32 



BULLETIN 475, U. S. DEPARTMENT OF AGRICULTURE. 



in the trees in hot, exposed situations and against their heating in 

 the bundles, crates, or while heeled in. 



Pains should be taken during the actual planting to observe the 

 following: The planting holes should be deep enough (10 to 12 

 inches) and broad enough (8 inches or more) to accommodate fully 

 the roots of the planting stock; the planting should be neither too 

 deep nor too shallow ; the soil packed around the roots should be 

 moist and well firmed ; the more fertile upper layers of soil should 

 be packed around the roots, but sod should be excluded because it 

 leaves air spaces and causes the drying out of the roots and the death 

 of the plant; and depressions should not be left around trees planted 

 under aspen or deciduous brush or on steep slopes (fig. 5). 



QUANTITY OF SEED AND NUMBER OF PLANTS PER ACRE. 



In the forest nature produces seed abundantly, depending upon 

 quantity to offset possible adverse conditions. In artificial sowing it 

 is not practicable to be so lavish ; and conditions that will permit the 

 germination of the seed and enable the plants to grow must, so far 

 as possible, be insured. One of the chief problems is to get the seed 

 into direct contact with the soil. An old grove of Douglas fir trees 

 may shed 25 pounds of seed to the acre, or 1,250,000 individual seed; 

 yet, because of needles and litter covering the ground, very few seed 

 reach the mineral soil, germinate, and grow. With Douglas fir direct 

 light is, of course, an important factor also. By removing the heavy 

 shade, burning the litter, and exposing the mineral soil, and by 

 poisoning destructive rodents, conditions may be so improved that 3 

 pounds of seed to the acre, sown broadcast, or 1 pound sown in seed 

 spots, will produce a full stand of young trees. Areas sown by the 

 seed-spot method suffer more damage from birds than do those sown 

 by other methods. A thicker sowing in the spots is therefore neces- 

 sary. 



Table 5. — Approximate percentage of germination of fresh seeds of different 

 species under greenhouse conditions. 1 



Species. 



Germina- 

 tion. 



Species. 



Germina- 

 tion. 





Per cent. 



33 



22 



242 



55 



«34 



«23 



«65 



67 



86 



83 



47 





Per cent. 

 89 



Arizona cypress (Cupressus arizoniea) . . . 





44 





51 



Douglas fir (Pseudotsuga taxifolia) 



Western white pine (Pinus monticola) . . . 

 Western yellow pine ( Pinus ponderosa).. 



57 

 75 





55 





Western red cedar (Thuia plicata) 



Engelman spruce (Picea engelmanni). . . 



67 





60 





48 



Lodeepole pine (Pinus rhurravana) 





51 



Mexican white pine (Pinus strbbiformis) . 







1 Individual lots of seeds vary greatly in their germinative ability. Under field conditions, germination 

 is usually less than in the greenhouse. 

 3 Tests not made by the Forest Service. 



