Introduction to Fire Effects

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Introduction to Fire Effects RX 310
Interrelationship Between Fire and Forest Insects
Dwight Scarbrough Forest Entomologist (Mr. Bugs)
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Presentation Topics

• Interrelationships between fire, insects and
  ecosystems.
• How fire affects Insects.
• How insects affect fire.
• Bark beetles and defoliators.
• Insects attracted to fire and smoke.

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Insects
Ecosystem
Fire
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• Insects are often overlooked when
• viewing forest ecosystems.

• Insects are a significant component of
• forest ecosystems and have co-evolved
• with them.

• Insects influence growth structure of
• forest stands the intensity frequency
• of fires occurring in them.

Thus, insects have a powerful and dynamic
role in our forest ecosystems
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• Insects kill trees.

• Sets stage for fire.

• Fire kills trees.

• Sets stage for
• insects.

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Fire

• Very complex and is affected and/or
• altered by many interrelated factors.

• Fire occurrence is a natural factor
• that affects insect population levels
• in forest ecosystems.

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Principal Effects of FIRE on Insects and Host
Plants
Beneficial One which favors or benefits an
organism. (ex. for insects,
reduction in host plant vigor reduced
resistance to attack some insects are drawn
to fire and smoke).
Adverse Those that are harmful or detrimental
to an organism (ex. for insects,
exposure to temperatures of 60C or
greater or extended cold periods
cause insect mortality).
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Direct Effects
Are the most visible and immediate effects.

• Loss of and damage to host plants.
• Loss or alteration of habitat.
• Consumption and direct damage by flames
• which can range from minor to severe and
• mortality.
• Mortality of insects.

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Indirect Effects
Are subtle and not readily apparent.

• Include both beneficial and adverse effects
• from heat and smoke.
• Affects both host plants and insects.

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Effects of HEAT on Insects

• Mortality occurs if temperatures exceed
• 60ºC (140ºF) or higher.

• Exposure to lower temperatures at different
• rates can also cause significant mortality.

• Exposure length is more important at lower
• temperatures.

(See handout 1 for summary table of Heat Smoke
Effects of Fire on Insects Diseases)
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Percent () Insect Mortality vs Exposure Time
Temp (C)
10 min
20 min
30 min
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Effects of SMOKE on Insects
Little is known about this topic, not much
research has been done.

• Some insects are attracted by smoke.
• Probably suffer some mortality.
• May experience discomfort.
• Might vacate smoky area.

(See handout 1 for summary table of Heat Smoke
Effects of Fire on Insects Diseases)
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Effects of Fire Severity Frequency on Insects

• Determines the type of post fire
• infestations that may occur.

• Can encourage insect pest spread
• and proliferation.

• Can also check insect pest spread,
• proliferation intensification.

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Low Intensity Fires

• Consume stand understory sometimes
• part of the overstory (thinning effect).

• Reduces stress in stands.

• Reduces hazard risk potential in stands.

• Can leave already infested trees in stands
• after a fire.

• Insects can spread from within a stand
• from adjacent stands after a fire.

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High Intensity Fires

• Entire stand can suffer mortality.

• Surviving trees suffer wounds/injuries
• which may predisposes them to increased
• susceptibility to insect attacks.

• Cause mortality of host trees and their
• insect pests.

• Check insect pest development, spread
• and intensification.

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Fire can kill some insect species that pupate in
the litter or near the surface of the soil.
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What are the impacts of FIRE on ground dwelling
arthropods?
Depends on the fire severity and frequency

• Total abundance and richness or diversity
• can be affected.

• Individuals, entire families and taxa could
• be significantly affected by the fire.

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In many natural forest communities there are
more than 200 species of arthropods per square
meter of soil usually in excess of 200,000
individuals.
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How do Insects affect fire?

• By influencing stand structure, composition,
• fuel complexes, and fire regimes.

• Characteristics of a developing stand (density,
• composition, age structure) are strongly
• influenced by insects which in turn directly
• affect the type of fire that may occur and
• when it may occur.

