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

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.