SILVICS II 



favorable. Foresters recognize this situation as Quality I for 

 the type, and usually speak of Qualities II and III as designating 

 respectively poorer sites. 



PURE AND MIXED STANDS. 



One of the first things to notice in the study of a forest is the 

 kind of trees that are present and the proportion of the more 

 important ones. In the virgin forests of northern New England, 

 for example, we find spruce, hemlock, birch, maple, beech, 

 probably basswood, and several other species. The hardwood 

 forests of Connecticut and Rhode Island, on the other hand, 

 consist of chestnut, oak, hickory, maple, birch, elm, hornbeam, 

 etc. Both of these are termed " mixed forests." But in the 

 former region, especially in Maine, there are extensive areas that 

 have been burned over which are now covered with canoe birch. 

 There are old pastures in northern Vermont now overgrown 

 with impenetrable thickets of arborvitae; and further south, 

 with white pine. These are "pure forests," being composed 

 of but one species. As used in this country a stand is called 

 "pure" if 80 per cent of the main crop is composed of one 

 species. 



A study of the causes of these differences reveals the fact that 

 pure forests are usually composed of trees whose seeds are light 

 and are, therefore, borne long distances and in great numbers 

 by the winds. Anyone accustomed to tramp in winter must 

 have seen the snow-covered fields, though far from trees, well 

 sprinkled with birch seed. Although these light-seeded species 

 often occur in mixed forests, the heavier-seeded varieties are 

 characteristic of them and never form pure forests except under 

 particularly unfavorable circumstances. Such exceptions are 

 the summits of the trap ridges of Connecticut where the soil is 

 too scant to support any tree life except a very open, pure forest 

 of chestnut oak. 



There are, of course, artificially pure forests, as those which 

 are planted, or those from which all but one species have been 

 removed. This brings us to the question which has been pro- 



