Applying Density Management to Develop

Late Successional Features

Klaus J. PuettmannOregon State

University

Studies

Study Location

Overstory Species

Age at thinnin

g% max

SDI Remarks

ODFOR Coast Range D-fir 5-20 NA

Standard plantations

NewtonCole Corvallis D-fir 50 20 – 40

Thinned previously

Blodgett W.

Hemlock 50 20 – 35

YSTDSWillamette NF D-fir 40 20 – 60

Wildcat Suislaw NF D-fir 30 10 – 55

DMS BLM D-fir 45 20-75

LindhWillamette NF D-fir 20 15-90 PCT

Late successional features:

Overstory cover

Canopy layers

Large, dominant trees

Tree species mixtures, including hardwoods

Amount and composition of understory vegetation

Conifer regeneration

Spatial variability

Late successional features:

Overstory cover

Canopy layers

Large, dominant trees

Tree species mixtures, including hardwoods

Amount and composition of understory vegetation

Conifer regeneration

Spatial variability

Overstory Cover

0

10

20

30

40

50

60

70

80

90

100

1997 1999 2001

Year

Co

ve

r (%

)

Control

Heavy

Light

LtGaps

Willamette National Forest: Douglas-fir Beggs 2005

0

10

20

30

40

50

60

70

0 2 4 6 8

Year

Perc

en

t Conifer Ultra-High

Conifer High

Conifer Medium

Conifer Low

Overstory cover

Newton and Cole 2004

McDonald Forest: Douglas-fir, previously thinned

Crown structures

20

40

60

0 8Year since thinning

LC

R %

Control

Light th.

Moderate th

Heavy th.

Suislaw National Forest: Douglas-fir Chan et al. 2005

Foliage Height Diversity Index

0 m

10 m

5 m

30 m

25 m

20 m

15 m

35 m

< <STAND 1 STAND 3STAND 2

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

CR MC CF SC

BLOCK

FH

D

Control

Heavy

Light

LtGaps

Foliage Height Diversity Index

3 to 5 years after thinning Beggs 2005

Impact of thinning on volume and on growth rate (i.e., slope of volume curve)

Acceleration of “dominant old-growth” trees:

Diameter growth of largest 6 tpa

0

0.2

0.4

0.6

0.8

1

1.2

1.4

CR MC CF SC

Treatment

Control

Heavy

Light

LtGaps

Gro

wth

(cm

/

yr)

Willamette National ForestBeggs 2005

Douglas-fir

Golden chinquapin Hardwood

s

Control 14.0 (a) 27.1 (a) 36.1 (a)

(12.3 – 15.8)

(19.4 – 34.9)

(28.4 – 43.8)

Heavy 4.7 (b) 7.8 (b) 18.0 (b)

(0.1 – 9.3) (-1.1 – 16.7) (8.9 – 27.0)

Light 5.9 (b) 15.1 (a) (b) 15.3 (b)

(3.1 – 8.8) (1.5 – 28.8) 9.0 – 21.6

LtGaps 4.0 (b) 4.4 (b) 13.4 (b)

(0.8 – 7.2) (-3.6 – 12.5) (7.0 – 19.7)

Overstory Mortality (%)

Mostly competition relatedBeggs 2005

Late successional features:

Overstory cover

Canopy layers

Large, dominant trees

Tree species mixtures, including hardwoods

Amount and composition of understory vegetation

Conifer regeneration

Spatial variability

Late successional features:

Overstory cover

Canopy layers

Large, dominant trees

Tree species mixtures, including hardwoods

Amount and composition of understory vegetation

Tree regeneration

Spatial variability

Seedling survival 8 growing seasons after thinning

0

20

40

60

80

100W

. H

emlo

ck

S.

Spr

uce

D-fi

r

G.

fir

Redc

edar

Ald

er

B.

map

le

Survival

Adapted from Maas-Hebner et al. 2005 FEM

Seedling survival after 8 growing seasons

0

20

40

60

80

100W

. H

emlo

ck

S.

Spr

uce

D-fi

r

G.

fir

Redc

edar

Ald

er

B.

map

le

Survival

Good condition

Adapted from Maas-Hebner et al. 2005 FEM

0102030405060708090

100

Grand fir Cedar Hemlock Douglas-fir

Per

cent

Ultra-High

High

Medium

Low

Seedling survival

Newton and Cole 2004McDonald: Douglas-fir

Western Red Cedar

Douglas-fir Grand Fir Western Hemlock

Total % Damaged

41 46 35 45

Harvesting damage to regeneration

McDonald Forest Newton and Cole 2004

Impact of light availability on seedling growth

Maas-Hebner et al. 2005

0

20

40

60

80

100

120

140

160

0 2 4 6

Year

Cen

tim

ete

rs

High

Medium

Low

Western Hemlock

Newton and Cole 2004

Impact of overstory density

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6

Year

Mill

imet

ers

High-Plant

Low-Plant

High-Spray

Low-Spray

Effects of weed control

Western hemlock

Newton and Cole 2004Blodgett

Variation in overstory cover when gaps in interspersed

in thinned stands

Frequency

0 10 20 30 40 50 60 70 80 90 100

Overstory Cover (%)

0

5

10

15

20

25

30

35

40

Beggs 2005

Conclusions

Different late-successional components require different management strategies

Tradeoffs in terms of stand growth Overstory and understory

conditions before thinning are good indicators of responses

Some flexibility in thinning intensities

Repeated entries likely required

Density management needs to be an integral part of managing for late successional habitat,

but additional measures, (gaps, snag creation, or remnant trees) are also necessary

Questions