Date post: | 21-Dec-2015 |
Category: |
Documents |
View: | 221 times |
Download: | 5 times |
Different effects of thinning and burning on Sierran mixed-conifer ecosystems
Malcolm North, USFS, Sierra Nevada Research Center, Davis, CA
ST
UD
Y S
CA
LE
FU
NC
TIO
N / P
RO
CE
SS
TEAKETTLEEXPERIMENT
ECOSYSTEM(10 ac)
WATERSHED(3000-5000 ac)
FIRESURROGATE
STUDY
STAND(50-100 ac)
LANDSCAPE(up to 500,000 ac)
KINGS RIVERPROJECT
Large-scale fire movement & behavior, spotted owls
Water flow & nutrients; forest carnivores; birds; uneven-aged mgt.
PLUMAS /LASSEN STUDY
Stand dynamics, regene., management options; animals w/small home rangesSoils; microclimate; respiration; succession; food webs
Focus and Scale of Some of the Fuel Reduction Experiments in California
Thinning Level: No Burn Understory Burn
None Control Burn Only
25 cm < thin <76 cm
Thin from below/No Burn
Thin from below/Burn
25 cm < thin & leave 22 large t/ha
Overstory thin/No Burn
Overstory thin/Burn
bn1
un1
uc1
uc2
bs2
bs3
bn3
us1
bc3
bc2
bn2
bs1
bc1
un2
us2
us3
un3
uc3
bn1
un1
uc1
uc2
bs2
bs3
bn3
us1
bc3
bc2
bn2
bs1
bc1
un2
us2
us3
un3
uc3
18 plots, 4 ha each, 3 reps of each of the 6 treatments
Teakettle Location, Design, Plot Layout and Timeline
• Burned November 2001, ‘off season’, for containment & air quality
Pretreatment data(2-3 yrs for all studies)
Treatments
Post-treatment data (2-3 yrs for all studies)
1998
1999
2000
2001
2002
2003
2004
Monitoring (5-20 yrs)
Thinning Effects (using all trees in a 4 ha plot)
Understory: 25 cm< thin < 76 cmOverstory (shelterwood): Thin > 25 cm & leave 22 large tree/ha
Teakettle’s Focus: Ecosystem Structure, Composition and Function
Univ. of California, Berkeley, CATom Bruns, Antonio Izzo, Agneta Plamboeack, Todd Dawson
Mycorrhizal Diversity/Water Movement using Stable Isotopes
Univ. Metropolitan, San J uan, PRHeather EricksonSoil Nutrients
Univ. of Toledo, OHJ iquan Chen, Siyan Ma & Suong RhuMicroclimate, Soil Respiration
I NSTITUTIONPRI NCIPAL I NVESTI GATORSTUDY
Pacific Southwest Research, Davis, CAMalcolm North, J im InnesTree/Shrub Mortality & Growth, Truffles, Cones, Coarse Woody Debris, and Diameter Growth
Calif. State Univ. Fresno, CARuth KernSeed Dispersal
Univ. of California, Davis, CAMatthew Hurteau & Malcolm NorthGlobal Climate Change & Tree Demography
Univ. of California, Davis, CARebecca Wayman & Malcolm NorthUnderstory Herb & Shrub Diversity
Univ. of Washington, Seattle, WABrian Oakley, J erry Franklin & Malcolm North
Nitrogen Dynamics, Frankia Diversity & Response to Fire
Univ. of California, Davis, CATom RamboLichen Growth & Dispersal
Univ. of Washington, Seattle, WAJ im Marra & Bob EdmondsSoil & CWD Invertebrates
Univ. of California, Davis, CAMarc Meyer, Doug Kelt & Malcolm NorthFlying Squirrels, Chipmunks & Truffles
Univ. of California, Davis, CADavid Rizzo, Tom Smith, Tricia MaloneyTree Pest & Pathogens
Louisiana State Univ, Baton Rouge, LATim SchowalterCanopy Invertebrates
Pacific Northwest, Forest Inventory Analysis, Corvallis, OR
Andrew Gray & Harold ZaldTree Regeneration & Soil Moisture
Univ. of California, Davis, CAMichael Barbour, Rob Fiegener, Fire History
Michigan Technology University, Houghton, MI
Marty J urgensonDecomposition
Univ. of California, Berkeley, CATom Bruns, Antonio Izzo, Agneta Plamboeack, Todd Dawson
Mycorrhizal Diversity/Water Movement using Stable Isotopes
Univ. Metropolitan, San J uan, PRHeather EricksonSoil Nutrients
