FIRE EFFECTS
SPECIES: Eragrostis lehmanniana | Lehmann Lovegrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire effects on Lehmann lovegrass vary with fire severity.  Fires during
hot, dry months result in a high percentage of plants being killed,
while "cool" winter fires tend to kill very few plants.  For example, a
late June fire on the Santa Rita Experimental Range burned or charred
mature plants to within 0.13 to 0.75 inch (0.33-1.9 cm) of the root
crown, killing 98 percent of them.  This reduced the density of mature
plants per square foot from 2.67 before the fire to 0.04 1 month after
the fire [6].  Following a July wildfire in which "virtually all
aboveground vegetation was completely burned away", lovegrass (E.
lehmanniana and E. curvula) cover decreased dramatically.  One month
after this fire, lovegrass canopy cover was about 18 percent on burned
plots and 68 percent on nearby unburned plots [3].  Conversely, few
plants are killed by "cool" winter fires.  On the Tonto National Forest,
only 4.7 percent of Lehmann lovegrass plants died within 1 year of a
February fire.  Lehmann lovegrass mortality on nearby unburned areas was
1.6 percent [23].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Lehmann lovegrass generally recovers relatively quickly following fire
because of abundant seedling establishment.  For example, following a
late June fire on the Santa Rita Experimantal Range in which 98 percent
of mature Lehmann lovegrass plants were killed, large numbers of
seedlings became established following summer rains.  By September 10,
the density of these new plants was 6 times greater than the original
stand [6].

Within 1 year Lehmann lovegrass plant density usually equals or exceeds
preburn levels [20,22,23], but it may take 2 or 3 years for new stands
to reach preburn biomass [3,9].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Cox and others [9] observed that Lehmann lovegrass leaves appear within
14 days after burning whether burned in spring, summer, fall, or winter.
However, it took longer for fall-burned stands to attain preburn biomass
than stands burned at other times of the year.  This was attributed to
the killing of cold-sensitive new leaves during October and November on
fall-burned sites when night time temperatures varied between 41 and 50
degrees Fahrenheit (5 and 10 deg C).  In contrast, new leaves on sites
burned in February, June, or July remained active until night time
temperatures dropped below 41 degrees Fahrenheit (5 deg C) in
mid-December.


FIRE MANAGEMENT CONSIDERATIONS : 
Following severe fires which kill mature plants, Lehmann lovegrass
increases its dominance in mixed stands, especially when found with
grama grasses, because it establishes from seed more easily [27].

Cable [8] suggests that Lehmann lovegrass may be a useful fuel source
for shrub control in semidesert environments because it produces about
twice as much fuel as black grama (Bouteloua eriopoda).  In southern
Arizona, mortality of velvet mesquite (Prosopis velutina) larger than 2
inches (5 cm) in basal diameter, was 4 times as high when burned in
Lehmann lovegrass stands than when burned in black grama stands.

Prescribed fall burns are not recommended for Lehmann lovegrass because
fall-burned stands take longer to recover than stands burned at other
times of the year.  Fall burning also removes a grazing resource for 200
to 245 days.  It will take 2 to 3 years for Lehmann lovegrass biomass to
reach preburn levels in southern Arizona and southwestern New Mexico
[9].

Related categories for Species: Eragrostis lehmanniana | Lehmann Lovegrass