论文部分内容阅读
通过对不同个体水力导度(KL)的研究,揭示水力导度在树木水分利用中的关键作用,可为深入研究森林水分循环提供理论依据.采用热消散探针液流测定系统连续监测广州地区6棵不同大小荷木(Schima superba)样树的液流密度(JS),结合树木的叶片水势(ΨL)、土壤湿度、树高、边材面积(AS)、冠幅等参数,分析整树水力导度的日变化和干湿季变化,揭示不同大小样树水力导度的变化规律.结果显示:不同胸径大小的6棵样树液流密度差别明显,液流密度最大值未出现在胸径最大的样树中,而是在胸径略小的树木中.通过测定6棵样树的液流密度值可以进一步求算出样树的整树水力导度,总体上讲,6棵树的日均水力导度表现出明显的起伏波动;其中干季水力导度(0.017 g m-2s-1 M Pa-1)略低于湿季(0.019 g m-2 s-1 M Pa-1),但差异并不明显.样树土壤/叶片水势差与平均液流密度显著相关(P<0.0 01),而样树树形特征和水力导度之间关系表现为水力导度与树高呈现明显相关性(P=0.016),与胸径、冠幅相关性均不显著.上述结果表明,荷木水力导度表现出明显的日变化,其大小在一定程度上受到树形指标的影响.
Through the study on hydraulic conductivity (KL) of different individuals, the key role of hydraulic conductivity in tree water utilization can be revealed, which can provide a theoretical basis for further study on the water cycle of forest.Using the heat dissipation probe flow measurement system to continuously monitor the Guangzhou area The flow density (JS) of six tree species with different sizes was compared with that of the whole tree according to the leaf water potential (ΨL), soil moisture, tree height, sapwood area (AS) The results showed that the flow density of 6 tree species with different DBH sizes differed significantly, and the maximum value of liquid density did not appear at DBH The largest sample tree, but in the slightly smaller diameter tree.Through the determination of the density of six sample tree flow density values can be further calculated the overall tree hydraulic conductivity of the sample tree, the average daily average of six trees The hydraulic conductivity showed obvious fluctuations; the hydraulic conductivity in dry season (0.017 g m-2s-1 M Pa-1) was slightly lower than that in wet season (0.019 g m-2 s-1 M Pa-1) The difference was not significant, and the soil water / leaf water potential difference was significantly correlated with the average flow density (P <0.0 01) The relationship between tree shape and hydraulic conductivity showed that there was a significant correlation between hydraulic conductivity and tree height (P = 0.016), but not significant correlation with tree diameter and crown width.The above results showed that hydraulic conductivity A clear diurnal change, the size of the tree index to some extent by the impact.