| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 329 May 14, 2004 | aceska@victoria.tc.ca | Victoria, B.C. |
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The terrestrial ecosystems of British Columbia experience a variety of natural disturbances which may or may not form patterns in time, space and effects. The parameters of frequency, size and intensity define the regime of each disturbance agent - which are generally wildfire, wind, insects, diseases, mass movements (landslides and snow avalanches), flooding and siltation as well as snow and ice deposition.
On a provincial basis, wildfire is the most pervasive disturbance agent. Since 1912, when records were first collected by the B.C. Forest Service, about 180 000 known wildfires have burned over 11 million hectares of forest and grassland out of total areas of 54 million and 300 000 ha, respectively. We know the most about wildfires because we have been fighting them since 1905, have kept fairly accurate statistics since 1912, and maps of burned areas since 1919. Historically, British Columbia's forest fires have ranged from small spots resulting from a single lightning strike or man-caused ignition to fires of 200 000 hectares or more. The latter usually result from multiple lightning ignitions, erratic and strong winds, and nearly continuous fuel availability. One fire, which began in June, 1950 near Fort St. John, eventually burned 1.4 million ha over a four-month period, extending into northwestern Alberta.
Of the 20 largest wildfires known to have occurred within British Columbia since 1919, nine burned exclusively in the Boreal White and Black Spruce biogeoclimatic zone and five burned primarily there but also into the zone above it, the Spruce - Willow - Birch. These 14 fires account for 1 280 700 hectares of the estimated total of 1 556 300 hectares represented by the top 20 wildfires for the province (or 83% of that area). The largest fire on record occurred in 1958 and covered 285 900 hectares, mostly in the Boreal White and Black Spruce biogeoclimatic zone. Other large fires, ranging in size from 35 800 to 68 700 hectares, occurred in the Montane Spruce, Interior Cedar - Hemlock, Engelmann Spruce - Subalpine Fir and Interior Douglas-fir biogeoclimatic zones, almost exclusively in the early 1930s.
For further information about the biogeoclimatic zones, see http://www.for.gov.bc.ca/hre/becweb/
An animation of the known fire history can be viewed on the Pacific Forestry Centre (Canadian Forest Service) website: http://www.pfc.cfs.nrcan.gc.ca/fires/disturbance/top_ten_e.html
Field studies of fire history have also shown that fire has influenced most of our grasslands and forest types. The fire history of a particular area is related to a number of environmental factors such as climate (general and drought periodicity), aspect (warm versus cool slope), elevation (related to microclimate and lightning incidence), topography (fire behaviour and burn area patterns), fuel types (fire intensity and rate of spread), and ignition probability (lightning and man).
Fire researchers seek to understand the long-term natural role of wildfires, which are categorized by type and their effects on the ecosystem. Surface fires, which burn primarily in the understorey of forests, are most common in the Ponderosa Pine and Interior Douglas-fir biogeoclimatic zones. These fires were historically frequent and consumed the woody fuels, thinned out the smaller trees and rejuvenated many of the herbs and shrubs. Crown fires, which burn through the tree canopy and are usually linked to a surface fire, are the most dramatic kind of forest fire, and can be fast-moving and difficult or impossible to control under extreme fire weather conditions. They are common in most biogeoclimatic zones but rarer in the ponderosa pine and interior Douglas-fir forests.
There are variations on these two main themes, with surface fires also occurring in lodgepole pine forests of the Interior Douglas-fir and Sub-Boreal Pine - Spruce biogeoclimatic zones. Mixed fire regimes, involving both surface and crown fires, appear to be a function of combinations of slope, aspect, forest cover, fuel loadings and how those factors influence fire behaviour. They have yet to be well- described and likely occur primarily in the Coastal Douglas-fir, Ponderosa Pine, Interior Douglas-fir, Montane Spruce, Interior Cedar - Hemlock, Sub-Boreal Pine Spruce and Sub-Boreal Spruce biogeoclimatic zones.
Most surface fire regimes are "stand maintaining" as they maintain a particular combination of species composition and stand structure. In the absence of frequent stand maintaining fires the ecosystem will change - typically trees encroach onto grasslands and open ponderosa pine and interior Douglas-fir forests become denser, especially in the understorey and midcanopy. Crown fire regimes are stand replacing disturbances. They usually initiate secondary succession to establish another vegetative community on the site, probably very similar to the one which burned (especially true for lodgepole pine and black spruce forests).
