南亚热带丘陵土壤水分循环及其有效性的研究──Ⅶ.丘陵赤红壤-果树-大气连续体中水流阻力的变化及其分布规律

Studies on Water Cycle and Its Availability of Latored soils on Hills of South Subtropics──Ⅷ.Variation and Distribution of Hydraulic Resistance in Latored Soil-Fruit Tree-Atmosphere Continuum on Hill

依据田间实测资料，运用水流的电模拟原理，定且分析了南亚热带丘陵赤红壤-果树（荔枝、芒果和龙眼）-大气连续体中水流阻力各分量的大小、变化规律及其相对重要性．结果表明，连续体中的水流阻力主要分布于从叶气孔腔到大气的扩散过程，荔枝、芒果、龙眼叶-气系统的水流阻力Rla占连续体水流总阻力Rsa的比例分别为93.65％～98.03、95.68％～99.03％、90.13％～98.71％；果树植株体的水流阻力Rp居其次，占Rsa的比例分别为1．97％～6．35％、0.97％～4.32％、0．08％～9．87％：土壤阻力Rs最小，占Rsa的比例小到可忽略不计，故叶-气系统的水流阻力是决定连缤体中水流速率的重要因素．

This paper was concerned with quantitatively analyzing the mamgnitude, the variation, and the relative importance of each hydraulic resistance in latored soil-fruit tree (lychee mango and longan)-atmosphere Continuum on hill based on the experimental data obtained from fruit tree field and on the electrical analog principle of water flow. The results indicated that, when water flowing in the continuum, the main hydraulic resistancc took the first place in the course of water emitting out of the leaf, the hydraulic resistance in the leaf -atmosphere system reaching the range from 93.65% to 98.03%95.68% to 99.03% and 90.13% to 98.71% of the total hydraulic resistancc in the continuum. The hydraulic resistance in the fruit tree was the second place, the hydraulic resistance in plant reching the range from 1.97% to 6.35% 0.975% to 4.32% and 0.08% to 9.875% of the total resistance in the continuum. But the hydraulic resistance in soil was so small that its relative importance in the continuum could be omitted. Therefore,the hydraulic resistance in the leaf-atmosphere system was the importance factor, which determined the velocity of water flow the continuum.