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Error propagation in biomass estimates

Error propagation in biomass estimates. James M. Le Moine 28 April 2004. Overview. Introduction to Biomass Allometric equations for Height and Biomass Species specific height equations hardwoods Height estimates effects on hardwood biomass Pine heights relationships and biomass effects

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Error propagation in biomass estimates

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  1. Error propagation in biomass estimates James M. Le Moine 28 April 2004

  2. Overview • Introduction to Biomass • Allometric equations for Height and Biomass • Species specific height equations hardwoods • Height estimates effects on hardwood biomass • Pine heights relationships and biomass effects • Example: Data range and regression

  3. Study site Chequamegon National Forest • Community Types • Recent Clear Cuts • Mixed deciduous • Red Pine Plantations • Jack Pine Plantations • and naturally regenerating • Pine Barrens

  4. Biomass Biomass: dry mass (Mg) of standing trees w/ dbh. > 2.5 cm per ha • Accurate estimates useful for understanding • ANPP • C pools • Harvest yield http://bizpresenter.corbis.com/

  5. Allometric Equations • Biomass=C*Dd (Ter-Mikaelian and Korzukhin, 1997) • Simplified from Biomass= C*Dd *e*Hd (Perala & Alban, 1994) given • H=f*Dg • Reliance on 1. can compound errors

  6. Allometric Height Equations • Paper Birch (Betula papyrifera) • Bigtooth Aspen (Populus grandidentata) • Red Pine (Pinus resinosa) • Jack Pine (Pinus banksiana)

  7. Paper Birch N = 12 • Early successional • Abundant at tower plot • Published Equation: • H = 3.42 * D 0.5255 • Perala & Alban 1994 Height (m) H=1.5218*D0.8827 R2 = 0.9818 Residual (m) Dbh (cm)

  8. Paper Birch Developed Published Predicted Height (m) P = 0.978*A R2 = 0.98 P = 0.8211*A R2 = 0.5867 Actual Height (m) • Published equation over predicts small trees and under predicts large trees

  9. Bigtooth Aspen N = 73 • Common at our site • Logarithmic relationship • Published Equation: • H = 3.45 * D 0.5412 Height (m) H=9.5079*LN(D)-8.9046 R2 = 0.9818 Residual (m) Dbh (cm)

  10. Bigtooth Aspen Developed Published Predicted Height (m) P = 0.9766*A R2 = 0.8767 P = 0.9322*A R2 = 0.6768 Actual Height (m) • Published equation over predicts small trees intermediate sized trees

  11. N 12 km Implications for Biomass • 3 plots aged 14—71 years • Biomass= C*Dd *e*Hd • BEPA= • 0.6815*D2.194*H0.4466 • POGR= • 0.04072D2.211*H0.5304 • (Perala & Alban 1994)

  12. Hardwood Biomass • Biomass in Mg ha-1 • Difference = Published – Developed • % = 100 * Difference / Developed • Range reduced 40%

  13. Concerns about non-normal diameter distribution skewing regression Red Pine Height (m) H =0.9781*D0.816 R2 = 0.9265 Dbh (cm) • Relationship not as strong as for hardwoods

  14. Red Pine Height (m) Residual (m) Dbh (cm) • Randomly sampled 1/3 of trees dbh< 20 cm • Regress Height with Dbh on sample and dbh > 20 cm

  15. Red Pine Developed Published Predicted Height (m) P = 0.9332*A R2 = 0.9083 P = 1.1384*A R2 = 0.5353 Actual Height (m) • Predictions from regression of all points • Both Developed and Published under predict large trees • Developed better for small and intermediate trees

  16. Jack Pine • New towers located in jack pines • One relationship insufficient • Published Equation: • H = 6.117 * D 0.3579 H= 13.807*D 0.132 R2 = 0.1037 n=13 Height (m) H = 1.44*D 0.6825 R2 = 0.8381 n=268 Residual (m) Dbh (cm)

  17. Jack Pine Developed Published Predicted Height (m) P = 0.9662 * A R2 = 0.9122 Actual Height (m) • Published over predicts small trees and under predicts largest trees

  18. N 12 km Implications for Biomass • 3 plots aged 11—72 years • Biomass= C*Dd *e*Hd • PIBA= • 0.03837D1.95*H0.8369 • PIRE= • 0.04072*D2.211*H0.5304 • (Perala & Alban 1994)

  19. Pine Biomass • Difference = Published – Developed • % = 100 * Difference / Developed • Range reduced 8%

  20. Summary • Published Height equations seem to over predict small trees and under predict large ones • Height errors change biomass 10 to 70% for hardwoods and 6 to 140 % for pines • Directional nature of height error reduces biomass range 40% for hardwoods and 8% for pines

  21. Acknowledgment & Reference • Many thanks to John: field measurements, literature review, and perspective. • Soung for literature review and perspective • Reference: • Perala, D.A. & D.H. Alban. 1994. Allometric biomass • estimators for Aspen-dominated ecosystems in the upper Great Lakes. USDA-FS North Central Forest Experiment Station, Research Paper NC-314. 39pp. • Ter-Mikaelian, M.T. & M.D. Korzukhin. 1997. Biomass equations for 65 North American tree species. Forest Ecology and Management, 97:1-24 • Barnes, B.V., D.R. Zak, S.R. Denton, S.H. Spurr. 1980. Forest Ecology, 4th Edition. John Wiley & Sons, New York. 774pp

  22. N 5m Additional comment: Soil Respiration • 8 soil respiration collars • Soil respiration rate, T5 • Measurements every 2 wks • mid May—early September ’02 • late April—late October ’03 • 17 April ’04

  23. SRR = 0.0975*e 0.1224*T5 R2 = 0.8783 SRR (gCO2 m-2hr-1) T5 (oC) Range Management

  24. SRR (gCO2 m-2hr-1) SRR = 0.2093*e 0.0835*T5 R2 = 0.8316 T5 (oC) Range Management • No data prior to 15 May or post 23 August

  25. Effects on Q10 • Given SRRt=SRR0*e q*t • Q10=e10*q • Q10 all data= e 10*0.1224 • = 3.40 • Q10 parsed= 2.30

  26. Questions and Comments

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