树冠位置对香樟叶形态性状和异速生长关系的影响

Effects of Canopy Positions on Leaf Morphological Traits and Their Allometric Relationships of Cinnamomum camphora

摘要:

为深入了解树冠位置对植物叶形态性状的影响，在常绿乔木香樟树冠上下2层和东南西北4个方位开展调查取样，系统分析了不同树冠位置间叶形态性状(叶长、叶宽、叶厚、叶柄长、叶柄直径和叶形指数)及其异速生长关系的差异性。结果表明，叶形态性状在不同树冠方位间均差异显著，但上下2层变化趋势不完全一致。在树冠上层，除叶形指数和叶炳长外，其余4个性状均表现为东侧最大。在树冠下层，除叶形指数外，其余5个性状指标均表现为东侧最小。在同一方位上，叶形态性状在上下2层间也存在一定差异，其中叶形指数多为下层高于上层，而其他形态性状多呈相反趋势。此外，树冠层次和方位的交互作用对叶片长、叶片厚、叶柄长和叶柄直径有显著影响。各层次和各方位叶形态性状间多为异速生长关系(即异速生长指数不等于1)，且多无显著差异。在所有树冠层次和树冠方位，叶宽与叶厚、叶宽与叶炳长、叶长与叶厚及叶长与叶柄长之间均呈异速生长关系。可见，树冠位置对香樟叶形态性状的影响较大，但形态性状间的异速生长关系相对稳定，这是香樟叶形态性状表型可塑性和内在关系稳定性的重要体现。

Abstract:

Leaf morphological traits are the direct manifestation of plant environmental adaptability. Different canopy positions can form different microenvironments, which are direct places for plant leaves to interact with the external environment. In order to understand the influence of canopy position on leaf morphological traits, leaf morphological traits, including leaf length, leaf width, leaf thickness, petiole length, petiole diameter and leaf shape index, and allometry relationship among different crown positions of evergreen tree Cinnamomum camphora were analyzed. The results showed that there were significant differences in leaf morphological traits among different canopy orientations, but the change trends of the upper and lower layers of canopy was not completely consistent. In the upper layer of canopy, except leaf shape index and petiole length, the other 4 leaf morphological traits were the highest in the east side. In the lower layer of canopy, except leaf shape index, the other 5 leaf morphological traits were the smallest in the east side. In the same direction, there were some differences between the upper and lower layers of canopy, and the leaf shape index of lower layer was higher than that of upper layer, while the other morphological traits showed the opposite trend. In addition, the interaction of canopy layer and orientation had significant effects on leaf length, leaf thickness, petiole length, and petiole diameter. The leaf morphological traits in each canopy layer and canopy orientation mostly showed allometric relationship because allometric index was not equal to 1, and there were no significant differences in most of them. The leaf width vs. leaf thickness, leaf width vs. petiole length, leaf length vs. leaf thickness, and leaf length vs. petiole length showed allometric relationships for all canopy layers and directions. Therefore, canopy position had great influences on leaf morphological traits of C. camphora, but the allometric relationships between morphological traits were relatively stable, which was an important reflection of leaf phenotypic plasticity and the stability of internal relationships.