Systematic Error Trends of Existing Crown Biomass Equations for the Major Commercial Conifers of the...

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