SIMulating
Patterns and
Processes at
Landscape
scaLEs
HISTORIC RANGE of VARIABILITY
Landres, P.B., Morgan, P., and Swanson, F.J. 1999. Overview
of the use of natural variability concepts in managing ecological
systems. Ecol Appl. 9: 1179 - 1188
Swetnam, T.W., Allen, C.D., and Betancourt, J.L. 1999. Applied
historical ecology: using the past to manage for the future. Ecol
Appl. 9: 1189-1260
“Applying natural variability concepts require multiple sources
of information, ranging from site-specific data and simulation
models to expert opinion and judgement”.
“Creating static reproductions of past ecosystems is --- not
desired.”.
Landres et al. 1999
“… it may be misguided and fruitless to chose a
single fixed point or period of time”.
Swetnam et al. 1999
HRV using SIMPPLLE
Starting with the current landscape make a long-term
simulation (500 years) without fire suppression. The resulting
landscape can be saved and multiple simulations made
with it. The length of the simulation should be long enough
to observe cycles in processes and vegetation conditions.
Higher fire ignition probabilities can be used to account for
Impact of Native Americans
Different pathways can be used if processes such as insect or
diseases did not exist historically.
Questions concerned with using SIMPPLLE to represent “Historic
Range of Variability” are:
what size area is used?
what time frame is represented?
do we modify the current landscape before starting?
(example - adding back in species that are completely absence
increasing fire occurrences to reflect native american
ignitions)
Examples taken from:
Eastside Region One Assessment (Pintler Ranger District)
Bitterroot face, Bitterroot National Forest
Salmon River Canyon, Idaho
Watershed size analysis – Eastside Region One Assessmetn
Beaverhead-Deerlodge National Forest
SIMPPLLE – possible states (pathways) – current vs historic
Deerlodge
Helena
Lewis and Clark
Custer
Beaverhead
Gallatin
National Forest and “geographic areas” for
Eastside Region One assessment
Geographic Area #8 from East Side Assessment
1,500,291 acres
Missoula
Deerlodge
Hamilton
Anaconda
Butte
Forested habitat types
Nonforested habitat types
Extreme levels of stand replacing fire occur at intervals greater
than 5 decades. A 5 decade representation of historic conditions
could provide too small to quantify the range of variability.
600000
500000
400000
300000
200000
100000
0
decade
Forested habitat types
36
31
26
21
16
11
srf
6
1
acres
historic long term cycles modeled by
SIMPPLLE
Extremes of mixed severity fire levels sometimes coincide with
the stand replacing fire, but tend to occur more frequently.
600000
500000
400000
300000
200000
100000
0
decade
Forested habitat types
37
33
29
25
21
17
13
9
5
srf
msf
1
acres
historic long term cycles modeled by
SIMPPLLE
SPECIES DISTRIBUTION FOR GA8
before a decade of extreme stand replacing fire levels
SPECIES DISTRIBUTION FOR GA8
after a decade of extreme stand replacing fire levels
Thousands of Acres
600000
500000
400000
300000
200000
100000
0
decade
36
31
26
21
16
11
Forested habitat types
WB
AF
WB-AF
ES
ES-AF
LP
srf
msf
6
1
acres
historic long term cycles
LP-AF
DF-LP
DF-LP-ES
DF-AF
DF-LP-AF
DF
PP
PP-DF
QA
QA-MC
Xeric-shrubs
Mesic-shrubs
Native -forbs
WB
AF
WB-AF
ES-AF
ES
LP
LP-AF
DF-LP
DF-LP-ES
0
DF-LP-AF
0
DF
100
DF-AF
100
PP
200
PP-DF
200
QA
300
QA-MC
400
300
Mesic-shrubs
400
Native -forbs
500
Upland-grasses
500
Upland-grasses
Thousands of Acres
SIZE CLASS DISTRIBUTION FOR GA8
after a decade of extreme stand replacing fire levels
SIZE CLASS DISTRIBUTION FOR GA8
before a decade of extreme stand replacing fire levels
600000
500000
400000
300000
200000
100000
0
Forested habitat types
decade
36
31
26
21
16
11
srf
msf
6
1
acres
historic long term cycles
VLMU
VLTS
VERY-LARGE
LTS
LMU
LARGE
MTS
MMU
VLMU
VLTS
VERY-LARGE
LMU
LTS
LARGE
MMU
MTS
MEDIUM
PTS
PMU
POLE
SS
Closed-herb
Open-herb
Open-tall-shrub
Closed-low-shrub
Open-mid-shrub
0
Open-low-shrub
0
PMU
100
MEDIUM
100
PTS
200
POLE
200
SS
300
Closed-herb
300
Open-herb
400
Closed-low-shrub
400
Open-tall-shrub
500
Open-low-shrub
500
Open-mid-shrub
Thousands of Acres
Thousands of Acres
Historic cycles in mountain pine beetle (mpb) are at low levels,
only very infrequently does a very significant outbreak occur
because of fire cycles that keep susceptible lodgepole at a minimum.
