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Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 31
ReseaRch aRticle
VEGETATION RESPONSE TO BURN SEVERITY, NATIVE GRASS SEEDING,
AND SALVAGE LOGGING
Penelope Morgan1, Marshell Moy1, 3, Christine A. Droske1, 4, Sarah A. Lewis2,
Leigh B. Lentile1, 5, Peter R. Robichaud2, *, Andrew T. Hudak2, and Christopher J. Williams6
1 Department of Forest, Rangeland, and Fire Sciences, University of Idaho,
875 Perimeter Drive MS 1133, Moscow, Idaho 83844, USA
2 US Department of Agriculture, Forest Service, Rocky Mountain Research Station,
1221 South Main Street, Moscow, Idaho 83843, USA
3 Current address: US Department of Agriculture, Forest Service, Payette National Forest,
800 West Lakeside Avenue, McCall, Idaho 83638, USA
4 Current address: US Department of Agriculture, Forest Service,
Salmon-Challis National Forest,
1206 South Challis Street, Salmon, Idaho 83467, USA
5 Current address: Department of Forestry and Geology, University of the South,
735 University Avenue, Sewanee, Tennessee 37375, USA
6 Department of Statistical Science, University of Idaho,
875 Perimeter Drive MS 1104, Moscow, Idaho 83844, USA
* Corresponding author: Tel.: +1-208-883-2349; e-mail: probichaud@fs.fed.us
ABSTRACT
As the size and extent of wildres has
increased in recent decades, so has
the cost and extent of post-re man-
agement, including seeding and sal-
vage logging. However, we know lit-
tle about how burn severity, salvage
logging, and post-re seeding interact
to inuence vegetation recovery long-
term. We sampled understory plant
species richness, diversity, and cano-
py cover one to six years post re
(2006 to 2009, and 2011) on 72 per-
manent plots selected in a stratied
random sample to dene post-re
vegetation response to burn severity,
post-re seeding with native grasses,
RESUMEN
A medida que el tamaño y la extensión de los
incendios han aumentado en las recientes déca-
das, también lo ha hecho el costo y el alcance
del manejo post-fuego, incluyendo la siembra y
las cortas de recuperación. Sin embargo, cono-
cemos poco sobre como la severidad del fuego,
las cortas de recuperación y las siembras
post-fuego interactúan para inuir sobre la res-
tauración de la vegetación a largo plazo. En
este estudio muestreamos la riqueza de especies
del sotobosque, la diversidad, y la cobertura del
dosel vegetal entre uno y seis años después del
fuego (2006 a 2009, y 2011) en 72 parcelas per-
manentes seleccionadas en un muestreo estrati-
cado al azar, para denir la respuesta de la ve-
getación a la severidad del fuego, siembra
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 32
and salvage logging on the 2005
School Fire in eastern Washington.
Understory vegetation responded rap-
idly post re due, in part, to ample
low intensity rainfall events in the
rst post-re growing season. Vege-
tation was more diverse with greater
plant species richness and diversity
(Shannon-Wiener index) in low and
moderate burn severity plots in 2006
(species richness 18; diversity 2.3)
compared to high burn severity plots
(species richness 10; diversity 1.8),
with species richness on the high se-
verity plots reaching 19 in the sixth
post-re year, similar to the initial
values on the low and moderate burn
severity plots. Plants that commonly
resprout from rhizomes, bulbs, and
other surviving belowground sources
were abundant post re, while those
establishing from off-site seed sourc-
es, including non-native species, were
present but not abundant. Plots seed-
ed with native grass post re and not
salvage logged had the highest cano-
py cover of graminoid species: more
than 30 % six years after the re (in
2011), with low forb (15 %) and shrub
(1 %) canopy cover and species rich-
ness. For comparison, high severity
plots that were not seeded and not
salvage logged had 3 % graminoid
cover, 14 % forb cover, and 26 %
shrub cover. Plots that had been sal-
vage logged from one to three years
after the re produced less canopy
cover of shrubs and forbs, but three
times more canopy cover of gram-
inoids on the high burn severity plots
by 2011. High severity plots that
were salvage logged and not seeded
with native grasses had the lowest
species richness, diversity, and cover.
Very few non-native species were
found, regardless of salvage logging
post-fuego de especies gramíneas nativas y cor-
tas de recuperación en el incendio de School
Fire ocurrido en 2005, al este de Washington.
La vegetación del sotobosque respondió rápida-
mente después del fuego, debido en parte a
abundantes lluvias de baja intensidad en las pri-
meras temporadas de crecimiento tras el fuego.
La vegetación fue más diversa con mayor rique-
za de especies y diversidad (índice de Shannon-
Wiener) en parcelas con severidad de fuego baja
y moderada (riqueza de especies 18, diversidad:
2.3) comparado con parcelas con severidad de
fuego alta (riqueza de especies 10, diversidad
1.8), con riqueza de especies 19 en parcelas de
alta severidad seis años post-fuego, similar a los
valores iniciales en las parcelas con baja y mo-
derada severidad del fuego. Plantas que común-
mente rebrotan de rizomas, bulbos y otras que
sobreviven por debajo de la supercie del suelo,
fueron abundantes después del fuego, mientras
que aquéllas que se establecieron de fuentes de
semilla ubicadas más allá del perímetro quema-
do, incluyendo especies exóticas, aparecieron
pero no en abundancia. Las parcelas sembradas
con especies de gramíneas nativas después del
fuego y sin recuperación maderera tuvieron las
coberturas más altas de especies graminoides,
con más del 30 % seis años después del fuego
(en 2011), con una cobertura baja de hierbas
(15 %) y de arbustos (1 %) y de riqueza de espe-
cies. En contraste, las parcelas con severidad
alta que no fueron sembradas y en donde tam-
poco se recuperó la madera, presentaron un 3 %
de cobertura de especies graminoides, 14 % de
cobertura de herbáceas y 26 % de cobertura de
arbustos. Las parcelas en donde se ha recupera-
do la madera entre uno a tres años después del
fuego, produjeron menor cobertura de dosel de
arbustos y herbáceas, pero esta cobertura fue
tres veces más alta en el dosel de graminoides
en las parcelas con alta severidad del fuego en
2011. Las parcelas con alta severidad del fuego
cuya madera se recuperó y que no fueron sem-
bradas con gramíneas nativas, presentaron la
más baja riqueza, diversidad y cobertura de es-
pecies. Muy pocas especies exóticas fueron en-
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 33
INTRODUCTION
Characterizing post-re vegetation re-
sponse is important for predicting how land-
scapes will respond to large res, subsequent
management activities, and their interactions.
The mosaic of burn severities created as res
burn across a landscape of varying vegetation
and topography has major implications for
post-re plant species composition, diversity,
and abundance (Turner et al. 1997, 1999,
2003; Brown and Smith 2000). Post-re man-
agement after large, severe wildres can often
include seeding or mulching to reduce erosion
potential and the spread of invasive species,
and salvage logging to remove standing dead
trees and recover economic value of some of
the trees killed by the re. The number and
size of large res and total area burned has in-
creased in recent decades (Westerling et al.
2006, Littell et al. 2009), as have the costs of
post-re rehabilitation (Robichaud et al. 2000,
2010, 2014), with long-term implications for
ecosystem resilience (Abella and Fornwalt
2015). Interactions between the ecological ef-
fects of burn severity, seeding with native
grasses, and salvage logging on post-re re-
covery of native vegetation are little studied
and poorly understood.
Within large forest res, high burn severity
alters vegetation (Lentile et al. 2007) and
prompts post-re rehabilitation treatments to
reduce erosion and invasion by non-native
plant species (Robichaud et al. 2010), which
could alter post-re vegetation community de-
velopment. Many experts have predicted that
the large res of recent decades, portions of
which burn with high severity (Dillon et al.
2011), will become increasingly common in
the future (Littell et al. 2009, Spracklen et al.
2009).
Burn severity is broadly dened by the ef-
fects of the re on soil and vegetation (Lentile
et al. 2006; Morgan et al. 2014). Although
burn severity can be measured in a variety of
ways (Lentile et al. 2006, Keeley 2009; Mor-
gan et al. 2014), it is commonly mapped from
satellite imagery, validated with eld observa-
tions, and interpreted as relating to tree mortal-
ity (Clark and Bobbe 2006) and soil conditions
(Parsons et al. 2010). Burn severity can
strongly inuence post-re ecosystem recov-
ery (Morgan and Neuenschwander 1988, Len-
tile et al. 2007, Abella and Fornwalt 2015), but
the degree to which salvage logging and seed-
ing with native grass alters vegetation re-
sponse to burn severity is unknown. Hudak et
al. (2007) found that plots burned with low
Keywords: re effects, mixed conifer forests, plant succession, post-re rehabilitation, salvage
logging
Citation: Morgan, P., M. Moy, C.A. Droske, S.A. Lewis, L.B. Lentile, P.R. Robichaud, A.T. Hu-
dak, and C.J. Williams. 2015. Vegetation response to burn severity, native grass seeding, and
salvage logging. Fire Ecology 11(2): 31–58. doi: 10.4996/reecology.1102031
and seeding. Rapid post-re growth
dominated by native plants of high
diversity suggests that this forest’s
vegetation and soils are highly resil-
ient to disturbance. Overall, burn se-
verity and post-re seeding with na-
tive grasses were more inuential
than salvage logging on understory
plant abundance one to six years after
re.
contradas, independientemente de la recuperación
de la madera o de la siembra. El rápido crecimiento
post-fuego dominado por plantas nativas de diversi-
dad alta sugiere que la vegetación y los suelos de
este bosque son altamente resilientes a las perturba-
ciones. En general, la severidad del fuego y la
siembra post-fuego con especies de gramíneas nati-
vas fue más inuyente que la recuperación de ma-
dera en la abundancia de plantas del sotobosque,
entre uno a seis años después del fuego.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 34
and moderate burn severity were more spatial-
ly variable (with respect to post-re vegetation
and soil conditions) than plots burned with
high severity, and also that effects of burn se-
verity on the ground varied at a ner spatial
scale than within the overstory. Similarly,
Lentile et al. (2007) found that in plots burned
at high severity, vegetation cover and species
diversity was lower and less variable, while
species richness immediately post re was
high as some plants survived in unburned mi-
crosites but not all thrived thereafter in the
changed post-re environment. Halpern
(1988) found that understory vegetation recov-
ery following logging and burning was charac-
terized by initial rapid change varying with
disturbance intensity followed by gradual re-
covery to pre-disturbance composition. Abella
and Fornwalt (2015) found that species rich-
ness increased in the rst decade after the
Hayman Fire, which burned in mixed conifer
forests: plant species present before the re
ourished along with new colonizers. Further,
the prevalence of native plants indicated that
the forest vegetation was highly resilient, but
less so where res burned severely.
