Fan Ze-Xin, Sterck Frank, Zhang Shi-Bao, Fu Pei-Li, Hao Guang-You
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of SciencesMengla, China.
Forest Ecology and Forest Management Group, Department of Forestry, Wageningen UniversityWageningen, Netherlands.
Front Plant Sci. 2017 Sep 20;8:1619. doi: 10.3389/fpls.2017.01619. eCollection 2017.
Leaf-stem allometry is an important spectrum that linked to biomass allocation and life history strategy in plants, although the determinants and evolutionary significance of leaf-stem allometry remain poorly understood. Leaf and stem architectures - including stem area/mass, petiole area/mass, lamina area/mass, leaf number, specific leaf area (LA), and mass-based leafing intensity (LI) - were measured on the current-year branches for 28 species growing in a common garden in SW China. The leaf anatomical traits, stem wood density (WD), and stem anatomical and mechanical properties of these species were also measured. We analyzed leaf-stem allometric relationships and their associations with stem hydraulic ad mechanical properties using species-level data and phylogenetically independent contrasts. We found isometric relationship between leaf lamina area/mass and stem area/mass, suggesting that the biomass allocation to leaf was independent to stem size. However, allometric relationship between LA/mass and petiole mass was found, indicating large leaves invest a higher fractional of biomass in petiole than small ones. LI, i.e., leaf numbers per unit of stem mass, was negatively related with leaf and stem size. Species with larger terminal branches tend to have larger vessels and theoretical hydraulic conductivity, but lower WD and mechanical strength. The size of leaf lamina, petiole, and stem was correlated positively with stem theoretical hydraulic conductivity, but negatively with stem WD and mechanical strength. Our results suggest that leaf-stem allometry in species was shaped by the trade-off between stem hydraulic efficiency and mechanical stability, supporting a functional interpretation of the relationship between leaf and stem dimensions.
叶 - 茎异速生长是与植物生物量分配和生活史策略相关的重要指标，尽管叶 - 茎异速生长的决定因素和进化意义仍知之甚少。在中国西南部一个共同花园中生长的28个物种的当年生枝条上，测量了叶和茎的结构，包括茎面积/质量、叶柄面积/质量、叶片面积/质量、叶片数量、比叶面积（LA）和基于质量的叶发生强度（LI）。还测量了这些物种的叶片解剖特征、茎木材密度（WD）以及茎的解剖和机械性能。我们使用物种水平数据和系统发育独立对比分析了叶 - 茎异速生长关系及其与茎水力和机械性能的关联。我们发现叶片面积/质量与茎面积/质量之间存在等速关系，这表明分配到叶的生物量与茎大小无关。然而，发现LA/质量与叶柄质量之间存在异速关系，这表明大叶在叶柄中投入的生物量比例高于小叶。LI，即单位茎质量的叶片数量，与叶和茎大小呈负相关。具有较大顶枝的物种往往具有较大的导管和理论水力传导率，但WD和机械强度较低。叶片、叶柄和茎的大小与茎理论水力传导率呈正相关，但与茎WD和机械强度呈负相关。我们的结果表明，物种的叶 - 茎异速生长是由茎水力效率和机械稳定性之间的权衡所塑造的，支持了对叶和茎尺寸关系的功能解释。
