THE IMPORTANCE OF SEED CHARACTERISTICS IN 



THE NATURAL REPRODUCTION OF 



CONIFEROUS FORESTS 



INTRODUCTION 



Almost all coniferous trees are dependent on seed for their perpetuation 

 and distribution. Although in their natural state coniferous forests have 

 maintained themselves and extended their boundaries with only minor or 

 local changes of composition, this apparent equilibrium in nature is easily 

 upset by man's exploitations, such as destructive lumbering, repeated 

 fires, and unregulated grazing. The effort to find the cause for the ease 

 with which this climax type of the plant kingdom is disturbed or entirely 

 replaced led to a study of the seed. 



This study has brought out many valuable facts about seed character- 

 istics and their importance in the perpetuation and distribution of the 

 forest. Seeds and their behavior have been studied in the laboratory and 

 in the field with special emphasis on the importance of size, vitality, length 

 of time required to germinate, and other characteristics. 



AMOUNT OF SEED 



The production of seed is an important factor in the perpetuation of 

 the tree species, although the periodicity of seed years and quantity of 

 seed produced by one species may vary widely from these same factors in 

 another species. The variations of seed production of one species are 

 often weighed against the same factors of another species, to advantage 

 or disadvantage as the case may be. This appears to be true when associ- 

 ated species such as yellow pine (Pinus ponderosd) and lodgepole pine 

 (Pinus contorta) or Douglas fir (Pseudotsuga taxi/olio), hemlock (Tsuga 

 heterophylla), western red cedar (Thuya plicata), and western white pine 

 (Pinus monticold) are considered. The yellow pine is able to compete 

 successfully with lodgepole pine under conditions favorable to the yellow 

 pine. The lodgepole pine is, however, a much more prolific seeder, pro- 

 ducing greater quantities of seed than does the yellow pine. What the 

 lodgepole pine loses in ability to contend with unfavorable conditions, it 

 gains in having many more seeds and consequently more seedlings with 

 which to begin the struggle. 



This is also true of the hemlock and its associates. If the enormot 

 quantity of seed produced annually by the hemlock had the same chances 

 of success as the species with which it associates, such as the Douglas fir, 

 western white pine, and larch (Larix occidentalism the entire forest would 



