Fan Rong, Morozumi Tomoki, Maximov Trofim C, Sugimoto Atsuko
Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
Institute for Biological Problems of Cryolithozone, Siberian Blanch of Russian Academy of Sciences, Yakutsk, Sakha, Russia.
PeerJ. 2018 Sep 20;6:e5374. doi: 10.7717/peerj.5374. eCollection 2018.
Although stable carbon isotopic composition (δC) of plants has been widely used to indicate different water regimes in terrestrial ecosystems over the past four decades, the changes in the plant δC value under waterlogging have not been sufficiently clarified. With the enhanced global warming in recent years, the increasing frequency and severity of river floods in Arctic regions lead to more waterlogging on willows that are widely distributed in river lowland. To investigate the δC changes in plants under different water conditions (including waterlogging), we measured the δC values in the leaves of willows with three species, , , and , and also monitored changes in plant physiology, under several major flooding conditions in Northeastern Siberia. The foliar δC values of willows varied, ranging from -31.6 to -25.7‰ under the different hydrological status, which can be explained by: (i) under normal conditions, the foliar δC values decrease from dry (far from a river) to wet (along a river bank) areas; (ii) the δC values increase in frequently waterlogged areas owing to stomatal closure; and (iii) after prolonged flooding periods, the δC values again decrease, probably owing to the effects of not only the closure of stomata but also the reduction of foliar photosynthetic ability under long period of waterlogging. Based on these results, we predict that plant δC values are strongly influenced by plant physiological responses to diverse hydrological conditions, particularly the long periods of flooding, as occurs in Arctic regions.
尽管在过去四十年里，植物的稳定碳同位素组成（δC）已被广泛用于指示陆地生态系统中不同的水分状况，但淹水条件下植物δC值的变化尚未得到充分阐明。近年来，随着全球变暖加剧，北极地区河流洪水发生的频率和强度不断增加，导致广泛分布于河流低地的柳树遭受更多淹水。为了研究不同水分条件（包括淹水）下植物的δC变化，我们在西伯利亚东北部的几种主要洪水条件下，测量了三种柳树（、、）叶片的δC值，并监测了植物生理变化。柳树叶片的δC值各不相同，在不同水文状况下，其范围为-31.6‰至-25.7‰，原因如下：（i）在正常条件下，叶片δC值从干燥（远离河流）区域向湿润（河岸）区域降低；（ii）由于气孔关闭，在频繁淹水区域δC值升高；（iii）长时间淹水后，δC值再次降低，这可能不仅是由于气孔关闭，还因为长时间淹水导致叶片光合能力下降。基于这些结果，我们预测植物δC值受植物对不同水文条件，特别是北极地区出现的长时间洪水的生理响应影响很大。
