FIRE EFFECTS
SPECIES: Pinus strobus | Eastern White Pine 



IMMEDIATE FIRE EFFECT ON PLANT : 
Once eastern white pine reaches 60 feet (18 m) in height and develops
rough bark on the lower bole, it tolerates low-severity fire [32,69].
Large individuals usually survive moderate-severity fires [69].  Fires
of more than moderate severity during the first 50 years may destroy the
entire stand [60].

Total scorching of foliage typically kills eastern white pine [32], but
scorching less than 50 percent is usually not lethal [35,61,66].  Two
stands, in which 96 percent of the eastern white and red pines were 9
inches (23 cm) in diameter or larger, were prescribed burned in late
spring (May 31 and June 15).  The percent crown scorch was estimated
after the fire and 1-year mortality was assessed.  There was no
mortality in trees with less than 46 percent crown scorch.  Mortality
was 50 percent in the 81 to 85 percent crown scorch class and 100
percent in trees with more than 96 percent crown scorch [35].

Many eastern white pine were crown scorched up to 50 percent in a March
prescribed fire ranging in intensity from 30 to 250 btu/s/ft (100-850
kW/m), but all buds emerged later in the spring [66].

A laboratory study in August in which eastern white pine seedlings were
exposed to different temperature regimes for 4 minutes, demonstrated
even less mortality with high percentages of needle scorch.  The
seedlings withstood up to 90 percent needle scorch with only 10 to 20
percent mortality.  The author suggests that there may be two lethal
temperatures, one that kills needles and one that kills terminal buds.
Therefore percent needle scorch may not be directly related to
mortality in eastern white pine [35].

Deep-burning ground fires may cause root injuries that are more serious
than crown injury.  Where 75 percent or more of the major surface roots
had been killed or severely damaged by fire, but only a third or less of
the crown was scorched, mortality 3 years after the fire was 100, 60,
and 40 percent for small trees (2 to 6 inches [5-15 cm] in diameter),
medium trees (7 to 11 inches [16-29 cm]), and large trees (greater than
12 inches [30 cm]), respectively.  For trees with less than 25 percent
root kill or injury and more than two-thirds of the crown scorched,
mortality for small, medium, and large trees was only 80, 46, and 14
percent, respectively [32].

Heated air at 144 degrees Fahrenheit (62 deg C) applied for 1 minute
killed 50 percent of 5-year-old eastern white pine seedlings that
averaged 16 inches (40 cm) in height, 0.2 inch (0.5 cm) butt diameter,
and less than 0.04 inch (0.1 cm) in bark thickness [24].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Eastern white pine colonizes burns if a seed source is nearby
[5,18,32,33].

A thick organic layer is an unfavorable seedbed because roots of new
seedlings desiccate before reaching mineral soil.  The higher the fire
severity, the more organic material is removed.  However, severe fire
also consumes seeds and rhizomes and thus reduces the early postfire
herbaceous cover which serves to shelter young seedlings from heat.
Initially, as the amount of postfire shelter is reduced by increasing
fire severity, eastern white pine survival decreases.  Eventually,
however, the reduction in organic matter depth is sufficient to
compensate for the lack of shelter and the survival of eastern white
pine increases.  Establishment is highest when mineral soil is exposed
[56].

Fire wounds provide entry to fungi which cause heart rot in eastern
white pine [32].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed fire is used for eastern white pine seedbed preparation.  Two
fires conducted in consecutive years are recommended before the first
partial cut of a shelterwood system.  A fire conducted after the partial
cut may be too hot because of slash and may cause mortality of the
remaining trees.  The first fire should be in the spring before the
understory leaves emerge so that the fire is hot enough to remove most
of the soil surface organic material.  A second fire after the leaves
emerge the following year helps reduce competition.  A suggested
reasonable fire intensity for preparing a seedbed and controlling
competition is 116 to 173 btu/s/ft (400-600 kW/m).  Extreme care must be
taken if prescribed burning stands younger than 80 years old [61].

Two consecutive annual fires in a 90-year-old eastern white and red pine
stand in Ontario improved the conditions necessary for pine
regeneration.  The fires were low in intensity (22 to 23 btu/s/ft [78-79
kW/m]) and did not harm the overstory.  The litter layer was consumed,
and the understory changed from one dominated by balsam fir saplings to
one dominated by herbaceous species.  However, very little eastern white
pine reproduction occurred in the first 3 postfire years [36].

The white pine cone beetle larvae spend 9 to 10 months a year in dead
cones on the forest floor.  The beetle can be controlled by a
low-severity surface fire in early spring before it emerges [66].

Related categories for Species: Pinus strobus | Eastern White Pine