Mencuccini M, Grace J
University of Florence, Institute of Forest Ecology and Silviculture, Via S. Bonaventura 13, 50145 Firenze, Italy.
Tree Physiol. 1995 Jan;15(1):1-10. doi: 10.1093/treephys/15.1.1.
We tested the hypothesis that the leaf area/sapwood area ratio in Scots pine (Pinus sylvestris L.) is influenced by site differences in water vapor pressure deficit of the air (D). Two stands of the same provenance were selected, one in western Scotland and one in eastern England, so that effects resulting from age, genetic variability, density and fertility were minimized. Compared with the Scots pine trees at the cooler and wetter site in Scotland, the trees at the warmer and drier site in England produced less leaf area per unit of conducting sapwood area both at a stem height of 1.3 m and at the base of the live crown, whereas stem permeability was similar at both sites. Also, trees at the drier site had less leaf area per unit branch cross-sectional area at the branch base than trees at the wetter site. For each site, the average values for leaf area, sapwood area and permeability were used, together with values of transpiration rates at different D, to calculate average stem water potential gradients. Changes in the leaf area/sapwood area ratio acted to maintain a similar water potential gradient in the stems of trees at both sites despite climatic differences between the sites.
苏格兰松（Pinus sylvestris L.）的叶面积/边材面积比受空气水汽压亏缺（D）的立地差异影响。选择了两个相同种源的林分，一个在苏格兰西部，一个在英格兰东部，以便将年龄、遗传变异性、密度和肥力所产生的影响降至最低。与苏格兰较凉爽湿润立地的苏格兰松树相比，英格兰较温暖干燥立地的树在1.3米树高和活树冠基部每单位传导边材面积的叶面积都较小，而两个立地的树干导水率相似。此外，干燥立地的树在树枝基部每单位树枝横截面积的叶面积比湿润立地的树少。对于每个立地，使用叶面积、边材面积和导水率的平均值，以及不同D值下的蒸腾速率值，来计算平均树干水势梯度。尽管两个立地气候不同，但叶面积/边材面积比的变化起到了维持两个立地树木树干相似水势梯度的作用。
