Proceedings of the 7th International Conference on Global Change: Connection to the Arctic(GCCA-7), 2nd edn. IARC, University of Alaska at Fairbanks. pp. 351-358

The effects of intensive forest fire on forest revegetation patterns in interior Alaska(mid-term report, February 2007)
TSUYUZAKI Shiro1, NARITA Kenji2 and KODAMA Yuji3
1 Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810 Japan
2 Faculty of Education and Human Studies, Akita University, Akita 010-8502 Japan
3 The Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0810, Japan

Abstract: To detect the revegetation patterns of Picea mariana forests after large-scale fire occurred in
the summer of 2004, we monitored 96 1 m × 1 m quadrats within 16 10 m × 10 m plots at Poker Flat,
interior Alaska, USA, from the spring of 2005 to the summer of 2006. To detect relationships between
fire intensity and revegetation, variously-burned sites were selected, i.e., the ground cover mostly
consisting of Sphagnum remained patchily. In six 1 m × 1 m quadrats on each plot, we recorded plant
cover on each species and marked all tree seedlings. Vegetatively-recovered shrubs and sedges were
dominant on the unburned ground surface, while Epilobium angustifolium was common on burned surface.
Of bryophytes, survived Sphagnum spp. were dominant on the unburned surface, but did not change incover from 2005 to 2006. While, Ceratodon purpureus increased in cover on the burned surface.
Therefore, the plant community structures differed greatly between unburned and burned sites.
Furthermore, the safe sites for seedling emergence varied greatly between tree species, i.e., Picea mariana
germinated more on Sphagnum mat and Betula neoalaskana and Populus tremuloides emerged only on
the burned surface. The survival of P. mariana did not differ between the burned and unburned surfaces,
while the growth was slower on the mat of Sphagnum. Broad-leaved trees grew faster than P. mariana.
The recovery of P. mariana is not plausible in the present state, and the re-establishment of Sphagnum
must be a key to promote the regeneration to P. mariana forest. The surveys on the relationships
between revegetation patterns and its related environmental factors will be continued in 2007.

Key words: forest fire; Picea mariana; plant cover; seedling emergence, growth and survival; permanent
plot; Sphagnum

Introduction
Wildfires with different intervals, intensities and scales
operate plant community structures and functions inregions where fires occur frequently, since fires alter theabove-and below-ground environments, i.e., light andnutrient (Johnson 1992; Keane et al. 2004). Wildfires
often take place in taigas, e.g., Siberia and Alaska, due
to lightning (van Cleve et al. 1986; Engelmark 1999).
Picea mariana is adapted to establish wet andnutrient-poor habitats that are distributed more in northslopes of mountains (van Cleve et al. 1986). On forest
regeneration, the initial stages are particularly important
to determine the patterns and dynamics. In Alaska,
ordinary forest fire is so-called crown fire (Bonan &Shugart 1989). ‘Crown fire’ is that the ground- surface
cover is incompletely burned. P. mariana, that issemi-serotinous tree, disperses seeds after fire after thecrown fire more than unburned periods (Bonan &Shugart 1989). In discontinuous permafrost regions,the scenarios of succession differ between north andsouth slopes, due mostly to the presence of permafrost
on the north slopes and the absence on the south slopes(van Cleve et al. 1986). Soil properties are also
different between south and north slopes in interior
Alaska (Ping et al. 2005). In general, Picea mariana
forest develops more on the north slopes, while mixed
white spruce forest establishes on the south slopes.
Since the frequency, intensity and scale of fire will351

forest that is situated in the northern part of Alaskan
boreal forest above the boundary between continuousand discontinuous permafrost zones.

