United States Department of Agriculture, Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
1000 Years of Forest History in the Glass Creek Watershed, Eastern Sierra
Nevada: Interpreting the influence of fire, climatic change, and environmental change on subalpine
forest structure and composition
The Research:
Much progress has been made in the past two decades in elucidating the
key role that recurring wildfire plays in determining forest structure and
composition. While other forces such as climate change and landscape
evolution obviously influence vegetation over longer terms, their relative
importance as co-architects at the management-timescale of decades to
centuries remains little investigated. We are studying forest history in a midelevation watershed in the eastern Sierra Nevada, the Glass Creek watershed.
The forest extends from lodgepole pine at low elevations, old-growth
eastside mixed conifer with red fir at middle elevations, to whitebark pine at
treeline. A large wet meadow with high species diversity dominates the valley
floor. Aside from domestic sheep grazing in the meadow, the watershed has
been minimally disturbed by recent human activities; even fire suppression
does not seem to have influenced fire regimes. The watershed has been
significantly influenced, however, by repeat eruptions of the nearby Inyo
Craters, whose most recent activities covered the watershed with many meters
of tephra ~750 years ago. In related studies, we have been documenting
the influence of climate on vegetation at nearby treeline elevations and
the influence of climate on conifer invasion of the meadow. In this study,
we investigate the main forest zones of this watershed as a case study in
dissecting the role of climate, fire, and volcanism in shaping stand structure
and composition.
Using dendrochronological, ecological plot, and fire-scar analyses in the
forest zones, we are reconstructing forest structure, climate relations, and
fire history over the last 1000 years. We find evidence for influence of
each of the forces (fire, climate, and eruption) on forest dynamics, with
relative importance changing over time. In some cases, the influences are
confounding, in that they have similar effects ecologically, and are thus
difficult to separate.
Important conclusions emerging from these studies include 1) the role
of each force is significant and vegetation diversity cannot be adequately
understood with reference to single one, 2) extreme events and variability
in events determine significant ecological pathways that become set for
hundreds of years, and 3) third order change is evident, that is - vegetation
changes are evident in response to physical systems that are themselves
changing.
Our Mission:
Sierra Nevada Ecosystems are
complex and our knowledge
of them is incomplete.
As a result, the long term
outcome of any given land
and resource management
strategy is uncertain. We
will provide assistance to
land managers and policy
makers by addressing this
management dilemma
through targeted research,
emphasizing an integrated,
ecoregional approach to
examine particular physical,
ecological, and socioeconomic issues, across a
range of appropriate spatial
and temporal scales specific
to each issue.
This unit will represent the
collective research expertise
and interests of scientists
located in Fresno, Davis
and Albany as well as other
scientists within the Pacific
Southwest Research Station.
With a full spectrum of
research, from long term,
fundamental research
to short-term, tactical
applications, this Center
is intended to support
conservation, restoration,
and sustainable utilization of
the lands within the Sierra
Nevada ecoregion.
Objectives:
Evaluate the relative roles of fire, climate change, and volcanic eruptions as architects
of forest structure and composition over the past 1000 years.
Application of Research Results:
This study is part of a complex of studies we are conducting in the Glass Creek
watershed designed to provide information for resource managers about the relative
influence of climate, fire, and volcanism on forest dynamics. Under conditions of
changing climates, and altered fire regimes, decision-makers need accurate information
about how forests respond to these forces. The Glass Creek Watershed is part of a
larger landscape analysis by the Inyo National Forest, and management decisions will
benefit from information provided in the suite of studies we are undertaking there.
Location:
Eastern Sierra Nevada:
Glass Creek watershed,
headwaters of the
Owens River.
Publications:
PDFs available at: http://www.fs.fed.us/psw/programs/snrc/staff/millar
• Poster: Millar, CI; Westfall, RD; Delany, DL; King, JC; and Alden, HA. 2004. HighElevation Response of Conifers to Climate Change in the Sierra Nevada and Western
Great Basin, USA: Treeline Elevation is Not the Primary Effect.
Poster: Millar, CI; Westfall, RD; Delany, DL; King, JC; and Alden, HA. 2004. Climate
as an Ecosystem Architect; Responses of High-Elevation Conifers to Past Climate
Variability.
http://www.fs.fed.us/psw/programs/snrc
USDA Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
Albany Location:
800 Buchanan Street
Albany, CA 94710
For further information contact:
Dr. Connie Millar
cmillar@fs.fed.us
Mailing Address:
P.O. Box 245
Berkeley, CA 94701
Dr. Peter Stine, Program Manager
Phone: 510-559-6300
Fax: 510-559-6440
Davis Location:
2121 Second Street
Suite A101
Davis, CA 95616
Phone: 530-759-1700
Fax: 530-747-0241
Fresno Location:
2081 E. Sierra Avenue
Fresno, CA 93710
Phone: 559-323-3200
Fax: 559-297-3355