CLASSIFICATION OF FOREST SYSTEMS 



Two sets of terms will be used to discuss forest systems in this chapter. 

 The first will be used to describe the functional aspects of the forest 

 system, such as energy flow, nutrient cycles, and food webs, and the other 

 will serve to group forests according to "forest types." 



Functionally, forests can be considered softwood, hardwood, or mixed. 

 Softwood stands are those in which two-thirds or more of the trees comprising 

 the canopy are softwood or coniferous (e.g., spruce, fir, and pine), whereas 

 in hardwood stands at least two-thirds of the canopy trees are hardwood or 

 deciduous (e.g., maple, birch, oak, and aspen). Mixed stands have neither a 

 predominance of hardwoods nor softwoods. This grouping is considered 

 functional since, with some exceptions, similar environmental conditions and 

 associated plant and animal life are found in stands dominated by softwood or 

 hardwood trees, regardless of the tree species composition, and 

 generalizations can be made about nutrient cycles and energy flow in both. 

 Along the coast of Maine there is a continuum from pure coniferous to pure 

 deciduous stands but the amount of forest land occupied by each of these 

 functional groups has not been quantified. 



Forests also can be separated into forest "types" as proposed by the Society 

 of American Foresters (1964). Forest types indicate tree species that "singly 

 or in combination make up the plurality (>50%) of the stands." This 

 nomenclature system recognizes that certain associations of tree species occur 

 repeatedly under similar conditions of topography, climate, soil type, and 

 moisture. 



For the purposes of this report, the three major forest types are spruce-fir, 

 white pine-hemlock-hardwood, and beech-birch-maple. These three types 

 incorporate the seven major types described by Ferguson and Kingsley (1972) 

 and include 19 local types (table 9-2). 



DISTRIBUTION OF FOREST TYPES 



Spruce-Fir 



Spruce-fir is the most abundant forest type in coastal Maine, making up 46% of 

 the commercial forest land (table 9-3). Spruce (red, white, or black) and 

 balsam fir, singly or in combination, dominate. Other tree species commonly 

 associated with this type are northern white cedar, eastern hemlock, eastern 

 white pine, tamarack, red maple, paper birch, aspen, white ash, American 

 beech, sugar maple, and yellow birch. 



Spruce-fir forests in Maine represent the southern extensions of the northern 

 boreal forest. This type is commonly found in low areas with poorly drained 

 soils (locally called spruce-fir swamps or flats), on thin soils at higher 

 elevations (spruce balds) and on islands, peninsulas, and coastal headlands. 

 These areas, called primary softwood sites (Westveld 1941), usually have a 

 colder microclimate than surrounding upland areas and indicate the adaptations 

 of these conifers for cold temperatures and shallow soils. Spruce-fir also is 

 found on the better drained soils at moderate elevations (secondary softwood 

 sites) but here competition from hardwoods is more intense and hardwoods 

 usually dominate. 



9-4 