Based on current knowledge, fire return intervals show tremendous variation through the province. In very dry, interior
ecosystems, the average return cycle can be as short as 4-5
years and in very wet coastal forests, over 500 years or more.
Fire sizes are also variable but show some patterns by
biogeoclimatic zone. For sites most commonly affected by fire, a
summary of fire frequency and size data follow.
This is meant to show the spectrum of fire regimes in a general
way. It is based on available literature for British Columbia
and related ecosystems in the Pacific Northwest states. Some
sites will be primarily affected by disturbances other than fire
(e.g. windthrow and landslides) so these figures are for
fireprone sites, intended to reflect conditions over the past
2000 years and for natural wildfires only, with no persistent
human influence.
The summer of 2003 brought some serious wildfires to the
southern interior of British Columbia. While the fire season was
not especially notable for the total area burned or the number
of wildfires, they exhibited extreme behaviour not previously
seen by people with 30 or more years of firefighting experience.
Some wildfires also entered communities and destroyed many
homes.
How does the last summer's weather compare? A 450-year
precipitation record reconstructed by Emma Watson of Western
University, based on tree rings collected near Kamloops, indi-
cated that an average of 300 mm of total precipitation falls
between August of one year and July of the next. However, from
August 2002 to July 2003, Kamloops received only 240 mm of
precipitation therefore only 21 of the previous 450 intervals
were drier. The result was very easy ignition, rapid rates of
spread (aided by strong winds) and considerable consumption of
the forest floor and decayed Coarse Woody Debris. An inspection
of several of the 2003 wildfires revealed that grasses and
shrubs such as willows and birch are resprouting, trembling
aspen are suckering, and Douglas-fir and lodgepole pine seed has
dispersed on some of the burned areas.
Knowledge of the natural fire regimes has been incorporated into
resource management documents such as the Biodiversity Guidebook
and the Landscape Unit Planning Guide and used to define seral
stage distribution, harvest block and leave area patch size and
landscape patterns. Regional plans, such as the Kootenay -
Boundary Land Use Plan, contain landscape level targets for
restoring grasslands and open ponderosa pine and interior
Douglas-fir forests which have suffered from encroachment and
ingrowth due to decades of fire exclusion. Maintenance of these
restored ecosystems will be accomplished by a cycle of
prescribed burning based on the historic fire cycle (which
included lightningcaused fires and aboriginal prescribed
burning).
Further information on natural disturbances in British Columbia and related ecosystems can be found in these recent sources:
A forest fire is an ecological disturbance that suddenly and
brutally can change a vital forest to a smoking heap of coal and
ash. For most organisms such an event is often lethal, at least
for those living above-ground. But for others, new possibilities
emerge. Not many weeks pass before an unusual fungal life
awakens - that is at least what we observe. Post fire sites
commonly host a broad range of fungi that are never observed
anywhere else, and are therefore referred as post fire fungi.
They are also called phoenicoid fungi - after the mythical bird
Phoenix arising from ashes. Other nicknames are carbonicolous
fungi (fungi dependant on coal) and pyrophilous fungi (fungi
that love fire). The majority of post-fire fungi are found
within the ascomycete order Pezizales (cup-fungi). A number of
myths are connected to the post fire fungi, and the theories for
why they only fruit on burnt ground have been many and varied.
Some have assumed that the fungal spores are dormant in those
periods between fires, and that the spores are dependent on the
heat stimuli to grow and fruit. Other theories assume that these
fungi are dependant on coal and ash to fulfill their life cycle,
that they are tolerant to the chemical products released by the
burning, that they appear due to the reduced competition from
other organisms, or that they simply are adapted to the special
conditions that arise after fires, such as high pH and reduced
moisture holding capacity of the substrate. While all these
theories may be true for some of the post fire species, few of
them give complete answers to a vital question: Where are the
post fire fungi hiding and living in the period between fires?
One of most prominent and common post fire fungi in northern
boreal parts of the world is the ascomycete Geopyxis carbonaria (Alb. & Schw.: Fr.) Sacc. (for a picture see
http://www.biologi.uio.no/bot/ascomycetes/Taxa/geopyxis.html).
