Wang Cunguo, He Junming, Zhao Tian-Hong, Cao Ying, Wang Guojiao, Sun Bei, Yan Xuefei, Guo Wei, Li Mai-He
College of Agronomy, Shenyang Agricultural University, Shenyang, China.
School of Geographical Sciences, Northeast Normal University, Changchun, China.
Front Plant Sci. 2019 Feb 4;10:58. doi: 10.3389/fpls.2019.00058. eCollection 2019.
Leaf size (i.e., leaf surface area and leaf dry mass) profoundly affects a variety of biological carbon, water and energy processes. Therefore, the remarkable variability in individual leaf size and its trade-off with total leaf number in a plant have particularly important implications for understanding the adaption strategy of plants to environmental changes. The various leaf sizes of plants growing in the same habitat are expected to have distinct abilities of thermal regulation influencing leaf water loss and shedding heat. Here, we sampled 16 tree species co-occurring in a temperate forest in northeastern China to quantify the variation of leaf, stomata and twigs traits, and to determine the relationships of leaf size with leaf number and leaf water loss. We examined the right-skewed distributions of leaf size, leafing intensity, stomatal size and stomatal density across species. Leafing intensity was significantly negatively correlated with leaf size, accounting for 4 and 12% of variation in leaf area and leaf mass, respectively. Species was the most important factor in explaining the variation in leaf size (conditional of 0.92 for leaf area and 0.82 for leaf mass). Leaf area and mass significantly increased with increasing diameter of twigs. Leaf water loss was strongly negatively correlated with leaf area and leaf mass during the first four hours of the measurement. Leaf area and leaf mass accounted for 38 and 30% of variation in total leaf water loss, respectively. Leaf water loss rate () was significantly different among tree species and markedly linearly decreased with increasing leaf area and leaf mass for simple-leaved tree species. In conclusion, the existence of a cross-species trade-off between the size of individual leaves and the number of leaves per yearly twig unit was confirmed in that temperate forest. There was strongly negative correlation between leaf water loss and leaf size across tree species, which provides evidences for leaf size in leaf temperature regulation in dry environment with strong radiation. The size-dependent leaf water relation is of central importance to recognize the functional role of leaf size in a changing climate including rapid changes in air temperature and rainfall.
叶片大小（即叶表面积和叶干质量）深刻影响着各种生物碳、水和能量过程。因此，植物个体叶片大小的显著变异性及其与总叶数的权衡对于理解植物适应环境变化的策略具有特别重要的意义。生长在同一栖息地的植物具有不同的叶片大小，预计它们具有不同的热调节能力，从而影响叶片水分流失和散热。在此，我们对中国东北温带森林中共存的16种树种进行采样，以量化叶片、气孔和小枝性状的变异，并确定叶片大小与叶数和叶片水分流失之间的关系。我们研究了不同物种间叶片大小、展叶强度、气孔大小和气孔密度的右偏分布。展叶强度与叶片大小显著负相关，分别解释了叶面积和叶质量变异的4%和12%。物种是解释叶片大小变异的最重要因素（叶面积的条件决定系数为0.92，叶质量的为0.82）。叶面积和叶质量随小枝直径的增加而显著增加。在测量的前四个小时内，叶片水分流失与叶面积和叶质量呈强烈负相关。叶面积和叶质量分别解释了总叶片水分流失变异的38%和30%。叶片水分流失率（）在树种间存在显著差异，对于单叶树种，随着叶面积和叶质量的增加显著线性下降。总之，在该温带森林中证实了单个叶片大小与每年小枝单位叶数之间存在跨物种权衡。树种间叶片水分流失与叶片大小呈强烈负相关，这为叶片大小在强辐射干旱环境中调节叶温提供了证据。大小依赖的叶片水分关系对于认识叶片大小在包括气温和降雨快速变化的气候变化中的功能作用至关重要。
