树木为何会长树皮？  

Why Do Trees Have Bark？

作　　者：唐智 

出　　处：《英语画刊（中级）》2015年第5期31-31,共1页English Pictorial

摘　　要：树皮对树木的意义，正如皮肤对于你。这是它的外在保护层。树皮下面的薄膜层，即形成层，是树干中唯一有生长着的活细胞的部分。形成层使得树干、树枝和树根随着时间推移越来越粗壮。树木粗糙的外皮和内皮有助于保护形成层免受天气、昆虫、动物和有机物的侵害所带来的疾病。一棵树的部分树皮脱落后还能继续生存，但如果脱落过多，树木就会死去。The bark does for the tree what your skin does for you. It＇s an outer protective layer. The thin layer that is .just underneath the bark, the cambium, is the only part of the treetrunk that has living, growing cells. It is what makes the trunk, branches and roots grow thicker over time. A tree＇s rough outer and inner bark help guard the cambium against damage by weather, insects, animals, and organisms that can cause disease. A tree can survive if some of its bark is stripped away. But if too much is removed, the tree will die.

关 键 词：树皮 树木 形成层 时间推移 保护层 薄膜层 活细胞 有机物 

分 类 号：S789.1[农业科学—林学]