Single-tree total height estimators for second-growth Douglas-Fir in the Inland Northwest

Abstract EN

The objective of this study was to develop and test various single- and multiple equation (composite) estimators for predicting total tree height from dbh using re-measured second-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var.

menziesii) in the Inland Northwest ٧$.

Single-equations and composite models we-re compared using residual plots, average residuals, standard deviation of the res؛-duals and coefficient of prediction.

The main results are: ١- The best single- equation estimator based on residual plots and fit statistics was model 2 [ln(H-4.5)=bQ+b.| In(dbh) +ل(س)هما2ط .

2- All models fitted by installation Rad better prediction statistics.

3- Composite models using historical and Permanent sample plot (PSP) prior models had smaller average residual variances than their components.

4- The composite model variance with a permanent sample plot (PSP) prior was one-half the minimum variance of the component models.

5- A single- equation model fitted as a function of initial dbh and height along with remeasured dbh [H^-Hq = وبم6ه-لأس2ط+وبم8&/وسمط)) had the best predictions.