NASP IMDS

Stand Density

THE BIG THREE:• Absolute stand density• Quadratic Mean Diameter• Basal Area

Graphical Guides

Size-Density Relationship

The predictable relationship between mean size of trees and their associated density in crowded (i.e., stem exclusion) populationsD

en

sity

Age

Boundary Line Examples (AKA: “-3/2 Power Law”)

Log-logScale

Growth Trajectories Wiley 1976

Stand Density Index

Stand Density Index (SDI) – Woodard paper

Reineke (1933) Species-specific upper limit Density when the stand has a standardized QMD Calculated as:

605.1

Imperial 10TPASDI

QMD 605.1

Metric 4.25TPHSDI

QMD

Stand Density Index Values

Maximum SDI Maximum SDI(English) (metric)

White fir 830 2050 Reineke, 1933Red fir 1000 2470 Reineke, 1933Mixed conifer for CA 750 1850 Reineke, 1933Douglas-fir for WA-OR 595 1470 Reineke, 1933Douglas-fir for CA 600 1480 Reineke, 1933Eucalyptus 490 1210 Reineke, 1933Redwood 1000 2470 Reineke, 1933Ponderosa Pine 800 1980 Reineke, 1933Loblolly Pine 450 1110 Reineke, 1933Longleaf Pine 400 990 Reineke, 1933Slash Pine 400 990 Reineke, 1933Shortleaf Pine 400 990 Reineke, 1933Upland Oak 230 570 Schnur, 1937Ponderosa Pine 830 2050 Long, 1985Lodgepole pine 690 1700 Long, 1985Douglas-fir 587 1450 Long, 1985Western Hemlock 790 1950 Long, 1985

Species Source

Suggested Maximum SDI by species and source. English units are number of10-inch trees per acre. Metric units are number of 25.4cm trees per hectare.

Long, J. N. 1985. A pratical approach to density management. Forest Chronicle 61:23-37. Reineke, L. H. 1933. Perfecting a stand density index for even-aged forests. Journal of Agricultural Research 46(7):627-638. Schnur, G. L. 1937. Yield, stand, and volume tables for even-aged upland oak forests. USDA Technical Bulletin No. 560, 87p.

StockingCharts & Guides

Size vs. Density Log-Log scale SDI on the “third axis” SDImax = 1000

Taylor WoodsLevel-of-Growing-Stock

Study

Flagstaff, AZ

Relative Density Index

Relative Density Index (RDI) Basically the percent of maximum SDI Communication across species (species have

maximums) Intuitive feel Magic thresholds for stand dynamics

0.15 - 0.30 for crown closure 0.40 for scheduling of growing space thinnings 0.55 for entering “the zone of imminent competition” 0.80 for certain mortality agents

DensityGuides

Density Management Diagrams

Packaging the concepts together

Simple management tool Old GSL “boat” diagrams Additional information on

the diagrams

INTERPRETING CHANGES

150

(800 TPA, 5.1”)

653 TPA

4”

340 TPA

6”

DensityGuides

Density Effects on Growth

Density Effects on GrowthTaylor Woods: Four decades of TREE DIAMETER growth; 1962 - 2002

y = -1.3146Ln(x) + 7.106

R2 = 0.97y = -1.415Ln(x) + 7.6447

R2 = 0.9793

y = -1.4821Ln(x) + 8.2557

R2 = 0.9873

y = -1.1867Ln(x) + 6.8112

R2 = 0.9767

0

1

2

3

4

0 20 40 60 80 100 120 140 160

basal area (sf/ac) at decade's beginning

DB

H g

row

th (

inch

es/d

ecad

e)

GSL40 1962-1972

GSL60 1962-1972

GSL80 1962-1972

GSL100 1962-1972

GSL120 1962-1972

GSL150 1962-1972

1962-1972

1972-1982

1982-1992

1992-2002

Log. (1962-1972)

Log. (1972-1982)

Log. (1982-1992)

Log. (1992-2002)

Density Effects on GrowthTaylor Woods: Four decades of TREE HEIGHT growth; 1962 - 2002

y = -2.1886Ln(x) + 14.675

R2 = 0.6736

y = -1.4543Ln(x) + 11.654

R2 = 0.3773

y = -2.3839Ln(x) + 16.391

R2 = 0.6455

y = -1.8418Ln(x) + 13.568

R2 = 0.6672

0

2

4

6

8

10

0 20 40 60 80 100 120 140 160

basal area (sf/ac) at decade's beginning

hei

gh

t g

row

th (

feet

/dec

ade)