Field methods
On a slope at Poker Flat, 16 10 m × 10 m plots were

Number of seeds

15

Picea mariana

10

5

0
5

H

M

L

M

L

Picea mariana
Number of seedlings

be altered by global warming (Dale et al. 2001;
Hinzman et al. 2005), fire may become larger and more
intense.
Also, fire frequency is related toseasonal-moisture variability in atmosphere (Lynch et al.
2004). As well, permafrost thaw accelerates in boreal
peatlands in the last century (Camill 2005). Therefore,
we have mentioned the effects of large-scale fire on theregeneration of Picea mariana forest on a north-faced
slope in interior Alaska. To predict the regeneration
patterns, we focus on the regeneration patterns of trees
and vegetation changes in this progressive report. The
major objectives are: 1) Detecting differences in plantcommunity recovery patterns between burned andunburned grounds, 2) Characterizing regeneration
dynamics after wildfire in a discontinuous permafrost
zone, and 3) Generalizing the revegetation patterns.
This mid-term report is situated in acomprehensive research on forest community dynamics
after large-scale fire (Team Leader, M. Fukuda, ILTS,
HU). The summary of researches in 2005 has beenpreviously reported (Tsuyuzaki & Narita 2005). Firstly,
we briefly summarize the results surveyed in 2005 in
the next section.
Then, we report our finding on
researches in 2005 and 2006, although we have to say
every study has been ongoing.

4
3
2
1
0

H
10

Betula neoalaskana

Poker Flat, approximately 50 km north of Fairbanks,interior Alaska, USA, was selected for monitoring
revegetation, because of large-scaled and intensive fire,
north slope, and high accessibility and convenience.
On climate data at Fairbanks during 1971 and 2000,
annual precipitation averages 297.4 mm, maximum
monthly mean air temperature is 23.0oC in June, and theminimum is -25.0oC in January (ACRC, 2007). The
forest fire was recorded in the summer of 2004. Basedon tree-ring analysis, we confirmed that the relationshipbetween height and age on P. mariana was positively
and linearly correlated (Tsuyuzaki & Narita 2005).
In the region, there are three types of upland taiga
forests: Picea mariana, Picea glauca, andBetula-Populus (Kielland et al. 1998). Of these forest
types, Picea mariana forest is characterized by the
predominance of Picea mariana on nutrient-poor
habitats (Bonan & Shugart 1989). Vegetation on
Poker Flat is typically categorized into the P. mariana

Number of seeds

Study area and methods
Study area

5

0

H

M
Fire intensity

L

Fig. 1. Number of seeds captured by seed traps withreference to three burned intensities, and number ofseeds germinated by the seed germination experiments.
Blue columns show the results in spring, and purple
columns show the results in summer. Mean number ofseeds per trap is shown with standard error. H =heavily-burned, M: moderate, and L = less. On P.
mariana, number of seeds captured by traps is notdifferent between three fire intensities and between
spring and summer (Tukey’s test with ANOVA). The
number of germinated seeds is different between thetwo seasons, and is not significantly different between
habitats. On B. neoalaskana, number of captured
seeds is different between the two seasons.

352

established in the spring of 2005. The burned area on
the ground surface was visually estimated in each plot.
In each plot, we measured tree height and diameter at
breast height (DBH = 1.3 m) for stems ≥ 1.3 m in height.
DBH was measured by a tape or a pair of calipers. All
dead and alive stems were measured to reconstruct
forest structure before the fire. The fallen trees with ≥1.3 m in height were included in the measurement.
Stem volume was calculated by DBH and height under
the assumption of conical-shaped stem.
In each plot, six 1 m × 1 m quadrats wererandomly set up. At every census, vegetated area wasmeasured on each quadrat. Then, cover on eachspecies was recorded separately between burned andunburned areas on each quadrat.
The voucher
specimens will be kept in the Hokkaido University
Museum (SAP). Photos were taken on each quadrat at
1.3 m above the ground surface by a fish-eye lens in thesummer of 2005, and canopy openness was measured
by the photos, using a freeware Gap Light Analyzer ver.
2.0 (Frazer et al. 1999). Albedo was measured ca 1 m
above the ground surface on each quadrat in spring andsummer, 2005, by a radiometer (MR-22, Eko
Instruments, Co. Ltd., Tokyo) that measured wavelength
between 0.3 μm and 3 μm. On each point, albedo wasmeasured twice and averaged. Duff (or moss-organic
layer) thickness was measured by a steel stake.
Two plastic seed traps were set up on each plot in
the summer of 2005. The design of trap is illustrated by

