Table 9-4. Tolerance Levels of Major Tree Species of Coastal Maine 



Intolerant 



Intermediate 



Paper birch 

 Quaking aspen 

 Northern red oak 



Jack pine 

 Pitch pine 



Tamarack 



Red pine 



White ash 



American elm 



Eastern white 

 pine 



Tolerant 



Black spruce 

 Red maple 

 Sugar maple 



Yellow birch 



American beech 



Northern white 

 cedar 



Very tolerant 



Balsam fir 

 White spruce 

 Red spruce 



Eastern hemlock 



released as the overstory is removed or as trees die. If large openings are 

 created in the canopy, by lumbering for example, conditions may be suitable 

 for intolerant species to propogate and grow. Without major disturbance, 

 however, climax associations are capable of dominating a site indefinitely. 

 In the characterization area two forest types are considered climax 

 associations: the spruce-fir and the northern hardwood types. Spruce-fir is 

 the climax association on wet lowland and shallow soils, and on coastal 

 islands, headlands, and peninsulas. The hardwoods are dominant on deep, well- 

 drained soils. White-pine can sometimes form a climax community with oak on 

 sandy, infertile sites but it is usually considered a serai stage and is 

 succeeded by northern hardwoods. Common forest subtypes that are important 

 serai stages include aspen-birch, elm-ash-red maple, northern white cedar, 

 gray birch-paper birch, and pin cherry. 



A climax community usually persists unless a major disturbance destroys a 

 large section of forest. Natural disturbances, such as wind storms, fire, and 

 insect defoliation, are known to have occurred in Maine's forests prior to 

 settlement. The relative importance of each of these types of disturbance to 

 Maine's forests is not known. Fire is thought to have been generally common 

 in the northern boreal forest (occurring approximately every 100 years; 

 Heinselmann 1971) but is not thought to have been common in Maine's spruce-fir 

 forests (Little 1974). Fire was relatively uncommon in northern hardwood 

 forests in New Hampshire (Bormann and Likens 1979), and this probably is true 

 of Maine's northern hardwoods as well. Indians along the southern coastal 



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