Sun Jun, Wang Mantang, Lyu Min, Niklas Karl J, Zhong Quanlin, Li Man, Cheng Dongliang
Fujian Provincial Key Laboratory of Plant Ecophysiology, Fujian Normal University, Fuzhou, Fujian Province, China.
School of City and Civil Engineering, Zaozhuang University, Zaozhuang, Shandong Province, China.
AoB Plants. 2019 Nov 19;11(6):plz063. doi: 10.1093/aobpla/plz063. eCollection 2019 Dec.
The trade-off between leaf number and individual leaf size on current-year shoots (twigs) is crucial to light interception and thus net carbon gain. However, a theoretical basis for understanding this trade-off remains elusive. Here, we argue that this trade-off emerges directly from the relationship between annual growth in leaf and stem mass, a hypothesis that predicts that maximum individual leaf size (i.e. leaf mass, , or leaf area, ) will scale negatively and isometrically with leafing intensity (i.e. leaf number per unit stem mass, per unit stem volume or per stem cross-sectional area). We tested this hypothesis by analysing the twigs of 64 species inhabiting three different forest communities along an elevation gradient using standardized major axis (SMA) analyses. Across species, maximum individual leaf size ( , ) scaled isometrically with respect to leafing intensity; the scaling constants between maximum leaf size and leafing intensity (based on stem cross-sectional area) differed significantly among the three forests. Therefore, our hypothesis successfully predicts a scaling relationship between maximum individual leaf size and leafing intensity, and provides a general explanation for the leaf size-number trade-off as a consequence of mechanical-hydraulic constraints on stem and leaf growth per year.
当年生枝条（嫩枝）上叶片数量与单叶大小之间的权衡对于光截获进而对净碳增益至关重要。然而，理解这种权衡的理论基础仍然难以捉摸。在此，我们认为这种权衡直接源于叶片和茎干质量的年生长之间的关系，这一假设预测最大单叶大小（即叶质量、或叶面积）将与展叶强度（即单位茎干质量、单位茎干体积或单位茎干横截面积上的叶片数量）呈负向且等比缩放关系。我们通过使用标准化主轴（SMA）分析，对沿海拔梯度分布的三个不同森林群落中的64个物种的嫩枝进行分析，来检验这一假设。在所有物种中，最大单叶大小（、）相对于展叶强度呈等比缩放；最大叶大小与展叶强度之间的缩放常数（基于茎干横截面积）在三个森林之间存在显著差异。因此，我们的假设成功预测了最大单叶大小与展叶强度之间的缩放关系，并为每年茎干和叶片生长所受机械 - 水力限制导致的叶大小 - 数量权衡提供了一个一般性解释。