Terry’s Lab. In early May and late July 2006, seeds
were collected from the seed traps. Then, sampledseeds were performed to seed germination test in an
incubator. The conditions of seed germination were
15oC/25oC (12 hr/12 hr) with discontinuous light (12hr/12 hr) in spring and with continuous light in summer.
When annual tree seedling was observed in any
quadrats, each seedling was marked by a numbered flag
and was recorded on height, crown diameter andlocation. The long and short axes of crown were
measured, and the crown area was calculated as an oval
shape.
For the further studies, we classified into threeintensities of forest damages by the fire, i.e., less-,
moderately-, and heavily-burned areas, based on burned
area and the ratio of alive trees. Less-burned plot
(hereafter, i.e., L) is characterized by high Sphagnum
cover retaining on the ground surface and higher
survival rate on trees. Moderately-burned plot (M) is
situated between less-disturbed and heavily-disturbed
areas, i.e., most trees were dead, but plant coverremained somehow on the ground surface.
Thevariance of mean on burned area in quadrats fluctuatedgreatly, in particular, in moderately burned plots.
Heavily-burned plot (H) is completely burned by thefire, i.e., all stems were killed and more than 80%
ground surface was burned out. Based on thoseinvestigations, four, six and six plots were grouped into
categories L, M and H, respectively.

Table 1. Number of seedlings emerged in 2005 and2006, with reference to burnt and un-burnt sites. The
density (/m2) is shown in parentheses.

Statistical analysis

Picea mariana
Betula neoalaskana
Populus tremuloides
Salix spp.
Unidentified
Total

Year
2005
2006
2005
2006
2005
2006
2005
2006
2005
2006
2005
2006

HabitatBurned364 (11.2)
200 (6.2)
2 (0.0)364 (11.2)
202 (6.2)

Unburned
95 (1.5)
63 (1.0)
20 (0.3)
17 (0.3)
93 (1.5)
169 (2.7)
4 (0.1)34 (0.5)
11 (0.2)
212 (3.3)
294 (4.6)*: The burnt area is based on the area determined in
2005. The values in 2005 are corrected from theresearch in 2006.

Linear regressions were applied to observe relationships
between dependent variables (e.g., stem height) andindependent variables (e.g., DBH). The differences instem height and crown area were examined between
habitat on P. mariana, and between P. mariana andbroad-leaved tree taxa on the burned surface by ANOVA(Zar 1999). The number of seeds captured by seedtraps and the number of germinated seeds werecompared between L, M and H and between spring andsummer by Tukey’s test after ANOVA.
The determinants on albedo were examined by amultiple regression analysis with a backward procedure.
At the first step, all examined environmental factors,
incident radiation, canopy openness, burned area andplant cover on each quadrat were input to the regression.

353

Brief summary and additional remarks on
surveys in 2005
Fires in 2004 and older
In every plot, 5-54 Picea mariana stems ≥ 1.3 m
established with a 13.0 m in maximum height. Threeother tree taxa, Alnus crispa, Betula neoalaskana andSalix spp., were recorded with extremely-low frequency.
In the 16 plots, 97% of tree stems was likely to consistof Picea mariana before the fire. Owing to the 2004
fire, 81% of Picea mariana stems were burned and dead,and the total stem volume declined about 78%. The
unburned ground surface was covered mostly by
Sphagnum spp. After the fire, the unburned plant
cover ranged from 0% to 100% on the ground surface,indicating that the forest floor was patchily burned withvarious scales and thus was suitable for this study.
Sampled tree cores showed that the maximum age
was 174.
Relationship between tree height (m,independent variable x) and age (yr, dependent variabley) was explained by a linear regression (y = +0.05x +0.05, r2 = 0.78, P < 0.01). The stem-diameter growth
has a peak at 40-60 years (and probably 130-140 years)
before 2005 on a few stems, suggesting that drastic
events, such as fire, occurred around 60 years before thepresent date. Therefore, the forest regeneration before
the 2004 fire was not simultaneously, and the previous
forest fires, that were presumably categorized into
‘crown fire’, incompletely killed the established stems.