Ecologists commonly group plant species
to aid analysis. Plant growth forms, including
shrubs, forbs, and graminoids, are commonly
used for evaluating response to disturbance.
However, ecologists have also used plant func-
tional types (Chapin et al. 1993, 1996) and
traits (Cornelissen et al. 2003) to understand
ecosystem dynamics through species per-
sistence after major disturbances. Short-term
vegetation response to disturbance is largely
dependent on how plants with differing regen-
eration strategies (e.g., off-site seeds, seeds
that survived the re in the seedbank, and
sprouts from surviving belowground materi-
als) respond to soil heating and thrive in the
post-re environment (McLean 1969, Flinn
and Wein 1977, Denslow 1980, Flinn and
Pringle 1983, Morgan and Neuenschwander
1988).
Post-re seeding is commonly used, but
has mixed success for reducing erosion and in-
vasive species establishment (Robichaud et al.
2000; Hunter and Omi 2006; Peppin et al.
2010, 2011; Stella et al. 2010). Seeding may
inadvertently transport alien plant species and
suppress natural regeneration of native woody
and herbaceous species (Beyers 2004, Peppin
et al. 2010, Stella et al. 2010). Because seed-
ing with native, locally adapted grasses may
be both more successful in establishing grass
cover and less disruptive to native vegetation
recovery, seeding with native species is in-
creasing (Peppin et al. 2011). Both native and
non-native perennial graminoids are able to
form dense below- and aboveground cover,
and often out-compete other early seral regen-
erating species (Taskey et al. 1989) such as na-
tive shrubs, forbs, and trees. In their systemat-
ic review of studies, Peppin et al. (2010) found
that 62 % of 26 studies reported reduced rates
of native vegetation recovery following seed-
ing, but concluded that long-term studies are
needed to evaluate lasting effects.
The consequences of salvage logging for
vegetation recovery after re are not well un-
derstood (Peterson et al. 2009). Post-re sal-
vage logging is often challenged due to the
perception of compounding detrimental eco-
logical effects following re (McIver and Starr
2001, Beschta et al. 2004). Few have studied
salvage logging effects on vegetation recovery,
but see Klock (1975), Lindenmayer (2006),
and Peterson et al. (2009). Post-re salvage
logging is done to extract marketable timber
(Franklin and Agee 2003, Sessions et al.
2004), decrease fuel accumulations (Brown et
al. 2003, McIver and Ottmar 2007) that could
fuel future res (Donato et al. 2006, Keyser et
al. 2009), and lessen the potential for insect in-
festation (Brown et al. 2003). Opponents of
salvage logging cite altered vegetation recov-
ery and nutrient cycling (Lindenmayer and
Noss 2006), lost habitat for cavity nesting
birds (Hutto 2006), and damage to established
tree seedlings (Donato et al. 2006). Fire-im-
pacted soils may also be susceptible to mineral
soil exposure, displacement, and compaction
by logging equipment, resulting in increased
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 35
potential for sedimentation and erosion (McIv-
er and Starr 2001, Karr et al. 2004, Wagen-
brenner et al. 2015) and potentially com-
pounding the effects of re on vegetation re-
covery trajectories.
Objectives and Hypotheses
We quantied the effects of burn severity,
salvage logging, and post-re seeding to help
dene their individual and combined effects
on four different aspects of post-re vegeta-
tion, including understory plant species rich-
ness and diversity, and percent canopy cover
by plant growth form and regeneration strate-
gy as a functional trait. We measured vegeta-
tion on permanent plots for six years after a
large wildre burned in dry mixed conifer for-
ests. We hypothesized that:
1) Species richness and diversity would
be:
a. greater in plots burned with low
and moderate burn severity
than plots burned with high se-
verity;
b. reduced by salvage logging, es-
pecially on low and moderate
severity burns; and
c. be greatly reduced in areas
seeded with grass, and become
more similar with time since
re.
2) Abundance of grasses, forbs, and
shrubs would all be inuenced by burn
severity, salvage logging, and seeding,
with forbs and shrubs affected less than
grasses, and that differences, though
persistent, would become less pro-
nounced with time since re.
3) Abundance of plants grouped by re-
generation strategies would all be in-
uenced by burn severity, salvage log-
ging, and seeding, with resprouting
plants less affected than those estab-
lishing from seed, and that differences,
though persistent, would become less
pronounced with time since re.
4) The combined effects of high burn se-
verity, salvage logging, and seeding
with grass would result in much lower
richness, diversity, and abundance of
all growth forms and regeneration
strategies.
5) Burn severity would be more inuen-
tial than salvage logging and native
grass seeding on post-re understory
vegetation richness, diversity, and
abundance, and that non-native species
would be more abundant in areas with
high burn severity followed by salvage
logging relative to areas without sal-
vage logging and also those with and
without grass seeding.
MATERIALS AND METHODS
Study Area
The August 2005 School Fire burned ap-
proximately 21 000 ha of forest and grassland
south of Pomeroy, Washington, on the Umatil-
la National Forest (Figure 1). Much of this
mountainous area contains high plateaus deep-
ly cut by canyons, with steep slopes ranging
from 10 % to 100 %. The re burned rapidly
due to extremely dry fuels (1000-hour fuel
moistures <14 %), high temperatures, and
strong winds (Umatilla National Forest, Pome-
roy Ranger District, Pomeroy, Washington,
USA; unpublished data). The re burned into
drainages on multiple fronts, and long-range
spotting was observed up to 1 km from the
main re. Before the re, invasive plant popu-
lations were concentrated along roadsides on
about 300 ha throughout the burned area
(Umatilla National Forest, Pendleton, Oregon,
USA; unpublished GIS data).
The forest vegetation of the study area
ranged from mixed-conifer forest of Doug-
las-r (Pseudotsuga menziesii [Mirb.] Franco),
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 36
grand r (Abies grandis [Douglas ex D. Don]
Lindl.) and lodgepole pine (Pinus contorta
Douglas ex Loudon var. latifolia Engelm. ex S.
Watson) on ridges and plateaus, to ponderosa
pine (Pinus ponderosa Lawson and C. Law-
son)-dominated forests along the Tucannon
River. Scouler’s willow (Salix scouleriana
Barratt ex Hook.), white spiraea (Spiraea bet-
ulifolia Pall.), common snowberry (Symphori-
carpos albus [L.] S.F. Blake), thinleaf huckle-
berry (Vaccinium membranaceum Douglas ex.
Torr), and currant (Ribes L.) species are com-
mon shrubs. Primary forb species include
heartleaf arnica (Arnica cordifolia Hook.),
reweed (Chamerion angustifolium [L.] Hol-
ub), Piper’s anemone (Anemone piperi Britton
ex Rydb.), and common yarrow (Achillea
millefolium L.). Graminoids are common in-
cluding bluebunch wheatgrass (Pseudoroegne-
ria spicata [Pursh] Á. Löve), California brome
(Bromus carinatus Hook. & Arn.), pinegrass
(Calamagrostis rubescens Buckley), Geyer’s
sedge (Carex geyeri Boott), Ross’ sedge (Car-
ex rossii Boott), Idaho fescue (Festuca ida-
hoensis Elmer), Sandberg bluegrass (Poa se-
cunda J. Presl.), and others as well as the
non-natives cheatgrass (Bromus tectorum L.),
orchardgrass (Dactylis glomerata L.), and bul-
bous bluegrass (Poa bulbosa L.). Introduced,
non-native species include prickly lettuce
(Lactuca serriola L.), common dandelion (Ta-
raxacum ofcinale F.H. Wigg), yellow salsify
(Tragopogon dubius Scop,), and salsify (Tra-
gopogon porrifolius L.).
Figure 1. Plot locations on the 2005 School Fire in southeastern Washington, USA. Plots were stratied
by burn severity, salvage logging (horizontal hatch), and seeding with native grasses (vertical hatch).
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 37
The dominant soil was an ashy loamy
sand: a Loamy-skeletal, isotic, frigid Vitrandic
Argixeroll. Soils derived from basalt, loess
deposits, and volcanic ash were 0.5 m to 1 m
deep on ridges and plateaus but shallower on
slopes (Johnson and Clausnitzer 1991; http://
websoilsurvey.nrcs.usda.gov/app/WebSoilSur-
vey.aspx, accessed 17 September 2013).
Average annual precipitation for the years
we sampled (2005 to 2011) was 1460 mm,
while average annual daily maximum and
minimum temperatures were 10.6 °C and
2.1 °C, respectively (data from nearest weather
station, Touchet SNOTEL (Figure 1) 1686 sta-
tion, 46° 6’ 36” N, −117° 51’ 0” W, elevation
1681 m). Annual precipitation in the year of
the re (2005) was 1135 mm, and in the subse-
quent six years was 1671 mm, 1285 mm, 1631
mm, 1572 mm, 1455 mm, and 1473 mm.
Thus, except for the very dry year of the re,
these years were slightly wetter than long-term
average annual precipitation (1434 mm yr-1),
but similar to average annual daily maximum
and minimum temperatures (10.1 °C and
1.5 °C, respectively, from 1989 to 2010).
