INTRODUCTION 



Pinyon and juniper trees are commonly small and scrubby, have rapid taper and a 

 bushy appearance. These characteristics, which are different from those of tree species 

 conventionally managed for production of sawlogs, give both the private landowner and 

 the public forester some unusual problems in estimating wood volume. Few volume tables 

 have ever been published, and volume equations are virtually nonexistent. Howell and 

 Lexen published some tables in the late 1930 's and early 1940' s (Howell and Lexen 1939; 

 Howell 1940 and 1941) and Moessner later published an aerial photo volume table (1962) . 

 All these tables were published within one cover by Barger and Ffolliot (1972) , 



DATA COLLECTION 



The lack of adequate equations or tables for estimating cubic volumes of pinyon 

 and juniper plus the interest of personnel on the Carson National Forest in New Mexico 

 in assessing the current situation in their pinyon and juniper resources resulted in 

 plans for a cooperative study. Participants were the Intermountain Forest and Range 

 Experiment Station's Renewable Resources Evaluation work unit, the Carson National 

 Forest, and the Southwestern Region of the Forest Service. The data used to develop 

 the cubic volume equations presented here were collected on the Carson National Forest 

 as part of this cooperative study. Independent variables collected and used in the 

 data analysis were: 



1. Species 



2. Basal diameter outside bark--diameter at ground line 



3. Total tree height 



4. Number of 3-in (7.62 cm) and larger forks anywhere on the stem where both 

 stems coming out of the fork were 3 in or larger diameter outside the bark 



5. Number of stems 3-in (7.62 cm) diameter and larger outside the bark and 

 originating within the first 12 in (30.43 cm) above ground line. 



The two independent variables measured for use in determining cubic- foot volume of 

 each sample tree were: (1) the number of segments in each tree by 2-ft (0.61 m) length 

 classes, and (2) 2-in (5.08 cm) midpoint diameter classes (2 to 8 ft, or 0.61 to 2.44 m) . 

 The midpoint diameter classes were even 2-in (5.08 cm) classes; 2-in (5.08 cm) diameters 

 were the smallest. If any segment (except for the 2-ft length class) had more than 

 2 in of taper, it was divided into two or more segments such that maximum taper within 

 a segment could not exceed 2 in (5.08 cm). 



Of the several species of pinyons and junipers native to the Rocky Mountain West, 

 only three were encountered in this study: pinyon {Finns edulis -Engelm.) and Rocky 

 Mountain and Utah junipers {Juniperus saopuZorum Sarg. and J. osteospeima^ [Tott .] 

 Little). Of the total of 2,318 trees measured, 1,559 were pinyons and 759 were junipers. 

 The trees were selected from 96 field plots randomly scattered about the Carson National 

 Forest . 



DATA ANALYSIS 



Using diameter and length class, the cubic volume was calculated for each segment 

 in each sample tree assuming the segment was a cylinder having diameter equal to the 

 segment midpoint diameter and length equal to the segment length class (Huber's formula). 



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