Laboratory Analysis 



The tree disks, along with the samples of twigs, foliage, 

 and deadwood, were used to determine the moisture 

 contents of the various size fractions. The disks were also 

 used to determine the specific gravity of the wood. On all 

 disks greater than 1 inch (2.5 cm), the bark was removed in 

 the laboratory, dried, and weighed separately. The 

 samples were ovendried to a constant weight at 95° C, and 

 moisture contents were computed on a green-weight basis. 

 Percentage of bark was determined by a dry-weight basis 

 from the disks greater than 1 inch (2.5 cm). The moisture 

 content values were utilized to convert the green weights 

 of the size fractions determined in the field to ovendry 

 weights. 



The specific gravity of the wood was determined from the 

 green volume and the ovendry weights of the disks. 



RESULTS 



Total Tree Biomass 



The results include aboveground biomass measure- 

 ments for 109 trees, 76 pinyon and 33 juniper. The 

 individual tree weights are given in appendix C. The means 

 of the tree variables and the average biomass are shown 

 in table 1 by diameter classes. For a given diameter class, 

 the pinyon were taller, had a greater crown spread, had less 

 taper in the main stem(s), and weighed more than the 

 juniper. The largest pinyon sampled had a green weight 

 of 11,146 lb (5 066 kg) and the largest juniper, 3,421 lb 

 (1 555 kg). 



The proportions of the total biomass in the various size 

 fractions are shown in table 2. The component proportions 

 were also computed on a green-weight basis, but the per- 

 centages in each size fraction differed only slightly (1 to 2 

 percent) from the dry-weight basis calculations, and thus 

 are not reported here. The proportion of total biomass in 

 wood and bark greater than 3 inches (7.6 cm) is greater in 

 pinyon than in juniper. In both species, the proportion of 

 foliage decreases as tree size increases; also, juniper has 

 greater proportion of foliage than pinyon (table 3). 

 Although the proportion of deadwood increases as tree 

 size increases, the proportion of wood and bark greater 

 than 7.6 cm also increases. This indicates that these 

 species, or at least the trees sampled in this study, do not 

 reach an overmature or decadent stage as commonly 

 reported for the two species. The largest and oldest 

 pinyon sampled had over 70 percent of its total biomass in 

 wood and bark greater than 7.6 cm. The diameter growth of 

 this pinyon has been essentially constant for more than 

 three centuries (Meeuwig and Budy 1979). The tendency of 

 these species to increase in the proportion of tree weight 

 in wood and bark greater than 7.6 cm may be a character- 

 istic of woodland trees because studies on southern 

 conifers indicate that the proportions of tree weight in 

 wood or foliage remain relatively constant as tree size 

 increases (Taras and Clark 1977; Clark and Taras 1976). 

 The most important aspect regarding the distribution of 

 biomass is the amount of slash, that is, all the biomass less 



3 