Just a few weeks after a forest fire the first fruit bodies of
this species appear, and after another few weeks the burnt
forest floor is covered by orange cup-shaped fruit bodies (1-4
cm in diameter). After a forest fire in Oslo (Norway) in 1992,
we observed as many as 1000 fruit bodies per square meter on the
burnt spruce forest floor the following year. The theories
listed above poorly explain the mass occurrence of Geopyxis
carbonaria after boreal forest fires, since G. carbonaria
spores are not tolerant to heat, and do no not need any heat or
pH stimuli to grow. Another aspect is that the spores can probably not survive in the humid and biologically active boreal
forest soils for several decades between each fire event.
Until recently, mycologists tended to focus on fungal fruit
bodies, which are easily observable by eye. But the fruit bodies
are only the sexual stage in a fungal life cycle. The vegetative
stage is the dominant stage, commonly belowground, more difficult to observe and recognize, and rarely noticed. However,
understanding the ecology and behavior of the post-fire fungi
requires knowledge of their vegetative life in the periods
between fires.
After the forest fire in Oslo, we observed a mass-occurrence of
Geopyxis carbonaria in the burnt spruce forest, but no fruit
bodies were seen on surrounding burnt clear cut sites although
several other species of post fire fungi were fruiting there.
This strongly indicates that G. carbonaria is closely associated to the spruce trees in the pre-fire community. We
started therefore to search below ground on the spruce roots.
Aided by molecular techniques we were able to show that mycelium
genetically identical to G. carbonaria was repeatedly isolated
from ectomycorrhizal roots of the spruce trees at depths below
detrimental heat penetration. Based on these findings we
proposed a new hypothesis for the life cycle of this fungus:
Fungal spores of G. carbonaria are probably not dormant in the
soils in the long lasting periods between forest fires. They
neither require coal nor ash to grow and fruit. Instead we
believe that G. carbonaria lives in a vegetative, asexual life
as ectomycorrhizal (root symbiotic) partner with the roots of
spruce trees (and probably with a few more coniferous species)
in the periods between forest fires. Two fungal strains isolated
from ectomycorrhiza on Picea abies (L.) Karst. were shown to
have ITS sequence genotypes identical to that of G.
carbonaria, supporting the hypothesis that G. carbonaria
forms ectomycorrhizal associations with coniferous trees. In
pure culture (in vitro) G. carbonaria also produces an anamorphic (asexual) stage very similar to Dicyma ampullifera
Boulanger. It is therefore likely that the fungus always is
present in the rhizosphere as an ectomycorrhizal partner that
can reproduce and spread asexually anytime (independent of
fires) by the asexual spore-producing Dicyma-like anamorph.
Biologists generally agree that sexual reproduction is the most
important event in an organism's life. Fungi, however, have
several options for genetic recombination and spatial dispersal
belowground, where sex is not necessarily important. The main
part of the fungal life cycle is the vegetative mycelial stage
below ground or within the tissue of a host organism. But
changes and stress are factors that can induce fungal sexual
reproduction.
Ectomycorrhizal fungi live in close symbiosis with tree roots.
In this symbiosis the fungi provide the plants with water,
minerals and micronutrients through their expanding mycelial
networks in the soil, and receive in return photosynthetic
products (carbohydrates) from the plants. During a forest fire,
fungi associated with roots at depths below detrimental heat
penetration (like G. carbonaria) will not be eliminated by the
fire directly, but will starve when the host tree dies and the
carbon transfer terminates as a result of the fire. Fungi unable
to grow alone would be expected to die in this situation. But
some ectomycorrhizal fungi have the potential to grow, at least
for a short period, independent from their host. This is also
the case for G. carbonaria.
A fire is probably a tremendous stress situation for mycorrhizal
fungi where the food resources (carbon transfer from the host
trees) disappear. The only alternative to death is dispersal,
which for a fungus most effectively is done through sexual
reproduction, followed by spore dispersal. The fire in Oslo in
1992 induced an amazing mass occurrence of the sexual stage
(fruit bodies) of G. carbonaria, possibly reflecting a massive, specialized and successful fungal escape from a dying
partner. The billions of spores shot out from the fruit bodies
and dispersed through the air presents the opportunity to reenter a vegetative, symbiotic stage as ectomycorrhizal partners
with roots of living trees until a new forest fire provokes the
next sexual escape.
Basis reference for this note:
Previous literature on post-fire fungi and ecology:
Some recent studies on the topic:
A summer 2003 fire had scorched roadsides and forest in the west
end of the Columbia River Gorge east of Cascade Locks, on the
Oregon side. The woods, usually green and lush, had been dry
with summer drought. A falling power pole started the fire.
