FIRE EFFECTS
SPECIES: Gutierrezia microcephala | Threadleaf Snakeweed 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire kills or severely damages perennial snakeweeds [15,20,42,43,44].
Threadleaf snakeweed probably burns readily because it is resinous.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Threadleaf snakeweed may colonize recently burned sites from buried seed
or seed from adjacent unburned sites if moisture conditions are
favorable and grass competition is not severe.

Although information pertaining to the response of threadleaf snakeweed
to fire is lacking in the literature, the presence of threadleaf
snakeweed on unburned and burned sites has been documented.  In New
Mexico, threadleaf snakeweed had a density of 0.5 to 1.0 plant per
square meter on an arid grassland that had not experienced fire for at
least 30 years [30].  Threadleaf snakeweed was present on some burn
sites but not others in blackbrush communities in southwestern Utah.
The vegetation was examined on eight sites, each having been burned once
in the past 37 years.  Prefire species cover and frequency were not
known, and site histories differed.  Threadleaf snakeweed was not
present on sites burned 1, 2, 6, and 37 years previously.  It was
present on sites burned 12, 17, and 19.5 years previously, at absolute
covers of 0.3, 10.2, and 24.8 percent, respectively [5].  The authors
did not discuss reasons for the variable presence of threadleaf
snakeweed.  The 2-, 6-, and 12-year-old burns had been seeded with
grasses so colonization by threadleaf snakeweed may have been prevented
or delayed by grass competition.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed burning is frequently used as a management tool to increase
forage on rangelands [5].  Historically, fire played an important role
in controlling woody species [20,42].  However, prescribed burning for
control of perennial snakeweeds has met with mixed success [24,42].
Wright and Bailey [42] suggested that fire can be used to control
perennial snakeweeds during wet weather cycles when the grasses will not
be severely damaged.  The individual grass species and their ability to
recover from fire should be considered when prescribed burning for
perennial snakeweed control [42].

Prescribed burning of perennial snakeweeds is limited by inadequate fine
fuel.  In a study of a broom snakeweed-infested grassland in southeastern
New Mexico, the area burned by spring prescribed fires did not exceed 60
percent unless the fine fuel loading exceeded 534 pounds per acre and
the litter fuel exceeded 1,000 pounds per acre, or the two fuels combined
exceeded 1,500 pounds per acre.  If there is enough fuel, a headfire is
effective if the following criteria are met:  litter moisture is 3 to
4.5 percent, fine fuel moisture is less than 20 percent, relative
humidity is less than 20 percent, ambient temperature is between 75 and
90 degrees Fahrenheit (24-32 deg C), and the wind speed is 8 to 15 miles
per hour [15].

Related categories for Species: Gutierrezia microcephala | Threadleaf Snakeweed