Sampling Design
We established 72 permanent plots in 2006
at random locations stratied by burn severity,
with more plots located in areas burned with
moderate and low severity (Table 1) because
of greater heterogeneity and variability in the
post-re conditions than in those of high se-
verity (Lentile et al. 2007). We based our burn
severity strata on a Burned Area Response
Classication (BARC) map (US Department
of Agriculture, Remote Sensing Applications
Center, Salt Lake City, Utah, USA) using dif-
ferenced Normalized Burn Ratio values from
pre-re and immediately post-re Landsat 5
TM images (Clarke and Bobbe 2006). We
conrmed burn severity classes in the eld
with a small set of test plots immediately after
the re in 2005 and again in summer 2006 on
the full set of plots based on tree mortality
with low (<20 % tree mortality), moderate
(20 % to 70 % tree mortality) and high (>70 %
tree mortality) burn severity following Agee
(1993). The number of plots per treatment is
unequal in Table 1 because we initially select-
Treatment Number of plots
High severity burn, seeded, salvage logged 2
High severity burn, seeded, not salvage logged 4
High severity burn, not seeded, salvage logged 3
High severity burn, not seeded, not salvage logged 10
Moderate severity burn, salvage logged 9
Moderate severity burn, not salvage logged 17
Low severity burn, salvage logged 6
Low severity burn, not salvage logged 18
Unburned 3
Total number of plots 72
Table 1. Sampled plots were distributed among treatments that were combinations of burn severity (high,
moderate, and low burn severity, or unburned), seeding with native grasses (seeded or unseeded), and
whether or not salvage logging had occurred. Plots were located following a stratied random design with
respect to burn severity, seeding, and planned salvage logging. Salvage logging was not completed on all
planned plots, and seeding was limited to high burn severity plots, which resulted in an unbalanced exper-
imental design.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 38
ed plots based on planned salvage logging and
seeding treatments, not all of which were im-
plemented. There were few places where we
could nd unburned plots with similar site
conditions as the plots we sampled in the
burned areas. We searched extensively, but
only found three unburned locations within the
re perimeter that met our criteria for sam-
pling in that they were neither recently har-
vested nor heavily used for recreation or other
land use (Figure 1).
Native grass seeding was applied, using a
helicopter in October 2005, to some areas
burned with high severity (712 ha). The Uma-
tilla National Forest stores native grass seed
grown from locally adapted seed sources and
sows it to reduce the potential for soil erosion,
and to limit the establishment and spread of in-
vasive plants following re, logging, or other
disturbances. Four native grasses were seed-
ed, including Idaho fescue at 1.7 kg ha-1 with
goals of 34 pure live seed (pls) m-2, Sandberg
bluegrass at 3.0 kg ha-1 for 54 pls m-2, Califor-
nia brome at 39.7 kg ha-1 for 130 pls m-2, and
blue wildrye (Elymus glaucus Buckley) at 10.3
kg ha-1 for 54 pls m-2 (Umatilla National For-
est, Pendleton, Oregon, USA; unpublished
data).
Most (72 %) of the salvage logging on our
plots occurred during the fall and winter of
2006 to 2007. To the best of our knowledge,
of the remaining salvage logged plots, 14 %
were logged during the late fall and winter
2005 to 2006, 9 % in the spring and summer
2007 to 2008, and 5 % in the spring and sum-
mer 2008 to 2009 (Lewis et al. 2012). Plots
salvage logged in 2005 to 2006 prior to eld
sampling in 2006 were assigned to burn sever-
ity class based on both eld assessments after
the re in late 2005 and our assessment of
stumps and standing trees in the rst post-re
year. Although we placed half of all plots in
each burn severity class (low, moderate, and
high) in locations where post-re salvage log-
ging was planned (based on existing cruise
markings in summer 2006 and information
from local managers on the Umatilla National
Forest), litigation and weather conditions in-
uenced whether or not the plots were actually
salvage logged and affected the timing of the
salvage logging that did occur. Salvage log-
ging was more often planned and implemented
on plots burned with high severity than on
plots burned with low or moderate severity,
and the marked salvage units varied in size
from 1 ha to almost 90 ha, averaging 12 ha. In
2006, the Umatilla National Forest decision to
salvage log on 3818 ha total, including three
timber sales on 1486 ha, was appealed. In
2007, the salvage logging prescriptions were
changed so that no living, re-damaged trees
with more than 50 % of their basal cambium
living were harvested, and all remnant late and
old seral trees greater than 53 cm dbh were re-
tained whether they were dead or alive (USDA
Forest Service 2007). Salvage operations were
primarily ground based; logs were cut and
piled with tracked feller bunchers before a
rubber-tired forwarder was used to move the
logs to a staging area or landing.
Data Collection
Our plots were at least 30 m horizontal dis-
tance away from roads to minimize edge ef-
fects, and they were located either completely
within a planned salvage unit or entirely ex-
cluded from salvage. Each 60 m × 60 m (1.1
ha) sample plot fell within a single burn sever-
ity class as indicated by the BARC map, and
included ve 1 m2 subplots where eld sam-
pling was performed. One subplot was at the
plot center with four more subplots located 30
m slope distance away, with the rst directly
uphill and the others at 90o, 180o, and 270o or-
thogonal azimuths from the central subplot.
We logged a minimum of 100 positions at the
center of each subplot with a Trimble1 GeoEx-
1 Trade names are provided for the benet of the reader and do not imply endorsement by the US Department of
Agriculture.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 39
plorer GPS unit (Trimble Navigation Limited,
Sunnyvale, California, USA), then differen-
tially corrected and averaged to a locational
certainty of 2 m. We marked the center of all
plots with rebar, and we marked and geolocat-
ed all subplots so we could sample the same
plots and subplots in subsequent years.
Plot-level data are aggregated means of the
ve subplots on each plot.
We identied all plant species present in
the 1 m × 1 m subplots and ocularly estimated
percent canopy cover for each species and for
each plant growth form (graminoid, forb,
shrub, tree seedling, and moss or lichen) after
standardization among eld crew members to
reduce sampling error. During sampling, two
eld technicians concurred on plant identica-
tion and ocular estimates, and these were
cross-checked at least once each day. Any
vegetation hanging into the plot and less than
one meter high was considered part of the plot
vegetation. We calculated percent tree canopy
cover at each subplot using spherical densiom-
eter readings collected facing each of the four
cardinal directions surrounding each subplot.
When plants could not be identied, we desig-
nated and numbered them as unknowns; we
later veried all plant species identications in
the Stillinger Herbarium at the University of
Idaho. Nomenclature follows the USDA
Plants Database (USDA 2014). In the years
immediately post re, plants were generally
very small and species identication was often
difcult. In order to provide consistent and
detailed data, we compared subplot-level spe-
cies lists between years to identify unknown
species when possible.
We measured pre-re tree density as the
total of live and dead trees with dbh greater
than 12 cm. These were measured in 2006 on
an 8 m diameter circular area around the cen-
tral subplot on each plot. Of the federally
managed areas that burned, 47 % (~5935 ha)
of the lands had been mechanically treated
pre-re with thinning, prescribed re, or a
combination of prescribed re and thinning.
Unfortunately, despite consultation with local
managers, we were unable to condently as-
sign pre-re treatment methods to the stands.
Species Richness and Diversity
We calculated species richness and Shan-
non-Wiener diversity (Magurran 1988) for
each plot by year. Species richness was the to-
tal number of species found on site. We calcu-
lated the Shannon-Wiener diversity index as
H’ = Σ [pi ln(pi)], (1)
where pi = the proportion of cover for an indi-
vidual species relative to the total coverage of
all species found in that plot. The Shan-
non-Wiener index has been criticized as being
overly sensitive to changes in species that oc-
cur infrequently and in low coverage (Magur-
ran 1988). We did have species that were un-
common or rare on our plots, but we chose to
use this index because of its regular use in
plant ecological work and because it can be
easily interpreted.
We chose percent canopy cover as the
measure of abundance as it is widely used for
repeated measurements on permanent plots
and is related to the degree to which plants
compete for space and resources (Bonham
1989). Unfortunately, cover can vary with soil
moisture and environmental conditions. Den-
sity and biomass are alternative measures. The
plants we sampled varied in size and many of
the plants we sampled were rhizomatous,
which made counting individuals difcult, and
biomass measures require destructive sam-
pling and therefore they are not well suited for
repeated measures on the same plots (Bonham
1989). We chose to use ocular estimates of
cover on small multiple subplots, recognizing
that no single method is optimum for all
growth forms and all species.
We used repeated measures mixed-effects
models (Pinheiro and Bates 2000) to deter-
mine the effects of year (random effect with
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 40
four degrees of freedom for the ve years:
2006, 2007, 2008, 2009, and 2011), treatment
(xed effect with eight degrees of freedom for
the nine treatments listed in Table 1), and their
interaction (32 degrees of freedom for treat-
ment by year interaction). We analyzed rst
for species richness, and then separately for
species diversity. We conducted statistical
analyses in SAS 9.2 (SAS Institute, Cary,
North Carolina, USA) using Proc Mixed be-
cause this method can be used to model cor-
relations found when analyzing grouped data;
it can handle unbalanced, repeated measures;
and it can accommodate different covariance
structures. If any interaction effects were sig-
nicant for a particular variable (P ≤ 0.05), we
used the least squares means and simple ef-
fects tests (Winer 1971) to better understand
the nature of the interaction. Initial analyses
of these variables used an optimum covariance
structure for each variable chosen with
Akaike’s information criterion (AIC). For
species richness and Shannon-Wiener diversi-
ty, an “autoregressive” covariance structure
was used. To compare treatment values within
year, we used an ANOVA for each variable
and the Tukey-Kramer multiple comparison
method to control for experiment-wise error.