GSL40 1962-1972

GSL60 1962-1972

GSL80 1962-1972

GSL100 1962-1972

GSL120 1962-1972

GSL150 1962-1972

1962-1972

1972-1982

1982-1992

1992-2002

Log. (1962-1972)

Log. (1972-1982)

Log. (1982-1992)

Log. (1992-2002)

Density Effects on GrowthTaylor Woods: Four decades of CUBIC FOOT VOLUME growth; 1962 - 2002

y = 209.37Ln(x) - 241.19

R2 = 0.8082

y = 240.24Ln(x) - 387.18

R2 = 0.8335

y = 278.49Ln(x) - 516.98

R2 = 0.7585

y = 444.4Ln(x) - 1246.2

R2 = 0.8503

0

200

400

600

800

1000

1200

0 20 40 60 80 100 120 140 160

basal area (sf/ac) at decade's beginning

MC

F V

olu

me

gro

wth

(cf

/ac/

dec

ade)

GSL40 1962-1972

GSL60 1962-1972

GSL80 1962-1972

GSL100 1962-1972

GSL120 1962-1972

GSL150 1962-1972

1962-1972

1972-1982

1982-1992

1992-2002

Log. (1962-1972)

Log. (1972-1982)

Log. (1982-1992)

Log. (1992-2002)

PER ACRE

Density Effects on GrowthPER ACRETaylor Woods: Three decades of BOARD-FOOT VOLUME growth; 1972 - 2002

y = -0.2407x2 + 33.39x + 1134.4

R2 = 0.31

y = -0.3955x2 + 56.14x + 847.11

R2 = 0.6366

y = -0.2786x2 + 71.106x - 626.9

R2 = 0.8283

0

1000

2000

3000

4000

5000

0 20 40 60 80 100 120 140 160

basal area (sf/ac) at decade's beginning

Scr

ibn

er B

oar

d-F

oo

t V

olu

me

gro

wth

(b

f/ac

/dec

ade)

GSL40 1972-1982

GSL60 1972-1982

GSL80 1972-1982

GSL100 1972-1982

GSL120 1972-1982

GSL150 1972-1982

1972-1982

1982-1992

1992-2002

Poly. (1972-1982)

Poly. (1982-1992)

Poly. (1992-2002)

DENSITY EFFECTS ON GROWTH

Tree vigor and mortality rates Plasticity of the trees – think about this at

“Hoskins” LOGS study (chapter 7) Live Crown Ratio and “canopy depth” Crown Radius (branch length/size) and crown closure Height:Diameter and “stability” (e.g., in wind and snow) Wood utilization products; size and quality

Understory richness, diversity and abundance Net Primary Productivity distribution Ecosystem “stuff”

OTHER DENSITY MEASURES

CURTIS’ “RELATIVE DENSITY” RD = BA √QMD

RELATIVE or “AVERAGE SPACING”: (can be relative to heights, as well)

TREE-AREA RATIO: area occupied by tree crowns per unit land area; TA can be estimated from D or D2

CROWN COMPETITION FACTOR; TA relative to open grown trees

Spacing impacts Example calculations - Douglas-fir (SDImax = 600)

QMD TPA BA SDI RDI CRD Description

6 50 9.8 22 0.04 4 low-density young plantation

6 200 39.3 88 0.15 16 crown closure

6 400 78.5 176 0.29 32 well-stocked

10 50 27.3 50 0.08 9 low density, but great tree growth

10 200 109.1 200 0.33 34 well-stocked

10 400 218.2 400 0.67 69 moved into "the zone"

15 50 61.4 96 0.16 16 crown closure

15 200 245.4 383 0.64 63 moved into "the zone"

15 400 491 767 1.28 127 impossible, would have self thinned

24 50 157.1 204 0.34 32 well-stocked

24 200 628 815 1.36 128 impossible, would have self thinned

24 400 1257 1630 2.72 257 completely crazy idea

UNEVEN-AGED structures?

SDI calculated by diameter class from a stand table

BUT don’t stretch too far…why?

TPA BAPA SDI

2 50 1 4

6 10 2 4

10 0 0 0

14 60 64 103

18 80 141 205

22 20 53 71

220 261 388