Recommendations on the "best" equations to use are 

 difficult to make. As previously mentioned, definition 

 differences account for some of the equation differences, 

 but the unique developmental data for each equation 

 should also be considered. Potential users should identify 

 their desired volume definition standards and identify 

 their geographic location for application, and then choose 

 the equation that most closely fits their need. Users from 

 the northern Arizona National Forests and from the 

 Navajo Indian Reservation will have the most difficulty se- 

 lecting equations because no recent woodland volume data 

 have been published for their areas. Some of the 1940's 

 data reported in the Barger and Ffolliott work came from 

 Arizona and New Mexico National Forests, but precise 

 documentation is lacking. 



If choosing an appropriate woodland volume equation is 

 an issue, doing visual volume estimation (Born and 

 Chojnacky 1985) on a small sample of test trees (repre- 

 senting species and size diversity from the area of interest) 

 will provide data for making a decision. The volume equa- 

 tion that best predicts the test data then should be used. 



REFERENCES 



Andrews, S. A. 1988. Volume estimation and multipurpose 

 management of Prosopis velutina in Southern Arizona. 

 Tucson, AZ: University of Arizona. 67 p. Thesis. 



Barger, R. L.; Ffolliott, P. F. 1972. Physical characteristics 

 and utilization of major woodland tree species in 

 Arizona. Res. Pap. RM-83. Fort Collins, CO: U.S. De- 

 partment of Agriculture, Forest Service, Rocky Moun- 

 tain Forest and Range Experiment Station. 80 p. 



Belsley, D. A.; Kuh, E.; Welsch, R. E. 1980. Regression 

 diagnostics: identifying influential data and sources of 

 collinearity. New York: John Wiley & Sons. 292 p. 



Born, J. D.; Chojnacky, D. C. 1985. Woodland tree volume 

 estimation: a visual segmentation technique. Res. Pap. 

 INT-344. Ogden, UT: U.S. Department of Agriculture, 

 Forest Service, Intermountain Research Station. 16 p. 



Chojnacky, D. C. 1985. Pinyon-juniper volume equations 

 for the central Rocky Mountain States. Res. Pap. INT- 

 339. Ogden, UT: U.S. Department of Agriculture, Forest 

 Service, Intermountain Forest and Range Experiment 

 Station. 27 p. 



Chojnacky, D. C. 1988. Woodland volume equations for 

 Arizona Fort Apache and San Carlos Indian Reserva- 

 tions. Res. Note INT-379. Ogden, UT: U.S. Department 

 of Agriculture, Forest Service, Intermountain Research 

 Station. 7 p. 



Chojnacky, D. O; Ott, J. S. 1986. Pinyon-juniper volume 

 equations for Arizona Hualapai and Havasupai Indian 

 Reservations. Res. Note INT-363. Ogden, UT: U.S. De- 

 partment of Agriculture, Forest Service, Intermountain 

 Research Station. 4 p. 



Cook, R. D. 1977. Detection of influential observation in 

 linear regression. Technometrics. 19: 15-18. 



Gevorkiantz, S. R.; Olsen, L. P. 1955. Composite volume 

 tables for timber and their application in the Lake 

 States. Tech. Bull. 1104. Washington, DC: U.S. Depart- 

 ment of Agriculture, Forest Service. 51 p. 



Graybill, F. A. 1976. Theory and application of the linear 

 model. North Scituate, RI: Duxbury Press. 704 p. 



Gronski, S. 1987. Mesquite weight/volume estimate table. 

 The Mesquite Messenger. Austin, TX: Los Amigos Del 

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Howell, J., Jr. 1940. Pinon and juniper: a preliminary 

 study of volume, growth, and yield. Reg. Bull. 71. Al- 

 buquerque, NM: U.S. Department of Agriculture, Soil 

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Howell, J., Jr.; Lexen, B. R. 1939. Fuel wood volume tables 

 for Rocky Mountain red cedar (Juniperus scopulorum 

 Sarg.). Res. Note SW-68. Tucson, AZ: U.S. Department 

 of Agriculture, Forest Service, Southwest Forest and 

 Range Experiment Station. 4 p. 



Husch, B.; Miller, C. I.; Beers, T. W. 1982. Forest mensura- 

 tion. 3d ed. New York: John Wiley & Sons. 402 p. 



Olson, C. E. 1940. Mesquite woodlands on southern 

 Arizona Indian Reservations. Reg. Bull. 68. Albuquer- 

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Pillsbury, N. H.; Kirkley, M. L. 1984. Equations for total, 

 wood, and saw-log volume for thirteen California hard- 

 woods. Res. Note PNW-414. Portland, OR: U.S. Depart- 

 ment of Agriculture, Forest Service, Pacific Northwest 

 Forest and Range Experiment Station. 52 p. 



SAS Institute, Inc. 1985. SAS® user's guide: statistics, ver- 

 sion 5 edition. Cary, NC: SAS Institute, Inc. 956 p. 



SAS Institute, Inc. 1985. S AS/GRAPH® user's guide, ver- 

 sion 5 edition. Cary, NC: SAS Instutute, Inc. 596 p. 



Schreuder, H. T.; Anderson, J. A. 1984. Variance estimates 

 for volume when D 2 H is the covariate in regression. 

 Canadian Journal of Forest Research. 14(6): 818-821. 



U.S. Department of Agriculture, Forest Service. 1985. 

 Arizona forest survey field procedures. Ogden, UT: U.S. 

 Department of Agriculture, Forest Service, Intermoun- 

 tain Research Station, Forest Survey. 2 parts. 



Whisenant, S. G.; Burzlaff, D. F. 1978. Predicting green 

 weight of mesquite (Prosopis glandulosa Torr.). Journal 

 of Range Management. 31(5): 396-397. 



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