摘要： <正>研究了树冠对太阳光（包括直接光和漫射光）的遮蔽作用，重点比较了两种形体的树冠阴影面积及影长的差异，从而讨论林带对空间的遮蔽效应。

Abstract: A tree screens effects on space, i. e. its crown screens the sunlight (including the dierect sunlight and the diffuse light). This paper emphasizes the differences of the shadow area and length of two kinds of crown shapes. The screen effects are dicussed for treebelt on space.