Miller Creek Demonstration Forest Wildfire Tour
Penelope A. Latham
Raymond C. Shearer
Kevin L. O’Hara
This separate guide describes the Wildfire
Tour and demonstrates differences in forest
development on three units that were burned
by wildfire on July 23, 1967. Prior to the wildfire, South-8 was clearcut and prescribe broadcast burned, while South-13 and South-14
were uncut old growth forest. To find the trail
through the units burned in the wildfire drive
northwesterly from the junction of Good Creek
Road (#60) and Miller Creek Road 0.75 miles
to the junction with Road #2875; turn right on
Road #2875 and proceed northerly 2.0 miles to
the junction of Keith Mountain Road (#2876).
Turn left on Keith Mountain Road and drive
1 mile to the trailhead of the Wildfire Tour
Trail. This trail descends through South-8,
South-13 by the Amphitheater, and South-14
and ends at Road 9807. If you do not have
transportation at the lower road, you will
need to return on the same trail to your
vehicles.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
1
South-8: Clearcut and Summer Prescribed Burn Followed by Wildfire
In 1967, South-8 was clearcut, slashed, and prescribed
Site Conditions
burned in the summer, then reburned 2 weeks later by a
wildfire. Wildfire and clearcutting affected all the sur-
Elevation (ft)
4,851
rounding forest. Despite similar pre-disturbance condi-
Slope (%)
21
tions among the three south-facing units on this trail and
Azimuth (degrees
clockwise from 0 or
north)
193
have developed differently. We describe site conditions
Size (acres)
10
on South-8, the treatments that were applied, and how
Physiography
Dry slope 91%
Flat or bench 1%
Rock outcrop 7%
Moist slope 1%
Habitat type,
phase
Subalpine fir/
queencup beadlily,
beargrass
clearcut South-1 on the Prescribed Fire Tour, the stands
these factors influence the current and future forest
stand development.
Vegetation Development_________
Fire nearly eliminated the duff layer (vegetation litter
on forest floor) throughout this unit. Vegetation established
from seed stored in the upper soil and from surviving
unit South-13 (fig. 1). Following disturbance, two-thirds
roots and rhizomes. Seed dispersed mostly from sources
of the 1984 tree composition was western larch and
far from the site.
Douglas-fir, and small amounts of other conifers (fig. 2).
Before disturbance, tree species composition on South-8
probably was similar to the average species composition of
Initial reduction of western larch did not occur as it did
on South-1. Since 1979, stocking of western larch has
decreased while stocking of Douglas-fir has increased
2
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
(fig. 3). (Stocking surveys record the percent of plots on
which a conifer species occurs.) Total tree density is low:
an average of 379 seedlings and saplings per acre in 1984.
Vegetation development after a stand-replacing disturbance is related to many factors, such as intensity, duration, and severity of disturbance, the seed available from
species present before disturbance, and site conditions.
Also, finer scale disturbances such as browsing affect the
composition of the new forest stand and its rate of develFigure 1—Composition of the old growth forest prior to harvest of
South-8 is based on average basal area of trees greater than 6
inches diameter at breast height growing on south-facing units,
Miller Creek Demonstration Forest, 1967.
opment. The primary factors influencing vegetation development on South-8 were hot, dry summer conditions
resulting in a severe fire, destruction of the onsite seed
Figure 2—In 1984, 17 years after fire treatment, composition of
western larch and Douglas-fir on South-8 was high based on the
number of established seedlings and saplings.
Figure 3—Changes in stocking (percentage of plots on which a species
occurs) of five conifer species by year on South-8. Total stocking was 11
percent in 1974, 41 percent in 1979, and 33 percent in 1984.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
3
source by clearcutting, and the long
Treatments and Results
distance to the nearest seed source.
