By Jim Arney – Personal Correspondence (1972 – 1974)

In early 1972, the Canadian Forestry Service (CFS) held a meeting at the Petawawa Forest Experiment Station in Ontario of forest mensurationists from across Canada to discuss the tree growth simulation program within the CFS (Honer, 1972).  A six-member working group (Brian Armitage, Jim Arney, Imre Bella, Jim Cayford, Frank Hegyi and Terry Honer) was appointed to develop recommendations for tree growth simulation research within the CFS (Honer, 1973).  Their report includes the following statements:

“If the extensive forest management practices in Canada were to continue, yield table methods would probably provide results significant for planning purposes; however, if we assume that forest management will intensify in the future, we will need methods that can used to forecast the outcome of a range of alternative silvicultural strategies.  The impact on tree and stand growth of spacing, density, site, defoliation, and fertilization will have to be considered.  Finding solutions to these problems through thinning, spacing and fertilization studies, and then fitting this fragmented information together cannot be done effectively with the framework of yield tables.”

“… we need a new kind of framework, a model, that is complex enough to combine and integrate the effects of all these factors.  What is required is an operational tree growth simulator capable of providing yield estimates for natural and managed forest stands.”

These recommendations were accepted by the Programs Operations Directorate (CFS) early in 1973, and a program of testing and evaluating was initiated the same year at the Pacific Forest Research Centre (Victoria, BC), the Forest Management Institute (Ontario) and the Great Lakes Forest Research Centre on Douglas-fir, White Spruce and Jack Pine, respectively.

Arney sent a personal letter in summer of 1972 to mensurationists in the West with the following invitation:

“Because there is a high level of interest among mensurationists, an informal workshop will be convened on September 6 and 7, 1972 at the U.S. Forest Service, Forest Sciences Laboratory near Olympia, Washington.  Interested Mensurationists are invited to participate.  No formal papers will be presented so that maximum advantage can be taken of this opportunity to discuss common problems and evaluate various approaches to tree growth modeling.  Enclosed is a list of scientists who have expressed an interest to participate.”

Everyone on the list accepted the invitation.

Participant list is of historical interest

Weyerhaeuser Research Centralia, WA Dave Bower, Dave Lewis, Jim Woodman, Dale Shaw
Crown Zellerbach Research Camas, WA Bob Strand, Jim Lin
MacMillan-Bloedel Nanaimo, BC Don Reimer
PNW Forest Expt. Station Olympia, WA Dick Miller, Don Reukema, Don DeMars, Dick Williamson, Bob Curtis & Dave Bruce
Depart. Natural Resources Olympia, WA Gerry Hoyer
Faculty of Forestry, UBC Vancouver, BC Don Monro
Canadian Forestry Research Victoria, BC Jim Arney, Jim Lee
INT Forest Expt. Station Moscow, ID Al Stage
Rocky Mt. For. Expt. Sta. Fort Collins, CO Cliff Myers
NE Forest Expt. Station Columbus, OH Sam Gingrich
PSW Forest Expt. Station Berkeley, CA Dave Sharpnack
PNW Silviculture Lab Bend, OR Walt Dahms, Jim Barrett
BC Forest Service Victoria, BC Al Fraser, Nick Kovac

Within two years an informal correspondence among a wide geographic array of growth modelers developed.  This correspondence was mostly by personal letter or phone conversation among modelers.  The correspondence grew to include Al Ek (1987), Lee Wensel (1986) and Harold Burkhart (1975).  The discussions and comments were highly technical and dedicated to specific model building questions and alternatives.  This was a new science and there was ample room to share ideas without treading on anyone else’s developmental efforts.  As a result, almost none of this is documented in the retrievable literature.  Building on this series of correspondence, various forest modelers began documenting their progress.  Ken Mitchell (1973) began developing the Tree and Stand Simulator (TASS) at the Research Branch of the British Columbia Ministry of Forests in Victoria.  Jim Arney (1972, 1981, 1985) (Weyerhaeuser) and Bob Curtis (1981) (USFS PNW Station) were commissioned in a joint venture to replace the paper yield table “Bulletin 201” with a dynamic growth model.  The DFSIM and SPS Growth Models were the result of this USFS-Weyerhaeuser joint project.  Al Stage (1973) began building the Prognosis growth model at the Intermountain Forest Experiment Station in Moscow, Idaho.  Lee Wensel (1986) established a redwood growth and yield cooperative among Northern California forest land owners to build the CRYPTOS and CACTOS growth models.  Rolfe Leary (1975) developed the STEMS growth model in the Lake States Experiment Station.  Each of these modelers was in contact with the others and aware of the relative success and approaches being attempted elsewhere.  There were actual pieces of Fortran source code sent among modelers where similar problems were encountered and someone found an efficient solution.

