Transcript Slide 1

Forest Ecological Relationships: Teakettle and
Plumas Lassen Administrative Study
Malcolm North, Sierra Nevada Research Center, Davis, CA [email protected]
What does the information gathered over the
last 10 years of Sierran ecological studies
suggest for managing forests?
 Processed-centered restoration
 Historic diameter distribution
 Historic spatial patterns
 What is the seral development (shrub
response, future tree composition) of treated
stands?
• What influences the ‘health’ of current and
treated forests?
• In fire suppressed mixed conifer, limited water is
a primary driver of many ecological processes
• Treatments that reduce stand density,
significantly increase water availability, BUT
increases in slash and litter can stall process
recover
• Fire jumpstarts most processes, boosts
environmental and habitat heterogeneity, and
significantly increases biodiversity
What is process-centered restoration?
(courtesy of Don Falk, Tree Ring Lab, UA)
• Ecological processes are placed at the
center of restoration design
• A range of process values estimated (based
on suitable reference)
• Composition and structure are varied as
needed to bring process within targeted
range, or left to equilibrate on their own
Falk 2006; Cortina et al. 2006
Proceed Centered Restoration: Methods
1. Begin with bracketed estimates of (a) fire regime
and (b) individual fire events under historical
conditions
2. Model effects of structural treatments on fire
behavior and effects across a range of
prescriptions
3. Set structural prescription to achieve process
target values
4. Test model on the ground and adapt
(courtesy of Don Falk, Tree Ring Lab, UA)
Covington et al. 2001; Fulé et al. 2004; Falk 2006
Model assumptions and conditions (90th
– 95th percentile wx)
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Modeling in FVS 6.31, Nexus 2.0, Behave+
32-48 km hr-1 windspeed @ 6 m
Slope 5%
Surface fuel moisture:
– 1 hr fuels 3-8%
– 10 hr 4-10%
– 100 hr 5-12%
• Live fuel moisture 80-100%
• Fuel models 9-10
Fulé et al. 2004; Falk 2006
(courtesy of Don Falk, Tree Ring Lab, UA)
Target (reference) values for key fire
behavior and effects (response) variables
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Primarily surface fire, occasional torching OK
Overall flame height  2 m
Headfire spread rate  3 - 4 m min-1
Fireline intensity  1000 km m-1
TI  40 km hr-1, CI  65 km hr-1
Percent mortality by size class
–  2% overstory trees ( 40 cm dbh)
–  80% saplings and understory trees ( 15 cm dbh)
Agee 1993, Sackett and Haase 1996, Pyne, Andrews et al. 1996
Structural (input) variables
Thin progressively across a range of maximum thin
diameters: unthinned – 40 cm (16 in). This alters:
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–
–
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Tree density (stems ha-1)
BA (m2 ha-1)
Crown base height distribution (m)
Crown bulk density (kg m-3)
Size distribution (dbh, cm)
Graham et al. 2004; Peterson et al. 2005
Proportion of response by max diameter thinned
100%
FVS flame length severe (ft)
TI severe (mph)
CI severe (mph)
CBD (kg/m^3)
Stand mortality severe (% BA)
Trees/ha
BA (m^2/ha)
QMD (cm)
90%
Proportion of max response
80%
70%
60%
50%
40%
30%
20%
10%
0%
0.0
5.0
10.0
15.0
20.0
25.0
Max thin dbh (cm)
30.0
35.0
40.0
Current diameter distribution in
fire-suppressed mixed conifer
#/stems by dbh and species on 20 ac
1000
pila
pije
cade
abma
abco
600
400
200
DBH in 2" classes
41
37
33
29
25
21
17
13
9
5
0
1
# of stem
800
Before 1865, tree death and recruitment is pulsed by fire and El Nino events
27
Fire
6
6
3
0
0
-3
-6
1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910
est.date
PDSI
# established
12
abco
abma
cade
pije
pila
PDSI
Diameter distribution at Teakettle
after treatments compared to 1865
245
Pretreatment
Burn/no thin
Unburned/understory thin
Burn/Understory thin
Unburned/Overstory thin
Burn/overstory thin
1865 Reconstruction
205
165
Density (# of stems/ha)
125
85
30
20
10
0
0
25
50
75
100
125
25 cm dbh size classes
Diameter distribution
150
Carbon Storage and Rate of Accretion
Treatment:
Tons of
C/ha
B.A.I.