Because of the Gorge winds, it was mostly a fast, hot fire.
After highway closure for more than a day for firefighting, the
ground lay black and ashy through the winter, the conifer and
deciduous tree trunks char-blackened. .sp In April we went what
fungi might be there. The previous spring, there'd been a carpeting of tiny pale apricotcolored cups littering the ashy
remains of a 2002 fire near the summit of the Cascades east of
Salem. Wearing our prescribed hard hats against the assumed
danger of falling dead branches, we walked among huge now-bare
boulders, the former mittens and scarves of mosspads reduced to
fine black wiry tendrils. Moving into the winter-moistened area,
we scanned the Douglas-fir needle duff. Sallie Jones had checked
earlier: "Millions of little pale cups!"
The little cups (Geopyxis sp.) were indeed a fantastic littering of warm color. Later, over her microscope and chemicals,
Judy Roger would identify the Peziza proteana Boud., a
Plicaria sp., and several "little orange critters that feast
on charcoal."
The trunks of the great Douglas- firs, Pseudotsuga menziesii,
were charred black at their bases. Touching the char, I was
surprised at the fragile softness of it: living fir bark is not
soft. Looking up, I could see that some of the firs were still
living, usually the oldest. Bare, blackened branches laced the
sky. But on the ground, light brown needles carpeted everything.
These had not died instantly. And they were creating a soft,
absorbent ground cover. Moving along, we saw sizable disc-shaped
fungi, probably the Peziza proteana, most a nearblack color,
but many of the young ones pale lavender to a deep mauve-black.
Some grew singly; others seemed to need company. Fewer of these
than of the Geopyxis, and harder to see against the dark soil.
One group of these actually fruited inside a charred pocket of a
stump, on almost no substrate.
Sallie chirped, "Morel!" and we adjusted to take in more than
cups and dishes. In an hour, just a scant six or seven burn
morels, most very young. One bug-chewed larger pale one looked
more like a "natural," but close to it grew a very young one
with different coloring. Darker.
The sword ferns (Polystichum munitum) had not survived well;
their blackened crowns spotted the area like large cones, held
to the ground by their seared root masses. A few showed green
curled fronds, but only where the fire, not so hot at these
areas, had rushed quickly along.
Then I saw it. A brown and tan mushroom, patterned rather like a
honey mushroom, Armillaria mellea Vahl (Quel.). Perhaps six
inches across, its stipe maybe four inches from the ground. But
the season was wrong for honey mushrooms. I reached down to
touch it. Robust, firm, its stipe was thicker and more solid
than expected.
I picked it, and examined the surface beneath the cap. Not
gills, but oval pores of pale creamy white, perfect patterning.
I'd never seen one of these before. Then at the base of a large,
fire-blackened maple, an older one, its cap beginning to
deteriorate around the edges. And next to it, a younger one. We
gathered to examine them. Was it an Albatrellus sp.? That was
the closest we could come. But it was fruiting in the wrong
season. Not until I came to yet another did I think to dig down
further beneath the stipe. First, two or three rootlike structures, fleshy. And more of something beneath! I began digging
downward and found a larger harder mass. And there was the
clue: a sclerotium! Was it a Tuckahoe, Poria cocos (Schw.)
Wolf?
We found a few more, still assuming them more like Albatrellus
than anything else. Eventually,we'd spotted a total of nearly a
dozen of these. Only one of us ever having seen them before;
Judy Roger, remembered finding one several years ago near
Gladstone, Oregon, in a Willamette River park Eventually we came
up with Polyporus tuberaster (Pers.:Fr.) Fr., pictured in
Arora's Mushrooms Demystified, color photo #151. So the question arose: are they a fungus that fruits only occasionally? Are
they there every year, but hidden by lush green ground-cover
plants? Or perhaps more important, was it the fire that caused
them to fruit?
Later, in a newsletter article by David Rose, I read that C.G.
Lloyd, the cranky curmudgeon of mycology, had clearly described
the differences between the Tuckahoe and the Polyporus
tuberaster. The Tuckahoe's sclerotium is quite like a potato in
texture, and is considered edible by some. But no one could
consume any part of of the P. tuberaster sclerotium, a rigid,
heavy, mass of dense mycelium threads throughout soil, rocks and
other inclusions.