Vegetation Abundance by Plant Growth Form
and Regeneration Strategy
We calculated the average percent cover
by plant growth form (graminoid, forb, shrub,
tree, and moss or lichen) and post-re regener-
ation strategy by summing the averaged ob-
served values on the ve 1 m × 1 m subplots
for each plot in each year. We identied post-
re regeneration strategies (NS = nonsurvivor;
OC = off-site colonizer; SR = survivor rhi-
zomes; RC = residual colonizer; and SRCB =
survivor taproot, caudex, or bulb) for each in-
dividual species using the categories of Stick-
ney and Campbell (2000), the Fire Effects In-
formation System (FEIS 2010), the USDA
Plants Database (USDA 2014), and regional
plant identication guides (Taylor and Doug-
las 1995, Johnson 1998, Kershaw et al. 1998).
We divided resprouters into two groups based
on observations by Morgan and Neuenschwan-
der (1988) that rhizomatous plants respond
differently than other resprouters to burn se-
verity, although we did not account for depth
of rhizomes, bulbs, and other structures from
which plants resprout.
We again used repeated measures mixed-ef-
fects models (SAS Proc Mixed, Pinheiro and
Bates 2000) to determine the effects of year
(random effect with four degrees of freedom
for the ve years: 2006, 2007, 2008, 2009, and
2011), treatment (xed effect with eight de-
grees of freedom for the nine treatments listed
in Table 1), and their interaction (32 degrees of
freedom for treatment by year interaction).
First we analyzed abundance by plant form,
and then abundance by regeneration strategy.
Because the results of the xed-effects tests did
not change over a variety of candidate covari-
ance structures, we used an “unstructured” co-
variance structure for all variables to allow for
easier comparisons. In order to meet the as-
sumptions of normality and equal variances,
we used a square root transformation for cover
of all plant forms and most regeneration strate-
gies (Table 2), but we did not need to transform
the species richness and diversity measures.
With the low amount of cover in each of the
survivor rhizome (SR) and residual colonizer
(RC) regeneration strategy groups, a square
root transformation did not meet the normality
and variance assumptions, so a Box-Cox trans-
formation procedure (Box and Cox 1964) led
to the use of a one-quarter power transforma-
tion, which best stabilized the variance of the
residuals.
Factors Inuencing Vegetation Response
In order to understand how site-specic
variables contributed to vegetation composi-
tion, we used regression analysis (Proc GLM,
SAS Institute 2001) to analyze the 2009 vege-
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
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Table 2. Graminoid, forb, and shrub species listed by scientic names, common names, status (N = na-
tive, I = introduced), primary regeneration strategy (NS = nonsurvivor; OC = off-site colonizer; SR = sur-
vivor rhizome; RC = residual colonizer; SRCB = survivor taproot, caudex, or bulb), and source for regen-
eration strategy information. All nomenclature is consistent with the USDA Plants Database (USDA
2014).
Scientic name Common name
Regeneration
Status Strategy Source1
Graminoids
Achnatherum thurberianum (Piper) Barkworth Thurber’s needlegrass N SRCB FEIS
Agrostis scabra Willd. rough bentgrass N OC S&C 2000
Alopecurus L. spp. foxtail N OC FEIS
Apera interrupta (L.) P. Beauv. dense silkybent I OC Burke Museum
Bromus L. spp.brome N/I OC FEIS
Bromus carinatus Hook. & Arn. California brome N OC FEIS
Bromus tectorum L. cheatgrass I OC S&C 2000
Calamagrostis canadensis (Michx.) P. Beauv. bluejoint N SR FEIS
Calamagrostis rubescens Buckley pinegrass N SR S&C 2000
Carex L. spp. sedge N RC S&C 2000
Carex concinnoides Mack. northwestern sedge N SR Burke Museum
Carex geyeri Boott Geyer’s sedge N SR S&C 2000
Carex rossii Boott Ross’ sedge N RC S&C 2000
Dactylis glomerata L. orchardgrass I OC S&C 2000
Danthonia unispicata (Thurb.) Munro ex Macoun onespike danthonia N OC FEIS
Elymus glaucus Buckley blue wildrye N SRCB S&C 2000
Festuca campestris Rydb. rough fescue N SRCB FEIS
Festuca idahoensis Elmer Idaho fescue N SRCB FEIS
Hordeum jubatum L. foxtail barley N OC FEIS
Koeleria macrantha (Ledeb.) Schult. prairie Junegrass N SRCB FEIS
Oryzopsis asperifolia Michx. roughleaf ricegrass N SRCB Kershaw et al. 1998
Phleum pratense L. timothy I OC S&C 2000
Poa bulbosa L. bulbous bluegrass I SRCB FEIS
Poa nervosa (Hook.) Vasey Wheeler bluegrass N OC Kershaw et al. 1998
Poa secunda J. Presl Sandberg bluegrass N SRCB FEIS
Pseudoroegneria spicata (Pursh) Á. Löve bluebunch wheatgrass N SRCB FEIS
Schedonorus pratensis (Huds.) P. Beauv. meadow fescue I SR Burke Museum
Forbs
Achillea millefolium L. common yarrow N/I OC S&C 2000
Actaea rubra (Aiton) Willd. red baneberry N SRCB FEIS
Agastache urticifolia (Benth.) Kuntze nettleleaf giant hyssop N OC USDA Plants
Agoseris Raf. spp. agoseris N OC S&C 2000
Allium L. spp. onion N/I SRCB S&C 2000
Anaphalis margaritacea (L.) Benth. western pearly everlasting N OC S&C 2000
Anemone piperi Britton ex Rydb. Piper’s anemone N SRCB S&C 2000
Antennaria Gaertn. spp. pussytoes N OC S&C 2000
Apocynum androsaemifolium L. spreading dogbane N SR S&C 2000
Arabis hirsuta (L.) Scop. hairy rockcress N SRCB Kershaw et al. 1998
Arabis holboellii Hornem. Holboell’s rockcress N OC S&C 2000
Arabis sparsiora Nutt. sicklepod rockcress N OC Burke Museum
Arenaria congesta Nutt. ballhead sandwort N OC S&C 2000
Arnica cordifolia Hook. heartleaf arnica N SR S&C 2000
Artemisia ludoviciana Nutt. white sagebrush N SRCB Kershaw et al. 1998
Astragalus L. spp. milkvetch N/I SRCB S&C 2000
Besseya rubra (Douglas ex Hook.) Rydb. red besseya N SR Kershaw et al. 1998
Brassica L. spp. mustard I OC Kershaw et al. 1998
Calochortus apiculatus Baker pointedtip mariposa lily N SRCB Kershaw et al. 1998
Capsella bursa-pastoris (L.) Medik. shepherd’s purse I OC Kershaw et al. 1998
Chamerion angustifolium (L.) Holub reweed N OC S&C 2000
Circaea alpina L. small enchanter’s nightshade N NS Kershaw et al. 1998
Cirsium Mill. spp. thistle N/I OC S&C 2000
Cirsium arvense (L.) Scop. Canada thistle I OC S&C 2000
Cirsium vulgare (Savi) Ten. bull thistle I OC S&C 2000
Clarkia pulchella Pursh pinkfairies N OC Kershaw et al. 1998
Claytonia perfoliata Donn ex Willd. miner’s lettuce N SRCB Kershaw et al. 1998
Collinsia grandiora Lindl. giant blue eyed Mary N RC S&C 2000
1FEIS = Fire Effects Information System (http://www.feis-crs.org/beta/), accessed 7 July 2014; S&C 2000 = Stickney and Camp-
bell 2000; USDA Plants = USDA Plants Database (http://plants.usda.gov), accessed 12 May 2015; Burke Museum = University
of Washington Burke Museum (http://www.burkemuseum.org/herbarium), accessed 9 July 2014; Kershaw et al. 1998.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 42
Scientic name Common name
Regeneration
Status Strategy Source1
Collomia linearis Nutt. tiny trumpet N RC S&C 2000
Conyza canadensis (L.) Cronquist Canadian horseweed N OC Kershaw et al. 1998
Crepis elegans Hook. elegant hawksbeard N OC Kershaw et al. 1998
Cryptantha Lehm. ex G. Don spp. cryptantha N UNK
Cynoglossum ofcinale L. gypsyower I RC FEIS
Cypripedium parviorum Salisb. lesser yellow lady’s slipper N OC FEIS
Delphinium bicolor Nutt. little larkspur N OC Kershaw et al. 1998
Dodecatheon pulchellum (Raf.) Merr. darkthroat shootingstar N OC S&C 2000
Draba verna L. spring draba I OC Kershaw et al. 1998
Epilobium L. spp. willowherb N OC S&C 2000
Erigeron L. spp. eabane N/I SRCB Kershaw et al. 1998
Eriogonum Michx. spp. buckwheat N SRCB Kershaw et al. 1998
Erysimum capitatum (Douglas ex Hook.) Greene sanddune wallower N OC Kershaw et al. 1998
Erythronium grandiorum Pursh yellow avalanche-lily N SRCB S&C 2000
Eurybia conspicua (Lindl.) G.L. Nesom western showy aster N SR S&C 2000
Fragaria vesca L. woodland strawberry N SR FEIS
Frasera speciosa Douglas ex Griseb. elkweed N SR FEIS
Galium boreale L. northern bedstraw N NS FEIS
Galium triorum Michx. fragrant bedstraw N NS S&C 2000
Geum triorum Pursh old man’s whiskers N SR FEIS
Goodyera oblongifolia Raf. western rattlesnake plantain N NS S&C 2000
Hackelia Opiz spp. stickseed N SRCB Kershaw et al. 1998
Heuchera L. spp. alumroot N SRCB Kershaw et al. 1998
Hieracium albiorum Hook white hawkweed N RC FEIS
Hieracium scouleri Hook. var. albertinum (Farr) G.W.
