Often unmerchantable sized classes need additional cultural work to improve 

 species composition, especially to reduce the over-abundance of beech in favor 

 of the higher-value sugar maple. Removing trees above 2 inches (5 cm) dbh may 

 be necessary. 



Management of even-aged stands . Management of even-aged stands is 

 recommended for growing a high proportion of intermediate and intolerant 

 northern hardwoods. Among these the commercially important species are yellow 

 birch and white ash (intermediates), and paper birch (intolerant). When 

 managed appropriately, even-aged stands will produce top-grade products. This 

 form of management, as stated previously, is also well suited for pulpwood 

 production, particularly in view of the trend toward more mechanization in 

 harvesting. 



Special attention must be given to cutting and cultural practices where high 

 proportions of birches are to be naturally regenerated. Generally, complete 

 stand removal is necessary for successful stand establishment. Complete stand 

 removal can be done in patches, strips or blocks. In each case, the 

 harvesting of merchantable trees is followed by mechanical or chemical removal 

 of all unmerchantable trees above 2 inches (5 cm) dbh. 



Patches range from 0.1 to 0.75 acre (0.04 to 0.3 ha) in size. Patch cuttings 

 encourage the regeneration of both yellow and white birch and are appropriate 

 when used in combination with selective cutting under uneven-aged stand 

 management. Groups of mature, overmature, or defective trees are used as 

 nuclei for the patches (Gilbert and Jensen 1958) . 



Optimum conditions for regenerating white ash have not been determined 

 experimentally; however, conditions that are favorable for yellow birch 

 regeneration tend to be favorable for white ash regeneration, also. 



Strip cutting is similar to patch cutting, but is more feasible to apply over 

 large areas. Strips are particularly favorable for regenerating yellow birch 

 (ratios as high as 10 yellow birch to 1 paper birch have been obtained). 

 Strips can be 50 to 100 feet (15 to 30 m) wide. For best yellow birch 

 regeneration, they should be about 50 feet (15 m) wide and oriented in an 

 east-west direction. 



Block cutting is more favorable for regenerating paper birch than yellow 

 birch. This cutting method results in regeneration composed of approximately 

 2/5 paper birch, 1/5 yellow birch and white ash, and 2/5 sugar maple and beech 

 (Leak and Wilson 1958) . A seed source must be available to insure prompt and 

 adequate natural birch regeneration. Adjacent stands can provide the seed 

 source in block cuttings up to 10 acres (4 ha). In larger blocks the cutting 

 should be done between September and April during a good seed year to take 

 advantage of the seed from harvested trees. Birch seeds usually do not remain 

 viable beyond the first growing season (Fowells 1965). 



Birch regenerates best on disturbed seedbeds where mineral soil is partially 

 exposed or mixed with humus (Barrett 1962; Marquis 1965; and Filip 1967). If 

 about 50% of the soil surface is not disturbed during the logging operation, 

 additional scarification (breaking up the surface) should be considered. 

 Seedbed preparation with power equipment provides the desired mineral soil- 



19-16 



