FIRE EFFECTS
SPECIES: Mahonia trifoliolata | Agarito 



IMMEDIATE FIRE EFFECT ON PLANT : 
Agarito is described as "very resistant to fire" [49].  It is readily
top-killed by fire [5,49], but underground regenerative structures such
as roots often survive [49].  In south Texas chaparral, mortality is
typically greatest on the windward side of large mottes, and least on
the leeward side.  Centers of large mottes are often undamaged [11].

Few plants were root-killed by a prescribed burn conducted in Tom Green
County, Texas [49].  However, 33 percent of individual agarito plants
were killed after a fall burn in south Texas chaparral [11].  Burned
plants generally exhibit damage such as split stems and shredding bark
[11].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Agarito commonly sprouts from the roots or root crown after aboveground
vegetation is consumed by fire [5,11,19].  Lateral sprouting is most
common where the motte growth pattern existed prior to fire.  Centers of
large mottes often survive and subsequently increase in size in the
postfire community [11].  Individual plants and small mottes are
generally less likely to sprout.

Fire can cause reductions in canopy cover and relative abundance of
agarito [10,12].  A single burn reduced cover by as much as 58 percent
in south Texas chaparral [10].  Following fire, many of the sprouts were
of poor vigor and some plants produced only a single sprout.
Approximately 40 percent of the plants that eventually died produced new
sprouts during the first spring [11].  However, many sprouts died during
the summer.  Some postfire establishment from seed may occur as birds
and mammals disperse seed from adjacent unburned sites.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed fire:  On west Texas rangeland, fires tend to favor climax
grass species and, when used in combination with other methods, can help
to reduce the cover of woody colonizers such as mesquite and agarito
[10].

Fire is most effective in reducing agarito when large mottes are first
mechanically treated [11].  In southern Texas grasslands, density of
agarito was reduced by 28 percent on plots which had been roller
chopped, shredded and burned, or roller-chopped, treated with
herbicides, shredded, and burned.  Density was unchanged on plots which
had been roller-chopped and shredded but not burned [22,23].  Without
pretreatment, burns are often patchy and uneven and leave many large
mottes intact [12].  Best results can often be obtained by waiting up to
3 years after the brush is chopped or shredded and allowing grass and
forbs to grow vigorously among the drying woody fuels.  The herbaceous
growth and chopped portions of old brush tops can provide fuel for a
relatively hot fire [11,12], which is presumably more effective in
reducing agarito.  The following canopy cover of agarito was reported 1
year after a fall burn in south Texas chaparral [11]:

                  unburned          burned

control           5.6               1.1
shredded          1.2                .9
chopped            .7                .7
scalped            .3                .4

Evidence suggests that both fall and winter burns can reduce agarito.
However, winter burns tend to favor forbs, whereas fall burns often
decrease forb production and increase grass production[12].  In experiments
in south Texas chaparral, a fall fire with a winter reburn was more
effective in reducing agarito than either a single fall or winter fire
[12].  Response by season of burn was as follows on the Welder Wildlife
Refuge of Texas [12]:

            control           fall        winter      fall and winter
                        (percent composition)

            4.1               2.8         1.6         2.2

Wildlife:  Agarito is often replaced by more desirable browse species
such as honeysuckle (Lonicera spp.) and hackberry (Celtis spp.) after
fire in Texas shinoak rangeland [44].

Related categories for Species: Mahonia trifoliolata | Agarito