Douglas & G.A. Allen Scouler’s woollyweed N OC S&C 2000
Hydrophyllum capitatum Douglas ex Benth. ballhead waterleaf N SR Kershaw et al. 1998
Iliamna rivularis (Douglas ex Hook.) Greene streambank wild hollyhock N RC S&C 2000
Iris missouriensis Nutt. Rocky Mountain iris N SRCB Kershaw et al. 1998
Lactuca serriola L. prickly lettuce I OC S&C 2000
Leucanthemum vulgare Lam. oxeye daisy I SR Kershaw et al. 1998
Linnaea borealis L. twinower N NS S&C 2000
Lithophragma parviorum (Hook.) Nutt. ex Torr. & A.
Gray smallower woodland-star N SR Museum
Lomatium dissectum (Nutt.) Mathias & Constance fernleaf biscuitroot N RC Kershaw et al. 1998
Lupinus L. spp. lupine N SRCB S&C 2000
Luzula campestris (L.) DC. eld woodrush I RC S&C 2000
Madia Molina spp. tarweed N OC Kershaw et al. 1998
Maianthemum stellatum (L.) Link starry false lily of the valley N SR FEIS
Mitella breweri A. Gray Brewer’s miterwort N SRCB S&C 2000
Mitella stauropetala Piper smallower miterwort N SR FEIS
Moehringia lateriora (L.) Fenzl bluntleaf sandwort N SR USDA Plants
Nemophila breviora A. Gray basin nemophila N SRCB Burke Museum
Nothocalais troximoides (A. Gray) Greene sagebrush false dandelion N SRCB Burke Museum
Oenothera villosa Thunb. hairy evening primrose N SRCB Kershaw et al. 1998
Olsynium douglasii (A. Dietr.) E.P. Bicknell Douglas’ grasswidow N UNK Burke Museum
Orthilia secunda (L.) House sidebells wintergreen N NS S&C 2000
Osmorhiza berteroi DC. sweetcicely N SRCB S&C 2000
Packera Á. Löve & D. Löve spp.ragwort N SR Kershaw et al. 1998
Packera streptanthifolia (Greene) W.A. Weber & Á. LöveRocky Mountain groundsel N SRCB Burke Museum
Pedicularis L. spp. lousewort N SRCB Burke Museum
Penstemon Schmidel spp. beardtongue N SRCB Kershaw et al. 1999
Penstemon glandulosus Douglas stickystem penstemon N SRCB Kershaw et al. 1998
Petasites frigidus (L.) Fr. arctic sweet coltsfoot N OC Kershaw et al. 2000
Phacelia Juss. spp. phacelia N SRCB S&C 2000
Plantago lanceolata L. narrowleaf plantain I SRCB Burke Museum
Plantago major L. common plantain I OC Kershaw et al. 1998
Polemonium pulcherrimum Hook. Jacob’s-ladder N SRCB Kershaw et al. 1998
Polygonum douglasii Greene Douglas’ knotweed N OC Kershaw et al. 1998
Potentilla L. spp. cinquefoil N/I SCRB Burke Museum
Potentilla argentea L. silver cinquefoil I SRCB Kershaw et al. 1998
Table 2, continued. N = native; I = introduced; NS = nonsurvivor; OC = off-site colonizer; SR = survivor
rhizome; RC = residual colonizer; SRCB = survivor taproot, caudex, or bulb.
1FEIS = Fire Effects Information System (http://www.feis-crs.org/beta/), accessed 7 July 2014; S&C 2000 = Stickney and Camp-
bell 2000; USDA Plants = USDA Plants Database (http://plants.usda.gov), accessed 12 May 2015; Burke Museum = University
of Washington Burke Museum (http://www.burkemuseum.org/herbarium), accessed 9 July 2014; Kershaw et al. 1998.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 43
Scientic name Common name
Regeneration
Status Strategy Source1
Potentilla gracilis Douglas ex Hook. slender cinquefoil N SRCB Kershaw et al. 1998
Potentilla recta L. sulphur cinquefoil I SRCB FEIS
Prosartes trachycarpa S. Watson roughfruit fairybells N SR S&C 2000
Prunella vulgaris L. common selfheal N OC S&C 2000
Ranunculus L. spp. buttercup N/I SRCB FEIS
Ranunculus uncinatus D. Don ex G. Don woodland buttercup N SRCB Burke Museum
Rudbeckia alpicola Piper showy coneower N SR Kershaw et al. 1998
Rumex acetosella L.common sheep sorrel I SR FEIS
Sedum stenopetalum Pursh wormleaf stonecrop N OC Kershaw et al. 1998
Silene L. spp. catchy N/I SR S&C 2000
Solidago canadensis L. Canada goldenrod N OC Kershaw et al. 1998
Stellaria L. spp. starwort N/I OC Burke Museum
Stellaria media (L.) Vill. common chickweed I SR Kershaw et al. 1998
Tanacetum vulgare L. common tansy I SR FEIS
Taraxacum ofcinale F.H. Wigg. common dandelion I OC S&C 2000
Thalictrum occidentale A. Gray western meadow-rue N SRCB S&C 2000
Thelypodium laciniatum (Hook.) Endl. ex Walp. cutleaf thelypody N OC Kershaw et al. 1998
Tragopogon dubius Scop. yellow salsify I OC S&C 2000
Tragopogon porrifolius L. salsify I OC Burke Museum
Trautvetteria caroliniensis (Walter) Vail Carolina bugbane N SR S&C 2000
Trifolium repens L. white clover I OC S&C 2000
Triteleia grandiora Lindl. largeower triteleia N SRCB Kershaw et al. 1998
Urtica dioica L. stinging nettle N/I SRCB S&C 2000
Valeriana occidentalis A. Heller western valerian N UNK USDA Plants
Verbascum thapsus L. common mullein I OC S&C 2000
Viola L. spp. violet N/I SR Kershaw et al. 1998
Zigadenus Michx. spp. deathcamus N SRCB Kershaw et al. 1999
Zizia aptera (A. Gray) Fernald meadow zizia N SRCB USDA Plants
Shrubs
Acer glabrum Torr. Rocky Mountain maple N SRCB S&C 2000
Alnus Mill. spp. alder N SRCB FEIS
Amelanchier alnifolia (Nutt.) Nutt. ex M. Roem. Saskatoon serviceberry N SRCB S&C 2000
Arctostaphylos uva-ursi (L.) Spreng. kinnikinnick N SRCB FEIS
Ceanothus velutinus Douglas ex Hook. snowbrush ceanothus N RC S&C 2000
Chimaphila umbellata (L.) W.P.C. Barton pipsissewa N NS S&C 2000
Mahonia repens (Lindl.) G. Don creeping barberry N SR FEIS
Menziesia ferruginea Sm.rusty menziesia N SRCB S&C 2000
Philadelphus lewisii Pursh Lewis’ mock orange N SRCB S&C 2000
Physocarpus malvaceus (Greene) Kuntze mallow ninebark N SRCB S&C 2000
Prunus L. spp. plum N/I SRCB USDA Plants
Prunus emarginata (Douglas ex Hook.) D. Dietr. bitter cherry N SRCB USDA Plants
Ribes L. spp. currant N/I RC S&C 2000
Ribes lacustre (Pers.) Poir. prickly currant N RC S&C 2000
Ribes viscosissimum Pursh sticky currant N RC S&C 2000
Rosa L. spp. rose N/I SRCB S&C 2000
Rubus L. spp. blackberry N/I RC S&C 2000
Rubus idaeus L. American red raspberry N/I RC S&C 2000
Rubus parviorus Nutt. thimbleberry N SR S&C 2000
Salix scouleriana Barratt ex Hook. Scouler’s willow N SRCB S&C 2000
Sambucus racemosa L. red elderberry N RC S&C 2000
Spiraea betulifolia Pall. white spirea N SR S&C 2000
Symphoricarpos albus (L.) S.F. Blake common snowberry N SR S&C 2000
Vaccinium membranaceum Douglas ex Torr. thinleaf huckleberry N SR S&C 2000
Trees
Abies grandis (Douglas ex D. Don) Lindl. grand r N OC S&C 2000
Larix occidentalis Nutt. western larch N RC S&C 2000
Picea engelmannii Parry ex Engelm. Engelmann spruce N OC S&C 2000
Pinus contorta Douglas ex Loudon var. latifolia Engelm.
ex S. Watson lodgepole pine N RC S&C 2000
Pinus ponderosa Lawson and C. Lawson ponderosa pine N OC S&C 2000
Pseudotsuga menziesii (Mirb.) Franco Douglas-r N OC S&C 2000
Table 2, continued. N = native; I = introduced; NS = nonsurvivor; OC = off-site colonizer; SR = survivor
rhizome; RC = residual colonizer; SRCB = survivor taproot, caudex, or bulb.
1FEIS = Fire Effects Information System (http://www.feis-crs.org/beta/), accessed 7 July 2014; S&C 2000 = Stickney and Camp-
bell 2000; USDA Plants = USDA Plants Database (http://plants.usda.gov), accessed 12 May 2015; Burke Museum = University
of Washington Burke Museum (http://www.burkemuseum.org/herbarium), accessed 9 July 2014; Kershaw et al. 1998.
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 44
tation response (species richness, species di-
versity, abundance of the three different plant
growth forms, and the four different regenera-
tion strategies) by treatment. We used only the
2009 data for this analysis because we antici-
pated that differences in vegetation response
would be evident four years post re, and that
these differences have long-term consequenc-
es. We combined slope and aspect to form a
continuous variable for ease in statistical anal-
ysis {Aspslp = percent slope × [cosine (as-
pect)]} (Stage 1976). The other site-specic
variables were treatment, tree density class, el-
evation, and average tree canopy cover post
re.