The herbarium at Oregon State University, Corvallis reported
their only specimens of Polyporus tuberaster, four of them,
had been found in Douglas County, Oregon, far to the south of
the Columbia River Gorge. Had they appeared after a burn? We
don't know - yet.
The Pacific Northwest Key Council, a group of mycologists dedicated to the creation and publication of field keys to the fungi
of the Pacific Northwest, met for their 2003 spring foray at
Suttle Lake, Oregon, May 16 to 18, 2003.
Two fires occurred in this area in 2002:
This is the Suttle Lake list with some questionables left out.
The post-fire fungi (burned ground or burned wood is mentioned
in descriptions from the literature):
Other fungi seen on this foray:
Southern Africa is at present experiencing one of the worst
droughts in 40 years. Some areas, such as Pretoria in the interior of South Africa have received less than 20 % of its mean
annual summer rainfall. The region is in general a dry area with
rainfall varying from 1200 - 1500 mm per annum in the east to
less than 200 mm per annum in the west.
The drought has resulted in huge pressures on already water
stressed catchments and associated mires. Especially in areas
where groundwater resources are exploited peatlands are in
peril. The karst peatlands in the western part of South Africa
(refer to article in IMCG Newsletter issue 2001/2, June 2001)
are hit particularly hard. One of these peatlands, Bodibe, is
currently one fire. The area is located in the midst of a rural
community and the inhabitants are suffering from a overdose of
acrid peat fire smoke, a fire hazard, and a lack of grazing and
water of livestock. The fire has lead to the loss of at least
two cattle and one man has sustained severe burns when trapped
in the burning peat. Deep desiccation fissures along which the
fire spreads also poses a health and safety risk.
Peat fires are part of the eco- system dynamics of the Okavango
Delta in Botswana further towards the northwest. Ash layers
within the peatland indicate that also in this part of the
country fire is not an isolated incident. The peat fire was
probably started when the peatland vegetation was deliberately
burned to stimulate new growth for grazing.
The Working for Wetlands Programme has been requested by the
government of the North West province to render support. The
peat fire will be isolated by the digging of a trench after
which a cut-off wall will be constructed within the peat to
drown the fire with the remaining water within the peatland.
Care will be taken to allow water to migrate downstream to
maintain moisture levels in the wetland downstream of the peatfire.
Another peat fire is raging in the central part at the Rietvlei
Nature Reserve near Pretoria. This is also a karst peatland and
is one of sites that will be visited during the 2004 IMCG congress in Southern Africa (refer to 2nd Circular in IMCG Newsletter issue 2003/3, October 2003). The peat fire occurred in an
area that has been on fire before due to a lowering in regional
groundwater resources. This fire was a result of arson that
originated outside the nature reserve. The fire is currently
under control. A cut-off trench was dug around it and a feeder
channel was dug by Working for Wetlands from the main channel to
rewet this part of the wetland. Half of the water in this channel consists of controlled discharge from a sewage treatment
plant up- stream of the peatland.
Two other peat fires are burning in the higher lying
Steenkamsberg Plateau in the eastern part of the country. One is
located in the Lakenvlei mire, which is also one of the sites
that will be visited during the 2004 IMCG congress. This peat
fire was caused by a run-away veld (grassland) fire. The mire is
in a good condition and the fire did not burn very deeply into
the substrate.
The other peat fire on this plateau occurred in an area that is
afforested with exotic Pinus and Eucalyptus plantations. These
plantations have a dramatic negative impact on regional watertables. The result is that peatlands dry out and it is ironic
that it are usually management fires that result in the combustion of degraded peatlands within these plantations. Severe peat
fires occur from time to time on the eastern seabord of South
Africa where extensive plantations are found.
These fires do not only poses a health and safety risk to man
and animal, result in the destruction of peatlands, but also
pose an environmental disaster with the release of carbon gases
into the atmosphere. More than anything else it is a reflection
of a changing environment, not only on a global scale, but also
on a local level - a monument of our failures as custodians of
our environment.
As I was reading the last chapter of Forgotten Fires, which
describes the forests of California from 1500s to the early 20th
century, the worst fires in California's history were still
raging out of control. Stewart's book explains why current fires
are far more intense than those of the 1500s.
