NATURAL AREAS AND REGIONS 



389 



(P. tremuloides) is also said to occur in 

 certain isolated localities. Beech, buck- 

 eye, hawthorns, and some other species 

 enter these types, though they reach 

 better development at lower elevations. 

 The subalpine types occur mostly at 

 altitudes of over 3500 ft. in northern 

 West Virginia and over 4500 ft. in North 

 Carolina and Tennessee, usually mixing 

 with other types at lower and even some- 

 times at higher altitudes than those 

 named. 



Intermediate group 6 



Hardwoods make up the great bulk 

 of these types, though hemlocks and 

 pines occur more or less abundantly, 

 often in pure stands. Considered 

 broadly as forest associations or groups 

 of forest types, these aggregates show 

 relatively small geographical as com- 

 pared with very marked local variations, 

 due to differences in the weight of 

 factors of exposure and altitude. In 

 this broad sense, therefore, these asso- 

 ciations may be "discussed as though 

 generally uniform' throughout the region 

 and even north of it, although there are 

 composition differences due to geo- 

 graphical limitations of range of some 

 species within the region. 



Upper moist slope types. These types 

 are the highest in altitude of all the 

 Southern Appalachian types below the 

 subalpine types. They are found on 

 high, moist, cool slopes and high ridge 

 crests and are characterized by so called 

 "northern hardwoods" yellow birch, 

 sugar maple, and beech and hemlock, 

 with buckeye often abundant, and 

 basswood (Tilia sp.), cucumber (Mag- 

 nolia acuminata), white ash (Frax- 

 inus americana), black cherry (Prunus 

 serotina) > red oak (Quercus rubra), and 

 chestnut (Castanea dentata) in varying 

 degrees of mixture. Red oak is impor- 

 tant where it appears, as on some 

 high crests. Chestnut similarly comes 

 sparsely into this association from 

 below. 



6 These types include approximately those listed 

 by Ashe as of the Alleghanian Area of the Transi- 

 tion Life Zone. 



Lower moist slope and cove types. 

 The types occupying the moist situa- 

 tions at lower altitudes than the upper 

 moist slope types are distinguished by 

 chestnut, yellow poplar (Liriodendron 

 tulipifera), red oak, white oak, and 

 hemlock, with a large number of asso- 

 ciated species. Among these are red 

 maple (Acer rubrum), chestnut oak 

 (Quercus prinus), hickories, white pine, 

 buckeye, black birch (Betula lenta), 

 black gum (Nyssa sylvatica), basswood, 

 cucumber, white ash, black locust 

 (Robinia pseudacacia) , butternut (Jug- 

 lans cinerea), black walnut (J. nigra~), 

 black cherry, dogwood (Cornus florida) , 

 hawthorns, and holly (Ilex opaca), 

 with silverbell (Halesia Carolina), sour- 

 wood (Oxydendrum arboreum), and other 

 species in the southern part of the region. 

 Species intruding from the upper moist 

 slope and dry slope types, are also found. 

 With such a large number of species a 

 great complexity of mixtures is inevi- 

 table, and there are several well marked, 

 widely occurring formations, such as 

 those characterized by the dominance 

 respectively of yellow poplar, chestnut, 

 and hemlock (Tsuga canadensis). 



Ridge and dry slope types. These 

 occupy the ridges and dry slopes from 

 the Plateau types at about 2000 ft. 

 altitude in the southern part of the 

 region, lower in the north to the upper 

 moist slope types on exposed aspects. 

 The dry exposure is mainly the south- 

 erly one, though this formation may 

 extend around on the west as is the 

 case in the northern part of the region 

 where the influence of westerly winds is 

 felt and it may cover thin-soiled east- 

 erly exposures. The area occupied is 

 very extensive. As a result of exposure 

 to sun and wind, the light crown cover, 

 and repeated fires, the humus content of 

 the soil and the protecting cover of leaf 

 litter have been largely destroyed or 

 reduced beyond capacity to protect the 

 site from excessive evaporation. The 

 forest reflects the dryness of the site by 

 exclusion of moisture-needing species. 

 The species most characteristic are 

 chestnut, chestnut oak, black oak 



