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S9me Questions about Fire Ecology
In Southwestern Canyon Woodlands 1
William H. Moir
other factors of microsuccession are more critical·
for determining vegetation composition. To understand the role of fire in canyon woodlands we need
information on the autecology and fire tolerances
of the many dominant species that comprise the
vegetation.
Southwestern canyon woodlands, for purposes
of this paper, are vegetation types along canyon
bottoms for mostly third and fourth order drainages
whose streams may be permanent or intermittent.
These include habitat types within blue spruce,
white fir, ponderosa pine, narrowleaf cottonwood,
Arizona cypress, and evergreen oak series (Layser
and Schubert 1979). Nearly everywhere the canyon
woodlands are subject to fire suppression and intense utilization such as commodity harvests,
recreation, or development.
Fire management plans for canyon environments
may not require fire history knowledge. Such histories can be irrelevant if intense utilization
during the last hundred years has markedly changed
the vegetation or if management goals are not
directed to any kind of natural maintenance process.
However, if Southwestern canyon woodlands are envisioned as natural or scenic areas, refuges, preserves, or wilderness, then the historic role of
fire in bringing about or maintaining biotic diversity should be known if possible. In the absence
of such knowledge I see little reason why localized,
prescribed fires cannot be substituted for naturally
occurring fires. And fires may not be needed at all
along third and fourth order drainages where flash
floods or other natural channel and fluvial geomorphic processes set the stage for local succession and perpetuate the diversity of these canyon
environments.
Can studies in fire ecology from one canyon
woodland at a certain location be extended or
generalized to another location? At present I believe not. Fires in the ecological sense are part
of the environment, and we have not yet been.able
to sufficiently particularize these canyon woodland
envi~onments in a classificatory sense.
For example, my studies (Moir 1981) in Boot Canyon,
Chisos Mountains cannot be very relevant to Rhyolite
Canyon, Chiricahua Mountains although the vegetation of both areas is in the Arizona cypress series.
A habitat type classification provides a tool for
generalization, but is not yet available.
I have often seen dense conifer thickets
develop in a wide variety of disturbed upland or
slope forests in the Southwest, but these thickets
are usually absent, despite fire suppression, along
canyon streamside environments. How important,
then, is fire in maintenance and succession of
canyon vegetation? The Bandolier fire of June,
1977 is instructive. A holocaustic fire that
ravaged forests of mesa tops scarcely had any
important effect along forests of Frijoles Canyon
extending through the burn area. Along mesic
canyon bottoms fires may be very local, and perhaps
.
2
LITERATURE CITED
Layser, Earle F., and Gilbert H. Schubert. 1979.
Preliminary classification for the coniferous
forest and woodland series of Arizona and
New Mexico. USDA Forest Service Research
Paper RM-208, 27 p. Rocky Mountain Forest
and Range Experiment Station, Fort Collins,
Colo.
1Paper
'
presented at the Fire History Workshop.
(Laboratory of Tree-Ring Research, University of
Arizona, Tucson, October 20-24, 1980).
Moir, William H. 1981. Fire history of the Chisos
Mountains, Texas. The Southwestern Naturalist
27: in press.
2
Rodeo, N.M.
20