University of California

The Predictive Models and Procedures Used in the Forest Stand Generator (STAG)


Greg S. Biging
Timothy A. Robards
Eric C. Turnblom
Paul C. Van Deusen

Authors Affiliations

Greg Biging was Associate Professor, Department of Environmental Science, Policy and Management, University of California, Berkeley; Timothy A. Robards was Sustained Yield Forester with the California Department of Forestry and Fire Protection; Eric C. Turnblom was former Postgraduate Researcher, Department of Environmental Science, Policy and Management, University of California, Berkeley, and is now Assistant Professor at the University of Washington, Seattle; Paul C. Van Deusen was Research Scientist at the USDA Forest Service Southern Forest Experiment Station, New Orleans, Louisiana.

Publication Information

Hilgardia 61(1):1-36. DOI:10.3733/hilg.v61n01p037. November 1994.

PDF of full article, Cite this article


The Forest Stand Generator, STAG, is a microcomputer-based program that uses statistical routines to produce a projection set composed of individual tree measurements of diameter at 4.5 feet above ground (called the diameter at breast height or DBH), total height, height-to-crown base, species, and tree expansion factor. When data sets are not complete, STAG can be used to produce a projection set for a wide class of inventory procedures. The authors will discuss the estimation procedures used by STAG to (1) fill in missing measurements of tree height, height-to-crown base, or both; (2) generate stands from summary statistics; and (3) convert stand table data—numbers of trees by DBH classes and species—to individual tree records, so that these projection sets, composed of complete individual tree records, can be analyzed by the California Conifer Timber Output Simulator (CACTOS) for simulation of tree growth and mortality, even though the initial data sets could not have been used with CACTOS. Also discussed are the predictive equations and analytic procedures used to produce a projection set for these three categories of data availability. Recommended uses of STAG and the type of data required for accurate development of projection sets are presented.

Research reported here was conducted under UC Agricultural Experiment Station projects 3679-ms and 3815-ms. The authors gratefully acknowledge important contributions to this work by Peter J. Daugherty and Vaughan Landrum. They also are grateful to Lee C. Wensel and the members of the Northern California Forest Yield Cooperative for their support.

Literature Cited

Avery T. E., Burkhart H. E. Forest measurements. 1983. New York: McGraw-Hill.

Biging G. S. Volume tables for young-growth mixed conifers of northern California based upon the stem analysis data. Part I; Volume tables for mixed conifers. Part II; Taper equations for mixed conifers. Research Note 7, revised draft. 1983. University of California, Berkeley: Northern California Forest Yield Cooperative, Department of Forestry and Resource Management.

Biging G. S. Taper equations for second-growth mixed conifers of northern California. For. Sci. 1984. 30(4):1103-17.

Biging G. S., Wensel L. C. STAG: A forest STAnd Generator for producing complete CACTOS stand descriptions. Forest Growth Modelling and Prediction. 1987. 1:47-53. USDA Forest Service General Technical Report NC-120. In Ek A. Burk T. eds

Biging G. S., Turnblom E. C., Meerschaert W. J., Robards T. A. STAG user’s guide: The Forest Stand Generator for Mixed Conifer Species in California. Version 4.5 1995. Manuscript for the University of California Agricultural Experiment Station Bulletin series

Burk T. E., Hansen M. H., Ek A. R. Combining sources of information for improved in-place inventory statistics. 1982. Orno, Me: In Place Inventories.

Davis L. S., Johnson K. N. Forest Management. 1987. 3rd ed. New York: McGraw-Hill.

Ek A. R. Nonlinear models for stand table projection in northern hardwood stands. Can. J. For. Res. 1974. 4:23-27. DOI: 10.1139/x74-004 [CrossRef]

Husch B., Miller C. I., Beers T. W. Forest Mensuration. 1982. 3rd ed. New York: John Wiley &; Sons.

Hyink D. M., Moser J. W. A generalized framework for projecting forest yield and stand structure using diameter distributions. For. Sci. 1983. 29:85-95.

Knoebel B. R., Burkhart H. E. A bivariate distribution approach to modeling forest diameter distributions at two points in time. Biometrics. 1991. 47(1):241-53. DOI: 10.2307/2532509 [CrossRef]

Knox R. G., Peet R. K., Christensen N. L. Population dynamics in loblolly pine stands: Changes in skewness and size inequality. Ecology. 1989. 70:1153-66. DOI: 10.2307/1941383 [CrossRef]

Meerschaert W. J., Wensel L. C. SDAVG User’s Guide: The CACTOS Stand Description Averager Version 2.0. Research Note 19. Northern California Forest Yield Cooperative. 1987. Berkeley: University of California.

Meyer H. A. Structure, growth, and drain in balanced uneven-aged forests. J. For. 1952. 50(2):85-92.

Miller T. E., Weiner J. Local density variation may mimic effects of asymmetric competition on plant size variability. Ecology. 1989. 70:1188-91. DOI: 10.2307/1941388 [CrossRef]

Reineke L. H. Perfecting a stand density index for even-aged forest. J. Agric. Res. 1933. 46:627-38.

Reynolds M. R., Burk T. E., Huang W. C. Goodness of fit tests and model selection procedures for diameter distribution models. For. Sci. 1988. 34(2):373-99.

Shifley S. R. Analysis and modeling of patterns of forest ingrowth in the North Central United States 1990. Ph.D. dissertation, St. Paul, Minn.: University of Minnesota

Shifley S. R., Lentz E. Quick estimation of the three-parameter Weibull to describe tree size distributions. Forest Ecology and Mgt. 1985. 13:195-203. DOI: 10.1016/0378-1127(85)90034-9 [CrossRef]

Van Deusen P. C. Complete and partial generation of tree characteristics for mixed species stands 1984. Ph.D. dissertation, Berkeley: University of California

Wensel L. C., Biging G. S. The CACTOS system for individual-tree growth simulation in the mixed conifer forests of California. Forest Growth Modelling and Prediction. 1987. 1:175-83. USDA Forest Service General Technical Report, NC-120. In Ek A. Burk T. eds

Wensel L. C., Daugherty P. J., Meerschaert W. J. CACTOS user’s guide: The California conifer timber output simulator. 1986. Berkeley: University of Californial, Division of Agricultural Science Bulletin. 1920

Wensel L. C., Meerschaert W. J., Biging G. S. Tree height and diameter growth models for northern California conifers. Hilgardia. 1987. 55(8):1-20.

Biging G, Robards T, Turnblom E, Van Deusen P. 1994. The Predictive Models and Procedures Used in the Forest Stand Generator (STAG). Hilgardia 61(1):1-36. DOI:10.3733/hilg.v61n01p037
Webmaster Email: wsuckow@ucanr.edu