Department of Wood Science and Engineering, Oregon State University, Corvallis, OR 97330, USA.
New Phytol. 2010 Apr;186(2):439-50. doi: 10.1111/j.1469-8137.2010.03181.x. Epub 2010 Feb 12.
*Coniferous, diffuse-porous and ring-porous trees vary in their xylem anatomy, but the functional consequences of these differences are not well understood from the scale of the conduit to the individual. *Hydraulic and anatomical measurements were made on branches and trunks from 16 species from temperate and tropical areas, representing all three wood types. Scaling of stem conductivity (K(h)) with stem diameter was used to model the hydraulic conductance of the stem network. *Ring-porous trees showed the steepest increase in K(h) with stem size. Temperate diffuse-porous trees were at the opposite extreme, and conifers and tropical diffuse-porous species were intermediate. Scaling of K(h) was influenced by differences in the allometry of conduit diameter (taper) and packing (number per wood area) with stem size. *The K(h) trends were mirrored by the modeled stem-network conductances. Ring-porous species had the greatest network conductance and this value increased isometrically with trunk basal area, indicating that conductance per unit sapwood was independent of tree size. Conductances were lowest and most size-dependent in conifers. The results indicate that differences in conduit taper and packing between functional types propagate to the network level and have an important influence on metabolic scaling concepts.
针叶树、散孔材和环孔材在木质部解剖结构上存在差异，但从导管尺度到个体尺度，这些差异对功能的影响还不是很清楚。我们对来自温带和热带地区的 16 个树种的树枝和树干进行了水力和解剖学测量，这些树种代表了所有三种木材类型。用茎直径对茎导度（K(h)）进行标度，以模拟茎网络的水力导度。环孔材树木的 K(h)随茎大小的增加而急剧增加。温带散孔材树种处于相反的极端，而针叶树和热带散孔材树种则处于中间。K(h)的标度受到导管直径（变细）和与茎大小相关的排列（每木材面积的数量）的异速关系的影响。K(h)的趋势与模拟的茎网络导度相吻合。环孔材树种的网络导度最大，且该值与树干基部面积呈等比增加，表明单位边材的导度与树的大小无关。在针叶树中，导度最低且对大小的依赖性最大。结果表明，功能类型之间导管变细和排列的差异会传播到网络水平，并对代谢缩放概念产生重要影响。
