Natural Enemies 



Although many insects and diseases damage spruce and fir, spruce is relatively 

 free from these hazards until it matures. Fir, at all ages, is subject to 

 insect and disease attack. 



The most destructive insect is the spruce budworm. This insect is a 

 defoliator that attacks both spruce and fir, but prefers fir. Many millions 

 of cords of pulpwood have been lost due to large outbreaks of this insect in 

 the past, primarily in stands containing mature and over-mature fir. Large 

 aerial spraying programs in northern and western Maine have been directed 

 against the spruce budworm in the last several years. Epidemics have not been 

 severe in the characterization area. 



The balsam woolly aphid is an introduced insect that is becomming increasingly 

 damaging to fir. The salivary injections of the aphid kill or deform trees. 



The important fungal diseases of spruce include red ring rot, which enters 

 through dead branch stubs, and red-brown butt rot, which enters largely 

 through basal wounds (wounds in the lower trunk) . These diseases are usually 

 confined to overmature or damaged trees. One fungus, Stereum sanguinalentum , 

 causes over 90% of all trunk rot in living balsam fir trees. Often referred 

 to as "red heart," this disease enters the tree through broken tops, broken 

 branches, and other injuries. 



In stands where diseases are serious, commercial thinning should begin when 

 tree diameters are about 8 inches (20 cm). The pathological rotation of fir 

 and spruce-fir is 50 to 60 years. 



Spruce and fir are shallow rooted. Most of the feeding roots are in the duff 

 (pre-humus ground litter) and the top few inches of mineral soil. Because of 

 their shallow root systems, thin bark, and flammable needles, spruce and fir 

 trees of all ages are easily killed by fire. Their shallow root systems also 

 make them subject to windfall. Caution is necessary in stands subjected to 

 harvesting operations and in areas where windfall is known to be a problem 

 (i.e., coastal peninsulas). Damage can be reduced by leaving uncut portions 

 along the windward edges of the stand. Depth of these protective strips 

 should be a minimum of one-half the height of the trees to be harvested. 



MAPLE-BEECH-BIRCH TYPE 



Habitat Conditions 



Sugar maple, yellow birch, and American beech are the primary timber species 

 in the northern hardwood forests. In older stands, these three species 

 dominate, but younger stands also contain paper birch, white ash, and red 

 maple. Conifers such as eastern hemlock, balsam fir, and red spruce grow with 

 the hardwoods, especially on cool steep slopes and on poorly drained soils at 

 the lower elevations. Repeated cuttings, sometimes followed by wildfires, 

 have favored a variety of stand conditions. Consequently, numerous 

 combinations of stocking levels, age classes, and species are present. 

 Hardwood soils are usually stony and podzolic, but the most productive soils 

 are deep and well to moderately well drained. 



19-14 



