云南元江不同胸径厚皮树的水力性状变异格局

Patterns of variation in hydraulic traits of Lannea coromandelica with different diameters at breast height in Yuanjiang, Yunnan Province

关键词:  干热河谷, 水力性状, 形态性状, 水力分割, 水分传输

Key words:  hot and dry valley, hydraulic traits, morphological traits, hydraulic segmentation, water transport

摘要:

为探讨不同胸径径级树木的水力性状变异格局,该研究以元江干热河谷生态系统中优势乔木树种厚皮树(Lannea coromandelica)为研究对象,测定了56棵不同胸径(0<DBH≤9 cm)厚皮树的整枝(叶片和枝条)、叶片和枝条的导水率分布格局及其形态学特征,进而探讨这些性状在胸径径级(0<DBH≤3, 3<DBH≤6和6<DBH≤9 cm)间的变异格局。结果表明:(1)3个胸径径级的厚皮树的枝条导水率均显著大于叶片导水率,表明其枝条和叶片之间存在水力分割现象且水力分割程度相似。(2)在3个胸径径级之间,平均叶柄长度、树皮密度、边材密度、胡伯尔值和比叶重等形态学性状存在显著差异,但是整枝、叶片和枝条导水率无显著差异。(3)在3个胸径径级中,整枝导水率与叶片导水率和枝条导水率均呈显著正相关。枝条导水率与树皮密度呈显著负相关,与边材密度呈显著正相关。叶片导水率与胡伯尔值呈显著负相关。综上所述,尽管一些形态学性状在不同胸径径级之间存在显著差异性,但在不同生长阶段,厚皮树叶片和枝条之间存在着相似的水力分布格局。该研究结果为了解树木体内的水分传输机制具有重要的生理学意义。

Abstract:

In order to investigate the variation patterns of hydraulic traits of trees with different diameters at breast height(DBH)grades, we focused a dominant tree species(Lannea coromandelica)in the dry and hot ecosystem of the Yuanjiang, and measured the distribution patterns of hydraulic traits including shoot(leaf and stem), leaf, and stem hydraulic conductance, and morphological properties(DBH, leaf area/petiole length, leaf area/mass of petiole, mass of leaf/mass of petiole, average petiole length, bark density, wood density, Huber value and leaf mass per area)for 56 L. coromandelica individuals with different DBH grades(0 < DBH ≤ 9 cm), and then discussed the variation patterns of these traits among three DBH grades(0 < DBH ≤ 3, 3 < DBH ≤ 6 and 6 < DBH ≤ 9 cm). The results were as follows:(1)The stem hydraulic conductance was significantly greater than leaf hydraulic conductance in three DBH grades, indicating that there was a hydraulic segmentation between the stem and leaf, whereas the degree of hydraulic segmentation had a similar pattern.(2)Among the three DBH grades, there were significant differences in morphological traits such as average petiole length, bark density, wood density, Huber value and leaf mass per area, but there were no significant differences in the hydraulic conductance of the shoot, stem, and leaf.(3)Among the three DBH grades, the shoot hydraulic conductance was positively correlated with leaf and stem hydraulic conductance, indicating there was a coordination between leaf and stem hydraulic conductance. The stem hydraulic conductance was negatively correlated with bark density and positively with wood density, and leaf hydraulic conductance was significantly negatively correlated with the Huber value, indicating these leaf and stem morphological traits may impact shoot and leaf hydraulic conductance. Overall, this study suggests that there are similar hydraulic distribution patterns between leaf and stem of L. coromandelica at different growth stages, although some morphological traits differ significantly among different diameter grades. These results have important physiological significance for understanding the water transport mechanism in plants.