354 Forestry Quarterly. 



Under silvical characteristics of stands there should be dis- 

 cussed (i) such silvical characteristics of forest trees as are 

 exhibited by them only when they are growing in a stand ; and 

 (2) such influences on the factors of site or environment which 

 are produced by the stand. 



As soon as trees form a stand there arise new conditions which 

 change more or less the physiographical environment. The unit 

 of area occupied by a stand receives a different amount of pre- 

 cipitation than an area of the same size, but occupied only by a few 

 individual trees. A part of the precipitation that falls over a 

 dense stand is intercepted by the crowns of the trees. The snow 

 has a different depth and density ; it thaws differently within the 

 forest than on a similar area outside of the forest. Under a 

 dense forest cover the thermal and light conditions are altogether 

 different from outside a forest. The humidity of the air and the 

 wind velocity within the forest are also different from these 

 conditions outside of it. These differences in the physical con- 

 ditions inside and outside the forest are brought about by the 

 trees forming a dense stand. As a product of the social life of 

 forest trees there appears a leaf litter which has a great influence 

 upon the physical character and structure of the forest soil. The 

 foliage of trees in the forest, in addition to assimilation and 

 respiration, acquires still a third function, namely of protecting 

 and enriching the soil. The forest leaf litter is important to the 

 forest not only by its beneficial influence, but often also by its 

 harmful effect when a sour humus is formed. 



In addition to the dead ground cover in stands of different ages 

 and density, there appears also a living ground cover, the compo- 

 sition and ecological character of which is typical of the stands 

 under which it springs up. Under different conditions of density 

 and age of the stand the living ground cover varies greatly in 

 character ; one can find all gradations of vegetation characteristic 

 of the densest forest to vegetation characteristic of open meadows. 

 The living ground cover serves not only as a criterion of the con- 

 ditions prevailing in given stands but, together with the dead 

 ground cover, has an important influence upon the soil and repro- 

 duction of the stand. In connection with the general discussion 

 of the influence of the living ground cover, it may be advisable to 

 give specific description of certain typical and characteristic 



