THE RED SPRUCE. 17 
in the case of the thicker leaved hardwoods like maple, the duff not 
only sheds water and thus dries out quickly at the surface, hut it 
also offers a considerable resistance to the root penetration of the 
germinating spruce seedlings. 
The presence of moss is simply an indication of the presence of 
surface moisture throughout the growing season in sufficient amount 
to afford favorable conditions for spruce germination. An unbroken 
grass sod hinders the reproduction of spruce, both because it resists 
the progress toward the mineral soil of the rootlets of the young 
plant and because it makes excessive demands on subsurface mois- 
ture. In very moist and wet situations grass sod is seldom con- 
tinuous, and in such places spruce has no trouble in starting under 
the cover and protection of the rank growth. 
Protection from direct insolation and wind is also of importance, 
since they not only cause the drying out of the upper layers of the 
soil but induce rapid transpiration from the leaves of the young 
plants. This latter is particularly disastrous in the winter season 
when the soil is frozen and the seedlings are prevented from replenish- 
ing from the soil the supply of moisture thus given off. Such a 
condition is most likely to develop during a season of little snow, or 
where through exposure to an unbroken sweep of wind the snow has 
little chance to accumulate. In these open, bare situations, also, a 
warm day causing rapid thawing may be followed by freezing at 
night, which loosens the soil around the roots of the seedling and 
thus allows these tender members to be exposed to drought and frost. 
In addition to moisture, a certain amount of light is absolutely 
necessary if the seedling is to endure beyond the period of germina- 
tion. Since, however, spruce does not make extravagant demands 
in its light requirements, little difficulty is encountered in securing 
suitable conditions in this respect. 
SEED PRODUCTION. 
Authorities vary widely in their estimates of the frequency and 
abundance of spruce seed production. So far as is known, no obser- 
vations have been carried on over a sufficient period of years to 
determine this with any degree of certainty. Spruce unquestion- 
ably produces a certain amount of seed annually, and conditions 
may be such that a good crop will occur for two successive years. 
In general, however, the interval between succeeding full seed crops 
varies from three to seven or eight years. 
Spruce produces from 50 to 90 per cent perfect seed; from 60 to 
80 per cent of which germinate. The seeds retain their vitality for 
at least two years under ordinary conditions of storage, and probably 
much longer. Variations are due to the conditions in the seed year. 
An off year not only produces fewer seeds, but the quality is poorer. 
84949°— Bull. 544—17 2 