Environments and fire intensities
The altitudes on the plots ranged from 244 m to 437 m.
The slopes on all the plots faced 7.0o-43.5o from northto west. The slope gradient ranged from 4.8o to 19.0o.
Duff thickness ranged from 3 cm to 73 cm, andSurvival (%)

100
80
60
40
20
0

Picea mariana

Populus tremuloides

Betula neoalaskana
Salix spp.
Fig. 2. Survival rates on the four tree taxa on theburned (brown column) and unburned (yellow column)
surface.

was negatively correlated to burned area. The albedo
ranged from 0.7% to 19.6% in spring and from 3.9% to23.7% in summer on the quadrats. The fittest models
on the multiple regression analysis were explained by
the following equations:ysp = +0.065xsp + 2.542, (r2 = 0.762, n = 80)
ysu = +0.066xsu – 0.119xco + 17.252, (r2 =0.757, n = 80),
where ysp and ysu are albedo on each plot measured inspring and summer, respectively. xsp and xsu are total
plant cover on each plot in spring and summer,
respectively. xco is canopy openness. r2 is adjusted
correlation coefficients. The other variables were not
adopted in any cases. These results implied thatalbedo is determined mostly by total plant cover, andthe albedo can not return to the pre-fire conditions until
vegetation cover becomes higher enough to reflect
radiation.
Frozen soil layer probably developed in unburnedsites, but was not detected in burned sites (Sawada, et al.
2007). The canopy openness ranged from 57% to 95%
on the 80 quadrats. A forest unburned by the 2004 fire,of which height was comparable with the examinedburned area, showed the canopy openness was less than
54%. Even on L plots, therefore, plant cover on forest
floor decreased down to 40% by the fire. Those results
indicated that the surveyed area received fire damage
even on less-disturbed area.

Results surveyed in 2005 and 2006
Seed immigration on tree species
In total, seed traps captured 838 and 335 seeds in springand summer 2006, respectively. Of those seeds, 318
and 253 seeds were from P. mariana in spring andsummer, respectively. The other species were Betula
neoalaskana, Polygonum alaskanum, Calamagrostis
canadensis and Epilobium angustifolium.
Even though two years have passed for the last fire,
5-10 seeds per trap were still supplied on Picea mariana(Fig. 1). In spring, seed traps frequently caught Betula
neoalaskana seeds, although the seed density declined
greatly to summer. The seed germination on P.
mariana averaged 25.6% in spring and 14.6% insummer, while B. neoalaskana germinated few seeds.
Although the annual seedlings of Salix spp. wererecorded from the field, the seed traps captured only one
seed on Salix, probably because the layout was354

inadequate for willow seeds having light pappus.
Based on the results combined with seed dispersal andseedling emergence, the tree species producing
long-distance wind-dispersed seeds could immigrate
steadily even soon after the fire. In particular, P.
mariana could immigrate seeds even to heavily-burnedplots, showing that seed limitation did not restrict its
regeneration.
Interestingly, the seed germination
percentage declined from H to L via M.

Seedling emergence, survival, and growth
In 2005 and 2006, respectively, 576 and 496 seedlings
were marked (Table 1). Picea mariana was the mostcommon tree seedlings for the two years, and about 3/4
P. mariana seedlings emerged on the unburned surface.
The density was significantly higher on the unburned
surface.

1412Height (cm)

10
8
6
4
2
0
100

Crown area (cm2, log)