While South-1 (Prescribed Fire Tour)
remained in the herb stage of development for 15 years, South-8, in
the first year following fire, was
Clearcut
April 1967
Slashed
May 1967
Fire treatment
Prescribed burn: August 8, 1967
Reburned by wildfire: August 23, 1967
Duff moisture
Upper: 43%; Lower: 48%
Average: 46%
Relative fire intensity
993 g water lost from can analogs
Fine fuel reduction
74%
Duff reduction
84%
Ground surface
Burned duff
Bare
8/15/1974
16%
84%
Succession transects
None
Planting trial
None
Permanent plots
None
colonized by shrubs (primarily
ceanothus) that have dominated
the site for the past 20 years. Let’s
look at some of the factors contributing to vegetation development on
South-8.
Tree Seed
Availability _________
9/1974
4%
89%
Little seed was available for regeneration. Clearcutting eliminated the onsite conifer
least 1,500 feet below (this stand is the nearest
seed source. Seed came from:
• A few western larch that survived the wildfire above
clearcut South-8
source for spruce and subalpine fir)
Seedling density is greatest in the northeast corner
• Three western larch in the wildfire-burned forest below that survived the fire
• The intact mature stand near the stream bottom at
closest to surviving western larch trees above the unit.
Continued tree establishment has been affected by poor
and infrequent good seed years since 1971 and the long
4
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
distance to the nearest seed source. Some larger regen-
three units on this south slope (table 1). In contrast,
eration is now producing seeds, and distance will become
South-1 shown on the Prescribed Fire Tour—previously
less of an influence, restricting seedfall.
similar in fuels, growing conditions, and physical characteristics to these three units—burned with low intensity.
Growing Space Availability ______
Subsequent vegetation also developed much differently.
Combined measurements from Miller Creek and a
Duff Reduction—The prescribed burn followed by
wildfire reduced duff coverage by 84 percent, exposing
mineral soil and creating favorable germinating conditions
for tree seedlings that require mineral soil. Mineral soil
enables seedlings to obtain adequate moisture and nutrients for growth. Yet, tree regeneration was low.
similar study at Newman Ridge on the Lolo National
Forest indicate that soil temperature strongly affects
root mortality of nonconiferous vegetation. More severe
fires cause greater soil water loss, higher soil temperatures, higher root mortality, and greater duff reduction.
Fire Intensity—Relative fire intensity
was measured by the amount of water
lost from 36 specially calibrated gallon
Table 1—Comparison of effects of fire intensity on seedbed preparation in southfacing units. Data were collected the same year as the prescribed burn: South-1
(1968); South-8, South-13, and South-14 (1967).
cans systematically distributed within
some units, including South-1 and South8 (table 1). Initially each can contained
2,000 grams of water. The greater the
amount of water lost during the fire, the
more intense the fire. The prescribed fire
on South-8 took place in the summer
when the duff layer was relatively dry.
As a result, fire intensity was high on the
South
units
Fire
intensity
(g water
lost)
S-1
268
S-8
993
S-13
NM*
S-14**
NM*
*Not measured
Duff
reduction
(%)
Soil
exposure
(%)
16
84
100
100
14
84
100
NM
Duff moisture (%)
Average Upper
Lower
88
46
40
NM
41
43
24
NM
135
48
56
NM
**Comparable measurements were not collected on South-14 but due to
similarity of pre-fire conditions and post-fire results, they should be similar to
those on South-13.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
5
Figure 4 shows duff reduction in relation to maximum
fireweed (offsite seed source). A few conifer seeds dis-
soil temperature and depth of heating. Higher nonconif-
persed long distances from outside the burn. Among
erous root mortality yields more available growing space
the survivors showing slow regrowth are spiraea, blue
for tree seedlings.
huckleberry, and beargrass.
While a few plants survived the double-burn, revegetation was largely the result of colonization from offsite
Discussion and Comparisons _____
seed sources and fire-dependent seeds stored in the duff
The prescribed burn occurred on South-8 during the
and upper soil called the seed bank. The principal colo-
same time that lightning-caused fires normally occur.
nizers were shinyleaf ceanothus (onsite seed source) and
As a result of fire during a dry summer, the growing space
made available was greater than that released during
the spring burn on South-1; that is, more mineral soil
was exposed and less competing understory vegetation
survived. Timing of the fire treatment also coincided
with conifer seed maturation. Given these conditions,
conifer regeneration should have been greater on this
site, but onsite seed sources for coniferous trees were
not present. Figure 5 shows stocking comparisons by
year and species for South-1, South-8, and South-13.
