基于生长轮的杨树水分输导模式

Water Transfer Mode Based on Annual Ring of Populus alba × P. berolinensis

以生长轮为研究的基本单位,分析了杨树(银中杨)的水分输导模式。结果表明:杨树树干中最近2a的断面积生长量在阳冠以下基本相同;当年生长的生长轮是生理活动最旺盛的部分,其生长量的纵向分布是冠幅增加的力学支承和生理需求的综合结果。当年生生长轮承担全树66.98%的水分输导量,前1a生长的生长轮占24.24%。说明杨树最近2a生长的断面积是水分输导最旺盛的部分。在水分的纵向输送过程中,水分呈顺时针螺旋式扇形上升,并且各生长轮之间还略有差别。1d中(晴天)水分输导最强的时间是上午9时左右。

An experiment was conducted to study the water transfer mode of Populus alba × P.berolinensis based on annual ring.Results revealed that the stem cross-sectional area increments under sun-facing crown almost remained the same in recent two years and the current annual ring was the most physiologically active.The longitudinal distribution of cross-sectional area increment of the current annual ring was the integrated result of the mechanical supports and the physiological needs of canopy increase.The current annual ring accounted for about 66.98 percnet of the amount of water transfer,and the annual ring formed in the previous year accounted for only 24.24 percent,indicating that they are the most active rings for water transfer.It was also proved that waster transfer was conducted in a clockwise spiral ascending manner and slight differences existed among different rings.Water transfer was the most intensive at 9 am on sunny days.