Reproduction and Early Growth 



Red spruce produces good seed crops every 4 to 8 years, white spruce every 2 

 to 6 years, and balsam fir every 2 to 4 years (Fowells 1965). Seed production 

 may begin when trees are about 15 years, but significant production usually 

 does not begin until the trees are 25 to 30 years or older. Very few viable 

 seeds are stored in the forest floor for more than one year. Some of the 

 silvical characteristics of the major species are given in table 19-4. All 

 three spruce species are tolerant of shade but require considerable light for 

 rapid growth and development. In the coastal zone, white spruce develops pure 

 stands on oldfield sites. These stands exhibit the same characteristics of 

 growth and form that are expected in plantation-grown trees. All three 

 species may form physiographic climaxes on poorly drained sites but on the 

 better soils are subclimax to, and often mixed with, hardwoods such as sugar 

 maple and beech (Westveld 1953) . 



Spruce-fir stands normally reproduce readily and have remarkable recuperative 

 capacity (Barrett 1962). Advanced spruce-fir reproduction under many older 

 stands may assure new spruce-fir stands after the overstory is harvested, 

 unless fire occurs. Favorable seedling development is greatly affected by 

 light, temperature, and moisture conditions. Initially, the light 

 requirements conducive to early establishment seem not to exceed 10% of full 

 sunlight (Vezina and Peck 1964). However as the seedling develops, light 

 intensities of 50% or more are necessary for optimum growth (Shirley 1943) . 

 Soil surface temperatures between 115°F (46°C) and 130°F (54°C) result in the 

 death of most young conifer seedlings even when they are exposed for very 

 short periods of time (Baker 1929). Damage caused by late frost to leaders 

 and new lateral growth is seldom severe. 



Spruce seedlings are weaker and more fragile than fir and grow slower during 

 the establishment phase (Fowells 1965). Seedlings that have obtained a height 

 of 6 inches (15 cm) are considered to be established. Once a seedling becomes 

 established, early growth is determined largely by the amount and character of 

 overhead competition. Dense growth of bracken fern, raspberry, and hardwood 

 sprouts are the chief competitors of seedlings on heavily cutover lands, but 

 both fir and the spruces will survive many years of suppression and still 

 respond to release. If left undisturbed, most stands of this type will 

 contain a number of age classes because most species will survive under heavy 

 shade; however, the main canopy of many stands is even-aged because they 

 developed after depredation by insects, hurricanes, fire, and clear-cutting of 

 mature stands around 1900 (Coolidge 1963) . 



Management Methods 



The spruce-fir tree species in the characterization area are suited to 

 management in either even-aged or uneven-aged stands (Frank and Bjorkbom 

 1973). Both types of management are commonly used although the exact acreages 

 of each are unknown. Since the ecological interactions resulting from use of 

 each type are so clearly different, a detailed description of each follows. 



19-8 



