树木秋季叶片落地时叶面叶背朝向的探讨  

The explanation for the direction of front/back surface of falling leaf in autumn

作　　者：温宇光[1] 刘明伟[1] 孙红英[1] 

机构地区：[1]四平市林业局北河公司,吉林四平136000

出　　处：《吉林林业科技》2009年第5期7-9,共3页Journal of Jilin Forestry Science and Technology

摘　　要：观察不同环境条件下树木秋季叶片落地时叶面叶背的朝向比例与枯落叶片形态,并进行了理论推算论证。结果表明:秋季树叶失水枯萎时,由于叶面与叶背的组织结构不同,致使密度较大的叶面呈凹形,而密度较小的叶背呈凸形;叶片飘落时,能使其翻转的势能仅相当于叶片在空中作乱翻转运动的转动动能的1/54,如此微小的能量无法克服叶片乱翻转运动的转动动能,致使在林分内的地面上和静止水域的水面上的落叶面朝地与面朝天的比例基本相等。而林间小路及公路上的落叶绝大部分表现为面着地、背朝天的现象,是各种运动产生的风力作用使落叶再次运动后形成的结果。匡谬了以往认为的"叶面结构致密密度大、叶背结构疏松密度较小而致叶面着地占多数"的观点。Abstract： The ratios of front and back surface of the leaves on the ground and morphological characteristics of autumn leaves were observed in different environments, and theoretical demonstration was showed in this paper. The results indicated that because of the different density of tissue structure, the front leaf surface with higher density became concave while the back leaf surface with lower density became convex after wilting. The potential energy resulted from the difference of shape of front and back surfaces was only the 1/54 of the kinetic energy when the leaves chaotically fall. ing in the air, and such tiny energy could not conquer the kinetic energy of falling, resulting in the same ratio of front and back surface of leaves on the ground in untraversed forests and immobile water surface. However, most faint surface of leaves on the ground faced to sky in the footway in forests and on roads, which were the consequence of re - movement by wind induced from any activities. This paper corrected the idea that most leaves on the ground are front surface facing to the sky because of the different density of tissue structure of front and back leaf surfaces.

关 键 词：树木 叶片 朝向 

分 类 号：S718.43[农业科学—林学]