晋西黄土区主要灌木树种蒸腾特性

Transpiration characteristics of major shrub species for soil conservation on the Loess Plateau in western Shanxi Province,northern China

选择黄土高原地区常见的连翘、忍冬、山楂叶悬钩子、红瑞木,采用蒸腾量测定的经典方法——快速称重法,研究了各树种的叶片含水量、日蒸腾速率及叶水势,以期为水资源有限的黄土高原地区植被恢复与重建中低耗水树种的选择、合理种植密度的确定提供依据。结果表明:4个树种早晚的叶片含水量高于中午,含水量的日变幅以山楂叶悬钩子最大(94.4%～111.2%),红瑞木(78.7%～105.2%)和忍冬(69.6%～84.0%)居中,连翘(55.8%～61.2%)最小;灌木树种的叶鲜质量与叶面积可用指数曲线拟合;各树种日平均蒸腾速率的排序为:山楂叶悬钩子(1.985～2.578mmol/(m2·s))>红瑞木(1.570～1.754mmol/(m2·s))>忍冬(1.417～1.485mmol/(m2·s))>连翘(1.160～1.399mmol/(m2·s));4种灌木叶水势日变化呈波浪型,叶水势日变幅以山楂叶悬钩子最大,其次是红瑞木和忍冬,连翘最小;叶水势与蒸腾速率呈负相关,可用对数曲线拟合;统计分析得出各树种蒸腾速率与气象因子的拟合方程,再利用多元主成分方法得出各气象因子对蒸腾速率的贡献率,最后建立综合模型。对不同灌木树种而言,影响蒸腾速率的主导因子不同。

Leaf water content, daily changes Lonicera japonica, Rubus crataegifolius of transpiration rate, leaf water potential of Forsythia suspensa, and Swida alba were studied by using the classical method of measuring tree transpiration--rapid weighing method, which would be beneficial to vegetation reconstruction and reasonable density by selecting tree species of lower water consumption under condition of water deficiency on the Loess Plateau. The results showed that the leaf water content in the morning and evening was higher than at noon and its daily variation amplitude was in the following descending order： R. crataegifolius （94.4% - 111.2% ）was the largest , while F. suspensa （55.8% -61.2% ）was the smallest, S. alba （78.7% - 105.2% ） and L. japonica （69.6% - 84.0% ） were in the middle. The relationship between fresh weight and leaf areas can be fitted by Exponential curve. The four species had the average transpiration rate in the following order： R. crataegifolius （1. 985 -2. 578 mmol/（ m^2·s） ） 〉 S. alba （1. 5 70 -1. 7 54 mmol/（m^2·s）） 〉 L. japonica （1.417-1.485 mmol/（m^2·s） ） 〉 F. suspensa （ 1. 160 - 1. 399 mmol/（ m^2·s） ）. The diurnal variation of leaf water potential was a waveform curve and its daily variation amplitude was in the following descending order： R. crataegifolius was the largest, while F. suspensa was the smallest, S. alba and L. japonica were in the middle. Leaf water potential and transpiration rate were negatively related, and the relationship between them can be fitted by logarithmic curve. The equation and contribution of transpiration and meteorological factors were obtained, their integreted model was established with statistical analysis and principal component analysis, and the main factors of influencing transpiration rate were different from varied shrub species.