FIRE EFFECTS
SPECIES: Pinus banksiana | Jack Pine 



IMMEDIATE FIRE EFFECT ON PLANT : 
Mature individuals survive low-severity fires [65].  Jack pine is
typically killed by crown fires or by moderate-severity surface fires
[37].  Alexander [7] found that double fire scars were fairly common in
jack pine, but triple fire scars were rare, suggesting that an
individual tree may survive only one or two surface fires in a lifetime.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Serotinous cones opened by the heat of fire release jack pine seeds onto
seedbeds exposed by fire.  Jack pine establishment is limited primarily
by the depth of organic matter and, therefore, progressively increases
with greater fire severity [22,77].  The dead boles of the former stand
provide partial shade during the first few years of establishment
[18].

Regeneration is typically better after summer fires than spring fires.
In the Boundary Waters Canoe Area in Minnesota, a spring fire (The
Little Sioux Fire) occurred while the forest floor was still cool and
moist from snowmelt, and only the top few centimeters of duff were
removed.  In the first postfire growing season, jack pine seedling
density on three sites ranged from 0.86 to 1.58 seedlings per square
foot (9.3-17.0/sq m).  A summer fire (The Prayer Lake Fire) exposed
mineral soil almost everywhere and also destroyed many competing plant
seeds and reproductive structures.  Seedling densities on two sites
after the summer fire was 3.04 and 6.29 seedlings per square foot (32.7
and 67.6/sq m), considerably higher than the spring fire regeneration
[58].  On a Little Sioux Fire site, seedling density decreased from 0.91
seedlings/sq ft (9.8/sq m) in the first postfire year to 0.61
seedlings/sq ft (6.6/sq m) in postfire year 2 because of competition
[14].

In a 3-year study of postfire emergence of jack pine seed sown on two
recently burned seedbed sites, jack pine seeds germinated in the first 2
years after being sown, but not the third year.  On the wetter site,
37 percent of viable seed sown emerged the first year and 18 percent
the second year.  On the drier site, 14 percent emerged the first year
and 8 percent emerged the second year.  The seedbed may be more
favorable in postfire year 2 because of shade provided by regenerating
understory species.  The authors conclude that a 1-year delayed
emergence from soil-stored seed is an important strategy for postfire
jack pine regeneration [78].

Conflicting reports in the literature of the effect ash has on jack pine
germination may result from differences in type of ash and degree of
leaching.  Ash from burned surface organic matter is chemically neither
detrimental nor advantageous to the establishment of jack pine.  Wood
ash is detrimental because of its extreme alkalinity, and hardwood ash
is a poorer substrate than softwood ash.  Leaching of the ash improves
germination rates [79].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Dense, young stands are extremely susceptible to crowning wildfire which
is hard to control.  A prescribed fire for the purpose of creating
Kirtland's Warbler habitat escaped control in 1980 at Mack Lake,
Michigan.  The fire crowned in a sapling stand, at times spread as fast
as 175 feet per minute (53 m/min), and did not slow down until it ran
out of jack pines and into hardwoods [70].

Prescribed fire is used in the jack pine type to prepare seedbeds,
reduce fire hazard, remove slash for easier planting, and/or open
serotinous cones in jack pine seed trees [55].  Slash has also been
burned in order to release seeds from cones in the slash.  This method
is ineffective, however, because if the fire is hot enough to prepare an
adequate seedbed, it destroys the cones [10,19].  Reproduction after
slash fires is often no better than on unburned clearcuts [23].

The seed tree silviculture method in conjunction with prescribed fire is
the most promising method for regenerating jack pine.  A prescribed
early summer fire serves to burn the slash, prepare a seedbed, and open
the serotinous cones in the seed trees [55].

While headfires may be more likely to open serotinous cones high in the
crowns of trees, backfires are generally recommended for use in
seed-tree systems because they move slower, may burn more humus, and are
safer [5,11].  However, in a series of prescribed fires in central
Ontario, backfires removed no more duff than headfires.  Drought
conditions were the the most important criteria in whether or not the
fire resulted in an adequate removal of humus [20].

Because of drier conditions, summer fires prepare better seedbeds than
spring fires [19,20,21].  If managers are relying on a natural seed
source, the prescribed fire should be timed early enough in the season
so that seedlings become well-established before winter [11], or late
enough so that seeds overwinter before germinating [5].  See Fire Case
Study for more information on prescribed fires in seed-tree systems.

Full-tree harvesting, in which a tree is delimbed at a landing, is
becoming a common practice.  This method leaves little slash to use as
fuel for seedbed-preparation prescribed fire.  However, if feather
mosses such as Schrebers moss are present, they will carry fire.  Spread
rates up to 164 feet per minute (50 m/min) over short distances were
observed in this fuel type, and prescribed fires have resulted in
statisically significant reductions in duff depth [56].

Dwarf-mistletoe (Arceuthobium americanum), which parasitizes jack pine
in the western part of its range, persists on dry ridges with sparse
undergrowth where fires are less severe and do not kill every tree.
Dwarf-mistletoe is eliminated if fire kills all of the trees.
Prescribed burning of logging slash and residual trees sanitizes an area
[6].  Seeds of dwarf-mistletoe are explosively discharged up to 60 feet
(18 m) from the canopy margin, so a minimum buffer of 66 feet (20 m) is
recommended between infected trees and new pine regeneration [61].

Equations were developed to predict the forest-floor moisture content
under jack pine canopies and in stand openings from the Duff Moisture
Code (DMC) and the Fine Fuel Moisture Code (FFMC) [26].  DMC and FFMC
are weather-based codes of the Canadian Forest Fire Weather Index System
[42].  The DMC and FFMC have also been calibrated to predict the
forest-floor moisture content of clearcut jack pine sites in relation to
slash distribution and by forest floor strata [25].

In one test, the Canadian Forest Fire Weather Index overestimated jack
pine wood slash moisture by a factor of 3.5 and variability by 50
percent, but was only 25 percent low on foliage moisture and 6 percent
low for its variability.  The U.S. National Fire-Danger Rating System
underestimated the wood and foliage moisture by 50 percent and
underestimated their variability by 30 percent [71].

Based on 12 experimental fires, Stocks [75] developed regression
equations for predicting the fire behavior in the mature jack pine fuel
type from the Canadian Forest Fire Weather Index System.  Frontal fire
intensity was strongly correlated with the Fire Weather Index (FWI).

Related categories for Species: Pinus banksiana | Jack Pine