FIRE EFFECTS
SPECIES: Ambrosia psilostachya | Western Ragweed 



IMMEDIATE FIRE EFFECT ON PLANT : 
Western ragweed is top-killed by fire.  Shallow rhizomes may be killed
along with seeds on aerial stems.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Season of burning, community type, and subsequent environmental
conditions determine western ragweed response to burning.  In some
studies, no significant (P>0.05) difference was found in western ragweed
postfire herbage, cover, or occurrence, despite the season burned
[4,72,79,82,92,131].

Western ragweed cover was significantly decreased by annual spring
burning in tallgrass prairies and honey mesquite communities [2,66].
However, other studies showed that western ragweed significantly
increased in cover or was more abundant on spring burned grasslands and
oak savanna [7,13,68,124].  Late spring burning decreased western
ragweed cover, and winter burning increased it [4,15,20].  The density
of western ragweed was increased by annual fall (October) burning
[16,21,106].

One year postfire, western ragweed cover was significantly less on
burned areas compared to unburned areas [19].  Prescribed burning in
juniper (Juniperus spp.) communities of Texas in late winter or early
spring increased western ragweed density 1 year postfire [100].  The
second and following years showed no further effects on western ragweed
densities [100].

After a spring (May) fire in a Kansas tallgrass prairie, western ragweed
increased significantly by year 3 in number of stems per 3.3 square feet
(1 sq m) [46].  Other tallgrass prescribed spring fires were conducted
annually and on a 4-year rotation.  Western ragweed cover was
significantly greater on the 4-year rotation compared to the annual
burning [3].  Four-year fire rotation was used to compare vegetative
response on shallow upland soils with lowland soils in tallgrass prairie
in Kansas.  Western ragweed was significantly more abundant on the
shallow upland soils after burning [54].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Western ragweed has been classified as an increaser (by 100 percent or
more) on burned plots [77].

Related categories for Species: Ambrosia psilostachya | Western Ragweed