Much of South-8 became a shrubfield. Ceanothus seeds
germinated profusely from the seed bank, and the resulting shrubs dominated the site after about 7 years.
Ceanothus is intolerant of shade and dies as the over-
Figure 4—Percent duff reduction increases as soil temperature and
depth of heating increases.
6
story canopy closes. Although not present in the pre-fire
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
Figure 5—Comparison of stocking (percentage of plots on which a species occurs) by site (South-1, -8, -13), year (1974, 1979,
1984), and species (WL, western larch; DF, Douglas-fir; ES, Engelmann spruce; SAF, subalpine fir; and LP, lodgepole pine).
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
7
plant community, the seeds can remain dormant in the
Site conditions also influenced plant community devel-
duff for centuries. To germinate, ceanothus seeds need a
opment. After clearcutting, the hot, dry south-facing site
heat treatment followed by cold treatment (stratification).
limited conifer regeneration. Once herbs and shrubs pro-
Conditions on South-8 were ideal for this, although re-
vided shade, more conifer seedlings became established.
generation of ceanothus and fireweed competed strongly
As they must grow in the deeper shade provided by abun-
with tree seedlings for growing space because of delayed
dant shrubs, the species that continue to establish are
establishment of trees. A few trees in favorable microsites
relatively more shade tolerant, such as Douglas-fir (fig. 3),
were able to grow quickly enough to keep their terminal
which continues to increase in stocking. However, because
buds above the shrubs.
western larch regeneration needs more moisture and
light, the species has not established as well on the hot,
dry South-8 site.
The Future______________________
Trees that established early and grew above the shrubs
continue to grow taller (fig. 6). New tree seedlings will
establish slowly. Tree regeneration in this stand will
be similar to that of South-1 but slower due to greater
distance to a seed source and strong competition from
existing vegetation. Different species compositions developing on the four south-facing sites (South-8, South-13,
South-14, and South-1) will result in different mature
forest structures. More Douglas-fir grows in South-8,
Figure 6—In summer 1994, 27 years after fire treatment, tree
regeneration is patchy and shrubs dominate South-8.
8
while in South-13 we see mainly lodgepole. South-1
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
resembles the pre-disturbance forest. If South-8 were to
You Will Find These
Species on South-8
reburn, the species composition would probably shift
again. Seed resides in serotinous cones on larger lodgepole
pine on the site. Some western larch and Douglas-fir
seed disperses from larger regeneration, but most seed
comes from distant offsite trees.
Opportunities for wood production and mature forest
wildlife habitat will also be delayed on South-8. This
Trees: western larch, lodgepole pine, Douglas-fir,
Englemann spruce, subalpine fir, western white
pine, black cottonwood
Shrubs: Scouler’s willow, ceanothus, snowberry,
Rocky Mountain maple, buffaloberry, spiraea,
blue huckleberry
Herbs: pinegrass, beargrass, fireweed
forest may become less diverse in vertical structure and
species composition if the current shift toward Douglasfir continues. As the slower growing Douglas-fir rises
above the shrub canopy, its growth rate will increase.
