USDA Forest Service

Pacific Southwest Research Station
Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research Topics Ecosystem Processes

Sierra Nevada Ecosystems

Quaternary Biogeography of Pacific Southwest Tree Species
Implications of climate cycling to population ecology and genetics, conservation and land management

Research Project Summary

The Research

High Sierra forest Current research in paleoclimatology documents the magnitude of climate variability and its quasi-cyclic nature at decadal to multi-millennial scales over the past 2-3 million years. Similarly, many studies worldwide indicate that historic vegetation responses have been strongly correlated to abrupt as well as gradual climate changes, and that not only does vegetation change over time but physical forces change as well ("a variable chasing a variable"). Despite the abundant information of this nature, conceptual implications to ecology, evolution, and conservation of Quaternary climate as a recurring natural evolutionary force, and of the non-stationarity of ecological regimes, have been little integrated or adopted. We use available literature on paleoecological abundance and distribution to reconstruct range shifts and population levels likely to have prevailed throughout the Quaternary, and analyze dynamics over several timescales. With these examples, we interpret new conceptual approaches to conservation, restoration, and land management.


blue arrrow Using available literature, reconstruct spatially and temporally explicit with attention to low-frequency (glacial/interglacial), medium-frequency (millennial to century), and high-frequency (decadal) fluctuations, especially to periods of abrupt change.

blue arrrow Assess the role of climate variability and other disturbances (fire/geomorphologic change) as an ecological and evolutionary force at several timescales.

blue arrrow Interpret the importance of climate forcing to restoration and conservation strategies and applications.


map of the Sierra Nevada EcoregionPacific Southwest region, USA.

Lead Scientists/Collaborators

1) Millar, C.I. 2) Skinner, C. N. 3) Swetnam, T.W., 3) Falk, D., and 4) Woolfenden, W.

1) USDA Forest Service, PSW Research Station
Sierra Nevada Research Center
800 Buchanan St., Albany, CA 94706 USA
ph: 510-559-6300

2) USDA Forest Service, PSW Research Station, Redding, CA

3) Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ

4) USDA Forest Service, Mountain Heritage Associates, Lee Vining, CA

Publications and Reports
Last Modified: Aug 29, 2016 10:57:09 AM