FIRE ECOLOGY
SPECIES: Purshia mexicana var. stansburiana | Stansbury Cliffrose 



FIRE ECOLOGY OR ADAPTATIONS : 
The sagebrush, salt desert, and creosotebush (Larrea tridentata)
shrublands in which Stansbury cliffrose occurs have historically had low
fuel loads and long periods between fires.  Prior to invasion of exotic
cheatgrass, big sagebrush (Artemisia tridentata) communities burned at
30- to 70-year intervals [99,100].  Cheatgrass invasion in big sagebrush
communities of northern Nevada and Utah has increased fuel loads and
shortened fire-free periods to an average of 5.5 years [9].  Effects of
this fire interval change on Stansbury cliffrose are not documented but
have probably been detrimental.

Intervals between fire in the other two desert shrubland types where
Stansbury cliffrose occurs are very long and have not been quantified.
Vegetation is usually sparse.  Both saltbush (Atriplex spp.) and
creosotebush communities have been characterized as "essentially
nonflammable" [37] due to the open, infrequent distribution of dominant
shrubs and paucity of herbaceous associates [28].  Rare fires may
provide bare, disturbed seedbeds where Stansbury cliffrose can establish
from seed transported on-site.

Fire plays a more visible role in the other plant communities in which
Stansbury cliffrose occurs.  Open, dry-site ponderosa and Arizona pine
types within Stansbury cliffrose's distribution historically had periods
between low-severity surface fires averaging 1 to 13 years [2].
Frequent, low-severity fires probably maintained Stansbury cliffrose as
a low, bushy understory plant.

The mountain shrub and Arizona chaparral types are dominated by
sprouting shrubs and typically experienced fire every 3 to 60 years.
When these communities do not burn within 15 to 20 years, succeeding
fires are severe and likely to consume much of the existing vegetation
[16,47,47,100].  Relatively long-return interval (40+ years), intense
fires, which kill a larger proportion of sprouting shrubs than do
shorter-interval fires [42], may have provided opportunities for
Stansbury cliffrose seedling establishment by reducing competition and
providing a bare, disturbed seedbed.

Fire autecology:  The majority of the literature indicates that
Stansbury cliffrose is usually killed by fire [11,25,35,68,73,74,89,95].
Some sources cite a variable or weak ability to sprout after fire
[61,74,100].  

Since Stansbury cliffrose is a colonizer [61], it probably establishes
from wind- and animal-dispersed seed on fire-disturbed seedbeds, but
documentation of postfire seedling establishment is lacking.


POSTFIRE REGENERATION STRATEGY : 
NO-ENTRY

Related categories for Species: Purshia mexicana var. stansburiana | Stansbury Cliffrose