Rinnan Riikka, Impiö Miia, Silvola Jouko, Holopainen Toini, Martikainen Pertti J
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211, Kuopio, Finland.
Oecologia. 2003 Nov;137(3):475-83. doi: 10.1007/s00442-003-1366-5. Epub 2003 Sep 6.
O(3) concentrations in the troposphere are rising and those in the stratosphere decreasing, the latter resulting in higher fluxes of solar ultraviolet-B (UV-B) radiation to the earth's surface. We assessed whether the fluxes of CO(2) and CH(4) are altered by enhanced UV-B radiation or elevated tropospheric O(3) concentrations in boreal peatland microcosms (core depth 40 cm, diameter 10.5 cm) with different vegetation cover. At the end of the UV-B experiment which lasted for a growing season, net CO(2) exchange (NEE) and dark ecosystem respiration ( R(TOT)) were sevenfold higher, and CH(4) efflux 12-fold higher, in microcosms with intact vegetation dominated by Eriophorum vaginatum L. and Sphagnum spp., compared to microcosms from which we removed E. vaginatum. Vegetation treatment had minor effects on CH(4) production and consumption potentials in the peat, suggesting that the large difference in CH(4) efflux is mainly due to efficient CH(4) transport via the aerenchyma of E. vaginatum. Ambient UV-B supplemented with 30% and elevated O(3) concentrations (100 and 200 ppb, for 7 weeks) significantly increased R(TOT) in both vegetation treatments. Elevated O(3) concentrations reduced NEE over time, while UV-B had no clear effects on the fluxes of CO(2) or CH(4) in the cloudy summer of the study. Field experiments are needed to assess the significance of increasing UV-B radiation and elevated tropospheric O(3) concentration on peatland gas exchange in the long-term.
对流层中臭氧（O₃）的浓度在上升，而平流层中的浓度在下降，后者导致到达地球表面的太阳紫外线B（UV-B）辐射通量增加。我们评估了在具有不同植被覆盖的北方泥炭地微观系统（核心深度40厘米，直径10.5厘米）中，增强的UV-B辐射或对流层臭氧浓度升高是否会改变二氧化碳（CO₂）和甲烷（CH₄）的通量。在持续一个生长季节的UV-B实验结束时，与去除了细叶泥炭藓（Eriophorum vaginatum L.）的微观系统相比，以细叶泥炭藓和泥炭藓属（Sphagnum spp.）为主的完整植被微观系统中的净CO₂交换（NEE）和暗生态系统呼吸（R(TOT)）高出7倍，CH₄排放高出12倍。植被处理对泥炭中CH₄的产生和消耗潜力影响较小，这表明CH₄排放的巨大差异主要是由于通过细叶泥炭藓的通气组织进行的高效CH₄传输。补充30%的环境UV-B和升高的臭氧浓度（100和200 ppb，持续7周）在两种植被处理中均显著增加了R(TOT)。随着时间的推移，升高的臭氧浓度降低了NEE，而在研究的多云夏季，UV-B对CO₂或CH₄通量没有明显影响。需要进行野外实验来长期评估增加的UV-B辐射和升高的对流层臭氧浓度对泥炭地气交换的重要性。
