Effects of Silvicultural Practices on Woody Vegetation

John Kabrick, Steve Shifley, and Dan Dey – USDA Forest Service Northern Research Station

Randy Jensen, Mike Wallendorf, and David Gwaze –Missouri Department of Conservation

David Larsen—Univ. of Missouri

Zhaofei Fan—Mississippi State Univ.

Eric Zenner—The Pennsylvania State Univ.

Questions of interest

Ecology of oak-dominated ecosystems Composition

Productivity

Stand dynamics

Factors affecting tree mortality and survival Emphasis on oak decline

Effects of silviculture on composition and structure

Effectiveness of regeneration methods

Woody data

648 permanent vegetation plots

½-acre: trees ≥ 4.5 in. dbh (tagged)

Four 1/20-acre: ≥ 1.5 to 4.5 dbh

Four 1/100-acre: ≥ 3.3 ft tall to 1.5 in. dbh

Inventoried every three years

Additional measurements including site index, height growth, crown development and dieback, presence of cavities and dens, insect pests…

Ecology

Common name Basal area (ft2/ac) Trees/ acre

Black Oak 23.2 58

Scarlet Oak 20.3 49

White Oak 19.6 130

Shortleaf Pine 8.0 21

Post Oak 5.8 22

Pignut Hickory 3.8 49

Black Hickory 3.6 44

Mockernut Hickory 3.4 56

Flowering Dogwood 3.2 349

Black Gum 2.3 86

-- 71% of basal area: black oak, scarlet oak, white oak, and post oak--1% of basal area: other oaks, incl. chinkapin oak, blackjack oak, Shumard oak, and northern red oak

Ecology

Ecology

50

55

60

65

70

75

Summit Shoulder Backslope Bench Floodplain

Sit

e In

de

x (

ft.)

White Oak

Black Oak

50

55

60

65

70

75

Exposed ProtectedS

ite In

dex

(ft.)

White Oak

Black Oak

Ecology

Net Growth (growth + ingrowth - mortality)

-5

-4

-3

-2

-1

0

1

2

3

4

SUMMIT SHOULDER BACKSLOPE UPLANDWATERWAYS

Slope position

De

ca

da

l c

ha

ng

e (

sq

r.ft

/ac

)

white oaks

red oaks

Mortality risk factors

Species Red oak mortality 4X

that of white oaks Crown class

Int/supp 3X Dom/codom 20.8 5.5

14.2

38.3

13.9

Decadal mortality (%)

Species

Crown class Crown class

2.3 13.0

White oak, post oak

Black oak, scarlet oak

Intermediatesuppressed Suppressed Dominant,

codominant

Dominant,codominant

5.3

Intermediate

Mortality risk factors

Crown condition Healthy crowns: low mortality

DBH Large trees: low mortality

Mortality probability after 3 growing seasons

0.0

0.2

0.4

0.6

0.8

0 10 20 30 40 50 60 70 80

Tree dbh (cm)

Pro

bab

ilit

y o

f m

ort

alit

y Healthy

Slight

Moderate

Severe

Scarlet oak

0.0

0.2

0.4

0.6

0.8

0 10 20 30 40 50 60 70 80

Tree dbh (cm)

Pro

bab

ilit

y o

f m

ort

alit

y

Healthy

Slight

Moderate

Severe

Black oak

Mortality risk factors

0

2

4

6

8

10

12

UPLANDWATERWAY

BACKSLOPE BENCH SHOULDER SUMMIT

bababaa

A

A ABB B

Bas

alA

rea

(m2

ha-1

)B

asal

Are

a(m

2ha

-1)

0

2

4

6

8

10

12

Group 1 Group 2 Group 3 Group 4 Group 5 Group 7 Group 5 Group 6

UPLANDWATERWAY

BACKSLOPE AND SHOULDER BENCH

a

AA

a A

A

B

C

a aab b

A

A

a a

mortality

Initial abundance

Site factors are indirectly involved

Red oaks

Mortality risk factors

Oak borer attacks

Positively correlated to crown dieback

However, not correlated to oak mortality

Silvicultural practices

Even-aged management

10% designated as “old growth”