In contrast, on broad-leaved tree species, i.e.,
Populus tremuloides and Betula neoalaskana and Salix
spp., all seedlings established on the burned groundsurface in 2005, and most seedlings were on the burned
surface in 2006. However, there was only 1 stem ≥DBH on B. neoalaskana and no stems ≥ DBH on P.
tremuloides in the 16 10 m × 10 m plots surveyed.
This also meant that most seeds on broad-leaved trees
came from the external environments.
On P. mariana, seedling survival rate averaged
80% on the burned ground and 68% on the unburned
ground (Fig. 2), indicating that the survival did not
differ greatly between the burned and unburned surface.
Since there were no seedlings for broad-leaved tree
species on the unburned surface in 2005, seedlingsurvival on the unburned surface was not evaluated.
On the burned surface, the survival rates ofbroad-leaved trees were 50-90%. In particular, themost common broad-leaved tree, B. neoalaskana,showed 90% on survival.
Stem growth, evaluated by height and crown area,
was significantly higher on the three broad-leaved treetaxa than P. mariana (Fig. 3). On P. mariana, stem
growth was significantly slower on the unburned
surface than on the burned surface. Furthermore, stem
growth was slower on P. mariana than on any other tree
species even on the burned ground. Those indicatedthat the establishment of broad-leaved trees proceeded if
the ground was burned completely.

Plant communities in herb layer

10

1

0.1
Picea mariana

Populus tremuloides

Betula neoalaksana

Salix spp.

Fig. 3. Seedling growth of tree species from thesummer of 2005 to the summer of 2006. Brown andyellow columns indicate the growth on the burned andunburned ground surface, respectively. The height andcrown area of P. mariana are significantly different
between the burned and unburned surface at P < 0.01
(ANOVA).
The height and crown area aresignificantly different between P. mariana andbroad-leaved trees (Betula, Populus and Salix) on theburned surface.

For two years, i.e., 2005 and 2006, 42 plant taxa wererecorded from 96 quadrats. Of those, 30 taxa were
vascular plants, consisting of 4 trees, 13 shrubs, 11
herbs, and 2 ferns (Equisetum sylvaticum andLycopodium annotinum).
On trees, annual changes in cover weresynchronized with the changes in seedling density(Table 2), viz. broad-leaves trees, B. neoalaskana and P.
tremuloides, increased in cover on the burned surface,and P. mariana established on both the grounds. The
high cover on P. mariana was from juveniles survived
through the 2004 fire.
The dominant shrubs increased in cover on boththe habitats from 2005 to 2006.
By the fieldobservations and measurements, we confirmed thatmost shrubs, e.g., Ledum groenlandicum and Vaccinium

355

vitis-idaea,
came
from
legacies(vegetative
reproduction) through the latest fire even on the burned
surface. Since there were few seedlings on shrubs inthe quadrats, vegetative reproduction was the mostimportant for the regeneration of shrubs.
Herbs fluctuated in cover less than trees andshrubs on the unburned surface, and increased on theburned surface. In particular, a remarkable increase incover was observed for Epilobium angustifolium andCalamagrostis canadensis on the burned ground.
Mosses and lichens were also common. As
expected, Sphagnum spp. were predominant on the
unburned surface, while Ceratodon purpureus increased
greatly in cover on the burned surface.

Discussion
Seed immigration and seedling establishment
For tree regeneration on Poker Flat, seed immigration isunlikely to be prohibited by the fire. Picea mariana
and all the broad-leaved trees recorded in this study
usually produce a great amount of long-distance,
Table 2. Yearly changes in plant cover (/m2) on thethree leading species in each life form category (tree,
shrub, herb, and moss) on the burned and unburned
grounds from the summer of 2005 to the summer of2006. On each life form, three most frequent species
are shown. +: less than 0.1%. -: no individuals
observed.
Species

HabitatUnburned

Burned

2005

2006

2005

2006

Pieca mariana

1.6

1.6

0.1

0.1

Betula neoalaskana

-

+

+

0.8

Populus tremuloides

-

+

+

0.3

Ledum groenlandicum

8.6

11.6

1.9

2.6

Vaccinium vitis-idaea

3.9

5.4

0.3

0.5

Vaccinium uliginosum

3.9

4.6

1.4

1.8

Carex bigelowii

4.0

4.1

0.7

0.9

Calamagrostis canadensis

1.1

1.2

1.8

3.8

Epilobium angustifolium

+

+

2.8

4.7

Sphagnum spp.

