FIRE ECOLOGY
SPECIES: Pseudotsuga menziesii var. menziesii | Coast Douglas-Fir 



FIRE ECOLOGY OR ADAPTATIONS : 
Plant adaptations to fire:  Coast Douglas-fir is more fire resistant
than many of its associates and can survive moderately intense fires.
Thick, corky bark on the lower bole and roots protects the cambium from
heat damage.  In addition, the tall trees have their foliage
concentrated on the upper bole, which makes it difficult for fire to
reach the crown [58]; however, it should be noted that trees are
typically not free of lower branches up to a height of 33 feet (10 m)
until they are more than 100 years old [31].  Moderately severe
understory burns in 50- to 60-year-old mixed and pure stands near Mount
Rainier caused little cambial injury to Douglas-fir but killed most of
the thin-barked western redcedar [68].  Following the Hoh Fire in
Olympic National Park, Douglas-fir's survival rate was considerably
higher than Sitka spruce (Picea sitchensis), western redcedar, western
hemlock, and bigleaf maple (Acer macrophyllum) [3].

When trees are killed, Douglas-fir relies on wind-dispersed seed
off-site trees to colonize the burned area.  If catastrophic fires are
extensive, a seed source may be limited due to the lack of seed trees.
Under these circumstances, seeds come from mature trees which survive
fire, survivors in small unburned pockets, or from trees adjacent to the
burned area.  Where seed trees are scarce, it may take 100 years or more
for Douglas-fir to restock the burned area [65].  On the other extreme,
when fires do not kill all the trees in a stand, seedling establishment
may begin within a year or two after burning [34].  Mineral soils
exposed by fire are generally considered favorable seedbeds [17].

Fire regime:  Widely distributed as a canopy dominant in lower and
middle elevation forests throughout the Pacific Northwest, Douglas-fir
occupies forests with varied fire regimes.  In general, the size and
severity of natural fires tend to decrease, while fire frequency
increases southward from western Washington to northern California [58].
In western Washington, Douglas-fir is a primary component of moist
forests experiencing infrequent, widespread, stand-replacing fires that
occur at perhaps 400- to 500-year intervals [27,45].  Dry areas of the
western hemlock zone in the central Oregon Cascades experience both
frequent, low- to moderate-severity fires and stand-replacing fires
[58].  The mean fire interval in these forests is between 50 and 150
years [45,51].  Frequent, low- to moderate-severity fires occasionally
crown and create patches of even-aged stands.  Underburning is more
common and allows Douglas-fir to survive repeated fires.  Thus
uneven-aged old-growth Douglas-fir stands are more common in the central
Oregon Cascades [58,66].  In mixed evergreen forests of southern Oregon
and northern California, fires occurred at frequencies of 5 to 25 years
[45].  Where Douglas-fir is seral, its great longevity allows it to
maintain itself as a canopy dominant until the next catastrophic fire
[34].


POSTFIRE REGENERATION STRATEGY : 
   off-site colonizer; seed carried by wind; postfire years 1 and 2
   secondary colonizer; off-site seed carried to site after year 2

Related categories for Species: Pseudotsuga menziesii var. menziesii | Coast Douglas-Fir