A IUFRO Meeting was held in August, 1973, in Vancouver, British Columbia.  At this meeting Don Monro (1974) presented his paper on structure and approaches to growth and yield models.  His group labels used to identify types of growth models are still used 45 years later (i.e., Whole-stand; Tree-list, distant-independent; Tree-list, distant-dependent).

Literature Cited:

Arney, James D.  1972.  Computer simulation of Douglas-fir tree and stand growth.  Ph.D. Thesis.  Oregon State University.  Corvallis.  79 pages.

Arney, James D.  1981.  The Stand Projection System (SPS) – Growth model for Douglas-fir and Western Hemlock.  Forest Biometrics LLC.  Research Paper No. 3.  Under data sharing agreement with USFS PNW Research Station for USFS-WeyCo 1973-75 Douglas-fir permanent plot database.  47 pages.

Arney, James D.  1985.  A modeling strategy for the growth projection of managed stands.  Canadian Journal of Forest Research 15(3):511-518.

Burkhart, Harold E.  1975.  The status and future of yield projection:  Methodology in the southeast 1974.  In: Forest Modeling and inventory, selected papers from 1973 and 1974 meetings of Midwest Mensurationists.  University of Wisconsin, Madison.  Pages 10 14.

Curtis, Robert O., Donald J. DeMars and Gary W. Clendenen.  1981.  A new stand simulator for coast Douglas-fir: DFSIM user’s guide.  US Department of Agriculture.  Forest Service.  Pacific Northwest Experiment Station.  Portland, Oregon.  General Technical Report PNW-128.  79 pages.

Ek. Alan R., Stephen R. Shifley and Thomas E. Burk.  1987.  Forest Growth Modeling and Prediction:  Proceedings of the IUFRO Conference, August 23-27, Minneapolis, Minnesota.  USDA Forest Service.  NC Forest Experiment Station.  General Technical Report NC-120.

Honer, Terry G.  1972.  Editor.  Proceedings: Tree Growth Simulation Workshop.  Internal Report FMR-25.  Forest Management Institute.  Canadian Forestry Service.  Ottawa, Ontario.

Honer, Terry G.  1973.  Report of the Working Group on Tree Growth Simulation.  Internal Report.  Forest Management Institute.  Canadian Forestry Service.  Ottawa, Ontario.  34 pages.

Leary, Rolfe A.  1975.  Nonlinear functional equation models of forest dynamics.  In: Forest modeling and inventory, selected papers from 1973 and 1974 meetings of Midwest Mensurationists.  University of Wisconsin, Madison.  Pages 20 – 36.

Monro, Donald.  1974.  Forest Growth Models – A prognosis.  IN: Growth Models for Tree and Stand Simulation.  Forest Research Note 30.  Proceedings IUFRO Working party S4.01-4, Vancouver, British Columbia, Joran Fries Editor.  Royal College, Stockholm, Sweden.

Stage, Albert R.  1973.  Prognosis model for stand development.  US Department of Agriculture.  Forest Service.  Intermountain Forest Experiment Station.  Ogden, Utah.  Research Paper INT-137.  38 pages.

Wensel, Lee C., Peter J. Daugherty, and Walter J. Meerschaert.  1986.  Cactos User Guide:  The California Conifer Timber Output Simulator.  University of California.  Agricultural Experiment Station.  Bulletin 1920.  96 pages.

Author’s Note:  Guess where Al Stage got the idea for the name of his growth model?  Notice the title of Don Monro’s IUFRO paper.