Reid Douglas E B, Silins Uldis, Lieffers Victor J
Centre for Enhanced Forest Management, Department of Renewable Resources, University of Alberta, Edmonton, Alberta T6G 2H1, Canada.
Tree Physiol. 2003 Aug;23(12):833-40. doi: 10.1093/treephys/23.12.833.
Stem sapwood hydraulic permeability, tree leaf area, sapwood basal area, earlywood to latewood ratio of annual rings, radial variation in hydraulic permeability and stem hydraulic capacity were examined in dominant (D), codominant (CD) and suppressed (SP) lodgepole pine (Pinus contorta Dougl. ex Loud.) trees growing on medium and poor sites. Hydraulic permeability on a sapwood area basis (ks) was lower in suppressed trees (0.71 x 10(-12) m2) compared to dominants (1.97 x 10(-12) m2) and codominants (1.79 x 10(-12) m2), and higher on medium than on poor sites. The leaf/sapwood area ratio (S) varied with crown dominance position (D > CD > SP) but not by site type. Leaf specific conductivity (kL) did not vary between crown classes or site types. The relationship between leaf area and stem hydraulic supply capacity (Q*) was strong, but differed among crown classes. Dominant trees and trees from the medium sites had a greater proportion of earlywood in outer rings of sapwood than suppressed trees. Sapwood permeability declined from the cambium to the sapwood-heartwood boundary in all samples, but the decline was more gradual in dominant trees compared to codominant and suppressed trees; differences in the radial variation in sapwood permeability may be related to differences in S. Sapwood permeability is positively related to crown dominance, whereas subdominant (CD and SP) trees have greater Q* in relation to leaf area, leading us to propose that this may give subdominant trees a survival advantage, slowing self-thinning.
在生长于中等和贫瘠立地条件的优势木（D）、共优势木（CD）和被压木（SP）黑云杉（Pinus contorta Dougl. ex Loud.）中，研究了边材液流导度、树叶面积、边材断面积、年轮早晚材比率、边材液流导度的径向变化以及树干液流能力。基于边材面积的液流导度（ks）在被压木中较低（0.71×10⁻¹² m²），而优势木中为（1.97×10⁻¹² m²），共优势木中为（1.79×10⁻¹² m²），且在中等立地条件下高于贫瘠立地。叶/边材面积比（S）随树冠优势地位而变化（D＞CD＞SP），但不受立地类型影响。叶比导率（kL）在树冠等级或立地类型之间没有差异。叶面积与树干液流供应能力（Q*）之间的关系很强，但在树冠等级之间有所不同。优势木和来自中等立地的树木边材外环的早材比例比被压木更大。在所有样本中，边材导度从形成层到边材 - 心材边界均下降，但优势木的下降比共优势木和被压木更平缓；边材导度径向变化的差异可能与S的差异有关。边材导度与树冠优势呈正相关，而亚优势木（CD和SP）相对于叶面积具有更大的Q*，这使我们提出，这可能赋予亚优势木生存优势，减缓自然稀疏。