historic long term cycles
Forested habitat types
250000
acres
200000
150000
mpb
100000
50000
0
1
6
11
16
21 26
decade
31
36
Changing the scale of the figure makes it easier to see the frequency
of lower levels of mountain pine beetle activity
historic long term cycles
Forested habitat types
25000
acres
20000
15000
mpb
10000
5000
0
1
6
11
16
21 26
decade
31
36
The conditions that are conducive to an extreme mountain pine beetle
outbreak occur after decades of fire exclusion. The fuels created by
the outbreak can contribute to extremes levels of stand replacing fire.
historic long term cycles
acres
Forested habitat types
600000
500000
400000
300000
200000
100000
0
mpb outbreak
1
6
11
16
21 26
decade
mpb
srf
msf
31
36
Thousands
Acres
Comparison of Current and Historic
Range of Variability Simulated for a Decade
Forested Habitat Types
600
500
400
300
200
100
0
hist-qa
cur-qamc
hist-lp
cur-lp
histxericshrubs
Species
High, low, and median values from 5, 5-decade simulations for current
conditions and 5, 10-decade simulations for historic conditions.
cur-xericshrubs
histmesicshrubs
curmesicshrubs
Current mesic shrubs are below the range of what existed historically. Mesic
Shrubs on forested habitat types varied with fire cycles.
h is t- me s ic - c u r- m e s ic s h ru b s
s h ru b s
Thousands
Acres
Comparison of Current and Historic
Range of Variability Simulated for a Decade
Forested Habitat Types
600
500
400
300
200
100
0
hist-df
cur-df
hist-qa
cur-qa-mc
Species
High, low, and median values from 5, 5-decade simulations for current
conditions and 5, 10-decade simulations for historic conditions.
hist-lp
cur-lp
Thousands
Acres
Comparison of Current and Historic
Range of Variability Simulated for a Decade
Forested Habitat Types
600
500
400
300
200
100
0
hist-df
cur-df
hist-qa
cur-qa-mc
Species
High, low, and median values from 5, 5-decade simulations for current
conditions and 5, 10-decade simulations for historic conditions.
hist-lp
cur-lp
Historic Conditions
Probability of lodgepole pine
Historic conditions
Occurrence of quaking aspen
Comparison of Current and Historic
Range of Variability Simulated for a Decade
Thousands
Acres
Forested Habitat Types
600
500
400
300
200
100
cu
r-s
s
hi
st
-p
ol
cu e
r-p
ol
e
hi
st
-p
ts
cu
r-p
ts
hi
st
-p
m
u
cu
r-p
hi
m
st
u
-m
e
cu dium
r-m
ed
iu
m
hi
st
-m
ts
cu
r-m
ts
hi
st
-m
m
u
cu
r-m
m
u
hi
s
t-s
s
0
Size Class/Structure
High, low, and median values from 5, 5-decade simulations for current
conditions and 5, 10-decade simulations for historic conditions.
Thousands
Acres
Comparison of Current and Historic
Range of Variability Simulated for a Decade
Forested Habitat Types
600
500
400
300
200
100
0
histcc1
cur-cc1
histcc2
cur-cc2
histcc3
Canopy Cover
High, low, and median values from 5, 5-decade simulations for current
conditions and 5, 10-decade simulations for historic conditions.
cur-cc3
histcc4
cur-cc4
Bitterroot Face – fire return frequency
Multiple simulations, without
fire suppression were used to
develop a frequency of fire
return
Fire return frequency in years
Stevensville
This data set used the
nonforest from tsmrs and
agriculture designations –
neither of which were
Hamilton modeled to “burn” - thus a
Unrealistic frequency
of > 100 years in these areas
Darby
Probability of
Mixed-Severity-Fire
Historic landscape
Process probability
Current landscape
Salmon River Canyon - examples
Fire Risk – Salmon River Canyon
Current vegetation conditions
probability stand replacing fire
Probability percent
Historic vegetation conditions
probability stand replacing fire
Simulations display historic
stand replacing fire probability
was much lower than
current conditions.
