FIRE EFFECTS
SPECIES: Alnus rugosa | Speckled Alder 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire kills the aboveground portion of the plant.  Root crowns in the
mineral soil burn only under the most severe burning conditions, but
they can be killed by the heat generated during a fire.  Severe fires
that remove the organic layer and expose and char root crowns can
completely eliminate sprouting in speckled alder [63].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Open-growing alders are generally more vulnerable to fire than
thicket-growing alders because very little understory fuel accumulates
in speckled alder thickets.  In a New York study, 71 percent of the
open-growing alder were killed compared to only 33 percent of the
thicket-growing alder (55 percent overall).  Burn intensity was not
reported [9].



PLANT RESPONSE TO FIRE : 
Following mild fires, speckled alder sprouts quickly from persistent
root crowns.  An able competitor, it can outcompete some crop-tree
species and delay or arrest succesion [11,25].  Severe fires delay alder
regeneration.  Speckled alders in the Lake States reach peak abundance
10 years after fire [47].



DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
In Minnesota, cutting and burning reduced alder cover but resulted in
substantial increases in other tall shrubs and graminoids.  Low
temperatures, high humidity, and high fuel moisture characterized less
severe burns that did not inhibit alders.  Other tall shrubs showed an
opposite trend--more severe fires favored gramanoids and tall shrubs.
Severe burns reduce alder but, because alder increases significantly
with time after cutting and burning, its reduction is temporary.
Eventually speckled alder supplements the other tall shrub growth [2].



FIRE MANAGEMENT CONSIDERATIONS : 
Information on the postfire response of speckled alder comes from
studies of crop-tree silviculture in the boreal region where speckled
alder is a common understory species.  Postfire competition by speckled
alder sprouts can inhibit crop-tree regeneration [2,32,53].

Where speckled alder is present, fire and most logging practices will
favor it over competing species [25].  Speckled alder releases quickly
after overstory removal and readily invades disturbed sites.  Fire
suppression favors the continued growth of alder and other tall shrubs
in boreal forest understories (typically fir, spruce, and cedar).
Ladder fuels form which can carry fire to overstory crowns, destroying
conifer seed production [11,53].  Bergason [9] recommends 9-year fire
intervals to keep speckled alder stands at an early succesional stage.
Longer fire intervals may encourage the expansion of alder thickets at
the expense of other forest types [16].

Mild spring and early summer fires which kill only the aerial portion of
the stem are recommended for speckled alder regeneration, although
resprouting is not as vigorous after repeated fires [8].

The timing of a prescribed burn is important when managing alder
ecosystems for wildlife.  A May burn of a speckled alder understory in
Manitoba caused the loss of an entire ruffed grouse cohort when nests
burned [20].

Related categories for Species: Alnus rugosa | Speckled Alder