79.7

79.1

0.6

1.1

Polytrichum strictum

2.7

2.5

0.7

0.9

Ceratodon purpureus

+

+

2.5

7.3

Tree

Shrub

Herb

Moss

*: Sphagnum spp. contained a few species.

wind-dispersed seeds. Furthermore, P. mariana canprovide viable seeds for several years, by producing(semi-) serotinous cones (Bonan & Shugart 1989).
The different seed germination rates between the threefire intensities seem to be reflected to the ratio of seeds
from internal habitats (by serotinous cones) and external
ones.
The intensive forest fire, that removed duff layer,
promoted the immigration of broad-leaved trees for thetwo years surveyed. Between Yukon and British
Columbia, seedling recruitment on Picea mariana ishighest in the first five years after fires, while additional
establishment is not observed after 10 years (Johnstone
et al. 2004). Seed immigration from serotinous cones
must decrease over time, while long-distance seeddispersal could persist on broad-leaved trees. Therefore,
tree regeneration patterns, in particular, on P. mariana,
should be determined for the first several years after fire.
Furthermore, the seedling survival did not differ
between P. mariana and broad-leaved trees, and thegrowth was extremely higher on broad-leaved trees thanon P. mariana. Our findings may support that fireseverity may change the successional sere of P. mariana
forests towards mixed conifer and broad-leaved forests(Johnstone & Kasichke 2005).

Environmental changes
When moss mat remains on the ground surface
after fire, soil temperature keeps low. However, thecomplete removal of moss mat should promote soil
temperature increase and/or melting permafrost(Yoshikawa et al. 2002). In fact, permafrost was notdetected in a heavily-burned site on Poker Flat (Sawada
et al. 2007). Albedo is also changed by fire, and ismostly determined by total plant cover on Poker Flat.
By MODIS satellite observation in Queensland,
Australia, changes in albedo on visible light differs
between ecosystems, such as grasslands and savannas,
before and after fire (Jin & Roy 2005). Therefore, fireseverity, in particular, on the forest floor rather than onforest crown, must be mentioned to predict regeneration.
Albedo change also derives changes in temperature andradiation on the ground surface. For example in P.
mariana forest, surface temperature increases after, due
to increase in canopy openness and decrease in albedo(Chambers et al. 2005). Those environmental factors,
such as direct solar radiation, albedo and snow-cover356

period, interact with the plant communities (Liu et al.
2005). We have to clarify the relationships between
those environmental factors and the prime determinantson the environmental changes.

Prediction of regeneration patterns
Mean annual biomass increment is higher in dry sites
than in wet sites along a chronosequence on Picea
mariana forests in Manitoba, Canada, but carbon poolsin bryophyte, understory and forest floor are less for thedry sites (Wang et al. 2003). In Picea mariana forest,
the ground surface is mostly covered by mosses,
represented by Sphagnum spp., that may explain
80-90% of the aboveground biomass (Bonan & Shugart
1989). Forest fire, in particular, on north slopes ininterior Alaska, usually occurs as crown fire and thus
moss mat is removed incompletely (Bonan & Shugart
1989). In permafrost-free areas, surface soils become
dry because infiltration is not restricted (Hinzman et al.
2005). Those suggest that the patterns of removal andrecovery of plant cover on the ground surface are
prerequisite to predict the fates of tree seedlingemergence and growth after fire.
On Poker Flat, removal of plant cover on the
ground surface by fire determines immigration patterns
on tree species. The recovery of a few shrubs andherbs were also determined by presence/absence ofSphagnum mat.
Canopy openness influences the
distribution pattern and productivity of herbaceous
plants on the forest floor (Reich et al. 2001; Whigham
2004). However, initial tree composition after fire had
little effects on understory composition in the coniferous
forests of eastern Canada, while soil burn severity
significantly affected temporal changes in understory
species (Lecomte et al. 2005). Those suggest that
forest regeneration after large-scaled fire differs fromfires that have usually occurred so far.
Based on the changes in vegetation patterns from2005 to 2006, we concluded that the regeneration of P.
mariana is not possible if the ground surface completely
lost Sphagnum layer. Instead of P. mariana, theimmigration and establishment of broad-leaved trees,that occur usually in the intermediate stages ofsuccession on south slope, were faster. The keystone
species on the north slope of interior Alaska must be
Sphagnum spp.