Forgotten Fires is compelling to read - it should be mandatory
reading in college for everyone whether they are in natural
resources, finance, insurance, education, transportation, urban
planning, land management, law, medicine or any other profession. Public decision makers and land managers need to read this
book to understand that the suppression of fire by control does
not result in elimination of fire. The elimination of fuel
results in the elimination of fire. Just as Aldo Leopold's Sand
County Almanac changed the way we looked at the land and Rachel
Carson's Silent Spring changed our perception of environmental
pollution, Forgotten Fires has the potential to change our
perception of landscape wild fires.
Stewart, the original manuscript author, an anthropologist by
profession, developed a deep interest in the use of fire by the
early Native Americans. Co-editors Lewis and Anderson write
three chapters of introductory material. Lewis, an
anthropologist, outlines the process of bringing the book to
publication and critiques the anthropological aspects of the
book. Anderson writes a chapter which brings the ecological
importance of the book up to date. The first chapter cowritten
by the two editors, documents the long and arduous path to
publication (well over three decades) of over 750 page long
original manuscript of which this book is the culmination. Along
the way, Stewart faced criticism from his peers and colleagues
and was marginalized as a credible anthropologist. Contrary to
this criticism, his work is extensively researched and supported
by 583 reference citations. Lewis and Anderson further add 296
citations for their 3 chapters.
The introductory chapters by Lewis and Anderson illuminate the
controversial nature of Stewart's central thesis Native
Americans were not benign inhabitants of the landscape but,
through the repeated and deliberate use of fire for 10,000 to
20,000 years, shaped the ecological communities of North America
and their climax state. Although Stewart is an anthropologist,
he repeatedly cites the work and disagrees with the conclusions
of prominent ecologists, such as Clements and Weaver, who shaped
the viewpoints of ecologists for decades to come regarding the
prevalent climax communities.
Stewart divides North America into three major groupings Eastern
Woodlands, Prairies and Plains, and the Mountain West. Each
grouping is further subdivided, in many instances down to
specific states. The description of fire history and use for
each local area proceeds from the earliest historical time
period - around 1500 to mid-1900s, when Stewart completed the
research for his paper.
Stewart also describes how different tribal groups utilized
fire. Virtually all of the Native American tribes, from the East
Coast to the West Coast, utilized fire extensively and for many
of the same reasons. Early anthropological thinking suggested
that Native Americans only used fire for cooking and warmth and
perhaps very isolated clearing around semipermanent residence
areas. Stewart's work reveals an entirely different and more
widespread, aggressive, planned and systematic use of fire.
Fires were set to clear out underbrush to allow easier travel,
make game more visible for harvest, drive game to concentrated
points for easier harvest, increase the productivity and
nutrient content of grasses as well berry and nut producing
shrub and trees, control destructive and nuisance insects,
reduce cover that would shield enemies, reduce fuel loads and
lower the intensity of fiers, and maintain grasslands by using
fire to control the spread of woodland. Contrary to the notion
held by early settlers of the "ignorant savage", Native
Americans were extraordinarily knowledgeable and sophisticated
in the purpose and use of fire for managing vegetation and
enhancing nutrients and productivity. It was only after pioneer
settlement that widespread use of fire by Native Americans was
curtailed.
The plant community successional work completed by the early
ecologists, according to Stewart's research, was not reflective
of undisturbed landscapes, but was actually a "disturbed"
landscape due to the elimination of the 10,000 to 20,000 year
cycle of deliberately set fires.
Sewart also looked at the evidence pertaining to lightning-
indiced fire frequencies and whether lightning occurred frequently enough to explain plant community climaxes. In nearly
all instances, the documented evidence of lightning frequency
was not consistent with other evidence, suggesting more frequent
fire occurrences. Also, fires occurred in some locations far
more frequently and at the times of the year when lightning
fires were not likely to occur.
As with any work of this type, there are potential points of
criticism. I have read extensively about fire history in Minnesota and disagree with Stewart's statement that when "brush
accumulates ... fires which inevitably came, were much more destructive ...." In fact the Cloquet and Hinckley [California] fires referred to were the result of vast accumulation of residual logging slash which created a catastrophe
waiting to happen. Brush growth was a minor factor.
A lesson to be learned from Forgotten Fires is that unburned
fuel, whether in California, New Mexico, Arizona, Colorado,
Montana, Wyoming, or any other location is a catastrophe waiting
to happen. Fire management, as Native Americans discovered
millennia ago, is a matter of fuel reduction, not fire suppression.
