FIRE ECOLOGY
SPECIES: Eriophorum vaginatum | Sheathed Cottonsedge 



FIRE ECOLOGY OR ADAPTATIONS : 
Fire-free intervals in sheathed cottonsedge tussock tundra are not well
documented.  Fire on the Seward Peninsula appears to be frequent (11.9
lightning fires per 2,000 sq mi [5,000 sq km] per 23 yr).  Farther
northeast in the Noatak River Valley, fire frequency appears to be 7.3
fires per 2,000 square miles per 23 years [45].

Fire is important in maintaining the long-term growth and survival of
sheathed cottonsedge.  In the absence of fire, sheathed cottonsedge
tussock-shrub tundra undergoes a series of autogenic successional
changes.  These changes involve the accumulation of peat and burial or
submergence of tussocks by dwarf shrubs, mosses, and lichens.  This
results in raised permafrost levels, reduced frost action, and
senescence of tussocks.  Frost action prevents such changes by churning
soils, incorporating organics, and preventing the buildup of dwarf
shrubs, mosses, and lichens.  Frost action is renewed when enough
organics are burned so that thaw depth reaches into mineral soils
[26,44,59].

Sheathed cottonsedge survives fire because its growing points are
insulated by tightly bunched dead and live tillers, stem sheaths, and
scales.  The elevated position of tussocks increases resistance to
ground fire [62].  Fire provides an opportunity for seedling
establishment.  Since sheathed cottonsedge has both shallowly and deeply
buried seed, some viable seed is available regardless of depth of burn
into the peat horizon [45,62].  Burned peat is an ideal seedbed.  In a
comparison of sheathed cottonsedge seedling emergence on different
substrates, burned peat showed highest rates of emergence.  The study
also showed that sheathed cottonsedge seedling emergence is greater
where fire has melted soil ice and deepened the active soil layer.
Additionally, the study showed that fire releases nutrients and enriches
tundra soils [62].


POSTFIRE REGENERATION STRATEGY : 
   Tussock graminoid
   Ground residual colonizer (on-site, initial community)
   Secondary colonizer - on-site seed

Related categories for Species: Eriophorum vaginatum | Sheathed Cottonsedge