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towers have been constructed. The Department of Forestry aims to 

 disseminate knowledge concerning forestry to the public, to protect 

 carefully all State forests, to assist in the protection of private areas, 

 and make accessible for management and utilization all State forests 

 as rapidly as appropriations by the legislature will permit. Many 

 large areas in various parts of the State are devoid of any valuable 

 tree growth. Most of these areas are capable of developing useful 

 forests. In order to have them developed it is necessary that such 

 areas be stocked with valuable trees. It must be done by planting. 

 About 6,000 acres have already been planted to trees in this State, 

 which required a total of 11,970,500 seedlings. In order to produce 

 these seedlings and to insure a future supply 4 large fores-t nurseries 

 and 22 small ones have been established. Many other benefits are de- 

 rived from the forests. They serve as recreation grounds to the 

 public who seek their midst to regain or maintain health. Carefully 

 managed forests regulate stream flow and are also the sources from 

 which cities and towns obtain an excellent supply of unpolluted 

 water. They furnish local labor, and, through permits, suitable 

 camp sites to campers, hunters, and fishermen. The sale of material 

 from the State forests has already yielded over |84,000, eighty per 

 cent, of which will be set aside for "The State School Fund of Penn- 

 sylvania." 



THE STRUCTURE OP THE FOREST. 



Every region and, often, even every small locality has its peculiar 

 kind of forest. The composition of the forests along streams, on 

 slopes, and upon mountain tops usually shows great differences. The 

 climatic factors and physiographic features of a region influence the 

 composition of the forest very much. The more varied the factors 

 of the habitat are, the more varied the composition of the forest usu- 

 ally is. Upon the same mountain slope one can often find three and 

 sometimes more zones of trees. Each zone is composed of different 

 species or groups of species, which groups vary not only in composi- 

 tion, but also in form, density, and thriftiness. 



The forester seldom considers trees raised in isolated positions, 

 but rather concerns himself with trees raised in masses or stands. 

 Such masses of trees, irrespective of their kind, size, density, form, 

 number, or value are known as woodlands. Woodlands may be com- 

 posed of a single species or of two or more species. If one species 

 composes ninety per cent, or more of the total stand it is known as 

 a pure stand and if the stand is composed of two or more species 

 none of which forms ninety per cent, of the total stand it is known 

 as a mixed stand. Woodlands are rarely quite pure. A slight ad- 

 mixture of some species is usually present. The forests of Pennsyl- 



