FIRE ECOLOGY
SPECIES: Picea glauca | White Spruce 



FIRE ECOLOGY OR ADAPTATIONS : 
Plant adaptations to fire:  White spruce relies on wind-dispersed seeds
which readily germinate on fire-prepared seedbeds to colonize burned
sites.  However, it is not adapted to colonize large burns because (1)
most fires in boreal regions occur in the summer before white spruce
seeds are mature, and thus little or no seed is available for fall
dispersal, and (2) seeds in cones on surviving trees are dispersed over
relatively short distances [55,65].  Since fire-killed trees generally
do not contribute to seedfall, seed for colonizing burns must come from
nearby surviving trees.  Survivors include the occasional mature tree
which survives fire damage, trees escaping fire in small, unburned
pockets, and trees adjacent to burned areas [41].  Occasionally trees
that are severely injured by a summer fire will continue to develop and
disperse viable seed in the fall, even though the trees will die within
1 to 2 years [66].  Because seeds in trees are mature and ready for
dispersal by fall, white spruce can quickly invade areas after fall
burns, especially during good seed crop years [1].

Many researchers report that white spruce is not well adapted to
regenerate following fire because it has nonserotinous cones
[1,2,41,65].  Nearly all seed is dispersed in the fall or winter, but
cones remain on trees for 1 to 2 years after this peak dispersal period
[45].  However, in northern Saskatchewan, Archibold [3,4] found that
some seed remains in cones for up to 2 years and is an important factor
in postfire seedling establishment.  In these studies, an April wildfire
burned through a mixed spruce-hardwood stand containing 1,080 white
spruce trees per acre (2,667/ha) averaging 40 years old.  During the
first postfire year, fire-killed white spruce trees released 540,000
seeds per acre (1,338,000/ha).  During the 2nd postfire year, these dead
trees released 50,000 seeds per acre (123,500/ha), of which 70 percent
germinated in the labratory.

Fire regime:  Across its range, few white spruce stands are older than
200 years.  The oldest are floodplain white spruce stands, some of which
are older than 300 years [32].  Fire frequency in white spruce forest
types is generally between 60 and 200 years [45].  In Alaska, Foote [24]
observed that fire in white spruce forest types was less common than in
black spruce types.  She found numerous white spruce stands older than
100 years, but most black spruce stands sampled were less than 100 years
old.

White spruce stands typically have well-developed organic soil layers.
The depth to which this organic mat is consumed varies depending on the
type of fire.  Sometimes the organic mat is consumed, and mineral soil
exposed [24].


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

Related categories for Species: Picea glauca | White Spruce