Future plan (in 2007)
To clarify determinants on forest development, we havea plan to monitor the following five subjects in 2007.
1) Changes in plant community structures will bemonitored in the plots and quadrats. 2) Safe sites forseedling survival and growth will be determined withreference to the effects of Sphagnum cover. 3)
Relationship between seed immigration and seedlingestablishment will be clarified. 4) Temporal changes in
canopy openness will be measured, 5) Net primary
production, mostly derived from Sphagnum spp., will be
estimated. The other measurements not describedabove will be conducted, pro re nata. We expect thatthose investigations clarify plant community-climate
interactions
withmicro-andmacro-scaled,spatio-temporal changes not only in boreal forests after
disturbances.

Acknowledgements
We thank all members of this research project and IARC,
UAF, who served us various supports, Terry Chapin andhis collaborators for useful advice and help, members of
Asahi Press, and Shuko Nishiyama for her kindness.

References
ACRC (the Alaska Climate Research Center). 2007. Climate
Data: Climatological data and information for locations across
Alaska. Division normals (Interior). http:// climate. gi. alaska.
edu/ Climate/ Normals/ interior.html
Bonan, G.B. & Shugart, H.H. 1989. Environmental factors andecological processes in boreal forests. Annual Review of
Ecology and Systematics 20: 1-28.
Camill, P. 2005. Permasfrost thaw accelerates in boreal peatlands
during late-20th century climate warming. Climatic Change
68: 135-152.
Chambers, S.D., Beringer, J., Randerson, J.T. & Chapin III, F.S.
2005. Fire effects on net radiation and energy partitioning:
contrasting responses of tundra and boreal forest ecosystems.
Journal of Geophysical Research 110: doi: 10.1029/2004JD
005299.
Dale, V.H., Joyce, L.A., McNulty, S., Neilson, R.P., Ayres, M.P.,
Flannigan, M.D., Hanson, P.J., Irland, L.C., Lugo, A.E.,
Peterson, C.J., Simberloff, D., Swanson, F.J., Stocks, B.J. &Wotton, B.M. 2001. Climate change and forest disturbances.
BioScience 51: 723-734.
Engelmark, O. 1999. Boreal forest disturbances. In: Walker, L.R.
(ed.). Ecosystems of the world 16: Ecosystems of disturbed
ground. Elsevier, Amsterdam. pp. 161-186.
Frazer, G.W., Canham, C.D. & Lertzman, K.P. 1999. Gap Light
Analyzer (GLA), version 2.0: Imaging software to extract357

canopy structure and gap light transmission from true-colour
fisheye photographs, users manual and program
documentation. Simon Fraser University, Burnaby, British
Columbia, and the Institute of Ecosystem Studies, Millbrook,
New York.
Hinzman, L.D., Bettez, N.D., Bolton, W.R., Chapin, F.S.,
Dyurgerov, M.B. Fastie, C.L., Griffith, B., Hollister, R.D.,
Hope, A., Huntington, H.P., Jensen, A.M., Jia, G.J., Jorgenson,
T., Kane, D.L., Klein, ,D.R., Kofinas, G., Lynch, A.H., Lloyd,
A.H., McGuire, A.D., Nelson, F.E., Oechel, W.C., Osterkamp,
T.E., Racine, C.H., Romanovsky, V.E., Stone, R.S., Stow, D.A.,
Sturum, M., Tweedie, C.E., Vourlitis, G.L., Walker, M.D.,
Walker, D.A., Webber, P.J., Welker, J.M., Winker, K.S. &Yoshikawa, K. 2005. Evidence and implications of recent
climate change in northern Alaska and other arctic regions.
Climatic Change 72: 251-298.
Jin, Y. & Roy, D.P. 2005. Fire-induced albedo change and its
radiative forcing at the surface in northern Australia.
Geophysical Research Letters 32: doi: 10.1029/2005GL
022822.
Johnson, E.A. 1992. Fire and vegetation dynamics: Studies fromthe North American boreal forest. Cambridge University Press,
New York.
Johnstone, J.F., Chapin III, F.S., Foote, J., Kemmett, S., Price, K.
& Viereck, L. 2004. Decadal observations of tree regeneration
following fire in boreal forest. Canadian Journal of Forest
Research 34: 267-273.
Johnstone, J.F. & Kasischke, E.S. 2005. Stand-level effects of soil
burn severity on postfire regeneration in a recently burned
black spruce forest. Canadian Journal of Forest Research 35:
2151-2163.

