THE AUTHORS 



CONTENTS 



DENNIS E. FERGUSON is a research forester in the 

 research \Nork unit investigating the silviculture and 

 genetics of Rocky Mountain conifers at the Intermoun- 

 tain Research Station's Forestry Sciences Laboratory 

 in Moscow, ID. He received a Ph.D. degree in forest 

 resources from the University of Idaho in 1991 . He has 

 worked primarily with modeling regeneration establish- 

 ment and growth of young trees and stands. 



CLINTON E. CARLSON is a research forester in the 

 research work unit investigating the silviculture of sub- 

 alpine forest ecosystems at the Intermountain Research 

 Station's Forestry Sciences Laboratory in Missoula, MT. 

 He received a Ph.D. degree from the University of 

 Montana in 1978. His studies have focused on the 

 effects of western spruce budworm on regeneration, 

 growth, and development of Northern Rocky Mountain 

 forests. His current studies focus on relationships 

 among forest structure and composition, forest health, 

 and fire. 



RESEARCH SUMMARY 



Data on regeneration of 10 conifer species commonly 

 found in the Northern Rocky Mountains of the Western 

 United States were collected by stratified random sam- 

 pling of 12,128 Vsoo-acre plots in 537 stands. These 

 data were collected in Montana, central Idaho, and north- 

 ern Idaho, representing five habitat type series having 

 various combinations of regeneration harvest methods 

 and site preparations. Also included is the influence of 

 western spruce budworm {Choristoneura occidentalis) 

 on regeneration success. The resulting Regeneration 

 Establishment Model is a part of the Prognosis Model. 

 Together, these models can be used to predict growth 

 and yield for even-age and uneven-age management 

 systems. The regeneration model predicts the prob- 

 ability of stocking, seedling density, species composi- 

 tion, and seedling heights 2 to 20 years after harvest 

 for various combinations of regeneration methods, site 

 preparations, habitat types, and budworm defoliation 

 histories. 



ACKNOWLEDGMENTS 



Work reported in this publication was partially funded by 

 the Canada/U.S. Spruce Budworms Program (CANUSA). 

 We thank Albert R. Stage, William R. Wykoff, David A. 

 Hamilton, Jr., and Nicholas L. Crookston for their ideas, 

 encouragement, and many hours of consultation that 

 led to this model. Thanks to Ward W. McCaughey for 

 his time and devotion to field sampling in Montana. 



Page 



Introduction i 



Study Design 3 



Modeling Technique 5 



Logistic Regression Equations 6 



Linear Regression Equations 7 



Weibull Distributions 7 



Habitat Type Groupings 7 



Western Spruce Budworm Defoliation History 8 



Planting 8 



Variables in the Model 8 



Results 1 1 



Probability of Stocking 12 



Number of Trees per Stocked Plot 18 



Number of Species per Stocked Plot 19 



Probability of Advance Regeneration 19 



Probability of Subsequent Regeneration 20 



Probability of Excess Regeneration 21 



Heights of Regeneration 21 



How the Prognosis Model and Regeneration 



Model Interact 23 



Steps in the Regeneration Model 24 



Step 1: Initiate Regeneration Model 24 



Step 2: Determine Plot Site Preparation 24 



Step 3: Compute Years Since Last 



Disturbance 26 



Step 4: Calculate the Increment in Stocking 26 



Step 5: Estimate Number of Trees 26 



Step 6: Predict Number of Species 27 



Step 7: Calculate Probability of Species 



Occurrence 27 



Step 8: Estimate Heights 27 



Step 9: Add Planted Trees 27 



Step 10: Identify Best Trees 28 



Step 1 1 : Accumulate Stand Statistics 28 



Step 12: Pass Tree Records 28 



Step 13: Print Regeneration Summary 28 



Model Behavior 29 



Example Projection 29 



Comparison of Habitat Types 29 



Example of Spruce Budworm Effects 31 



Other Model Features 33 



Calibration 33 



Consistency of Predictions 34 



Ingrowth 36 



Automatic Tallies 36 



Site Preparation 37 



Regeneration Model Variants 37 



Regeneration Sprouts 37 



Discussion 37 



References 39 



Appendix A: Habitat Type Groupings 41 



Appendix B: Coefficients for Equations 44 



