太行山南麓3种典型灌木枝-叶功能性状及其适应策略

Branch-leaf functional traits and adaptation strategies of three shrubs on the southern foot of Taihang Mountains,North China

研究荆条、扁担杆和酸枣枝条水力结构和叶片功能性状,探讨其适应策略,为太行山区植被恢复提供理论依据。以成龄荆条、扁担杆和酸枣为研究对象,测定多年生枝条水力结构,包括边材比导率、叶比导率、胡伯尔值和气穴化栓塞程度等,以及多年生枝条叶片厚度、比叶面积、叶片大小、水势、蒸腾速率和气孔导度日变化。利用光学显微镜和扫描电镜测定木质部导管和纹孔解剖性状。结果表明:1)荆条水力直径和纹孔密度均显著高于扁担杆和酸枣,因此荆条具有较高的水分传输效率,且荆条具有较高的气孔导度和蒸腾速率,体现出快速获取资源的适应策略。2)扁担杆导管水力直径较小、比导率较低,且叶片厚度显著高于荆条和酸枣,比叶面积显著低于荆条和酸枣,体现出较为保守的资源获取策略。3)酸枣水力直径和比导率最小,但是其抗气穴化栓塞能力最强,且水势日变幅最大,可忍耐较低的水势。另外酸枣比叶面积显著高于荆条和扁担杆,且具有较高的气孔导度和蒸腾速率,表明酸枣具有较强的碳获取能力。3种灌木具有不同的功能性状从而表现出多样化的适应策略,占据不同的生态位,因此可以较好的适应太行山区严峻的环境。。

To provide theoretical basis for vegetation restoration in Taihang Mountain,the study measured branch and leaf functional traits and discussed adaptation strategies of Vitex negundo,Grewia biloba and Ziziphus jujuba.The hydraulic architecture of stems from perennial shoots were determined,including sapwood specific hydraulic conductivity,leaf specific hydraulic conductivity,Huber value and drought induced cavitation.In addition,Leaf thickness,specific leaf area,leaf size,leaf water potential,and the diurnal transpiration rate and stomatal conductance were also measured.Vessel and pit traits were determined by light microscopy and scanning electron microscopy.Results showed that:1)The hydraulic weighted vessel diameters and pit density of V.negundo are significantly higher than those of G.biloba and Z.jujuba,therefore V.negundo shows higher water transport efficiency,and also V.negundo exhibits higher stomatal conductance and transpiration rate,which reflects a rapid resource acquisition adaptive strategy.2)G.biloba has lower hydraulic weighted vessel diameter and specific hydraulic conductivity,and leaf thickness is significantly higher than that of V.negundo and Z.jujuba,and the specific leaf area is significantly lower than that of V.negundo and Z.jujuba,reflecting a relatively conservative resource acquisition strategy.3)Z.jujuba exhibits the lowest hydraulic weighted diameter and specific hydraulic conductivity of vessels,while it shows the strongest ability to resistant drought induced cavitation,as well as the largest daily variation of leaf water potential,and can tolerate lower water potential.In addition,the specific leaf area of Z.jujuba is significantly higher than that of V.negundo and G.biloba,and also it exhibits higher stomatal conductance and transpiration rate,indicating that it has a strong carbon harvesting ability.Three shrub species exhibit different functional traits,indicating diversified adaptation strategies.They occupy different ecological niche,and thus they can better adapt to the stress environment in Taihang Mountain.