18 FORESTRY 



shallow-rooted, it will probably blow over in the first big 

 wind. If it is exacting in its demands for soil moisture, 

 the roots will dry out and the tree will die. This often 

 happens to species which habitually grow only under the 

 shade of other trees. If it is a young tree with thin bark, 

 the bark may sun-scald badly, causing wounds which give 

 entrance to spores of fungi that will cause the tree to rot. 

 But if the tree is naturally deep-rooted, fairly stocky, with 

 thick bark, it will survive the change and will at once begin 

 to strengthen its base against the unusual wind strain, at 

 the same time enlarging its crown and roots. The growth 

 will probably increase and the tree will begin to bear seed 

 in great abundance. 



The forest form of the species is therefore not as well 

 adapted to sudden changes as the open grown tree, but it 

 is vastly more useful in the production of material. The 

 taller and more cylindrical a tree is, the greater will be 

 the per cent of its volume that can be used. The fewer 

 branches it has and the sooner these fall off, the more valu- 

 able will be the products. 



Left to themselves, trees will always form forests in 

 regions with sufficient rainfall to support tree life. This 

 fact, and the immensely greater production both in quan- 

 tity and value of material when trees are grown in forests, 

 makes it necessary to consider the forest stand as the real 

 unit in forestry, instead of the single tree. 



The Early History of a Forest Stand. — The development 

 of a stand of trees is best illustrated by taking the example 

 of an area which has been seeded to a single species all 

 about the same time. This occurs with certain pines, as 

 for instance on an abandoned field. Such natural seeding 

 is never uniform, but the seedlings occur in groups, and 

 many small openings are left, while in other spots a dense 

 mat of seedlings may spring up. But on the whole the 

 stand may be fairly uniform and the trees within a few 

 years of the same age. The open spots not occupied by 



