长期暴露于深水位并不会降低泥炭藓对极端干旱的敏感性；我们没有检测到源自湿润开阔和自然干燥的树木繁茂生境的泥炭藓在排放率或干旱响应方面的差异。然而，源自湿地和泥沼的泥炭藓之间的差异表明，在干旱之后，BVOC 质量变化存在局部变异性，这可能会改变北方泥炭地 BVOC 排放的气候反馈。