As ceanothus disappears from the stand, huckleberry
should also increase. This stand may progress from stand
initiation directly into understory reinitiation even in
the absence of additional tree establishment. Willow,
serviceberry, mountain maple, and ceanothus currently
provide food for wildlife, but the sparse cover on this site
limits its usefulness.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
9
South-13: Uncut Forest and Wildfire
Of the four similar south-facing units, South-13 and
Site Conditions
South-14 were uncut when they burned in the summer
Elevation (ft)
4,670
Slope (%)
24
vest and by prescribed burning. Wildfire or clearcutting
Azimuth (degrees
clockwise from 0 or
north)
189
affected all the surrounding forest. We describe site con-
Size (acres)
10
ditions on South-13, the effect of natural fire, and influ-
Physiography
Dry slope 94%
Ridgetop 1%
Rock outcrop 3%
Habitat type,
phase
Subalpine fir/queencup
beadlily, beargrass
Pre-disturbance
forest understory
Shrubs: blue huckleberry,
Rocky Mountain maple,
spirea, dwarf bilberry,
prince’s pine
Herbs: beargrass
wildfire of 1967. This let us observe natural processes of
forest regeneration at work. We could also see contrasts
between regeneration processes initiated by timber har-
ences on current and future forest development.
Vegetation Development__________
Following the natural wildfire, stand initiation began
with abundant regeneration on South-13. Fire is an important ecological force in the Northern Rocky Mountains because it can change the structure of native plant
communities. Many plants have adaptive characteristics
that allow them to recolonize a site quickly after wildfire. Herbs, shrubs, and trees grew abundantly in the
composition in 1984 showed a dramatic shift to predominantly lodgepole pine (fig. 7 and 8). Since 1979,
stocking of western larch has decreased while stocking
growing space on South-13.
of lodgepole pine has increased. (Stocking surveys
More Douglas-fir and subalpine fir occupied South-13
record the percent of plots on which a conifer species
than was average for Miller Creek. Post-disturbance tree
10
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
occurs.) Compared to South-1 and South-8, total tree
density is high, an average of 2,283 seedlings and saplings per acre in 1984. By 1990, average tree density for
all species was 2,400 trees per acre.
Many factors affect vegetation development. Genetic
characteristics may help or hinder a species to live and
reproduce on a site. These characteristics interact with
recurrent and predictable natural disturbances such as
Figure 7—Composition of the old growth forest on South-13
in 1967, prior to being burned by wildfire on July 23, 1967,
based on basal area of trees greater than 6 inches diameter
at breast height, Miller Creek Demonstration Forest.
fire or wind to determine the natural occurrence of species. In addition, environmental factors such as aspect,
physiography, and animal browsing also affect survival.
On South-13, the primary factors in the plant development were dry summer conditions that caused intense
fire, the presence of an onsite seed source for trees and
shrubs, and shade cast by standing dead trees killed in
the wildfire.
As more vegetation grew, the dominant life form shifted
from herbs to shrubs and finally to trees. South-13, in
contrast to South-1 and South-8, has progressed more
quickly through the herb and shrub stages of development. Herbs, primarily fireweed, dominated for the first
5 years. Shrubs, primarily shinyleaf ceanothus, domi-
Figure 8—In 1984, 17 years after fire treatment,
South-13 shows a dramatic shift in tree composition to
a stand dominated by lodgepole pine.
nated for the next 10 years. Since that time, trees have
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
11
gradually gained dominance above the shrubs.
Treatments and Results
If you study figures 9 and 10, you will see the
Clearcut
Uncut, pristine forest
Slashed
None
Fire treatment
Wildfire: August 23, 1967
Duff moisture
Upper: 24%; Lower: 56%
Average: 40%
community began life in the first post-fire
Relative fire intensity
Not measured
ring largely because of rapid development of
Fine fuel reduction
About 90%
conifers and declining growth of herbs and
Duff reduction
About 100%
Ground surface
Burned duff
Bare
Post-disturbance forest
understory (9th year)
8/20/1968
Not measured
74%
life form and dominant species development
on South-13. All species you see in the current
plant community. Vegetation change is occur-
shrubs, especially ceanothus, rather than re9/1984
22%
75%
Shrubs: ceanothus, spirea,
blue huckleberry, Rocky
Mountain maple
Herbs: fireweed, beargrass,
pinegrass
placement of species. Let’s look at the factors
contributing to vegetation development on
South-13.
Tree Seed Availability _____
The crown fire in South-13 killed the ma-
Succession transects
Present
Planting trial
None
jority of the overstory trees leaving the near-
Permanent plots
Present
est live tree seed source about 1,300 ft away.