Univ. of Toledo, OHJ iquan Chen, Siyan Ma & Suong RhuMicroclimate, Soil Respiration
I NSTITUTIONPRI NCIPAL I NVESTI GATORSTUDY
Pacific Southwest Research, Davis, CAMalcolm North, J im InnesTree/Shrub Mortality & Growth, Truffles, Cones, Coarse Woody Debris, and Diameter Growth
Calif. State Univ. Fresno, CARuth KernSeed Dispersal
Univ. of California, Davis, CAMatthew Hurteau & Malcolm NorthGlobal Climate Change & Tree Demography
Univ. of California, Davis, CARebecca Wayman & Malcolm NorthUnderstory Herb & Shrub Diversity
Univ. of Washington, Seattle, WABrian Oakley, J erry Franklin & Malcolm North
Nitrogen Dynamics, Frankia Diversity & Response to Fire
Univ. of California, Davis, CATom RamboLichen Growth & Dispersal
Univ. of Washington, Seattle, WAJ im Marra & Bob EdmondsSoil & CWD Invertebrates
Univ. of California, Davis, CAMarc Meyer, Doug Kelt & Malcolm NorthFlying Squirrels, Chipmunks & Truffles
Univ. of California, Davis, CADavid Rizzo, Tom Smith, Tricia MaloneyTree Pest & Pathogens
Louisiana State Univ, Baton Rouge, LATim SchowalterCanopy Invertebrates
Pacific Northwest, Forest Inventory Analysis, Corvallis, OR
Andrew Gray & Harold ZaldTree Regeneration & Soil Moisture
Univ. of California, Davis, CAMichael Barbour, Rob Fiegener, Fire History
Michigan Technology University, Houghton, MI
Marty J urgensonDecomposition
Collaborators
1. What effect do shrubs have on forest succession and water dynamics?
2. Why is mixed conifer so strongly clustered? Are trees grouped by age cohorts?
3. Do significant reductions in canopy cover reduce regeneration survival and understory herb cover?
4. Did the fire and thinning treatments produce a desired diameter distribution?
Teakettle Results: Focus on 4 Vegetation Questions Relevant to Developing Thinning and Burning
Prescriptions
• Saplings and shrubs compete for shallow water in early summer
•Trees rely on deep water through summer drought
0
20
40
60
80
100
May June July AugustPer
cen
t o
f d
eep
wat
er u
sed
Tree saplings
Overstory trees
Shrub (Arctostaphylos spp.)
(using isotope signatures of soil and plant water)
Manzanita
20
30
40
50
60
70
80
90
100
Ma
y-0
2
Jun
-02
Jul-
02
Au
g-0
2
Se
p-0
2
Oct
-02
No
v-0
2
Date
Pe
ren
tag
e (
%)
Forest
203040506070
8090
Ma
y-0
2
Jun
-02
Jul-0
2
Au
g-0
2
Se
p-0
2
Oct
-02
No
v-0
2
Mycorrhizae ExclosureRoot ExclosureControl
1. What effect do shrubs have on forest succession and water dynamics?
From A. Plaemboeck
• Low tree seedling survival in shrubs and without root exclosure
• Shrubs become islands that can ‘lock’ a site against seedlings and herbs
2. Why is mixed conifer so strongly clustered? Are trees grouped by age cohorts?
Bonnicksen and Stone (1982) suggested pattern is due to grouped cohort age structure
0 50 100 150 200 250
East (m)
0
50
100
150
200
250
Nor
th (m
)
abcoabmacadepijepilaquchquke
-1
0
1
2
3
4
5
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Distance (m)
L(t
)
clustered
18731898
1853 1884
18871887
1887 1895
1887
18591862
1898
1826
1843
1916
1893
19031856 1895
1889
18951903
1888
1894
188618511885
187418731879
1873
1892
1897
1891
18911890
1844
1898
18321832
1669
1891
1866
1730
1851
1848
1894
1864
1882
1844
1869
1864
1866
1860
1866
1836
1755
1894
1853
1637
1874
1886
1895
1863
1876
1808
1808
18571833
1805
1843
1845
1838
1836
1883
18001810
1813x abcox abmax cadex pijex pila
Are trees grouped by age cohorts?
