Implications of Clumpiness on Growth & Yield

1. Implications of Clumpinesson Growth & Yield Managing Stand Density Symposium March 16, 2005 Canyonville, Oregon James D. Arney, Ph.D. Forest Biometrics Research Institute Missoula, Montana

2. What is Clumpiness? • Clumpiness is a Stand Attribute • Clumpiness is an Index of Spatial Regularity • How to Get There: • Phototype the Forest into Stand Polygons • Typically by Species, Size & Density • Set Minimum Polygon Size (Typically 5-acres) • Absorb Small Openings and Thickets (< 5-acres) • Clumpiness is the Dispersion within the Polygon • Use Cruise Compiler to Compute the Index • Load the Index into your Inventory Database

3. Tree versus Plot Attributes • Plot Parameters • Site Index • Stand Density (SDI, CCF, Rd, Tpa, Basal Area) • Clumpiness (spatial pattern) • Species Parameters • Genetic growth form, Shade Tolerance • Tree Parameters • Species, Dbh, Height, Taper, Age • Tree-centered Density (CSI)

4. Stand Density Indices • Stand Density Index (SDI), Reineke (1933) • Assumes Quadratic Mean Dbh • Assumes All Trees with Dbh > 0 • Relative Density (Rd), Curtis (1982) • Assumes Quadratic Mean Dbh • Includes Only Trees with Dbh > 0 • SDI = 5.8 * Rd • Crown Competition Factor, Krajicek etal (1961) • Summation of Individual Tree Growing Space • Includes All Trees, All Sizes including Dbh = 0 • CCF = 5.0 * Rd (General Rule of Thumb)

8. Crown Competition Factor • Sum of Crown Areas: • From within-Plot Trees • On Fixed-Area Plot • Divide by Plot Area • Multiply by 100 • CCF scale 100 to 1000+ • Where: • =<100 is Open-grown • >200 crown recession • >300 suppression mortality

9. A Tree-Centered Density Index • Competitive Stress Index (CSI),Arney (1973) • Uses Same Individual Tree Growing Space Area as CCF • Includes All Trees, All Sizes (even Dbh = 0) • Competing Trees Overlap into “Subject Tree” Growing Space • Primary Sampling Unit is the Individual Tree • Provides Distribution of Density across Plot • Plot-Centered Density Index (CCF) • Competing Trees Overlap into “Plot” Growing Space • Primary Sampling Unit is the Plot • Provides only Average Density across Plot

10. Competitive Stress Index • Sum of Overlap Areas: • From neighboring Trees • On Subject Tree • Divide by Subject Area • Multiply by 100 • CSI scale 100 to 1000+ • Where: • 100 is Open-grown • >200 crown recession • >300 suppression mortality

11. Application of Clumpiness Index • Spatial Variability Index on Research Plot • Stem Map Trees on Research Plot • Clumpiness = Spatial Variance / Mean Spacing • FPS Translates to 0 – 1 Clumpiness Scale • Tree Sizes and Spacing determine CSI • Estimate of Density Distribution on Cruise • Prism Plots provide Point Estimates of CSI • Clumpiness = CSI Variation / Average CSI

19. 25 Year Mortality Storyat Stampede Creek LOGS

20. 25 Year Mortality Storyat Stampede Creek LOGS

25. 33 Year Thinning Trialsat OSU Black RockInitial Conditions on Three 1-acre Plots

26. 33 Year Thinning Trialsat OSU Black Rock

27. Observed Dbh Growth by CCF

28. Observed Dbh Growth by CSI

31. Typical Clumpiness Distributionsin Oregon Forests

32. Plantation at 0.95 Clumpiness

42. Natural Stand at 0.85 Clumpiness