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Can We Emulate Early Seral Forest Through Silviculture
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Can we emulate early seral forest through silviculture?
Klaus J. PuettmannEdmund Hayes Professor in
Siviculture Alternatives
Adrian AresResearch Associate
Oregon State University
Background– Structure – Composition– Legacies
Management of vegetation– after stand replacing disturbances– after partial disturbances
o - Thinning o - Gaps
Outline
Early seral forestconditions after a disturbance
that removes overstory
Background
Structure: “Open growing space”; allowing for establishment of vegetation and associated insects, animals, etc.– Shift towards “tall” canopy layers
Composition: dominance of early successional species– Shifts towards late seral species
(within and among canopy layers) Legacies from pre-disturbance
vegetation
Background
Legacies Important for ecosystems
processes and function
Influence development of early and late seral conditions– Sprouting– Seed source– Cover that prevents
establishment of early seral species
Background
Suislaw NF Willamette NF
From Yang et al. 2005
Structural development of plantations Conifer cover
20 years6 years 13 years
Management – Stand replacing disturbances
ODF land OR Coast Range
Dave Powell, USDA Forest Service, Bugwood.org
Management – Stand replacing disturbances
“Arrested” stand development Ceanothus after wildfire, Umatilla NF
P. Anderson, USFS
L. Kayes L. Kayes
2nd growing season
3rd growing season
Management – Stand replacing disturbancesImpacts of legacies – Sprouts
Timbered Rock, BLM
P. Anderson, USFS
Management – Stand replacing disturbances
Shrub removal No treatment
Hardwood control initially maintains “open” structure
T. Harrington USFS
Management – Stand replacing disturbances
Intensive hardwood control accelerates dominance of conifers
Unmanaged
125 snags/ha (range 21-229 )
Management – Stand replacing disturbances
0
10
20
30
40
50
60
# D
omin
ant s
eedl
ings
est
ablis
hed/
year
0
10
20
30
40
50
60
Years after fire
2 4 6 8 10 12 14 16 18 200
10
20
30
40
50
60
2005
2005
C
2005
B
A
High elevation
Low to moderate elevation
Natural regeneration (no salvage logging or planting) suggest longer early seral phase
Management – Stand replacing disturbances
# d
om
ina
nt
se
ed
ling
se
sta
blis
he
d
Conifer size distribution
DBH (cm)
0 2 4 6 8 10 12 14 16 18 20 22 24
Con
ifers
/ ha
0
50
100
150
200
1500
2000
2500 Unmanaged Managed
M. J. Lopez 2008
•Management (salvage, fuel treatment, planting, release) speeds up conifer dominance* Spatial evenness (!!)
Management – Stand replacing disturbances
> 15 feet = gap
How many gaps are in ODF plantations?
Management – Stand replacing disturbances
Low density
Gap Road
Measurement line
0.0
2.0
4.0
6.0
8.0
10.0
12.0
1984 1986 1988 1990 1992 1994 1996
YEAR planted
% a
rea
in g
ap
Puettmann and Berger 2005
Management – Stand replacing disturbances
Gaps contain early seral vegetation, but disappear as stands develop
Spatial scale and variability
Timber production
Structural Diversity
Management – Stand replacing disturbances
No management Management – keep gaps open
Gap - scale
Management – stand replacing disturbances
Ongoing studies:
6% of plantation in gaps
Does wildlife notice the difference?
Gap and stand scale
Management – Stand replacing disturbances
Ongoing studies:
YSTDS - Christy Flats
Management – Partial disturbancesThinning and gaps = managing for early seral legacies in mature forests
Un
der
sto
ry S
pec
ies
Ric
hn
ess
(#
/ plo
t)
0
5
10
15
20
25
30
Late Seral Forest Omni-presentOpen / Early Seral
Control High Moderate Variable density
Modified from Berryman, unpubl.
Management – Partial disturbances
Structural development:
Herbs take advantage of disturbance
Tall shrubs recover slow
Study Results
0
10
20
30
40
0
10
20
30
40
ControlHeavy thinningLight thinningLight thinning w/gaps
Co
ve
r (%
)
0
10
20
30
40
0
10
20
30
40
Herbs
Low shrubs
Tall shrubs
Bryophites
aabb
a
aaa
b
a
bbb
a
bb
b
a
bb
b
a
bbb
1 3 5 10 Year
a
bb
b
aabab
b
From Ares et al. 2009
Management – Partial disturbances
Harvesting layout to protect shrubs (legacies)
Management – Partial disturbances
0
5
10
15
20
25Ric
hnes
s (n
o. s
peci
es)
0
5
10
15
20
25
Cov
er (%
)
All herbs Forest herbs Early seral herbs Later seral herbs P = 0.04 P < 0.001
P < 0.001
P = 0.02
P < 0.001
(a) (b) (c) (d)
(e) (f) (g) (h)
A
ABB AB
AB
B B
A
B B B
AC BC BCB
A
B B B
C LC MC HC C LC MC HC C LC MC HC C LC MC HC
From Ares et al. 2009
Management – Partial disturbances
Early seral herbs are responsive: structure and composition
C = ControlLC = Low complexity thinningMC = Moderate complexity thinningHC = High complexity thinning
Co
ver
(%)
0
15
30
45
60
A
A
AA
C LC MC HC C LC MC HC C LC MC HC
Ric
hn
ess
(no
. sp
ecie
s/p
lot)
0
15
30
45
60
A AB BC C
AB B
AB
All shrubs Forest shrubs
A AB BC C
A B B B
A B B
Early seral shrubs
B
P < 0.001 P < 0.002 P < 0.001
P = 0.03 P < 0.001
(a) (b) (c)
(d) (e) (f)
Management – Partial disturbances
Shrub layer slow to recover and dominated by “legacies”
C = ControlLC = Low complexity thinningMC = Moderate complexity thinningHC = High complexity thinning
Co
ver
(%)
0
10
20
30
40
b
a
a
a a
ab
CON HD MD VD300 VD200 VD100
Early seral vegetation 11-years after thinning
Management – Partial disturbances
“Long-term” impact
C = ControlHD = High densityMD = Moderate densityVD = Variable density
Lindh and Muir 2004
Management – Partial disturbances
Gap influence Encourages early seral
vegetation Limited to “gap” Early seral species
– Physical disturbance
– Competition for light (large gaps only)
Fahey and Puettmann, FEM 2008
CompetitorManagement – Partial disturbances
Conclusion
– Distinction between structure and composition
– Slow vegetation development- Short-term versus medium term
impacts of management practices- Choice of legacies
– Repeated disturbancesThinning and gap creation
– Attention to scale allows early seral legacies in mature forests
Acknowledgements: L. Kayes, P. Anderson, T. Harrington, M. Lopez, J. Shatford, D. Hibbs and all people
involved in the various thinning studies
Questions and comments?