REPRODUCTION OF WESTERN YELLOW PINE. 99 



animals. A normal grass cover returns, excepting in places where 

 the brush was unusually dense. Of special importance is the thin 

 layer of semidecomposed organic matter covering the surface of the 

 soil. As demonstrated under "Herbaceous Vegetation," this material 

 is a decided aid to germination. In scattered brush this surface 

 layer usually disappears in from 10 to 15 years, but where large 

 quantities of brush are concentrated, as in piling or pulling tops, it 

 may last 25 or 30 years. The final stage is, on the whole, favorable 

 to reproduction. 



1914 Experiment. 



More decisive results have been secured on another area near the 

 Fort Valley Experiment Station. This site receives 2 or 3 inches 

 more rainfall and the soil is clayey and is not covered with cinders. 

 Altogether it is more favorable for reproduction than the cinder area 

 east of Flagstaff. 



In July. 1914. one-tenth acre was sown broadcast to western yellow 

 pine on plowed ground under fence. In anticipation of large con- 

 sumption by mice and chipmunks, as is usually the case when a small 

 isolated plot is sown, the seed was scattered very thickly, 10 pounds 

 being used on this plot. A brush harrow was employed to cover 

 the seed. A strip 15 to 18 feet wide all around the area was sown 

 heavily with old seed with the hope of diverting the attention of 

 rodents from the prepared plot. The season was unusually favor- 

 able to germination and establishment of seedlings. A dense stand 

 was secured over the. entire plot. After germination, three strips 5 

 feet wide and 1 chain long, extending across the plot on the north 

 and south sides and in the middle, were laid out. Green pine 

 branches were scattered lightly over the middle strip, leaving the 

 other two uncovered. Counts were made on a plot 5 by 10 feet in 

 size in the middle of each strip. The results are shown in Table 23. 



High mortality occurred on all plots after, as well as during, the 

 first year. On the whole, however, the loss is considerably less than 

 that usually experienced under average forest conditions in this 

 region. The severe damage by snow in the winter of 1915-16 is 

 abnormal, but damage b} 7 white grub is a common occurrence. The 

 greatest loss took place on the plots on which no brush was scat- 

 tered. The two untreated plots showed, on an average, less than 

 half as many seedlings per square foot as the brush-covered plot. 

 For the entire strips the ratio in 1919 was three to eight in favor 

 of the brush-covered area. 



