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Implications of Clumpiness on Growth & Yield

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Presentation on theme: "Implications of Clumpiness on Growth & Yield"— Presentation transcript:

1 Implications of Clumpiness on 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) 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)

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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

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19 25 Year Mortality Story at Stampede Creek LOGS
#Trees CCF CSI (Min-Max) 1968 1,345 334 1973 1,235 368 1978 1,065 387 1983 760 373 1988 585 369 1993 465 366

20 25 Year Mortality Story at Stampede Creek LOGS

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25 33 Year Thinning Trials at OSU Black Rock Initial Conditions on Three 1-acre Plots
Treatment #Trees CCF CSI (Min-Max) Control 497 324 134 – 865 Light 84 207 160 – 388 Heavy 52 144 127 – 223

26 33 Year Thinning Trials at OSU Black Rock

27 Observed Dbh Growth by CCF
0.04 0.08 0.12 0.16 0.20 0.24 100 2.150 2.946 2.922 200 0.244 1.076 2.011 1.487 300 0.02 0.152 0.568 1.104 400 500 600 700 800

28 Observed Dbh Growth by CSI
0.04 0.08 0.12 0.16 0.20 0.24 100 2.558 2.322 200 0.399 0.910 1.529 1.498 300 0.148 0.759 1.144 1.487 400 0.156 0.590 1.083 1.478 500 0.07 0.179 0.574 1.059 600 0.01 0.085 0.457 1.070 700 0.00 0.020 0.283 800 0.091

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31 Typical Clumpiness Distributions in Oregon Forests

32 Plantation at 0.95 Clumpiness

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42 Natural Stand at 0.85 Clumpiness

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52 Natural Stand at 0.75 Clumpiness

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62 Natural Stand at 0.65 Clumpiness

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72 Comparison of Yield Site 100, Age 60 by Clumpiness
Spp Dbh BA CCF BdFt NPV 0.95 DFWH 15.3 403 496 70,039 2,790 0.85 14.6 329 414 54,679 2,180 0.75 14.2 290 370 47,969 1,914 0.65 13.7 243 315 39,777 1,590 0.55 13.2 195 258 31,575 1,273 0.45 12.3 144 197 21,893 878

73 Within Polygon Effect of a 100-ft Edge Buffer

74 Spatial Pattern within an Existing DF, WH
Clumpy Mature Stand

75 Apply 1-acre group selection thinning

76 Control brush & animals to facilitate natural regeneration

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80 Apply overstory removal

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85 Forest Projection & Planning System (FPS) Version 6.4

86 Clumpiness in Growth Models
Monro 1973 Clump Index Dbh Density Examples Stand Model No Mean Stand DFSIM Distance Independ. Tree FVS, ORGANON, SPS, CACTOS, CRYPTOS Dependent Yes FPS

87 Silviculture in Clumpy Stands
DI Models will Over-Estimate Growth DI Models will Under-Estimate Mortality DI Models tied to Research Plot Spacing Size of Openings Determines Regeneration Tree Species and Abundance Brush Species and Abundance Grass Species and Abundance

88 Is Clumpiness Important?
Composition Origin Important? Single Species Plantation No Natural Regeneration Yes Multi-Species Natural Stand Group Selection Thinnings


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