Systematic Error Trends of Existing Crown Biomass Equations for the Major Commercial Conifers of the Inland Northwest Brian R. Turnquist M.S. Candidate University of Montana College of Forestry and Conservation

What kind of prediction equations are out there?  National, Regional, and Local  Tree and stand level  Predictions for tree-level component weights such as branches, foliage, stem, stem bark, etc.  Found in research papers, technical reports  Papers which act as compilations of many biomass equations  Jenkins et al. (2004), TerMikaelian & Korzukhin (1997)

Weight and Density of Crowns of Rocky Mountain Conifers Brown (1978)  Describes crown allometries for 11 species  Weighed the entire tree crown, and estimated component proportions  Used data from 2 previous studies (Storey (1955) & Fahnestock (1960))  Produced equations which use DBH, height, and crown ratio (these variables are sometimes log transformed)

National-Scale Biomass Estimators for United States Tree Species Jenkins et al. (2003)  Provides prediction equations for species groupings for use across the country  Trees were not sampled, rather a compilation of prediction equations was used  Pseudo-data was created, and regression equations produced

Methods

Analysis of differences between equation predictions and RBS estimates Positive differences = under-prediction Negative differences = over-prediction RBS field estimate Brown’s equation predictionJenkins’ equation prediction

Results Sampling Region

Site Conditions

Ponderosa Pine

Differences between equation predictions and RBS field estimates for ponderosa pine

Differences from Brown (1978) equation predictions LPPP WLDF

Differences between equation predictions and RBS field estimates for ponderosa pine

Differences from Jenkins (2003) equation predictions DF LP WL PP

Discussion

Differences in Crown and Stem Definitions Storey et al. (1955)

2 lbs 12 lbs 12 inch

Conclusions  These equations are biased, and shouldn’t be used without these bias correction models  Some of the bias can be associated with a few differences in sampling methods, methods of equation creation  The amount of bias present could have immense impacts on management decisions  Creation of new equations for use in this region is an appropriate next step

Acknowledgments David Affleck John Goodburn INGY members Spokane Tribe of Indians Plum Creek Salish-Kootenai Tribes Coeur d’ alene Tribes Joint Fire Science Program Ryan, Jamie, Kagan, Eric, Jesse, Shane, Alex

RBS Sampling Schematic Stem Diameter 1 meter Branch Diameters x 1,0 x 1,1 x 1,2 x 1,3 x 1,4