380 Proceedings Portland Society Natural History 



flammable than dry needles and there is also a larger 

 amount of green shrubby undergrowth. The succession of 

 vegetation after a fire differs, depending on whether the hu- 

 mus is only slightly injured, or completely destroyed. 



Association-types where humus is little injured 



When a climax forest is burned the first noticeable re- 

 sult is the profuse growth of herbaceous species that ap- 

 pears the season after the fire. Some of these are forms 

 which formerly grew on the forest floor, such as Cornus 

 canadensis, Clintonia borealis, Muiunthcmum canadense and 

 Linnaea borealis var. americana ; while others are new spe- 

 cies which are able to invade the area owing to the increase 

 in light. Conspicuous among these are several of the gold- 

 en rods (Solid ago bicolor, S. nemoralis and S. puberal a ), 

 Aster lateriflorus, Erechtites hieracifolia, Lactuca cana- 

 densis and the fireweed ( Epilobium angustifolium), this lat- 

 ter plant forming dense masses and often carpeting the en- 

 tire area. Shrubs also may be present, chief among which 

 are the raspberry (Rubus idaeus var. canadensis ), the bush 

 honeysuckle (Diervilla Lonicera), red berried elder (Sam- 

 bucus racenwsa ) and gray birch. Meanwhile certain of the 

 tiers have begun to sprout from the root collar and give 

 rise to a dense coppice growth. This is particularly true 

 in the case of the paper birch and to a lesser degree of the 

 red maple and beech. The birch, also, seeds in freely and 

 owing to its rapid growth soon develops a characteristic 

 forest. Associated with it are a few other light-loving and 

 rapid growing trees, the bird or fire cherry (Prunus penn- 

 sylvanica), and the "popple", a term used in Maine to de- 

 note both the large-toothed aspen (Populus grandidentata ) 

 and the quaking aspen (Populus tremuloides ). This birch- 

 popple forest is of widespread occurrence throughout the 

 region, and is almost always an indication of a previous 

 burn. After a time conifers begin to come in underneath 

 the hardwoods and form a definite layer society, as is shown 



