THE AUTHORS 



ALBERT R. STAGE is principal mensurationist with the 

 Forestry Sciences Laboratory, Intermountain Research 

 Station, Moscow, ID. 



DAVID L. RENNER is a forester with the Forestry Sciences 

 Laboratory at Moscow, ID. 



ROGER C. CHAPMAN is an associate professor of forest 

 management, Department of Forestry and Range Manage- 

 ment, Washington State University, Pullman. 



ACKNOWLEDGMENTS 



Tabulation of yields by site index and age was requested 

 by members of the Inland Northwest Growth and Yield 

 Cooperative, who also specified the species and manage- 

 ment regimes to be represented. 



RESEARCH SUMMARY 



Yields arrayed by site index and age have been tabulated 

 for plantations of 500 trees per acre, with five thinning 

 regimes, for each of three planted species: Douglas-fir, 

 grand fir, and western larch. In addition, yields have been 

 tabulated for naturally regenerated stands of the grand fir- 

 cedar-hemlock ecosystem of the Inland Empire. The yields 

 were estimated with the Prognosis Model for Stand Develop- 

 ment, version 5.2, including the Regeneration Establishment 

 Model. Each planted species and the natural regeneration 

 were simulated for the full range of site, geographic, and 

 ecologic variables represented in a random inventory of the 

 National Forests of the Inland Empire. Site index was 

 obtained from the simulations by extracting heights of the 20 

 tallest trees per acre when they accumulated 50 rings at 

 4.5 feet. 



Individual simulations were sorted into 10-foot site index 

 classes and average yields were calculated. Weights in the 

 averaging were proportional to the relative frequency with 

 which the sites occur in the forests of the Inland Empire. 



Simulations showed great variation in yields for stands of 

 the same site index. Furthermore, comparisons between 

 these yield tables for natural stands and 1 02 permanent 

 sample plots show that these tables give less accurate 

 estimates of growth than the Prognosis Model from which 

 they were derived. Therefore, these yield tables should be 

 used only when use of the Prognosis Model is precluded by 

 lack of data on the site, geographic, and ecologic factors. 



CONTENTS 



Page 



Introduction 1 



Applicability 1 



Methods .' 2 



Definition of Variables 2 



Yield Tables for Natural Regeneration 2 



Yield Tables for Plantations 8 



Douglas-fir 8 



Grand fir 25 



Western larch 41 



Comparison to Related Yield Estimates 55 



References 56 



Appendix Tables: Inventory Classes Used for Simulation 



Douglas-fir 57 



Grand fir 57 



Western larch 58 



Naturally regenerated stands 58 



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