212 FORESTRY IN NEW ENGLAND 



of these hardwood trees various conifers spring up. The conifers 

 gradually enter, usually five to ten years after the hardwoods 

 have started, and form an understory. The conifers are the more 

 persistent growers and longer-lived trees, so that finally they out- 

 live the hardwoods and gain possession of the land, causing the 



By permission of the U. S. Forest Service. 

 Fig. 71. — The birch and poplar type, starting after fire on lumbered land. 



type to revert to one of the four permanent types previously 

 described. 



On extensive burns where conifers have failed to seed in, owing 

 to the absence of seed trees, the birch and poplar type may hold 

 the land for several generations. Unless the type is burned over 

 after cutting, the conditions are not especially favorable for 

 seedhng reproduction of birch and poplar, but paper birch fre- 

 quently sprouts prohfically from the cut stumps, while poplar 

 sends up large numbers of root suckers. These root suckers 

 persist, and will reach merchantable size. 



