FIRE EFFECTS
SPECIES: Cupressus arizonica | Arizona Cypress 



IMMEDIATE FIRE EFFECT ON PLANT : 
Low-intensity surface fires are lethal to Arizona cypress with stem
diameters less than 4 inches (10 cm) [47].  Larger trees are also not
very resistant to fire.  Cuyamaca cypress has thin exfoliating bark
which offers little fire protection [66].

A simulated exposure of cones to canopy fire conditions reduced
germination success but did not kill all seeds.  Cones open as the resin
melts and boils.  Rapid charring of the thick cone scales extinguishes
the flames, leaving seeds unburned (Armstrong in [66]).  Surface fires
kill all seeds in cones on the forest floor [46].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Historically, fires in Arizona cypress groves were patchy, resulting in
a mosaic of different-aged stands of uniform height and density [1].
Patchy surface fires would probably leave some seedling and sapling
stands untouched, and thus able to survive to fire-resistent heights
[39].


PLANT RESPONSE TO FIRE : 
Vogl and others [66] reported the occurrence of thickets of Cuyamaca
cypress saplings that appear to have originated after a 1950 wildfire
that killed some of the larger trees in the grove.  A small grove of
Piute cypress was reduced from three trees to one by a September
wildfire.  However, 40 seedlings were produced the following year, and
the total acreage occupied by Arizona cypress was unchanged [21].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Fire plays a necessary but delicately balanced role in cypress life
history.  Too frequent fires can destroy a grove, but elimination of
fire may lead to its extinction [1].

Moir [40] has suggested that low-intensity surface fires at up to 50- to
60-year intervals will help keep Mexican pinyon (Pinus cembroides)
thickets from developing and excluding Arizona cypress.  A fire-return
interval of more 80 years will allow fuel build-up and produce a shift
in dominance patterns from those species that are maintained by
recurrent fire.

Arizona cypress was used to sample for live fuel moisture values, and
can can be used as an indicator of fire behavior [53].  The moisture
content (measured as the weight of water to the total dry weight) for
Arizona cypress sampled in November ranged from 84 to 123 percent and
averaged 96 percent.  This is considered relatively dry and was the
lowest of sample species.  The author concluded that the potential for
crowning is great in Arizona cypress, especially when the dry branches
are low in the crown.  Arizona cypress does tend to have a "ladder-fuel"
branching habit, with many branches hanging low to the ground [53].

In the Chisos Mountains of Big Bend National Park, Texas, downed woody
fuels totalled 15.44 tons per acre (34.7 T/ha), with a litter layer
continuous enough to carry fire [12].

Related categories for Species: Cupressus arizonica | Arizona Cypress