RESULTS
Plant Species Richness and Diversity
Both richness and Shannon-Wiener diver-
sity of understory plants varied with treatment,
year, and the interaction of treatment and year
(Figure 2). Plant species richness and diversi-
ty were higher on plots burned with low and
moderate burn severity than on some unburned
plots, and plots burned with high severity had
the lowest richness and diversity overall. Sal-
vage logging and seeding both signicantly
decreased richness and diversity (Figure 2, Ta-
ble 3). At higher pre-re tree density, both
species richness (P = 0.02) and diversity (P =
A A A A A
A
AB
ABC
BC
C
1234 61234 61234 61234 61234 6
Post-fire years
1
2
3
4
SW diversity index
Low severity
Moderate severity
High severity, seeded
Unburned
High severity
B AB AB A A
A
A
B
B
1234 61234 61234 61234 61234 6
5
10
15
20
25
30
AC B AB AB
A
AB
AB
BC
C
1234 61234 61234 61234 61234 6
5
10
15
20
25
30
Species richness
Low severity
Unburned
Moderate severity
High severity, seeded
High severity
A A A A A
A
A
A
B
1234 61234 61234 61234 61234 6
Post-fire years
1
2
3
4Low severity
Moderate severity
High severity, seeded
High severity
Salvage loggedNot salvage logged
Figure 2. Species richness (number of species, top) and Shannon-Wiener (SW) diversity index (bottom)
for all severity and seeding treatment combinations. Data are contrasted by not salvage logged (left) and
salvage logged (right). Error bars represent standard error. Capital letters next to the years on the x-axis
and next to the treatments in the legend represent signicant differences between means by year or by
treatment; legend items are ordered from highest to lowest mean value over all years
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 45
0.003) were less four years after the re, while
richness was greater with higher tree canopy
cover (P = 0.005).
I
n the rst year post re, species richness
was signicantly lower on high severity burns
than on unburned, low, or moderate severity
plots, regardless of whether they were salvage
logged or not (P < 0.001) (Table 3). In the
second, third, fourth, and sixth years post re,
species richness did not differ signicantly on
plots burned with high, moderate, and low se-
verity that were not salvage logged (P >
0.05); species richness increased signicantly
between the rst post-re year and the sixth
post-re year on both salvage logged and not
salvage logged plots (Figure 2). Of plots that
were salvage logged, species richness was
lower in the fourth post-re year in high se-
verity burned plots than in either low or mod-
erate burn severity plots (P = 0.002). Species
richness was higher on the seeded and unseed-
ed high severity plots that were not salvage
logged than on the salvage-logged counter-
parts (P = 0.03 and < 0.001, respectively)
(Table 3).
Species diversity was higher on low sever-
ity burned plots compared to high severity
burned plots in the second and fourth years
post re (P = 0.005 and P = 0.001, respective-
ly), and on moderate burn severity plots com-
pared to high severity plots four years post re
(P = 0.005). However, species diversity did
not differ among treatments in the third and
sixth years post re (P > 0.05). Species diver-
sity was also lower on plots that were salvage
logged and burned at high severity than in
plots burned at low and moderate severity in
the second post-re year (P = 0.009). Consid-
ering all years together, species diversity was
lower on unseeded high severity plots than on
low and moderate severity plots (Figure 2),
and diversity of the seeded plots was overall
higher than the unseeded high-severity coun-
terparts (P = 0.004, Figure 2).
Measure F-value P-value
High burn severity, seeded
Richness 4.53 0.03
Diversity 1.07 0.30
Grass 0.20 0.66
Forb 2.16 0.14
Shrub 0.13 0.72
Survivor rhizome (SR) 0.98 0.32
Offsite colonizer (OC) 0.70 0.40
Survivor taproot, caudex, or
bulb (SRCB) 0.10 0.75
Residual colonizer (RC) 12.56 <0.001
High burn severity, unseeded
Richness 12.47 <0.001
Diversity 8.61 0.004
GrassA9.64 0.002
Forb 7.40 0.007
Shrub 9.12 0.003
Survivor rhizome (SR) 0.49 0.48
Offsite colonizer (OC) 0.87 0.35
Survivor taproot, caudex, or
bulb (SRCB) 0.06 0.80
Residual colonizer (RC) 7.04 0.008
Moderate burn severity
Richness 0.84 0.36
Diversity 1.17 0.28
GrassA10.11 0.002
Forb 29.99 <0.001
Shrub 0.66 0.42
Survivor rhizome (SR) 0.59 0.44
Offsite colonizer (OC) 8.99 0.003
Survivor taproot, caudex,
or bulb (SRCB) 5.16 0.02
Residual colonizer (RC) 0.58 0.45
Low burn severity
Richness 2.29 0.13
Diversity 3.42 0.07
Grass 0.00 0.97
Forb 1.64 0.20
Shrub 4.14 0.04
Survivor rhizome (SR) 0.03 0.86
Offsite colonizer (OC) 0.01 0.91
Survivor taproot, caudex, or
bulb (SRCB) 1.53 0.22
Residual colonizer (RC) 2.10 0.15
Table 3. The effect of salvage logging on plant
cover type, by regeneration strategy. Plots are
compared over all study years with simple effects
tests at the same severity level; for example, high
burn severity salvage logged plots are compared to
high burn severity plots that were not salvage
logged. Signicant differences between salvage
logged and not salvage logged plots are indicated
in bold. Unless indicated by a footnote, salvage
logging decreased the richness, diversity, or cover
of each signicant measure.
A Grass cover was higher on the salvage logged plots
compared to the not salvage logged plots.
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 46
Plant Growth Form
Regardless of burn severity and salvage
logging, graminoid cover was less than 15 %
throughout the study period except on plots
seeded with native grasses (Figure 3). Within
high severity burns, graminoid cover was sig-
nicantly greater on seeded plots than burned
plots that were not seeded for each year mea-
sured (P < 0.05). In years two and three post
re, graminoid cover was signicantly greater
on burned seeded plots than on unburned plots
A
A
A
B
B
B A A A A
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
Forb cover (%)
A A A A A
A
AB
B
B
1234 61234 61234 61234 61234 6
0
10
20
30
40
50 High severity, seeded
Moderate severity
High severity
Low severity
B AB A AB AB
A
B
B
B
1234 61234 61234 61234 61234 6
0
10
20
30
40
50 Low severity
Moderate severity
High severity
High severity, seeded
B A AB AB A
A
B
B
BC
C
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
Grass cover (%)
High severity, seeded
Low severity
Moderate severity
Unburned
High severity
C B AB A AB
A
AB
B
B
B
1234 61234 61234 61234 61234 6
Post-fire year
0
10
20
30
40
50
Shrub cover (%)
High severity
Moderate severity
Low severity
Unburned
High severity, seeded
B A AB A A
A
A
A
A
1234 61234 61234 61234 61234 6
Post-fire year
0
10
20
30
40
50
Moderate severity
High severity
High severity, seeded
Low severity
Salvage logged
Not salvage logged
Figure 3. Percent canopy cover for grasses, forbs, and shrubs by burn severity. Data are contrasted by not
salvage logged (left) and salvage logged (right). Error bars represent standard error. Capital letters next to
the years on the x-axis and next to the treatments in the legend represent signicant differences between
means by year or by treatment; legend items are ordered from highest to lowest mean value over all years.
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 47
(P < 0.01 for both). Burn severity (P = 0.001),
year (P ≤ 0.001), and the interaction of burn
severity and year (P = 0.009) all signicantly
inuenced graminoid cover. Interestingly,
graminoid cover was higher on the salvage
logged moderate and unseeded high severity
plots (P = 0.002 for both) than on the not sal-
vage logged counterparts (Table 3). However,
graminoid cover did not signicantly increase
during the study period on the salvage logged
plots (Figure 3). Elevation was the only site
factor to inuence graminoid cover (P =
0.001) by post-re year four; graminoid cover
was greater at low elevations.
Forbs constituted a majority of total under-
story plant cover, up to 35 %, regardless of
whether plots were salvage logged or not.
Forb cover was signicantly lower on plots
that burned at high severity than plots that
burned at low severity or those that were un-
burned (P ≤ 0.001 for all comparisons). On
the plots that were not salvage logged, forb
cover was lowest in the rst post-re year and
signicantly higher in each other year (Figure
3). On the salvage logged plots, forb cover
was lower on the moderate and high burn se-
verity plots than on the not salvage logged
counterparts (P < 0.001 and P < 0.007, respec-
tively) (Table 3). Salvage logging might have
hindered forb recovery over time; forb cover
was not signicantly higher in post-re year
six than it was in the rst post-re year (Figure
3). Average tree canopy cover (P = 0.001) and
combined slope and aspect (P = 0.01) affected
forb cover four years after the re; forb cover
was greater on more mesic sites.
Shrub cover increased through time re-
gardless of salvage logging or burn severity
(Figure 3), which was different than graminoid
and forb recovery over the same period. In the
rst year post re, shrub cover on plots not
salvage logged was signicantly lower on high
and moderate burn severity plots than on un-
burned plots (P = 0.003), but there were no
signicant differences in shrub abundance
among treatments in subsequent individual
years (P > 0.05), regardless of whether plots
had been seeded or salvage logged. With all
years considered, unseeded plots that burned
at high severity and were not salvage logged
had the highest overall shrub cover (Figure 3),
and seeded high severity plots had the lowest
shrub cover. In post-re year six, high severi-
ty plots that were seeded had signicantly less
shrub cover than plots that were not seeded (P
= 0.02). In year four, shrub cover differed for
all treatments (P ≤ 0.05) with the exception of
plots burned with high severity and seeded,
but neither salvage logged nor burned. Con-
sidering all years, low and high severity plots
that were salvage logged had signicantly
lower shrub cover than the not salvage logged
counterparts (P = 0.004 and P = 0.003, respec-
tively) (Table 3). The only site factor to affect
shrub cover in post-re year four was com-
bined slope and aspect (P = 0.03). As com-
bined slope and aspect increased, shrub cover
increased.