(See handout 2 for bark beetle defoliator
effects)
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Forest Type/Infestation Relationship
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Bark Beetles
Bark beetles can affect stand age, structure,
composition, fuel loads, etc.
In the Intermountain Region Vegetation Type
Insects
Douglas-fir, larch Douglas-fir beetle
Pine forests Mountain pine beetle
Ponderosa pines Western pine beetle
Engelmann spruce Spruce beetle
All pines, spruce, larch Red turpentine
beetle
(See handout 3 for bark beetles)
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By killing trees on a landscape scale bark
beetles strongly affect the way we manage our
forests.
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Douglas-fir beetle (Dendroctonus pseudotsugae)
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Eggs are laid in 8-10 vertical galleries.
Larvae bore feeding tunnels perpendicular to the
adult passage.
Adult Douglas-fir beetles bore into the tree
bole leaving tell-tale piles of bark dust.
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Douglas-fir beetle normally attacks felled,
injured or diseased trees.
Most broods overwinter as adults in the outer
bark. Mass attack occurs from mid-April to early
June.
Douglas-fir beetle mortality (as with most bark
beetles) is usually visible the year following
mass attack. Beetles commonly occur in
localized pockets, killing several trees each
year.
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Mountain pine beetle (Dendroctonus ponderosae)
Lodgepole and ponderosa pine
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Pitch tubes, a common sign of mountain pine
beetle attack, result from the trees effort to
defend itself against beetle attack.
Mountain pine beetles create J shaped
galleries in the cambial layer tightly packed
with frass. Larvae are present during the fall
and winter. Adults emerge in July.
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Mountain Pine Beetle is currently the most
destructive insect in Idaho because of the
impact it is having across the landscape
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Western pine beetle (Dendroctonus brevicomis)
Ponderosa and Coulter pine of all ages and vigor
classes that are 6 inches or larger (dbh).
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Western pine beetle initially attacks midway up
the tree. Pitch tubes, ¼ to ½ inch (6 to 13 mm)
in diameter, formed on the tree trunk around
entry holes made by attacking female beetles.
Egg galleries are winding, crisscrossing the
inner bark and on the surface of the sapwood.
Conspicuous serpentine galleries distinguish
Western pine beetle.
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Group killing of trees is common in pure, dense,
overstocked even-aged stands but also occurs
among dense clumps of pine in stagnating
mixed-conifer stands.
One million or more trees containing more than 1
billion board feet of timber may be killed each
year during an outbreak.
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Spruce beetle (Dendroctonus rufipennis)
Spruce beetle is the most significant natural
mortality agent of mature spruce. Outbreaks of
this beetle have caused extensive spruce
mortality from Alaska to Arizona and have
occurred in every forest with substantial spruce
stands.
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Woodpeckers frequently debark infested spruce in
search of beetles. The first sign of spruce
beetle infestation is reddish-brown boring dust
accumulating at the beetle's entrance holes, in
bark crevices, and on the ground around the
trunk of infested trees.
Throughout most of its range, two years are
generally required for the spruce beetle to
complete its life cycle. Adults may emerge any
time from May to October, depending on
temperature.
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Spruce beetle outbreak in Utah
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Spruce beetle outbreak in Alaska
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Red turpentine beetle (Dendroctonous valens)
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Red turpentine beetle occurs in nearly all pine
forests. Ordinarily the beetle is not
aggressive and does not become epidemic.
Red turpentine beetle attacks injured, weakened,
or dying trees, and freshly cut logs and stumps.
It often attacks leave trees after
harvest. More often red turpentine beetle
weakens trees rather than killing them.
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Defoliators
Can kill extensive stands of timber.
More characteristically, they deform and
retard tree growth.
Outbreaks occur at long intervals and affect
hundreds of thousands of acres.
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Douglas-fir tussock moth (Orgyia pseudotsugata)
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Douglas-fir tussock moth is a defoliator of
major importance in the interior Douglas-fir
and true fir forests of North America.
Douglas-fir and true firs
Outbreaks occur every 10 years and last approx.
3 years.
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Douglas-fir tussock moth life stages
Eggs September - May
Larvae June - August
Adult July - September
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Western spruce budworm (Choristoneura
fumiferana)
Feed on current year buds.
Outbreaks are cyclic, occurring Every 15-20
years.
Douglas-fir and true firs.
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Outbreaks cause
- Growth loss
- Tree deformity
- Topkill

• Mortality commonly
• occurs in the
• understory

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Eggs are laid in July and August. Hatch in about
10 days. Larvae do not feed but
overwinter. Tunnel into swelling buds in
spring. Feed on new foliage as it develops.
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Balsam woolly adelgid (Adelges piceae)
(Ratzeburg)
Serious pest of grand fir, alpine fir and Fraser
fir
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Balsam woolly adelgid
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Persistent crown infestation results in visible
thinning of the foliage,top-killing, broken tops
and eventual death of the tree.
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Interaction of Management Practices for Fire,
Insects, Diseases
Monitoring Techniques to Evaluate Insect
Disease Populations
(See Handout 4 for this information)
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Insects Attracted to Fire or Smoke
Nearly 40 species of insects are attracted to
fire or smoke.

• Roundheaded wood borers
• Flatheaded wood borers
• Wood wasps
• Ichneumonid wasps
• Bark beetles, usually post fire

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Ichneumonid Wasps Parasitic insects of other
forest insects
Also know in fire jargon as
Stump F_at_S !!
(Shame on you fire folks)
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A number of wood-boring insects exploit trees
weakened by fire.
Roundheaded Wood borers or Longhorned
Beetles Family Cerambycidae
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Flatheaded or Metallic Wood Borers Family
Buprestidae
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Fire Beetles Firebugs (Melanophila sp.)
Melanophila accuminata Pp, Lpp
Melanophila consputa Pp, Lpp
Melanophila drummondi - D-f, T-firs,Sp,Hem,Larch
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Wood Wasps or Horntails Family Siricidae
Tremex columba

• In Western North America
• there are 12 species
• in 4 genera.
• Sirex
• Tremex
• Urocerus
• Xeris

Urocerus gigas
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Venomous Snakes vs. Venomous Insects

• Each year in the U.S., about 7,000 people are
  bitten
  by venomous snakes.
  Only 14 die.

• In contrast, at least 40 people die every year
  from anaphylactic shock resulting from bee, wasp,
  and hornet stings.

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Stinging and venomous insects are always a
concern when working around fire. Smoke and
flames can incite them. Bald-faced hornets like
to nest in trees.
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Ground-dwelling yellow jackets sometimes attack
en masse without warning.
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Forest Health Protection Northern and
Intermountain Regions
http//www.fs.fed.us/r1-r4/spf/fhp/index.html
(See Handout 5 for this information)
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http//www.na.fs.fed.us/spfo/pubs/fidlpage.htm
(See Handout 5 for this information)
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Thats My Story and Im Stickin to it!!
THE END