Reich, P.B., Peterson, W., Wedin, D.A. & Wrage, K. 2001. Fireand vegetation effects on productivity and nitrogen cycling
across a forest-grassland continuum. Ecology 82: 1703-1719.
Sawada, Y., Harada, K., Ishii, Y., Yamazaki, G., Kodama, Y.,
Narita, K., Tsuyuzaki, S. & Fukuda, M. 2007. Possible thermaland hydrological changes in permafrost and active layers after
the 2004 Boundary Fire in Poker Flat Research Range, interior
Alaska. (in this report).
Tsuyuzaki, S. & Narita, K. 2005. The effects of intensive forest
fire on revegetation in interior Alaska (mid-term report,
February 2006). IARC/JAXA Terrestrial Team Workshop February 22, 2006. Monitoring the Influence of the Large
Alaskan Forest Fires in 2004 on the Terrestrial Environment.
International Arctic Research Center. University of Alaska at
Fairbanks. pp. 93-101
van Cleve, K., Chapin III, F.S., Flanagan, P.W., Viereck, L.A. &Dyrness, C.T. 1986. Forest ecosystems in the Alaskan taiga.
Springer-Verlag, New York.
Wang, C., Bond-Lamberty, B. & Gower, S.T. 2003. Carbon
distribution of a wel-and poorly-drained black spruce fire
chronosequence. Global Change Biology 9: 1066-1079.
Whigham, D.F. 2004. Ecology of woodland herbs in temperate
deciduous forests. Annual Review of Ecology, Evolution and
Systematics 35: 583-621.
Yoshikawa, K., Bolton, W.R., Romanovsky, V.E., Fukuda, M. &Hinzman, L.D. 2002. Impacts of wildfire on the permafrost in
the boreal forests of Interior Alaska. Journal of GeophysicalResearch 107, 8148, doi:10.1029/2001JD000438.
Zar, J.H. 1999. Biostatistical analysis (4th ed.). Prentice-Hall,Englewood Cliffs, NJ.

Kielland, K., Barnett, B. & Schell, D. 1998. Intraseasonalvariation in the δ15N signature of taiga trees and shrubs.
Canadian Journal of Forest Research 28: 485-488.
Keane, R.E, Gary, G.J., Davies, I.D., Flannigan, M.D., Gardner,
R.H., Lavorel, S.L., Lenihan, J.M., Li, C, & Rupp, T.S. 2004.
A classification of landscape fire succession models: spatial
simulations of fire and vegetation dynamics. EcologicalModelling 179: 3-27.
Lecomte, N., Simard, M., Bergeron, Y., Larouche, A., Asnong, H.
& Richard, P.J.H. 2005. Effects of fire severity and initial treecomposition on understorey vegetation dynamics in a boreal
landscape inferred from chronosequence and paleoecological
data. Journal of Vegetation Science 16: 665-674.
Liu, H., Randerson, J.T., Lindfors, J. & Chapin III, F.S. 2005.
Changes in the surface energy budget after fire in boreal
ecosystems of interior Alaska: An annual perspective. Journalof Geophysical Research 110: doi 10.1029/2004JD005158.
Lynch, J.A., Hollis, J.L. & Hu, F.S. 2004. Climatic and landscapecontrols of the boreal forest fire regime: Holocene records
from Alaska. Journal of Ecology 92: 477-489.
Ping, C.L., Michaelson, G.J., Packee, E.C., Stiles, C.A., Swanson,
D.K. & Yoshikawa, K. 2005. Soil catena sequences and fire
ecology in the boreal forest of Alaska. Soil Science Society ofAmerica Journal 69: 1761-1772.

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