| Possible tradeoffs between hydraulic conductivity and mechanical properties of Acer negundo, A. saccharinum, A. rubrum, A. nigrum, and A. saccharum were assessed. It has been shown that tradeoffs between xylem specific conductivity (Ks max) and modulus of elasticity (MOE) and modulus of rupture (MOR) occur in cogeneric chaparral shrubs and vines versus trees and shrubs. The current study attempted to determine if this tradeoff is present in five cogeneric tree species in a similar habitat. Acer negundo, A. saccharinum, and A. rubrum are considered soft maples and are known to be fast growing and shade-intolerant. Conversely, A. nigrum and A. saccharum are classified as hard maples and are slow-growing and shade-tolerant. It was hypothesized that the soft maples would have lower MOE and MOR, but higher Ks max than the hard maples. Minute anatomical and general morphological characteristics were measured in an attempt to correlate them to any water transport and/or mechanical strength differences between species. No difference was found between species in vessel diameter, water conductivity, or percent embolism. Similarly, no tradeoff was found between Ks max and MOE or MOR across the genus. Fiber lumen diameter was inversely correlated to both MOE and MOR. Surprisingly, percent ray parenchyma was positively linearly related to MOE. This suggests that transport/mechanical tradeoffs are not universal across every genus within a similar environment. |