•No: ages were not spatially autocorrelated (variogram not shown)
Krigged distribution of tree basal area in a 4 ha area
Depth to bedrock for the a 4 ha area, where deeper soils are in red.
(Determined by seismic survey)
Why is mixed conifer so strongly clustered?
• One influence may be that tree groups reflect the geomorphic template (depth to bedrock)
Note correlation between the grouping of tree basal area, mostly driven by clusters of large trees and the depth to bedrock
• Mortality episodic: associated with La Nina droughts
• Most mortality in areas of high density
• Significantly higher than expected mortality for large trees
• Are small/intermediate trees depleting deep soil water pockets?
0
5
10
15
20
25
30
35
40
45
50
0 - 100 100 - 500 500 - 2000 >2000
High Density Classes Low
Per
cent
age
ALL
DEAD
0
5
10
15
20
25
30
35
40
45
50
0 - 100 100 - 500 500 - 2000 >2000
High Density Classes Low
Per
cent
age
ALL
DEAD
*
* 0
10
20
30
40
50
60
5.0
- 20
.0 c
m
20.1
- 4
0.0
cm
40.1
- 6
0.0
cm
60.1
- 8
0.0
cm
80.1
- 1
00.0
cm
>100
.1cm
Perc
enta
ge All T rees
All Dead Trees
(A)
*
*
How Might This Explain Current Mortality Patterns?
* Significantly different than expected (Chi-square)
3. Do significant reductions in canopy cover reduce regeneration survival and understory herb cover?
Persistent gaps in mixed-conifer without regeneration and having few herbs
Surface temperature by Julian date (y axis) and hour (x axis) for 3% and 76% canopy cover
Post-treatment: Germinant Survivorship
•Burned treatments had higher pine germinant survival •Burn and thin treatments (BC and BS) also had the lowest white fir and incense-cedar survivorship• Herb cover and richness (not shown) significantly greater in all burned vs. thinned treatments, regardless of canopy cover reduction
0
2
4
6
8
10
12
14
16
BN BC BS UN UC USTREATMENT COMBINATION
1ST
YR
SU
RV
IVO
RS
HIP
ABCO ABMA CADE PIJE PILA
NOSPP
ABCOABMA
CADE
PIJEPILA
PREM
QUKE
AVG02SMAVG03SM
DSF
-0.4
-1.2
0.0 0.4 0.8
-0.8
-0.4
0.0
0.4
TK POSTREAT SDL
Axis 1
Axi
s 2
TRT0
Axi
s 2
• Increased separation of sugar pine and white fir based on light level and soil moisture
Increased Micro-site Heterogeneity
Pre-Treatment Post-Treatment
Data and slide from Harold Zald and Andy Gray, PNW Research
Light
Light
Soil H2O Soil H2O
#/stems by dbh and species on 20 ac
0
200
400
600
800
1000
1 5 9 13
17
21
25
29
33
37
41
DBH in 2" classes
# o
f ste
m pilapijecadeabmaabco
Before fire suppression (1865) recruitment and mortality was ‘pulsed’ by fire and El Nino events
Hypothesized pre-fire suppression 'pulse' diameter distribution
0
50
100
150
5
15
25
35
45
55
65
75
85
95
10
5
11
5
DBH class
Ste
ms
/ac
Pine
Fir/Cedar
Current diameter distribution
4. Did the fire and thinning treatments produce a desired diameter distribution?
10-30 31-60 61-90 >90
Size Class (cm)
0.0
0.2
0.4
0.6
Pro
port
ion
VTM* (‘desired’ dist.)ControlBurn.onlyUnderstory.onlyUnderstory...BurnOverstory.onlyOverstory...Burn
4. Did the fire and thinning treatments produce a desired diameter distribution?
No: Not enough small and too many intermediate size trees taken
* VTM is >2400 vegetation type mapping plots collected in the early ’30’s
• Thinning alone ‘stalls’ herb development and does not favor shade-intolerant regeneration
• Fire’s important for reducing shrubs which are strong competitors with trees and herbs
• Group selection doesn’t appear to be needed
• Thinning treatments may need to target small trees in high density areas, particularly around large, old trees
• If prescribed fire is applied ‘off season’, thinning must be aggressive about cutting small trees
• Observation: Thinning prescriptions should stay focused on trees as fuels rather diameters or board feet
What did we learn at Teakettle?