Fire Risk – Salmon River Canyon
Current vegetation conditions
probability mixed severity fire
Probability percent
Simulations display historic
mixed severity fire probability
was much higher than
current conditions.
Historic vegetation conditions
probability mixed severity fire
Fire Risk – Salmon River Canyon
Simulations display historic
light severity fire probability
was much higher than
current conditions.
What size watershed do we model to characterize both historic and
current trends?
Geographic Area 8
• Eight fifth-code
watersheds, in two
different areas, bounded
by exterior basins (i.e. the
surrounding landscape)
were modeled in two ways:
– 1) in isolation from
other watersheds, and
Geographic Area
17
– 2) in context of the
surrounding landscape
(From analysis by Robert Ahl, graduate student, University of Montana)
Geographic Area 8
Very distinct boundaries
between watersheds.
Geographic Area 17
Watershed boundaries are
less distinct and tend to be
forested.
Simulation Comparisons
GA 8 Watershed-Only to Landscape-Context Comparison
ACRES
71,314
71,984
68,322
45,003
FIVECODE
1701020205
1701020204
1701020202
1701020203
DF-Beetle
not different
not different
not different
not different
Compare to Z8sp_area-ls-sa
Severe-LP-MPB Stand-Replacing-Fire
not different
not different
different
different
not different
not different
not different
not different
GA 17 Watershed-Only to Landscape-Context Comparison
ACRES
117,571
69,789
166,271
124,573
FIVECODE
1003010501
1003010309
1004010301
1003010307
DF-Beetle
different
different
different
different
Severe-LP-MPB
different
different
different
different
Stand-Replacing-Fire
different
different
different
different
“Not different” means there is no statistical difference in the level of the
simulated process when simulated as a single watershed vs. as part of
the larger landscape. There is a difference for all processes for GA 17
while only one is different for GA 8
GA 8: Stand-Replacing Fire
SRF: 170102020203 30-ls vs 30-ls-sa
7000
Average Acres
6000
5000
4000
3000
2000
1000
0
1
2
3
4
5
6
7
8
9
10
Decade
watershed only
landscape context
For stand-replacing-fire there is little difference between the means
of multiple simulations because the processes does not easily spread
across watershed boundaries in this type of landscape.
GA 17: Stand-Replacing Fire
SRF: 1003010309 30-ls vs 30-ls-sa
25000
Average Acres
20000
15000
10000
5000
0
1
2
3
4
5
6
7
8
9
10
Decade
watershed only
landscape context
For stand-replacing-fire there is a difference between the means
of multiple simulations because the processes easily spread across
watershed boundaries in this type of landscape. In this case simulating as
a separate watershed would significantly underestimate the amount of
stand replacing fire.
Geographic Area 8
origin and spread taken from one simulation
Originated
Spread
Notice how watershed
boundaries restrict
spread
Geographic Area 17
origin and spread from one simulation
Originated
Spread
Notice how watershed
boundaries do not restrict
spread
Beaverhead – Deerlodge Forest - examples
The smaller the area, the
greater the variability
in conditions
“special areas” represented in the SIMPPLLE data set
for the entire B-D
535,834 acres
(156,405 acres of forested habitat
types)
Simulated historic - percent pole size class
Tobacco Roots
percent
30
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
decade
279,711 acres
(108,158 acres of forested
habitat types)
percent of landscape
Simulated historic - percent in pole size class
Madison
30
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
decade time step
1,194,247 acres
(542,359 acres of forested habitat
types)
Simulated historic - percent in pole size class
Clark Fork
percent
30
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
decade time steps
Simulated historic - percent pole size class
Big Hole
percent
30
888,949acres
(486,118 acres of forested
habitat types)
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
decade
Simulated historic - percent pole size-class
B-D landscape
percent
30
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
decade
8,311,038 acres –(3,142,265 acres of forested habitat types)
Pathways – current vs historic disturbance processes
Whitepine blister rust was not identified as a process
to be modeled. The decision was made to include it
within the current pathways since it is so “established”.
To make “historic” simulations we need pathways
that have blister rust removed.
“Applying natural variability concepts require multiple sources
of information, ranging from site-specific data and simulation
models to expert opinion and judgement”.
Landres et al. 1999
SIMPPLLE
SIMulating
Patterns and
Processes at
Landscape
scaLEs