THE AUTHORS 



RESEARCH SUMMARY 



J. DAVID BORN is a forester, Forest Survey, Inter- 

 mountain Research Station, Ogden, UT. Before going 

 to Ogden in 1967, he held a similar position with the 

 Pacific Northwest Forest and Range Experiment 

 Station in Alaska. He holds B.S. and M.S. degrees in 

 forestry from Purdue University, Lafayette, IN. 



DAVID C. CHOJNACKY is a research forester. Forest 

 Survey, Intermountain Research Station, Ogden, UT. 

 He has been with the Forest Service since 1979. 

 Before going to Ogden, he held a position with the 

 Forest Research Laboratory at Oregon State Univer- 

 sity, Corvallis. He holds a B.S. degree in mathematics 

 from the University of'idaho, Moscow, an M.S. degree 

 in watershed management from the University of Ari- 

 zona, Tucson, and a Ph.D. degree in forest biometry 

 from Colorado State University, Fort Collins. 



Visual segmentation, a technique for estimating 

 cubic foot volume of woodland tree species, was com- 

 pared with actual volume measurement. Comparison 

 was made during a forest inventory of pinyon-juniper 

 woodlands in Nevada and Utah. The visual technique's 

 accuracy, its usefulness in developing volume equa- 

 tions, and applicability to volume inventory were 

 studied. This study indicated visual segmentation is 

 not reliable for estimating volume for a single tree. 

 However, a sample of visually estimated volumes 

 proved adequate for developing volume equations. In 

 an application, a bias of to -9 percent of the mean 

 cubic foot volume per acre resulted from summary of 

 176 plots, using volume equations developed with 

 visually estimated data. An appendix includes a com- 

 plete description of the visual volume estimation tech- 

 nique for field use. 



ACKNOWLEDGMENTS 



Data for this study were collected in cooperation 

 with the U.S. Department of the Interior, Bureau of 

 Land Management in Nevada and Utah. Special thanks 

 to Dave Schmidt, Steve Langdon, and Jason 

 Teegaurden, former temporary employees of the Inter- 

 mountain Research Station, who collected most of the 

 field data. The Bureau of Land Management at Ely, 

 NV, provided the inventory data for use in table 3. 