Successional vegetation development transects are marked with
white plastic pipe. The area surrounding the transects serves as
a control to compare the effects of management. Corners of this
area are marked with green metal fenceposts.
Permanent tree regeneration plots are marked by iron rebar
painted red at the end. Each tree recorded is marked with metal
tags and white ribbon.
Only three western larch survived on the
west side of the unit. At the time of the wildfire, mature lodgepole pine seeds in serotinous
cones provided an onsite seed source. Tree regeneration originated from the seed crop in
the crowns of the trees at the time of the fire.
12
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
Fire Intensity—Relative fire intensity was not measured on South-13 because water can analogs were not
in place to measure evaporation loss when the wildfire
burned. However, it was intense enough to burn all the
duff. Duff moisture averaged 40 percent. The prescribed
fire on South-8 took place 2 weeks earlier under similar
conditions when duff moisture averaged 46 percent. So
we can assume that fire intensity on South-13 was simiFigure 9—Percent cover in life form development for unit
South-13 following stand replacing wildfire (cover less
than 100 percent reflects different layers of vegetation).
lar to that on South-8. (Duff reduction on South-8 was
84 percent.) Intense fire and dry soil combined to kill off
the existing vegetation. This created more growing space
Subsequent natural regeneration came mostly from the
for subsequent colonizing species.
distant seed sources.
Growing Space Availability ______
Duff Reduction—The duff layer on South-13 was
burned to the soil surface, creating abundant growing
space for tree seedlings, which require mineral soil for
germination and fast growth. Removal of duff helps promote seedling germination and survival by warming
mineral soil, allowing movement of air around the seedlings during the heat of the day, and keeping the seedlings warmer at night.
Figure 10—Changes in percent cover for lodgepole pine, evergreen
ceanothus, western larch, and fireweed following the stand replacing
summer wildfire on South-13.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
13
The creation of so much mineral soil on South-13 helped
western larch grow, with stocking in 1974 at 30 percent
Discussion and Comparisons _____
Tree regeneration, including that of western larch, was
compared to 4 percent on South-8 and 0 percent on
more abundant on South-13 than on nearby South-8, even
South-1. However, by 1984 stocking of western larch
though they both were far from a seed source. This is
had decreased to 19 percent on South-13. Competition
partially because on South-8 most of the seeds were con-
for moisture and light on this south-facing slope reduced
sumed by fire as the cones lay on the ground following
stocking of western larch but not of lodgepole pine. Fig-
clearcutting and slashing.
ure 11 shows the tremendous reduction in established
larch seedlings on South-13 in 1984 compared to the other
units. Differences among the units appear to be decreasing.
An important difference between South-13 and South-8
is that the wildfire on South-13 created many snags whose
shadows cast moving shade that moderated the surface
temperatures of the soil (fig. 12). On the average, the
shaded south-facing slopes had 11 times more seedlings
than the adjacent clearcuts. Fire facilitates the creation
of western larch forests when it provides an open site
relatively free of vegetation with full sun, moving shade,
and a mineral soil seed bed. Regardless of conditions
that seemed to favor western larch, the lack of an abundant seed source and the greater drought tolerance of
lodgepole pine contributed to the establishment of this
stand dominated by lodgepole pine. More western larch
is found on the west side of the unit where three mature
larch trees survived the wildfire, contributing to post-
Figure 11—Comparison of the number of western
larch seedlings per acre greater than a foot tall on
South-1, South-8, and South-13.
14
fire seeding.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
The Future______________________
Because of rapid vegetation development (principally
ceanothus) in South-13, trees now grow more slowly
(fig. 13). Increased shade from trees will cause reduction
in ceanothus cover, which will create more growing space
for other species.
Variation in the relative dominance of life forms and
species composition contribute to the structural diversity
and development of a stand. Many of the trees in this
Figure 12—Shade created by standing dead trees modifies
surface temperatures that affect regenerating seedlings.
