2<5 COMPOSITE TYPE OX THE APACHE NATIONAL FOEEST. 



than blue spruce. The light requirements for each species change 

 with an increase in age. After the seedling stage is passed trees 

 of all species make a better growth when full light is received. 



The great loss during the first year is due largely to the fact that 

 germination does not take place until after the summer rainy season 

 begins, with the result that the seedlings are very tender When 

 freezing weather sets in. While the low temperature may have some 

 effect upon the tissues of the plant, the greatest amount of damage 

 is done by heaving. If the soil is wet the loss from this source is 

 apt to be great; if dry, there is little or no damage done. By the 

 fall of the second year the roots penetrate more deeply into the 

 soil, and the loss from this cause is materially lessened. 



It appears that a brush covering decreases the loss in 1-year-old 

 seedlings. This is due to the moderating influence of the cover upon 

 extremes of temperature, and upon alternate freezing and thawing. 



The effect of heat at this altitude, and especially within the dense 

 stands of the composite type, is thought to be of secondary im- 

 portance. There is usually a cover of grass to protect the young 

 seedlings from the direct rays of the sun when they are not shielded 

 by tree growth. 



While it is not known how much loss results from drought, the 

 number of seedlings in the composite type which die from this cause 

 is probably lower than in the pure yellow type. The longest period 

 of drought occurs in the spring of the year. The heavy snows do not 

 melt until April, and since evaporation is checked by the dense stand, 

 it is likely that the soil seldom loses all the moisture available for 

 seedling growth before the beginning of the summer rainy season. 



MANAGEMENT. 



The composite type has its greatest value as a source of saw timber. 

 Mine stulls and lagging will no doubt be exploited, provided the 

 roads which open up the body of timber make direct connection 

 with the mining districts of southern Arizona. 



METHOD OF CUTTING. 



The combination of the three species found in the composite type 

 is one which should be perpetuated. No other species or combina- 

 tion native to the region is better fitted to satisfy the objects of 

 silviculture. As the result of differences in light requirements of 

 the three species the growing space is well utilized, making pos- 

 sible a yield more than twice as great as in the average forest of pure 

 yellow pine, while the density of the stand greatly increases the 

 quality of the lumber obtained. 



The clear length of western yellow pine is from 16 to 25 feet greater 

 in the composite than in the yellow-pine type. That of Douglas fir 



