FIRE EFFECTS
SPECIES: Pinus contorta var. latifolia | Rocky Mountain Lodgepole Pine 



IMMEDIATE FIRE EFFECT ON PLANT : 
Plant:  Lodgepole pine is more damaged by ground fires than thicker
barked species such as ponderosa pine or Douglas-fir are.  Because its
thin bark has poor insulating properties, many trees are killed from
ground fires as a result of cambial heating [65].  However, some trees
survive, and in general, low-intensity ground fires thin lodgepole pine
stands [50].  In northwestern Wyoming, Loope and Gruell [47] observed
numerous individuals in open lodgepole pine stands with two or three
fire scars.

Seed:  Seeds are well protected from heat inside sealed cones.  However,
the seeds can be destroyed by intense crown fires that ignite the cones
[4,8].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Although lodgepole pine trees are killed by all but light ground fires,
postfire recovery tends to be rapid as new stands quickly establish from
seed released by serotinous cones.  Seedling growth in fire-generated
stands is influenced by stocking rates.  In overstocked stands, trees
may not grow more than 4 feet tall in several decades, but in
understocked stands lodgepole pine grows fast.  On burned and unburned
clearcuts in western Montana, 9- to 11-year-old lodgepole pine seedlings
averaged 6.6 feet (2 m) in height, and were considerably taller than the
same-aged western larch (Larix occidentalis), Douglas-fir, Engelmann
spruce, and subalpine fir [77].  Twelve years after the Sleeping Child
Burn in western Montana, 30 percent of lodgepole seedlings were over 18
inches (45 cm) tall.  Here, seedling density was 17,700 per acre
(43,700/ha) [54].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Lodgepole pine seedling establishment following fire is influenced by
many factors, including prefire overstory density, competing vegetation,
and probably most important, fire intensity, which in turn affects
seedbed condition, opening of serotinous cones, and seed survival.  

High-intensity fires: High-intensity fires generally expose much mineral
soil and open serotinous cones [50].  Thus much seed is released onto
favorable seedbeds resulting in abundant seedling establishment.  An
example is the Sleeping Child Burn in western Montana, in which 28,000
acres (11,000 ha) of predominantly lodgepole forest was destroyed by a
high-intensity lightning-caused wildfire.  Three years after the fire,
lodgepole pine seedling density averaged 34,000 per acre (84,000/ha)
[54].  With abundant seed and favorable moisture following
high-intensity fires, stocking can be extremely high, with hundreds of
thousands of seedlings per acre [8,39].  Some stands have had as many as
300,000 lodgepole pine seedlings per acre (741,000/ha) by the first
postfire year [8].  Seedling growth in these overstocked stands
stagnates, and trees may be only 4 feet tall at age 50 to 70 years [39].

Occasionally, crown fires may be intense enough to ignite cones in the
crown.  This destroys much of the seed supply resulting in low stocking.
This occurred in central Idaho, where only 450 and 1,134 lodgepole pine
seedlings per acre (1,100 and 2,800/ha) were present 1 and 5 years,
respectively, following a high intensity wildfire in a lodgepole
pine/beargrass community [6f8].  One year following the Yellowstone
Fires of 1988, lodgepole pine seedling density was higher on
moderate-severity burns where the trees were killed but the crowns were
not consumed (1.6 to 21.9 seedlings/m2) than on sites where hot crown
fires killed the trees and consumed the needles and fine branches (0.4
to 3.1 seedlings/m2) [4].

Low-intensity fires:  Following low-intensity fires, lodgepole pine
stocking depends on the amount of mineral soil exposed.  Generally if
the duff is dry, ground fires will expose mineral soils, but if the duff
is moist, less mineral soil is exposed resulting in lowered stocking
[50].  Surface fires will not open serotinous cones in the tree crowns,
but most lodgepole stands in the Rockies have sufficient open-coned
trees to provide seed for restocking [50].


FIRE MANAGEMENT CONSIDERATIONS : 
Fire behavior of logging slash:  Fresh, cured coniferous logging slash
is generally very flammable because of its characteristic loose
arrangement and high percentage of needles and twigs.  Flammability
decreases with time as needles drop to the forest floor and as a result
of compaction by winter snow, but it may take more than 2 years for
lodgepole pine to lose most of its needles.  Fresh and 1-year-old
lodgepole pine slash can burn very hot.  Rate of fire spread during
experimental burns with fresh and 1-year-old lodgepole pine logging
slash was as follows [22]:

                 20 tons of slash/acre       32.5 tons of slash/acre

                 relative      rate of       relative       rate of
                 humidity      spread        humidity       spread
                   (%)       (sec./foot)       (%)        (sec./foot) 

fresh slash       84-88         48.5          52-64          17.5
1-year-old slash  73-92         88.8          54-93          33.5

Tree mortality:  Published models can be used to predict fire-caused
mortality of lodgepole pine [64,65,74].  Crown scorch and bole damage
are the most important variables for determining mortality/survival.  

Lodgepole pine girdled by ground fires, but with no crown scorching, may
appear healthy for a couple of years after fire even though they are
essentially dead.  This is because it often takes more than 2 years for
these trees to lose their needles [2].  

Susceptibility of injured trees to insects and disease:  Trees injured by
fire are susceptible to attack by insects.  Two years after wildfires in
Yellowstone National Park, 44 percent of living but scorched lodgepole
pines were infested by insects, primarily the pine engraver.  Most
commonly, trees infested were those with greater than 80 percent basal
girdling.  Mountain pine beetles, however, were not strongly attracted
to fire-scarred trees [2].

Lodgepole pines that survive ground fires are susceptible to attack in
later years by decay fungi that enter through basal wounds.  In an
85-year-old stand in Alberta, 46 percent of trees with basal scars that
resulted from a fire 33 years before sampling had decay fungi in the scars.
Of these trees, about half were infected with red stain fungi [62].  

Snagfall following fire-kill:  Fire-killed lodgepole pine trees begin to
fall 2 to 5 years after dying and most trees will be down in about 15
years [50].  Following the Sleeping Child Burn in western Montana, few 3-
to 8-inch-diameter (7.5-20 cm) snags fell during the first 2 years after
the fire.  After 2 years they fell at an annual rate of 8.4 percent
until postfire year 15 when about 30 percent remained [53].  

Related categories for Species: Pinus contorta var. latifolia | Rocky Mountain Lodgepole Pine