中国东部南北样带暖温带区栎属树种叶片形态性状对气候条件的响应

植物叶片的形态性状能够有效地反映生存环境的变化, 并且影响植物的基本行为和功能。该研究通过获取植物标本提供的叶片形态信息, 结合相关分析和标准化主轴分析, 探讨了南北样带暖温带区栎属(Quercus)树种叶片形态性状对气候条件的响应及适应策略。结果表明: 在南北样带暖温带区, 随着气候条件的变化, 栎属树种的叶片形态性状发生显著的变化。随着年平均气温的降低和年日照时数的增加, 栎属树种叶面积增加, 以利于吸收更多的光照辐射, 并增加叶片的边界层阻力, 减少叶片热量的散失; 而叶片分裂程度的增加不仅可以降低热量的散失, 也可以提高叶片液流的波动以增强叶片的生理活动; 叶脉密度随温度的升高、光照强度和降水量的增加而增加, 以响应叶片蒸腾作用的增强, 提高水分的运输能力和叶片的支撑能力。此外, 为适应南北样带暖温带区气候条件的变化, 栎属树种的叶片形成了一系列的形态性状组合, 随着叶面积的增加, 叶柄长度和叶片分裂程度逐渐增加, 而叶脉密度降低; 随着叶片倾向于向长条状发展, 叶柄长度和叶脉密度也随之增加。

Response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China

Aims Plant leaf morphological traits can effectively reflect changes of plant living environments and affect the behaviors and function of plants. Our objective was to reveal the response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China (NSTEC).
Methods We obtained leaf morphometric information by measuring plants in herbariums. We used mathematical methods of correlation analysis and standardized major axis to investigate relationships between leaf morphology and climate factors, as well as correlations among leaf morphological traits.
Important findings With changing climate conditions in the temperate zone of NSTEC, leaf morphological traits of Quercus species changed significantly. Leaf area of Quercus species increased with decreased annual temperature and increased annual sunlight, which helps leaves to absorb more light radiation and reduce the loss of heat. The degree of leaf division can not only decrease heat dissipation from leaves, but can also enhance the fluctuation of sap flow to improve the physiological activities of leaves. Vein density increased with increased temperature and light intensity, improving the water transportation capacity, and increased with increased precipitation, improving the supporting ability of leaves. In addition, in order to adapt to the changed climate conditions, Quercus species built a combination of leaf morphological traits, with increased leaf area, petiole length and degree of leaf division, while vein density decreased. Petiole length and vein density also increased with the leaves tending toward an elongated shape.