水在树中的上升。

A. J. Ewart
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引用次数: 34

摘要

在前面对这个问题的讨论中,人们默认认为,只需要找到足够的力来平衡与最高的树高度相等的水头,就可以解释树液的上升。然而,问题与其说是静力学的问题,倒不如说是动力学的问题,因为我们必须找到足够的力,不仅要使水头平衡,而且要使这些水以每小时几厘米到6米不等的速度在狭窄的管道中向上流动。事实上,Janse已经从经验上证明了,他的结果也得到了Strasburger的证实,要使水分以蒸腾速率通过针叶树的茎,需要数倍于茎长的水头。水是一种具有一定粘度的液体,即使它在小直径和相当长的管道中缓慢流动时所受到的阻力也是一个非常重要的因素。下面研究的目的是找出在特定情况下这种阻力的大小,克服它所需的力,从而找出以足够快的速度将水上升到一棵主动蒸腾的高大树木的顶端所需的总力。此外,还试图确定这种力在导电木材中产生和传播的可能方法。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The Ascent of Water in Trees.
In the earlier discussions of this problem, it has been tacitly assumed that it was only necessary to find forces sufficient to balance a head of water equal to the height of the loftiest tree to explain the ascent of sap in it. The problem is, however, rather one of dynamics than of statics, for we have to find forces sufficient not only to balance the head of water, but also to keep this water moving upwards in narrow tubes with a velocity varying from a few centimetres to as much as 6 metres per hour. Janse has in fact shown empirically, and his results have been confirmed by Strasburger, that to drive water through the stem of a Conifer at the transpiration rate requires a head of water several times the length of the stem. Water is a liquid of definite viscosity, and the resistance offered even to its slow flow through tubes of small diameter and considerable length is a factor of great importance. The purpose of the following research has been to find the amount of this resistance in definite cases, the forces required to overcome it, and hence the total force required to raise the water with sufficient rapidity to the summit of an actively transpiring tall tree. Furthermore, an attempt has been made to determine the possible means by which this force could be generated, and propagated in the conducting wood.
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