Plant Regeneration Strategies as
Functional Traits
The presence of survivor rhizome (SR) re-
generation strategy plants, such as Ross’ sedge
and bluejoint (Calamagrostis rubescens Buck-
ley), varied similarly with time and treatment,
whether plots were salvage logged or not (Fig-
ure 4). In year one post re, low, moderate,
and high severity plots all had signicantly
lower cover of survivor rhizomes than un-
burned plots (P < 0.001); year one also had the
lowest overall cover compared to the other
years (Figure 4). Over all years on the plots
that were not salvage logged, unburned and
low severity plots had higher SR cover than
the moderate and high severity, unseeded plots
(P < 0.001) (Figure 4). On the salvage logged
plots, there was no change in SR cover over
time, and only the low severity plots had sig-
nicantly higher SR cover than the unseeded,
high severity plots (P = 0.02) (Figure 4). Sal-
vage logging did not appear to have a signi-
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 48
Figure 4. Percent canopy cover for four different regeneration strategies (survivor rhizome [SR]; off-site
colonizers [OC]; survivor taproot, caudex, or bulb [SRCB]; residual colonizers [RC]) by year, burn severi-
ty, salvage logged, and seeded with native grass. Error bars represent standard error. Capital letters next
to the years on the x-axis and next to the treatments in the legend represent signicant differences between
means by year or by treatment; legend items are ordered from highest to lowest mean value over all years.
B A AB A A
A
A
B
B
1234 61234 61234 61234 61234 6
Post-fire year
0
10
20
30
40
50
Moderate severity
Low severity
High severity
High severity, seeded
B A A A A
A
A
AB
B
B
1234 61234 61234 61234 61234 6
Post-fire year
0
10
20
30
40
50
RC cover (%)
Unburned
Low severity
High severity, seeded
Moderate severity
High severity
B A AB A A
A
A
A
A
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
High severity, seeded
High severity
Moderate severity
Low severity
B A A A A
A
A
A
A
B
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
SRCB cover (%)
High severity, seeded
Moderate severity
High severity
Low severity
Unburned
B AB A A AB
A
AB
A
A
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
A
A
A
A
A
B A A A A
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
OC cover (%)
A A A A A
A
AB
AB
B
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
Low severity
Moderate severity
High severity, seeded
High severity
B A A A A
A
A
AB
B
B
1234 61234 61234 61234 61234 6
0
10
20
30
40
50
SR cover (%)
Unburned
Low severity
High severity, seeded
Moderate severity
High severity
Salvage loggedNot salvage logged
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 49
cant effect on SR cover types (Table 3). Aver-
age tree canopy cover was the only site factor
to inuence SR cover (P = 0.01) four years af-
ter the re; SR cover was greater where tree
cover was greater.
One year post re, offsite colonizers (OC)
canopy cover was low and did not differ by
treatment; year one also had the lowest OC
cover of any post-re year (Figure 4). In years
two, three, and four post re, however, moder-
ate and high severity plots had signicantly
greater canopy cover of OC plants than did
low severity plots (P < 0.005), and in year
three post re, high severity plots also had sig-
nicantly greater cover of offsite colonizers
than unburned plots (P < 0.001). Over all
years on the plots that were not salvage
logged, moderate and high severity plots had
higher OC cover than unburned, low severity,
and high severity seeded plots. Offsite colo-
nizers cover on plots that were salvage logged
was not statistically different than plots that
were not salvage logged, except on the moder-
ate severity plots, where salvage logging de-
creased OC cover (P = 0.003) (Table 3). The
OC cover differed with year (P < 0.001) and
the interaction of year and treatment (P =
0.003), but not with treatment (P = 0.17).
High severity, unseeded plots had higher OC
cover than low severity and high severity seed-
ed plots (Figure 4). Prickly lettuce, thistles
(Cirsium spp. Mill.), and many grasses com-
monly establish as OC. The OC cover four
years after re increased with greater pre-re
tree density (P = 0.01).
Shrubs, forbs, and graminoids that resprout
from a survivor taproot, caudex, or bulb
(SRCB) increased between the rst and sixth
post-re years, regardless of burn severity or
salvage logging (Figure 4). In year one post
re, only plots classied as burned with high
severity had signicantly lower SRCB cover
than those classied as low severity (P <
0.05). In the second post-re year, we found
abundant cover of Scouler’s willow, miner’s
lettuce (Claytonia perfoliata Donn ex Willd.),
and Idaho fescue on plots burned with high se-
verity that were seeded but not salvage logged.
Also in year two post re, high severity plots
that were both salvage logged and seeded had
signicantly greater SRCB cover than un-
burned plots, whereas in year three post re,
moderate severity plots had signicantly great-
er SRCB cover than unburned plots (P <
0.05). In year four and six post re, high se-
verity plots had signicantly greater SRCB
cover when compared to low severity plots.
Over all years, SRCB cover was lower on un-
burned plots than on all other plots (P < 0.05),
and salvage logging appeared to affect SRCB
cover only on moderate severity plots (com-
pared to the not salvage-logged counterparts)
(P < 0.05) (Table 3). Four years after the re,
there were no site factors that signicantly in-
uenced SRCB cover.
Residual colonizers (RC) plants were in
low abundance (<5 %) on all treatments in all
years (Figure 4). However low, RC plant cov-
er was greater in the second through sixth
post-re years than in the rst year, regardless
of salvage logging (Figure 4). On the plots
that were not salvage logged, across all years,
unburned and low burn severity plots had
higher RC cover than moderate and high se-
verity, unseeded plots. Similarly on the sal-
vage logged plots, low and moderate burn se-
verity plots had higher RC cover than high se-
verity plots. Lower RC cover was found on
the high severity salvage logged plots, regard-
less of seeding (P = 0.008 unseeded, P <
0.001 seeded) (Table 3). Currant, snowbrush
ceanothus (Ceanothus velutinus Douglas ex
Hook.) and Ross’ sedge species were plants
with this regeneration strategy and were found
on many plots. By the fourth post-re year,
RC increased with increasing elevation (P =
0.04), and combined slope and aspect (P =
0.02).
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 50
DISCUSSION
Burn Severity Inuenced
Vegetation Response
Vegetation cover generally increased
steadily after the re, as we expected, with
most differences occurring between plots clas-
sied as high severity burns and those plots
burned with either low or moderate severity
(Figures 2, 3, and 4). Vegetation cover, spe-
cies richness, and diversity were lower on high
severity plots than on plots burned with mod-
erate and low severity both immediately post
re and for the following six years. Lentile et
al. (2007) and MacDonald (2007) found no
signicant differences in species richness with
burn severity one year after western US wild-
res, whereas we found signicantly lower
species richness and diversity on the high se-
verity plots throughout the study period. Abel-
la and Fornwalt (2015) found that species rich-
ness increased immediately after burning, es-
pecially on sites burned with high severity, as
plants present pre-re increased in abundance
and additional plants established. Further,
they found, as we did, that differences persist-
ed, although they became less pronounced be-
tween areas burned with different burn severi-
ty. Morgan and Neuenschwander (1988) and
Lentile et al. (2007) found differences in spe-
cies cover with burn severity. In areas burned
with low and moderate severity, plants quickly
established in abundance post re by resprout-
ing, from seeds in the seedbank, or from near-
by surviving vegetation (Ryan and Noste
1985). Plots burned with high severity have
gaps for plants to establish within, but may
have fewer available nutrients, favorable soil
properties, and resources for plant coloniza-
tion. The lack of overstory vegetation com-
bined with a dark ground surface with high al-
bedo can increase plant exposure to high tem-
peratures that cause can cause heat stress.
Further, patches of high burn severity often
have a greater distance to seed sources from
unburned edges, harsher growing conditions,
and time lag in regeneration (Lyon and Stick-
ney 1976; Turner et al. 1997, 1999, 2003;
Hunter et al. 2006).
Lentile et al. (2007) found, as we did, that
understory plant species abundance was highly
variable, especially in low severity burns com-
pared to areas burned with high severity with-
in the same re. Likely this reects the ne-
grained spatial variability of re effects on the
forest oor within low and moderate severity
burns (Hudak et al. 2007), which creates a va-
riety of microsites for plant survival and post-
re establishment. Differences in site condi-
tions also contributed to multiple regeneration
strategies, likely reecting both differences in
site productivity and environmental condi-
tions, and pre-re vegetation composition—al-
though we do not know the composition of
vegetation prior to the re for our plots.
Native Grass Seeding Altered
Post-Fire Vegetation Response
Somewhat surprisingly, plots burned with
high severity that were not seeded did not have
signicantly greater species richness and di-
versity than high severity burned plots that
were seeded. Others have reported decreased
native species richness and diversity due to the
success of seeded grass species (Taskey et al.
1989, Sexton 1998). On our plots seeded with
native grass, the graminoid cover was dense in
the rst growing season (up to 80 % canopy
cover), likely due to favorable rainfall (Robi-
chaud et al. 2013). Nonetheless, other plant
species were able to establish and persist, al-
though with lower percent cover than on plots
without grass seeding. Hunter and Omi (2006)
found that both post-re canopy cover and
species richness of native plants were lower
where seeded grass cover was high in Arizona,
USA. Our results were similar, with less spe-
cies richness and lower forb and shrub cover
on the high burn severity seeded plots.
Native grass seeding following six large
wildres in Mesa Verde National Park, Colo-
rado, USA, resulted in plant species richness
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 51
and diversity ndings similar to ours (Floyd et
al. 2006). Seeded plots in that study produced
greater diversity and richness than unseeded
counterparts, although the plots in Mesa Verde
had much lower total vegetation cover than
our plots, likely due to drier conditions. We
found few non-native species, even in plots
that were seeded after re with grass. Others
found non-native species were introduced
through seeding (Hunter and Omi 2006, Hunt-
er et al. 2006).
Beyers (2004) and Peppin et al. (2010)
concluded from their reviews of multiple re-
search and monitoring projects that seeding re-
duced abundance of post-re native vegeta-
tion. For example, Stella et al. (2010) docu-
mented less abundant forbs for more than a
year post re on plots seeded with a mix of
native and non-native grasses. Schoennagel
and Waller (1999) found reduced abundance
of native plants when frequency and cover of
seeded non-native plant species were high. In
contrast, Hunter and Omi (2006) found that
vegetation cover did not differ for plots burned
with high and low severity four years after the
Cerro Grande Fire in New Mexico, USA.
