lO FORESTRY IN NEW ENGLAND 



appearance of a different forest type. Such influences are wind- 

 fall, extensive damage by heavy snows, by insects or fungi, by 

 fires, and by lumbering or clearing for farming. The type 

 following any change of this sort is a temporary type, as, for 

 example, the "poplar type" on burns, or the "old-field type" 

 on abandoned cleared lands. Gradually this temporary type, 

 if left to itself, will change into the permanent type and after 

 perhaps fifty or one hundred years the forest will have the 

 form and composition that it had before the change. Such 

 is nature's way of asserting her rights. 



Every forest type will be found under a considerable variety 

 of condition of soil, moisture, etc., and, of course, will make its 

 best development where the sum total of conditions is most 

 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 



