? Context Physiological ecologists have been fascinated by height- or position-linked differences of leaf morphology within tall trees >25 m, but the exact cause is still debated, i.e., is it due to light or height-induced water stress?? Aims The aim of this study was to demonstrate that relatively small trees (<15 m) have leaf morphologies that vary with height and that such variation depends on site-moisture variability.? Methods Leaves were collected from Robinia pseudoacacia trees at two sites in China with contrasting moisture variability to gather baseline data on leaf morphology parameters.? Results Most measured parameters changed regularly with height. Water potential linearly decreased with height. Leaf area and stomata area decreased with height, while leaf mass per area, carbon isotope composition (δ 13C), and stomata density increased with height. Mesophyll and epidermal cell width decreased with height, while leaf thickness and palisade cell length increased with height. All the morphology parameters between two sites were also significantly different.? Conclusions Based on the field results, it is concluded that minor variations in water potential at the time of leaf growth influence leaf morphology at both site-level and height-level. Controlled environment experiments will be conducted to confirm this conclusion. |
