TREES, SHRUBS, AND FORESTS 



373 



with spruce on the forest floor (Fig. 226), since it too is a tolerant 

 species, growing in the shade of the other forest trees. Balsam 

 is, however, the stronger competitor of the two in such situa- 

 tions, on account of its more plentiful seeds and rapid growth. 

 Seed production. The distribution of forest trees, and their 

 power to reproduce a 

 forest once destroyed, 

 is determined largely 

 by the number of 

 seeds produced and 

 by the viability of 

 the seeds, or their 

 power to germinate 

 and grow under the 

 conditions presented 

 in a given habitat. 

 Spruces, like other 

 cone-bearing gymno- 

 sperms, begin to pro- 

 duce large quantities 

 of winged seeds when 

 the trees have reached 

 the proper age. The 

 seed-producing stage 

 has been found to 



^ FIG. 226. Balsam, a tolerant tree, growing beneath 



with the conditions a virgin stand of red spruce in the White Mountains 

 Under which it lives. Photograph by the United States Forest Service 



In the forest it begins 



to bear when the crown succeeds in reaching the light, which 

 may be at the age of twenty or thirty years or may be delayed 

 until the tree is one hundred years old. "In the open, and 

 under favorable soil conditions, seed production begins as early 

 as the fifteenth or twentieth year, and heavy crops follow by 

 the thirtieth or thirty-fifth year." The seeds mature in late 

 September and germinate in the same fall or the next spring, 

 producing in good soil a new stand of spruce. 



