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



FIRE ECOLOGY OR ADAPTATIONS : 
Plant adaptations to fire:  The percentage of lodgepole pine trees
bearing serotinous cones varies considerably throughout the Rocky
Mountains, but in most stands both closed- and open-coned trees occur
[48].  This allows lodgepole pine to regenerate following both low- and
high-intensity fires.

Serotinous cones are advantageous for regeneration following
high-intensity fires because the heat opens the cones and releases the
seeds.  These cones store huge amounts of seeds.  Sometimes, 10 years of
annual seed production are stored in serotinous lodgepole pine cones,
which equals millions of seeds per acre [50].  This huge seed reserve
blankets the exposed forest floor within 3 years after fire [39].  Even
in areas where the nonserotinous habit is prevalent, such as in
Yellowstone National Park, seed released from serotinous cones can be
substantial.  Following the wildfires of 1988 in Yellowstone, estimates
of seed on the ground in burned-over lodgepole forests in the fall
ranged from 50,000 to 970,000 per acre (123,000-2,400,000/ha) [4].

Conversely, ground fires generate insufficient heat to open serotinous
cones.  Following this type of fire, seed for regeneration must come
from surviving, nonserotinous-coned trees.

Lodgepole pine produces seed at an early age.  Cones on young trees are
nonserotinous.  Thus, postfire seedlings contribute to seedfall within
about 10 years, and additional seedling establishment can occur if
seedbed conditions are favorable.

Fire regime:  Fire regimes in lodgepole-pine-dominated communities vary
greatly in the Rocky Mountains.  In areas having dry summers, low- to
medium-intensity ground fires occurred at intervals of 25 to 50 years
[5].  In areas with moist summers, however, sparse understories and slow
fuel build-up result in less frequent but more intense fires.
Stand-replacing fires in lodgepole forests of Alberta occurred at about
67-year intervals [17], while it may take over 300 years for fuels to
sustain stand-replacing crown fires in Yellowstone National Park [72].

Lotan and others [50] have described fire in many lodgepole pine stands
as an "all or nothing" proposition.  That is, fires either (1) go out
after a day or two or smolder in duff for extended periods or (2)
develop into rapidly spreading wildfires.  Smoldering fires are common
in lodgepole forests because understory fuels are sparse.  Furthermore,
fire spread to the crowns is difficult because they are elevated well
above the forest floor.  However, lodgepole pine stands become more
flammable as they age because dead woody fuels accumulate on the forest
floor.  These fuels result from past fires, insect and disease outbreaks
(especially from the mountain pine beetle), and overmaturity.  For
example, trees killed by a high-intensity fire eventually fall to the
ground creating a large fuel buildup.  Mountain pine beetle outbreaks
create ground fuels by killing trees and opening up stands to drying.
In general, the potential for high-intensity crown fires is great twice
in the life of a stand.  The first period is in young stands, when the
crowns of the growing lodgepoles are in proximity to dead woody fuels.
The second time is when overmature stands break up and are being
replaced by shade-tolerant associates.  During this period, dead fuels
accumulate as lodgepole snags fall, and young shade-tolerant conifers
provide a fuel ladder to the crowns of overstory trees.


POSTFIRE REGENERATION STRATEGY : 
   crowned-stored residual colonizer; long-viability seed in on-site cones
     (serotinous cones)
   crown-stored residual colonizer; short-viability seed in on-site cones 
     (nonserotinous cones)

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