Stands have developed more quickly on South-13 than
on South-8 or South-1. Delayed tree establishment on the
latter units allowed shrubs to become well-established
and to suppress tree growth. On South-13, tree and shrub
seedlings established together, allowing fast-growing
lodgepole pine and western larch seedlings to rise above
the shrubs before the shrub canopy closed. Shade-tolerant
tree seedlings grow under or within the shrub canopy.
The herb stage of development passed quickly due to the
presence of fast growing shrubs such as ceanothus and
spirea.
Figure 13—In the summer of 1994, 27 years after fire treatment,
tree regeneration, especially by lodgepole pine, is nearly
continuous across South-13.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
15
stand will be uniform in structure for some time due to
forest types across the landscape. Shifts in forest compo-
the dominance of lodgepole pine. Aging lodgepole will
sition and structure may also affect the way a forest
die or lose vigor, which will create more space for a new
functions. Composition and structure can change nutri-
age class of shade-tolerant understory trees. This stage
ent recycling, nitrogen fixation by microbes associated
is called understory reinitiation. Without disturbance,
with specific plants, susceptibility to insects and disease,
the dominant species in the stand will gradually change
diversity, the availability of animal foods, and the distri-
from lodgepole pine to other species. Because of its lon-
bution of those foods and living space.
gevity, western larch will remain a part of the stand for
several hundred years. If fires are allowed to burn, shadeintolerant species such as lodgepole pine and western
larch will remain a part of this forest. The dominant
Many factors determine the dynamics and complexity
of vegetation succession. In the Northern Rocky Mountains, fire contributes to the diversity of plant and animal communities.
shrub component of the stand, ceanothus, will begin to
decline as the canopy closes. Ceanothus stems exposed
to extreme cold during winters of low snow pack often
You Will Find These
Species on South-13
freeze and die.
If South-13 and the surrounding area were to reburn
in the near future, the subsequent forest would depend
upon the seed stored in the crowns of the trees. If the
second burn occurred before trees got old enough to produce viable seed, trees could disappear for a long time
while ceanothus shrubs dominate.
Suppression of naturally occurring fires currently contributes to changes in forest structure and the mosaic of
16
Trees: lodgepole pine, western larch, Douglasfir, subalpine fir, Englemann spruce, western
white pine
Shrubs: ceanothus, white spirea, Rocky
Mountain maple, Scouler’s willow, baldhip
rose, buffaloberry, blue huckleberry, grouse
whortleberry
Herbs: fireweed, northwestern sedge, beargrass,
pine grass, hawkweed
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
South-14: Uncut Forest, Wildfire, and Salvage Logging
Followed by Seeding with Western Larch
The uncut, pristine forest in South-14 below South-13
Site Conditions
also burned in the summer wildfire of 1967. Unlike
Elevation (ft)
4,525
Slope (%)
15
ment on this south-facing site differed from the three
Azimuth (degrees
clockwise from 0 or
north)
185
other south-facing units despite similarities in pre-
Size (acres)
10
Physiography
Not measured but
probably similar to
South-13
Habitat type, phase
Subalpine fir/queencup
beadlily, beargrass
Subalpine fir/queencup
beadlily, queencup
beadlily
South-13, this unit was further disturbed by salvage
logging, windrowing and burning salvage residues, and
aerial seeding with western larch. Vegetation develop-
disturbance conditions. Wildfire or clearcutting affected
all the surrounding forest. We describe the treatments
that were applied, events that occurred, and probable
influences on current and future forest development.
Vegetation Development_________
After a stand-replacing disturbance that removes most
regrowth of surviving vegetation compose the important
vegetation, the initiation of a new stand comes from sur-
developmental processes during reoccupation of avail-
viving roots, rhizomes, or seeds within the soil on the
able growing space.
site or from seed dispersed from offsite sources. Seed dispersal, germination and establishment of new plants, or
Before disturbance the tree species composition on
South-14 closely resembled the average species composi-
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
17
tion of Miller Creek forests (fig. 14). In
Treatments and Results
1983, the stand was dominated by west-
Clearcut
Uncut, pristine forest
Slashed
None
Fire treatment
Wildfire: August 23, 1967
This unit, with 3,400 trees per acre in
Salvage logging
October 1967
1984, has more trees than neighboring
Windrowing residues
Summer 1968
South-13, with 2,600 trees per acre in
Burning windrows
Fall 1968
1983 (fig. 16).