Peppin et al. (2010) suggested that burn sever-
ity, the species seeded, and the success of
seeding inuenced whether seeding altered
post-re vegetation response.
We saw a peak in graminoid cover in the
second post-re year, followed by a slight de-
cline and then a gradual increase through the
remainder of the study period (Figures 2, 3,
and 4), even though post-re precipitation was
above average. Peppin et al. (2010) attributed
this common post-re pattern to the successful
establishment of species seeded that then de-
clined in abundance by the fourth year post
re, but on our seeded plots neither total spe-
cies richness nor graminoid cover declined.
Salvage Logging Altered
Vegetation Response
Salvage logging signicantly altered spe-
cies richness, diversity, and understory plant
cover one to six years post re. Plots that were
salvage logged generally had less total vegeta-
tive cover of shrubs and forbs than plots of
similar burn severity that were not salvage
logged, but also had a higher percent cover of
graminoids in each year. However, vegetation
response differences due to burn severity were
more pronounced than differences due to sal-
vage logging (Figure 3).
Salvage logging inuenced vegetation re-
sponse perhaps because salvage logging in-
creased bare mineral soil exposure from an av-
erage of 43 % exposed soil after the re (but
before salvage logging) to an average of 73 %
exposed soil in year four post re on plots that
were salvage logged (Lewis et al. 2012). Fur-
ther, salvage logged plots burned with low se-
verity had less bare soil (54 %) than those that
had burned with moderate and high severity
(65 % and 74 %, respectively; Lewis et al.
2012). While nearly 75 % exposed soil is high,
the soil disturbance was largely restricted to
the individual salvage units and was not wide-
spread. In general, the salvage logging done
on the national forest after the School Fire was
low impact by design. Salvage logging that
reduces overstory tree canopy cover and stand-
ing snags result in altered light penetration,
gaps, and microsite conditions on the forest
oor (Ricklefs 1977, Gray and Spies 1997)
that could increase understory vegetation
abundance. Keyser et al. (2009) found that
understory plant communities on salvage
logged plots reached pre-re percent canopy
cover in as little as ve years, with no addi-
tional invasive species.
Salvage logged high severity burn plots
had the lowest species richness and diversity
of all plots, especially when they were seeded
with native grasses. Salvage logging can shift
vegetation structure to favor graminoid species
over other understory species (Sexton 1998),
likely because graminoids are highly resilient
to disturbance and often are not killed by re
due to their growth form and large proportion
of live biomass belowground (Bond and van
Wilgen 1996). The additional post-re treat-
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 52
ment of seeding with grasses in plots that were
salvage logged may likely shift vegetation
composition in favor of graminoids.
Plant Functional Traits and Pre-Fire Forest
Structure and Management
All resprouters were little affected by sal-
vage logging and seeding, and there were few
differences with burn severity. Careful assess-
ment, not just broad classications such as the
ones we used, is needed (Hooper and Vitousek
1998), especially as many plants use multiple
regeneration strategies (Lyon and Stickney
1976, Morgan and Neuenschwander 1988).
For example, we observed Scouler’s willow
growing as resprouts and apparently regenerat-
ing prolically from seed.
The pre-re plant composition is clearly
important (Halpern 1988), especially for
plants that resprout; however, we do not have
pre-re plant data. Without the pre-re data,
it is difcult to evaluate resilience dened as
the degree to which post-re vegetation re-
sembled pre-re vegetation, as was done by
Abella and Fornwalt (2015). Furthermore,
pre-re forest management would have affect-
ed forest structure at the time of the re, and
therefore burn severity as well (Graham et al.
1999, 2004; Hudak et al. 2011). Analysis by
pre-re forest density classes could prove use-
ful in similar studies in the future, although
the confounding effects of forest structure and
site make this challenging. While we found
site factors to have some effect on vegetation
cover, post-re vegetation composition
showed no consistent patterns relative to pre-
re tree density, average tree canopy cover, el-
evation, or combined slope and aspect. None
of these variables had a predominant or pre-
dictable effect on vegetation composition on
our study plots. This is likely due in part to
the unbalanced sampling design making it
more difcult to compare factors within and
across treatment classes. The numerous forest
disturbances (pre-re treatments, re at vary-
ing severity levels, salvage logging, and seed-
ing) also made it more difcult to test for sim-
ple effects, because there were so many treat-
ment classes and combinations to consider.
We would recommend future studies carefully
limit treatment classes and combinations for
more interpretable results.
Management Implications and Limitations
Understory vegetation recovered, but spe-
cies richness, diversity, and abundance were
lower on high severity burns, particularly if
those severely burned sites were also salvage
logged and seeded with native grasses. Burn
severity inuenced understory vegetation re-
sponse more than either salvage logging or
post-re seeding with locally adapted native
grasses. Differences were greatest immedi-
ately after disturbance, but less pronounced
six years post-re. Nonetheless, the initial
differences in understory vegetation could af-
fect future forest development (Abella and
Fornwalt 2015). On our plots on this re,
Droske (2012) found much lower density of
naturally established Douglas-r and grand r
tree seedlings on areas burned with high se-
verity (0 trees ha
-1
to 5166 trees ha
-1
) com-
pared to sites burned with low and moderate
burn severities (0 trees ha
-1
to 31 833 trees ha
-
1
), in part because much of the plots that
burned with high severity were far from sur-
viving trees that could provide seed. Here on
the School Fire, both salvage logging and
seeding were limited in extent, and their im-
pacts were carefully managed to minimize
detrimental effects. Such practices as using
certied weed-free seed with locally adapted
native species, and limiting the extent of soil
disturbance from salvage logging disturbance
should continue. Locally, managers still plan
to seed with native grasses after logging and
other disturbances, but with lower amounts of
seed than was used on the School Fire (D.
Groat, Umatilla National Forest, Pomeroy
Ranger Station, Pomeroy, Oregon, USA, per-
Fire Ecology Volume 11, Issue 2, 2015
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Morgan et al.: Vegetation Response to Salvage and Seeding
Page 53
sonal communication). We recommend that
managers locally and on other forests careful-
ly consider seed application locations and
rate, and highly recommend the use of native
seed when available. Minimizing the impact
and disturbance from salvage logging is also a
fundamental factor when considering short-
and long-term vegetation and soil recovery.
Vegetation here was resilient to the com-
bined effects of large re and post-re man-
agement, as was found by Abella and Fornwalt
(2015) on the Hayman Fire. Likely this is re-
lated to the relatively forgiving soils that did
not experience signicant erosion and near to
above-average precipitation in the early years
post re (Robichaud et al. 2013). Further-
more, this landscape was actively managed
through logging, thinning, and burning for de-
cades prior to the re. Local managers care-
fully conducted post-re management to limit
potentially detrimental effects.
This study has several limitations. First,
salvage logging extended over several years,
making it challenging to infer vegetation re-
sponse as a direct result of salvage logging
across the range of burn severities. Second,
despite our best efforts, the number of plots
was not balanced across burn severity, seed-
ing, or salvage logging treatments. Third, we
were unable to fulll our original intent of at-
tributing the contributions of pre-re stand
conditions (many of which resulted from prior
timber harvesting); this is important as prior
stand treatments surely inuenced burn severi-
ty and pre-re understory vegetation composi-
tion. Fourth, without comparison to other
studies, it is difcult to generalize without un-
derstanding the unique effects of the salvage
equipment and intensity applied here, site dif-
ferences, and post-burn climate. Additional
studies that help untangle the complexities as-
sociated with interacting disturbances will as-
sist in providing science-based directions for
forest managers tasked with managing post-
re landscapes.
CONCLUSIONS
Burn severity inuenced understory vege-
tation response more than post-re salvage
logging and seeding with locally adapted na-
tive grasses. Vegetation cover was lowest on
plots burned with high severity re that were
both seeded and salvage logged. Salvage log-
ging did reduce canopy cover in both forbs
and shrubs, but cover of graminoids was high-
er when salvage logged, indicating that sal-
vage logging may not affect all plant forms in
the same way. Seeding with locally sourced
native grasses allowed native forbs, shrubs,
and conifers to establish and grow but in lower
abundance when grass cover was high. Initial
differences, although pronounced, declined
with time so that vegetation richness, diversity,
and abundance of shrubs, forbs, and grasses
were all similar near the end of the study peri-
od, whether they were salvage logged or not.
Our ndings are consistent with theory and
previous ndings, suggesting that seeding and
salvage logging can hinder the recovery of un-
derstory vegetation, especially on sites that
burn at high severity. Few studies have simi-
larly monitored the post-re response of vege-
tation over half a decade, yet this early succes-
sional period shapes forest community devel-
opment and management implications for inte-
rior mixed-conifer forests.
ACKNOWLEDGEMENTS
This research was supported in part by funds provided by the US Department of Agriculture,
Forest Service, Rocky Mountain Research Station to the University of Idaho through Research
Joint Venture Agreement 08-JV-11221634-236; and also by the US Department of Agriculture,
Forest Service, and Department of Interior Joint Fire Science Program (Project 06-1-02-03), the
Fire Ecology Volume 11, Issue 2, 2015
doi: 10.4996/reecology.1102031
Morgan et al.: Vegetation Response to Salvage and Seeding
Page 54
Umatilla National Forest, and the University of Idaho. We thank C. Clifton, C. Busskohl, S. Ri-
ley, V. Erickson, M. Fujishin, and others on the Umatilla National Forest for their support of our
research efforts. We appreciate assistance with eld data collection from D. Carson, E. Berry-
man, M. Holthuijzen, J. Hulbert, G. Qualmann, S. Bunting, T. Moran, C. Bernau, and K. Kemp.
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