PART I. COLLECTION OF SEED. 

 SEED CROPS. 



All planting and sowing on the National Forests must begin with 

 the collection of seed. Trees, unlike some other plants, do not bear a 

 good crop of seed every year. Conifers in particular are very irregu- 

 lar in the matter of seed production. A few cones are produced 

 every year, but it is only at intervals of from two to five years, or 

 more, varying with the species and the climatic conditions, that a 

 heavy crop occurs. Years when seed of any species is produced in 

 abundance are known for that species as " seed years," while the 

 intervening years are called " off years." During " off years " not 

 only is seed produced in small quantities, but because of the concen- 

 trated demand for it by rodents and birds it is difficult to obtain. 

 Insect damage to the cones and to the seed itself is also concentrated, 

 so that a small crop is likely to be one of low quality as well. 



Usually a " seed year " for any species means an abundant crop of 

 seed throughout most of its range, though much better in some places 

 than in others. Even during an " off year," however, a species may 

 produce somewhere within its range a fair crop over a limited 

 territory. 



Studies made to determine what constitutes a good crop for differ- 

 ent species have given the following interesting figures : 



TABLE 1. Amount of seed per acre produced by different species. 



1 The sugar pine is a largo-seeded species, so that this weight of seed does not indicate 

 a greater number of seed per acre than is produced by some of the other species. 



The season of 1910 was an " off year " for both Douglas fir and 

 western yellow pine, the two most important trees of the West, yet 

 cones of sufficient quantity were collected in widely separated locali- 

 ties to furnish 30 tons of clean seeds of these species. The year was 



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