Helicopter seeding
western larch
Spring 1969
Duff moisture
Not measured but probably
similar to South-13
Upper: 24%; Lower: 56%
Average: 40%
ern larch and Englemann spruce (fig. 15).
Several factors interacted on South-14
to produce the pattern of vegetation development, primarily the nature of the disturbances and subsequent management
Relative fire intensity
Not measured
activities. After a relatively slow start,
Fine fuel reduction
Not measured but presumed
similar to South-13; about 90%
South-14 has progressed quickly through
Duff reduction
Not measured but presumed
similar to South-13; about 100%
Let’s look at some of the factors contribut-
Ground surface
Not measured
Succession transects
None
Planting trial
None
Permanent plots
None
the early stages of forest development.
ing to this development.
Tree Seed Availability _
If the fire-killed trees on South-14 had
not been salvaged and slash piled by bulldozers, regeneration probably would have
been similar to South-13. Most conifer seeds dispersed in 1967 (either from wildfirekilled trees or from an uncut and unburned forest 500 to 800 ft below) germinated in
18
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
1968. But, most of these seedlings were killed during
scarification and slash piling in the summer. Most larch
in the present stand originated from stratified seed sown
aerially in early spring 1969. Seedling survival from the
1969 aerially sown larch seed was estimated low, based
on 1971 data (fig. 16). In 1971, an abundant cone crop in
the uncut forest provided considerable seed to this area,
and by 1977 the amount of regeneration was similar on
both South-14 and South-13. Another good cone crop ocFigure 14—Composition of the old growth forest prior to
wildfire on South-14 is based on average basal area of trees
greater than 6 inches diameter at breast height growing on
south-facing units, Miller Creek Demonstration Forest, 1967.
Figure 15—The 1983 stand examination, 16 years after
wildfire, unit South-14 shows the new forest will probably
be dominated by western larch.
curred in 1980, and tree survival on South-14 in 1984
was substantially greater than on unit South-13.
Figure 16—Comparison of the number of trees per acre for all species
on South-14 (District stand exams) and South-13 (research data).
Measurement years refer to South-13 first and South-14 second.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
19
Growing Space Availability ______
Duff Reduction—Nearly 100 percent of the duff layer
Discussion and Comparisons _____
Tree regeneration following fire differed dramatically
was burned to the soil surface exposing mineral soil. Duff
among the south-facing units. Regeneration on South-13
removal before seedfall is important for many western tree
following wildfire was immediate and abundant. South-
species (see this section in the discussion for South-13).
14, next to South-13, experienced a lag in subsequent re-
Treatments associated with removal of the salvaged tim-
generation due to post-fire treatments. However, because
ber increased the amount of mineral soil available for
of aerial seeding of western larch in 1969, and because
tree seedlings.
South-14 is close to a mature forest, regeneration has
Fire Intensity—Because measurement instruments
since recovered and surpassed that on South-13 (fig. 16).
weren’t in place, fire intensity was not measured on
The combined activity of salvage logging and windrow-
South-14 before it was burned by wildfire. However,
ing in South-14 probably destroyed many germinating
the fire was probably severe to achieve complete duff
seedlings. While logging exposed additional mineral soil,
reduction. We did not measure duff moisture, but we
the distance to the nearest live tree seed source was still
assume it is similar to South-13, averaging 40 percent.
substantial. Subsequent seeding of western larch pro-
(For details, refer to discussion in this section for South-13.
vided abundant regeneration but was delayed compared
Refer to table 1 in discussions for South-1 or South-8 for
to South-13. Also, because most tree seedlings were not
a comparison of duff moistures and duff reduction in the
tall enough to be counted (generally 6 inches), the South-
south-facing units.) Severe fire combined with dry soil
14 stand survey in 1971 may also have underestimated
resulted in high root mortality of existing vegetation,
seedling density.
increasing the amount of growing space available. The
creation of abundant mineral soil and removal of existing
vegetation should have been beneficial for conifer regeneration, yet fewer tree seedlings initially regenerated on
On South-13 standing dead trees shaded seedlings.
