. Bulletin (Pennsylvania Department of Forests and Waters), no. 35. Forests and forestry. JAN. rcB. MAR. MAY JUNt JULY AUa Uff Wh£N Fokest Fires Occxni in Pcnnstlvam*. OCT likely to suffer. Shallow rooted species may be killed by the burning humus injuring the roots, or simply by the exposure of the roots. Hardwoods are likely to have crown fires only in thicket or pole stage, or in dense stands when dead or new leaves are on the twigs. The amount of damage varies greatly according to the age of the woods. In old timber the soil covering is usually scantier than in young wood, consequent
. Bulletin (Pennsylvania Department of Forests and Waters), no. 35. Forests and forestry. JAN. rcB. MAR. MAY JUNt JULY AUa Uff Wh£N Fokest Fires Occxni in Pcnnstlvam*. OCT likely to suffer. Shallow rooted species may be killed by the burning humus injuring the roots, or simply by the exposure of the roots. Hardwoods are likely to have crown fires only in thicket or pole stage, or in dense stands when dead or new leaves are on the twigs. The amount of damage varies greatly according to the age of the woods. In old timber the soil covering is usually scantier than in young wood, consequently there is less fuel and less damage. Surface fires 14 usually burn more slowly in old timber because protected from the wind. As trees grow older the bark of most species grows thicker and more corky. Bark is a non-conductor of heat, hence it protects the cambium from being scorched. Even to trees with thick bark every fire does some damage and a severe fire or frequent fires will kill them. Voung seedlings and coppice growth of most species, and even poles of some species, are killed by very light fire. Necessarily the kind and severity of the fire will influence the result- ing damage. A fire in one tree does little damage unless it becomes the means of starting other kinds of fires. Crown fires are destructive because the burning of the foliage usually results in the killing of a tree. Even in hardwoods the leaves, buds, and twigs are so badly scorched that death results. In many cases the finer twigs are con- sumed. Under-ground fires kill everything in their path, by killing or consuming roots, by exposing the roots, or by removing material from on top and around the roots so that it is only a matter of time until the trees are blown over or gradually die. Surface fires vary in their effects from slight injuries to complete destruction, depending upon their se- verity. Living tissue is killed when heated to 54°C. (°F). If under-bark is brown or black, after a fir
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectforests, bookyear1923
