张掖湿地芦苇蒸腾速率与叶性状关系对土壤水分的响应

The relationship between transpiration rate and leaf traits of Phragmites australis in response to soil moisture in Zhangye wetland

了解植物蒸腾速率与叶性状关系对环境因子响应,对于探索植物碳水代谢关系和叶性状构建模式之间耦合的生理生态学机制具有重要的意义。选择张掖国家湿地公园的沼泽湿地为实验地,按湿地中心向边缘土壤水分依次递减的规律设置Ⅰ(95.70%)、Ⅱ(67.50%)、Ⅲ(50.70%)、Ⅳ(30.17%)4个土壤含水量样地,研究了不同土壤水分影响下芦苇(Phragmites australis)的蒸腾速率与叶面积、叶厚度的关系。结果表明:随着土壤含水量下降,湿地植被群落的高度、盖度和地上生物量均呈现先增加后降低的趋势,芦苇的叶面积(LA)、叶片蒸腾速率(Tr)呈现先增加后降低的趋势,而叶厚度呈增加趋势;芦苇的Tr与LA关系在样地Ⅰ和样地Ⅳ存在极显著正相关(P<0.01),Tr与叶厚度关系在样地Ⅰ存在极显著正相关(P<0.01),而在样地Ⅳ呈极显著负相关(P<0.01);在样地Ⅱ和Ⅲ,芦苇的Tr与LA、叶厚度之间呈显著正相关(P<0.05)。在土壤水分饱和与土壤水分胁迫的样地,芦苇分别采取了小而薄和小而厚的叶片构建模式,实现了低Tr;而在土壤水分适中的样地芦苇采取了大而薄的叶片资源投资策略,实现了较高的Tr,反映了植物种群适应异质生境的表型可塑性机制。

The response of the relationship between transpiration rate and leaf traits to environmental factors is important for clarifying ecophysiological coupling mechanism between carbohydrate metabolism and constructing modes of leaf traits. In this study, we investigated the relationships between transpiration rate （Tr） and leaf area and leaf thickness ofPhragmites australis under different soil moisture levels along a transect from the central to the edge of the wetland in Zhangye National Wetland Park, Gansu Province, China. Four plots were established withdifferent soil moisture levels as Ⅰ （95.70%）, Ⅱ （67.50%）, Ⅲ （50.70%） and Ⅳ （30.17%）. The results showed that the height, coverage, and aboveground biomass of the wetland community showed an increase and then decrease trend with the decreases of soil moisture. The leaf area and Tr presented an increase and then decrease trend, while the leaf thickness displayed an increasing trend from plots Ⅰ to Ⅳ. Tr was significantly positively correlated with leaf area in plots Ⅰ and Ⅳ （P〈0.01） and leaf thickness in plot Ⅰ （P〈0.01）, but negatively correlated with leaf thickness in plot Ⅳ （P〈0.01）. Meanwhile, positive correlations between Tr and leaf area, leaf thickness were found in plots Ⅱ and Ⅲ （P〈0.05）. In plots with saturated soil moisture （Ⅰ） andserious soil water deficit （Ⅳ）, Phragmites australis built up through a small thin leaf mode, and a small thick leaf mode, respectively, to keep lowerTr. In the moderate soil water condition （Ⅱ, Ⅲ）, they built up through a large thin leaf resource investment strategy to achieve higher Tr. All these changes in plants reflect the phenotypic plasticity of plant adaptation to heterogeneous habitats.