But on South-14 dead trees were either removed as
salvage or pushed into windrows and burned, which
reduced shade. Shade is important for survival of tree
South-14 than on South-13.
20
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
seedlings on south-facing sites. The need for shade may
across the drainage. Few trees have regenerated where
have been reduced (but not eliminated) by the more favor-
residues were windrowed. Currently, shrubs and herbs
able topographic position of South-14.
dominate. Several species have the ability to fix nitrogen
Biotic effects influenced seedling survival. Because of
the lack of food following the wildfire, rodents ate most
seeds shed onto the burned forest floor. Test plots showed
that seeds sown on lightly burned sites were less susceptible to predation than seeds sown on severely burned
sites. In early May 1968, the peaks of western larch and
and are modifying soil conditions. Among these are
buffaloberry, ceanothus, alder, lupine, and clover. The
abundance of buffaloberry in these strips may be because
of the availability of perch sites for birds on partially
burned wood combined with the high mortality of preburn herbs and shrubs after the windrows were burned.
Douglas-fir germination coincided with feeding by migrating Oregon juncos. This resulted in the loss of nearly all
The Future______________________
seedlings that had not shed their seed coats. Englemann
Many small areas within South-14 are in the stem
spruce was less affected because it germinates later (fig.
exclusion stage of development, just like on South-13.
15). In 1969, helicopter seeding of larch seed intermixed
Single species dominate both sites. South-14, however,
with poisoned oats may have reduced rodent depredation,
is predominately western larch rather than lodgepole
but the number of established seedlings per acre in 1971
pine. Because of larch’s deciduous canopy and short clus-
was low (fig. 16). Tree seedlings continued to establish
tered needles, light and moisture are more available on
on South-14 creating dense conditions in many parts of
the forest floor for understory species. Also, larch needles
the stand.
decompose more quickly because they have thin surface
Soil compaction and sterilization of the soil from intense heating in the burned windrows have produced
visible evidence of this localized treatment 30 years later.
The windrows are visible from Council Rock in East-3
layers and low lignin content. Although greater understory diversity may result on South-14 than on South-13,
degraded soils may have long-term detrimental influence on the understory community where windrows were
burned.
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998
21
South-14 may exhibit some of the same limitations
wildlife habitat. Thinning or group selections open the
caused by uniform species composition and structure as
stand and create opportunities for additional conifer re-
South-13. Western larch’s high quality wood and aesthetic
generation or development of herbs and shrubs, thus
appeal make it desirable, and opportunities exist for thin-
speeding the onset of understory reinitiation. Western
ning and pruning in South-14 to further improve wood
larch is a large and long-lived tree, so larch can provide
quality, increase economic return (fig. 17), or improve
habitat for raptors and cavity nesters for hundreds of
years.
The windrows will remain visible for several decades
before the soil naturally rehabilitates and they blend
into the landscape.
You Will Find These
Species on South-14
Trees: western larch, Douglas-fir, subalpine fir,
Englemann spruce, western white pine
Shrubs: white spirea, Rocky Mountain maple,
Scouler’s willow, ceanothus, baldhip rose, buffaloberry, blue huckleberry, grouse whortleberry
Figure 17—In the summer of 1994, 26 years after
salvage logging and windrowing, tree regeneration
(especially western larch) is nearly continuous
within South-14.
22
Herbs: fireweed, northwestern sedge, beargrass,
pine grass, hawkweed
This publication is a supplement to USDA Forest Service Gen. Tech. Rep. RMRS-GTR-7. 1998