44 BULLETIN 285, U. S. DEPARTMENT OF AGRICULTURE. 



(/) Old-growth with yellow birch 'predominating: 



The shelterwood method is applicable in stands running largely to birch. The 

 first cutting should remove about 50 per cent of the upper crown cover. The remain- 

 ing half of the upper crown cover should include the crowns of thrifty yellow birches 

 and less tolerant species like ash, elm, oak, or bass wood, whose reproduction is 

 desirable. Where groups of thrifty young growth of mixed species exist these should 

 be lightly thinned and left for subsequent cutting. The subordinate stand should 

 be removed if merchantable, except that especially thrifty small and large poles, 

 well situated as to light and protection from wind, may be left for a later cut, in the 

 discretion of the marker. 



The brush should be lopped and scattered. 



(g) Old-growth with sugar maple predominating: 



According to the composition of the stand, the management should follow the prin- 

 ciples laid down in (a), (b), (c), or (d). In general, the management should aim (1) 

 to eliminate beech and other species of lesser value, (2) to perpetuate sugar maple, 

 or (3) in the presence of more valuable species, to increase their proportion in the 

 stand at the expense of the maple. Provisions aiming to secure (1) and (3) are given 

 above. Maple is the most aggressive reproducer in the forest, of the northern hard- 

 woods. To perpetuate it either the selection or the shelterwood method may be used. 

 The severity of the selection cutting should be expressed in terms of the crown classes 

 and species to be removed. If preferred, the approximate percentage of the mer- 

 chantable timber corresponding to the species and crown classes to be removed may 

 be added . Unless it increases the danger of windthrow or results in loss to the operator, 

 marking will be lighter in stands containing a large proportion of thrifty young and 

 middle-aged timber, and heavier in stands containing a large proportion of mature 

 and overmature timber; except that on steep slopes the cutting should be very 

 light. When crowded groups of small trees occur among older timber they will be 

 thinned, provided they contain marketable material. 



Brush should be lopped and scattered. 

 Young-growth hardwoods (even-aged): 



In young hardwoods, cuttings should be restricted to (1) improvement and incre- 

 ment thinnings in stands of the tolerant, longer-lived species, and in immature stands 

 of intolerant, short-lived species (aspen and paper birch), wherever merchantable 

 material can be removed practicably; and (2) to clear cuttings of aspen and paper 

 birch which have reached physical maturity. 



(1) The thinnings should remove (a) merchantable defective trees, (b) merchantable 

 trees of the less valuable species in the stand, (c) not over 50 per cent of the trees 

 comprising the dominant, codominant, and intermediate crown classes, and (d) all 

 merchantable trees of the subordinate crown classes. The degree of thinning should 

 depend upon the stem density of the stand and the consequent degree of windfirm- 

 ness which the individuals will be likely to possess when the stand is opened up. 

 This must be judged on the ground by the person conducting the marking. 



Brush should be lopped and scattered. 



(2) To reproduce these stands in situ early spring clear cutting should be practiced. 

 Aspen root suckers and birch stump sprouts which result will probably grow rapidly 

 enough to take care of themselves if the competing hardwood growth is not too abun- 

 dant. Where a desirable reproduction of conifers or hardwoods exists, all mer- 

 chantable birch and aspen should be removed, with, care to prevent damage to the 

 reproduction . 



Brush should be lopped and scattered. 



