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
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