shelter 69 



Of course, the value to grouse depends on the character of the 

 coniferous element, too. Whether the conifers exist primarily in the 

 understory as reproduction, primarily in the crown as mature trees, 

 or in all age classes is of great significance; the latter is most satis- 

 factory, the second class poorest ( see Plate 13 ) . 



Just as we find it necessary to distinguish the line between hard- 

 woods and mixed woods, so we must also define the point of change 

 from mixed woods to coniferous woods. This criterion appears to be 

 about seventy per cent of conifers. The mixed woods is thus a bal- 

 anced stand containing hardwoods and from twenty per cent to 

 seventy per cent conifers, based on area of crown coverage. It pro- 

 vides grouse with food and shelter for all seasons, although the cover 

 in summer is imperfect. 



The subtypes of mixed woodland follow the same general distinc- 

 tions as the hardwood types: differences in age class, in prevalence 

 of small openings, and in species composition. The mature and 

 second- giowth stands are distinguishable as in the hardwoods, the 

 critical point being in the neighborhood of an average twelve inches 

 d.b.h. The species associations follow the hardwood types with coni- 

 fers added: in the North, spruce, red pine, and balsam fir grow in 

 combination with the northern hardwoods; white pine, hemlock, and 

 sometimes Banks' or other pines in combination with the beech- 

 birch-maple group; the southern oak and hickory types contain 

 some white pine and hemlock at higher altitudes, but, toward the 

 south, include more of the hard pines, especially Virginia pine, 

 pitch pine and shortleaf pine. 



The shrub species are substantially those in the hardwood stands. 

 In the ground cover we find some significant variations, notably the 

 addition of partridgeberry, wintergreen, and club mosses {Lyco- 

 podium). 



Coniferous woodland: Woodland, predominately coniferous trees 

 (excepting tamarack), having less than about thirty per cent of its 

 crown taken up by hardwoods, constitutes the last of the important 

 northeastern type groups. In young stands, this type is usually very 

 deficient in food though well provided with shelter, but in mature 

 stands there is usually a hardwood understory of significance. Sub- 

 types, as with the last two type groups, are based on age class and 

 species composition ( see Plate 15 ) . In addition to the mature stands 

 and the second-growth stage, it is sometimes desirable to add a third 

 ageclass subtype, the pure, one-species reproduction ( or reforesta- 



