FIRE EFFECTS
SPECIES: Medicago sativa | Alfalfa 



IMMEDIATE FIRE EFFECT ON PLANT : 
Moderately severe fires will top-kill alfalfa shoots, and severe fires
may cause damage to or kill the root crown, killing the plant [85].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Alfalfa fields that were burned to control insect pests were monitored
for soil changes and plant response.  The root systems of the plants
were not adversely affected by the fire, and subsequent crops were
similar in appearance and productivity to that of unburned control
plots.  Soil preburn conditions (organic matter and nitrogen) were
attained within 160 days [28].  Canopy coverage of alfalfa increased by
the end of the first growing season following a prescribed fire in May
but showed no significant difference from unburned controls in the
second growing season (which may be attributed to the low precipitation
that year) [85].  Mixtures of cool-season grasses and alfalfa and/or
sweetclover respond best (in productivity) to prescribed fires from
March to June.  The lowest response by alfalfa is to late summer-early
fall fires [52,65,85].

In a study of individual plant responses to a spring fire in a tallgrass
prairie stand, Pemble and others [87] found that a moderate-severity
fire resulted in a slight decrease in the amount of flowering (flowers
per plant and plants in flower) in alfalfa.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
The fire susceptibility of rangeland vegetation depends on the reduction
of fuel loads through animal use or drought which reduces standing crop
size [49].

Seeded alfalfa fields are often burned prior to growth initiation in the
spring to reduce insect pests.  This treatment results in destruction of
insect eggs and adults, and reduces debris from the previous growing
season that encourages insect population growth.  Since soil preburn
conditions are attained within 160 days of the fire, it is unlikely
that a 3-year interval between fires would be detrimental to the soil
[28].

Under current evaluation is a method of presuppression fire management
called "greenstrip management."  This involves the production of a
vegetative fuelbreak of green plants that are less flammable than the
surrounding native vegetation.  Alfalfa is the most commonly used forb
for this purpose [86].

Related categories for Species: Medicago sativa | Alfalfa