Regeneration with clearcutting with reserves (10 to 15% of site per entry)

Intermediate tending (thinning, improvement cutting)

100-year rotation, 15-year re-entry

clearcuts

Uneven-aged management

10% designated as “old growth”

Regeneration and tending with single-tree and group selection (5%) (Law and Lorimer, 1989)

Target q-value = 1.5 (range 1.3-1.7); RBA = B-level stocking (Roach and Gingrich, 1968)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

DBH (INCHES)

TP

A

TPA

Guiding Curve

Group openings

Harvest removals

Treatment Land area Clearcut Thinned Volume

(thousand bd. ft.)

Even-aged 2,802 11% 15% 2,454

Uneven-aged 3,694 -- 57%1 3,442

1Includes both single-tree and group selection

Harvest removals

0% 20% 40% 60% 80% 100%

Cut trees even-aged

Cut trees uneven-aged

Live trees even-aged

Live trees uneven-aged

Live trees Noharvest

Black oak Scarlet oak White oak Post oak Hickory

Shortleaf pineOther

Effects

Basal area (ft2/ac) Canopy cover (%)

before after before after

Clearcut stands 97 6 86 3

Thinned stands (EAM)

100 71 86 55

Selection cutting units (UAM)

100 76 85 57

Diameter distributions

Regeneration

Regeneration

white oaks

0

100

200

300

400

500

600

700

1995 1998 2002 2006

Year

Tre

es p

er a

cre

clearcut

unharvested

single-tree

single and group

harvest

Regeneration

red oaks

0

100

200

300

400

500

600

700

1995 1998 2002 2006

Year

Tre

es p

er a

cre

clearcut

unharvested

single-tree

single and group

harvest

Regeneration

Year 2002

0

1000

2000

3000

4000

5000

6000

7000

8000

unharvested single-tree single and group clearcut

Tre

es p

er a

cre

Oaks

Competitors

Other species

9%11%

15%

14%

Findings…

Clearcutting increased white oak and red oak regeneration and recruitment

Single-tree and single-tree + group selection increased regeneration of white oaks

Red oaks may be in trouble!

Oaks were a small proportion of the reproduction

Shortleaf pine??

Site interactions

3 Exp. RO/UG Backslopes

5 Exp. LG/EM Backslopes

4 Pro. RO/UG Backslopes

6 Pro. LG/EM Backslopes

South- and southwest-facingNorth- and northeast-facing

Regeneration

Unharvested

0

500

1000

1500

2000

3 5 4 6

Ecological land type

Tre

es p

er a

cre

white oaks red oaks

competitors other species

Regeneration—year 10

Single-tree selection

0

500

1000

1500

2000

3 5 4 6

Ecological landtype

Tre

es p

er a

cre

white oaks red oakscompetitors other species

Regeneration—year 10

Single and group selection

0

500

1000

1500

2000

2500

3000

3500

3 5 4 6

Ecological land type

Tre

es p

er a

cre

white oaks red oaks

competitors other species

Regeneration—year 10

Clearcut harvest

0

2000

4000

6000

8000

10000

12000

3 5 4 6

Ecological land type

Tre

es p

er

acre

white oaks red oaks

competitors Other species

Percentage of oaks

Clearcut harvest

0

2000

4000

6000

8000

10000

12000

3 5 4 6

Ecological land type

Tre

es p

er

acre

white oaks red oaks

competitors Other species

24%

24%

11%

3%

Findings…

Oak reproduction decreased with increasing site quality

Red oaks affected more than white oaks

“Intrinsic accumulators” vs. “recalcitrant accumulators”

Density of competitors and other species increased with increasing site quality and harvest intensity

Acknowledgments

Support was provided by the Missouri Department of

Conservation, the USDA Forest Service Northern

Research Station, and the University of Missouri