Physiological mechanism for the reduction in soil water in poplar (Populus deltoides) plantations in Dongting Lake wetlands
Physiological mechanism for the reduction in soil water in poplar (Populus deltoides) plantations in Dongting Lake wetlands
复制标题
洞庭湖湿地杨树人工林土壤水分减少的生理机制
DOI：
10.1007/s11273-013-9319-1
复制
发表时间：
2014-02-01
影响因子：
1.8
通讯作者：
Zhang, Canming
中科院分区：
文献类型：
--
作者：
Li, Youzhi;Qin, Hongyan;Zhang, Canming
大规模植树造林的使用引起了人们对不同生态系统中对当地环境的负面影响的日益关注。然而，湿地乔木人工林减少土壤水分的生理机制尚不清楚。本研究旨在探讨杨树人工林对土壤水分的影响及其生理机制。为此，我们对洞庭湖区中国湿地11年生和5年生杨树和芦苇的土壤水分含量(SWC)、植物光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和水分利用效率(WUE)进行了为期1年的定位调查。湿地土壤水分含量芦苇最高，11年生次之，5年生最低，说明杨树人工林湿地土壤水分含量较低。5~7月，芦苇的净光合速率显著高于两种杨树林，但不同树龄杨树的净光合速率差异不显著。总体而言，杨树林分的Gs和Tr较高，WUE较低，说明Gs和Tr是杨林土壤水分较低的关键生理机制。各植被类型的净光合速率、气孔导度和蒸腾速率之间均呈正相关(P<；P<0.01)。这些数据表明，杨树人工林可能会导致湿地向旱地的转变，因为较低的WUE导致了土壤的大量水分流失。这反过来又会对人工林建立后的群落组成和生态系统功能产生影响。
The use of large-scale tree plantations has provoked increasing concern regarding the negative effects on local environments in different ecosystems. However, the physiological mechanism underlying the reduction in soil water by tree plantations in wetlands is not clear. The aims of this study were to investigate the effects of poplar (Populus deltoides) plantations on soil water content and to elucidate the underlying physiological mechanisms. To this end, we conducted a 1-year fixed-plot investigation of soil water content (SWC), plant photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and water-use efficiency (WUE) of individual leaves of 11- and 5-year-old poplars and of reed (Triarrherca sacchariflora, a native herbaceous plant) in the Dongting Lake wetlands, China. SWC was highest in reed, intermediate in 11-year-old poplar, and lowest in 5-year-old poplar, suggesting that poplar plantations produce a lower soil water content in wetlands. From May to July, Pn was significantly higher in reed than in the two poplar stands, but did not differ between the different-aged poplars. As a whole, Gs and Tr were higher, but WUE was lower, in the poplar stands than in reed during the growing season, indicating that Gs and Tr are the key physiological mechanisms associated with the lower soil water in poplar stands. Relationships among Pn, Gs, and Tr showed positive correlations (P< 0.01) for each type of vegetation. These data suggest that poplar plantations may cause the transformation of wetlands into dry land due to a lower WUE leading to a massive water loss from soil. This, in turn, would have an influence on community composition and ecosystem function after establishment of the plantations.