(cm2/yr)
1865 Reconstruction
Current condition
(Control)
Burn only
Understory thin (CASPO)
Understory thin and burn
Overstory thin
(shelterwood)
Overstory thin and burn
150.7
73.3
NA
15.26
68.4
61.8
57.1
45.4
16.14
18.68
22.93
20.58
41.4
23.17
Pretreatment Forest
abco
abma
cade
pije
pila
50
Highly Clustered
y
0
-50
-100
-90
-50
-10
30
x
70
1865 Reconstruction
abco
cade
pije
pila
unk
70
Slightly clustered
Yfin
30
Random
-10
-50
-90
-90
-50
-10
Xfin
30
70
Overstory Thin (similar to DFPZ)
abco
cade
pije
pila
50
Clumped
y
0
Regular
-50
-100
-100
0
-50
x
50
Stand attribute
1865
Pretreat
ment
Underst
ory thin
only
Overstor
y thin
only
Burn
only
Burn/Un
der-story
thin
Burn/Ov
erstory
thin
Basal area (m2/ha)
51.5a
56.4a
41.2b
22.7c
53.7a
37.5b
17.2c
Total Density
(stems/ha)
67a
469b
239.5c
150.3d
353.8e
143.4d
93.6a
Cut (stems/ha)
B.A. removed
(m2/ha)
NA
NA
0
0
170.8
20.2
192.3
33.9
0
0
162.8
21.3
198.9
37.0
Canopy cover (%)
Unk
80.7a
72.8b
63.4c
80.5a
70.9b
60.2c
Quadratic mean dbh
(cm)
49.5a
19.6b
23.4b
21.9b
22.0b
28.9b
24.2b
Volume (m3/ha)
393.2a
434.6a
397.7a
200.5b
423.0a
372a
141.8c
Abies concolor
33.7%a
67.6%b
67.2%b
66.3%b
67.6%b
64.1%b
57.7%b
A. magnifica
2.9%a
3.0%a
4.7%a
1.9%a
2.5%a
1.2%a
1.0%a
Calocedrus
decurrens
14.5%a
13.4%a
11.8%a
9.5%a
15.8%a
20.8%b
22.4%b
Pinus Jeffreyi
22.1%a
6.2%b
3.9%b
8.1%b
3.6%b
7.4%b
7.6%b
Pinus lambertiana
26.8%a
7.9%b
9.8%b
12.1%b
9.2%b
5.1%b
8.8%b
Other*
Unk.
1.9%a
2.6%a
2.1%a
1.3%a
1.4%a
2.5%a
Snag (stems/ha)
Unk.
39.0a
37.8a
32.3a
92.4b
120.3b
123.4b
White fir and incense cedar produce far more seed than pines
NB-NT: No burn/no thin
NB-UT: No burn/understory
thin
NB-OT: No burn/overstory
thin
B-NT: Burn/no thin
B-UT: Burn/understory thin
B-OT: Burn/overstory thin
Canopy Openness Effects on Understory Vegetation Cover
Percent Cover
Herb
Canopy Openness
80
Canopy Cover
40
Stanislaus Tuolomne
Experimental Forest Methods
of Cutting Plot 1929
Historic forests probably had
higher shrub cover
Some studies suggest shrubs
are important habitat for birds
and small mammals
For Jeffrey or ponderosa pine, if
sapling is established, shrub
may not reduce survival
However sugar pine may need
forest canopy for early growth
How much shrub cover and how
distributed?
Summary I: Some suggestions from recent
ecological research
Put fire back into the system whenever possible.
Where fire can’t be used, thin stand to control
intensity of inevitable wildfire
Trees should not be evenly spaced after
thinning
Different treatments by species—not uniform
diameter limits
Summary II: Some suggestions from recent
ecological research
Need to mix it up at multiple scales—leave some
dense clumps, some gaps
Plant pine seedlings to overcome natural seeding,
shrub competition, and limited mineral soil and
direct sunlight
We still don’t know exactly how stands are going
to develop in DFPZs, SPLATs or other fuels’
treatments