Most individuals reading this book will likely find some aspects
to take issue with, but the book's fundamental message cannot be
ignored. The use of fire by the early Native Americans had a
significant impact on the entire ecological landscape of North
America. Plant communities were in a subclimax state, maintained
in that condition by the frequent and repeated use of fire for a
variety of purposes by the Native Americans. The work of Stewart
needs to be seriously examined and significant efforts at subsequent research need to be directed at better understanding the
role of repeated fires in shaping the past and current development of the landscape.
[Note: The same issue of the Natural Areas Journal (February
2004) also brought a review of the 2002 book Flammable
Australia: The Fire Regimes and Biodiversity of a Continent
edited by Bradstock, Ross A. et al., and published by the
Cambridge University Press, NY.]
FIRE RETURN INTERVAL BY BIOGEOCLIMATIC ZONE (years)
Zone(*) Min Avg Max
BG 4-5 5-15 15-25
PP 4-5 5-15 15-25
surface fires (understorey)
rare rare rare
crown fires (overstorey)
SBS 75-100 100-150 150-250
BWBS
Sb 50-75 75-125 125-175
At Pl Sw 75-100 100-150 150-250
Pl Sw Bl 100-150 150-200 200-300
SBPS 100-125 125-175 175-250
ICH 100-150 150-250 250-350
IDF 5-10 10-20 20-50
surface fires (understorey)
100-150 150-250 250-350
surface and crown
CDF 50-100 100-300 300-400
MS 125-175 175-275 275-350
CWH 100-150 150-350 350-500
ESSF 150-200 200-300 350-500
SWB 150-200 200-350 350-500
AT 250 300-400 500-600
MH 300 350-450 550-650
Tree abbreviations for the BWBS zone data:
At Trembling aspen
Bl Subalpine fir
Pl Lodgepole pine
Sb Black spruce
Sw White spruce
FIRE SIZE BY BIOGEOCLIMATIC ZONE (ha)
Zone (*) Min Avg Max
AT .1-5 5-50 50-150
BG .1-5 5-50 50-150
PP .1-5 5-50 50-150
surface fires (understorey)
.1-5 5 5-50
crown fires (overstorey) CDF
.1-5 5-50 150-500
MH .1-5 50-150 150-500
CWH .1-5 50-500 > 500
SBPS .1-5 50-500 > 1000
IDF .1-5 5-50 50
surface fires (understorey)
.1-5 50-500 > 5000
surface and crown
MS .1-5 50-500 > 5000
ESSF .1-5 50-500 10,000
SBS .1-5 50-500 15,000
ICH .1-5 150-500 > 25,000
SWB .1-5 150-2,000 > 5,000
BWBS .1-5 3000-10,000 200,000
(*) Zones:
AT: Alpine Tundra, BG: Bunchgrass, BWBS: Boreal White and
Black Spruce, CDF: Coastal Douglas-fir, CWH: Coastal Western
Hemlock, ESSF: Englemann Spruce - Subalpine Fir, ICH: Inte-
rior Cedar - Hemlock, IDF: Interior Douglas-fir, MH: Mountain
Hemlock, MS: Montane Spruce, PP: Ponderosa Pine, SBPS: Sub-
Boreal Pine - Spruce, SBS: Sub-Boreal Spruce, SWB: Spruce -
Willow - Birch.
SEXUAL ESCAPE AFTER FIRES
From: T. Vrålstad, Department of Biology, University of Oslo, Norway [trudevr@ulrik.uio.no]
FIRE-FUNGI IN THE COLUMBIA RIVER GORGE, SPRING 2004
From: Maggie Rogers [Rogersmm@aol.com]
POST-FIRE FUNGI: SUTTLE LAKE FORAY, OREGON - MAY 16-18, 2003
From: Ian Gibson [ig@islandnet.com]
SOUTH AFRICA - PEATLANDS ON FIRE
From: Piet-Louis Grundling [peatland@mweb.co.za] originally published in International Mire Conservation Group Newsletter, 2004/1: 21 in March 2004 see also http://www.imcg.net/ [posted in BEN with permission]
BOOK REVIEW: USE OF FIRE BY NATIVE AMERICANS
From: Franklin J. Svoboda [franks@gpsinnovations.com] originally published in the Natural Areas Journal 24(1): 72-73. [Posted in BEN with permission]
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