14 BULLETIN 544, U. S. DEPARTMENT OP AGRICULTURE. 



SECOND-GROWTH STANDS OF SPRUCE. 



Partial or complete destruction, such as is effected by lumbering, 

 windfall, or foes, will alter more or less completely the original char- 

 actor of any of these types, depending on the severity of the cutting 

 or the extent of the windfall or fire. The succeeding second growth 

 will develop a strong tendency to produce a groupwise association of 

 the species, which in case of extended destruction may effect a tem- 

 porary replacement of the original growth by either of two general 

 forms — pure, even-aged stands of spruce or balsam alone or in mix- 

 ture with each other, hemlock, arborvitse, and hardwoods, or a two- 

 storied form comprising an over wood, usually of such hardwoods as 

 aspen, grey birch, fire cherry, and the like, and an understory of 

 spruce. The last named is the typical one following fire. Never- 

 theless, if left undisturbed, the characteristics of these stands will 

 usually revert to those of the parent type. 



OLD-FIELD SPRUCE. 



Because of their economic possibilities, particularly as forecasting 

 the results which may be expected from plantations, the old-field 

 spruce stands merit special mention. As their name implies, they 

 occupy abandoned lands formerly under cultivation or in pasture. 

 They are essentially even-aged and composed chiefly of spruce. Here- 

 after the discussion of second growth will refer to this character of 

 the stand unless otherwise specified. 



SOIL AND MOISTURE REQUIREMENTS. 



Spruce is found on all kinds of soil. It is not exacting in its 

 demands as to chemical composition, but prefers the well-drained 

 gravelly and sandy loam soils of the mountain slopes and benches 

 because of their favorable moisture conditions. Heavy soils are 

 unfavorable to spruce because they hinder root penetration, accentu- 

 ating its shallow rootedness, and thus render it more than ever liable 

 to windthrow. 



Moisture is the most potent factor influencing the local distribution 

 of spruce on tho various soils. Soils like sand or coarse gravel, which 

 are devoid of binding material, quickly lose their surface moisture. 

 They therefor© afford scant opportunity for the development of spruce, 

 even though the water table is but a few feet below the surface, since 

 the water can not be reached by tho superficial root system. Spruce 

 can endure a wet soil, such as the clays and fine alluviums occurring 

 in swamps. It reaches its best development, however, on the inter- 

 mediate gravelly or sandy loam soils with free drainage, yet with a 

 plentiful supply of surface or subsurface moisture. 



Aside from these preferences of spruce, its distribution is dependent 

 largely upon its ability to grow on sites unfavorable to its competitors. 

 Spruce is not infrequently found almost solely in possession of large 



