Post on 29-Jan-2016
Systematic Error Trends of Existing Crown Biomass Equations for the Major Commercial Conifers of the
Inland Northwest
Brian R. TurnquistM.S. Candidate
University of MontanaCollege 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 SpeciesJenkins 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-predictionNegative differences = over-prediction
RBS field estimate
Brown’s equation prediction
Jenkins’ 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
LP PP
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 AffleckJohn GoodburnINGY membersSpokane Tribe of IndiansPlum CreekSalish-Kootenai TribesCoeur d’ alene TribesJoint Fire Science ProgramRyan, Jamie, Kagan, Eric,
Jesse, Shane, Alex
RBS Sampling Schematic
Stem Diameter
1 meter
Branch Diameters
x1,0
x1,1
x1,2
x1,3
x1,4