10 COMPOSITE TYPE ON THE APACHE NATIONAL FOREST. 



spruce seedlings are found usually on the north sides of mother trees 

 and in dense thickets of spruce and Douglas fir, where there is a 

 maximum amount of shade and, consequently, relatively lower 

 temperature and more soil and air moisture. 



The chief secondary species of the type — white pine and white 

 fir — though not now competing with the more valuable species, may 

 form a larger portion of the stand in the future, unless cutting is 

 properly regulated. This is especially true of white pine, the quan- 

 tity of which, as indicated in Table 1, seems to be increasing. It is 

 believed that both species are somewhat less exacting as to light than 

 are the principal ones. A succession of counts on reproduction plots 

 proves that a larger proportion of white fir and white pine seedlings 

 which germinate succeed in establishing themselves than do those of 

 yellow pine, Douglas fir, and spruce. This is no doubt due in part 

 to the large size of the seeds and to the exceptionally strong condition 

 of the seedlings immediately after germination. Therefore, unless 

 white fir and white pine are cut very close, there is danger that the 

 composite type may undergo further changes, with a possibility of 

 these two species predominating. 



Aspen, though of no commercial value in the region at present, 

 plays an important part in the composite type as a nurse tree. In 

 spite of the fact that aspen is commonly classed as intolerant, it is 

 found in considerable numbers even in the densest stands. Where 

 the most light is received it usually occurs in groups, but in dense 

 stands of the other species often grows singly. The protection 

 afforded by a cover of aspen is excellent for the growth of Douglas .fir 

 and spruce in the seedling stage, and the shade does not retard the 

 growth even of saplings. Western yellow pines occasionally start 

 under aspen, which, by the time more light is required, die out, leav- 

 ing the pine to develop unhampered. 



COMPARATIVE GROWTH OF WESTERN YELLOW PINE, DOUGLAS 

 FIR, AND BLUE SPRUCE. 



Complete stem analyses data for each of the three principal species 

 in the type form the basis for the growth studies outlined in the 

 following pages. The fact that the trees were cut especially to 

 secure this data made it possible to use great care in their selection 

 as well as in that of the plots on which the cutting was done. For 

 this reason it is believed that the comparatively small number of trees 

 on which complete stem analyses were obtained is sufficient, and that 

 the resulting tables accurately represent the growth in virgin stands. 



The cutting was done in two localities on eight sample plots, vary- 

 ing in size from 1 to 2 acres. Different subtypes, as well as stands of 

 different density, were represented. Only normal trees were selected 

 for analysis, which was conducted hi accordance with the usual 

 method. In the case of trees under 12 inches hi diameter the stems 



