THE BARK IS A DISTINCT FEATURE OF THE TREE AND IS ITS PERMANENT CLOTHES
The bark is a set of outer tissues covering wood (xylem) of the given tree. This complex layer is composed, from the outside to the inside, of: epidermis (during the first years of the tree life), cork, cork cambium, parenchyma cortex and phloem supporting the plant with assimilates. The bark can be smooth, without large fissures, like in beech and hornbeam or distinctly coarse with cracks like in oak or pine. The bark insulates the inner part of the tree from water, fungi and oxygen, however, is some sites of this complex tissue special pores called lenticels are developed. They are of original size and shape and together with characteristic colour and surface of the bark there are provided tools for well determination of the tree species. Such bark image is especially useful during leafless status of the tree (late autumn, winter, early spring) in the temperate climatic zone. In mountains we can often meet such trees like spruce, pine, fir, larch, oak, beech or birch – they have very distinct bark. Others, like willow, ash, maple, sycamore, black and green alder, can also grow in lower sites. Details of the bark can sometimes be very spectacular and changed after infection by fungi or penetration by insects and other animals. The present status of the tree bark tells well on the mountain ecosystems and can improve our efforts to protect them.
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