INSTAAR Dendrochronology Lab

The INSTAAR Dendrochronology Laboratory was operational from January 2000 until June 2009. The equipment and wood samples collected by Lab staff are now at the University of Arizona's Laboratory of Tree-Ring Research under the supervision of Connie Woodhouse.

About the Lab 

The focus of the Lab's research was the assessment of hydroclimatic variability in the western U.S. over the last millennium, in particular, the reconstruction of annual streamflow. Nearly all of the tree-ring collections were from three moisture-sensitive conifer species: pinyon pine, ponderosa pine, and Douglas-fir. In all, over 100 tree-ring chronologies from Colorado and adjacent states were developed in the Lab; most of these are available through the International Tree-Ring Data Bank (ITRDB). All of the streamflow and climate reconstructions generated in the Lab's projects are available through the TreeFlow web resource. The Lab staff also conducted projects in dendroecology and dendroarcheology.

Jeff Lukas, Lab Manager, is now with the CIRES-NOAA Western Water Assessment. He can be contacted at 303-497-6212, or lukas[at]

Connie Woodhouse, Lab Director, is with the University of Arizona's Department of Geography and Regional Development and Laboratory of Tree-Ring Research. She can be contacted at (520) 626-0235, or conniew1[at]

Other former Dendro Lab staff and associates:
Mark Losleben - currently Research Associate, Laboratory of Tree-Ring Research, University of Arizona
Kurt Chowanski - currently Cl
imatologist, Mountain Research Station, University of Colorado
Nichole Barger – currently Assistant Professor of Biology, University of Colorado
Henry Adams – currently PhD student, Biology, University of Arizona
Curtis Nepstad-Thornberry – currently consulting archeologist, Iowa
Margot Kaye – currently Assistant Professor of Forest Ecology, Penn State University
Gary Bolton – currently Lecturer in Botany, University of Wyoming


The Dendro Lab's Research Projects

TreeFlow: Streamflow Reconstructions for the West (2002-2009)

For the TreeFlow project, we partnered with water management agencies in Colorado and across the West to develop long, high-quality reconstructions of streamflow from the extensive network of tree-ring chronologies we have developed. We worked to ensure that the data products are meaningful and useful to water managers and other users, and the data are widely accessible through the TreeFlow web resource. While these tree-ring data, like the gaged records, can’t be used to predict future droughts, they can help water managers incorporate into their planning and operations the resilience necessary to sustain water supplies during those events. By 2008, 35 streamflow reconstructions were developed by Lab personnel and collaborators.

NOAA Office of Global Programs: Climate Change Data and Detection Program for “Extended Hydroclimatic Records for the Upper Colorado River Basin”, and Western Water Assessment - A Regional Integrated Sciences and Assessments Program
PI: Connie Woodhouse
June 2002 - July 2009

Woodhouse, C.A., S.T. Gray, and D.M. Meko. 2006. Updated streamflow reconstructions for the Upper Colorado River basin. Water Resources Research 42(5): W05415

Woodhouse, C.A. and J.J. Lukas. 2006. Multi-century tree-ring reconstructions of Colorado streamflow for water resource planning. Climatic Change 78: 293-315.

Woodhouse, C.A. and J.J. Lukas. 2006. Drought, Tree Rings, and Water Resource Management in Colorado. Canadian Water Resources Journal 31(4): 1-14.


Remnant collections to extend tree-ring chronologies, Upper Colorado River basin (2005-2009)

As of 2003, our moisture-sensitive tree-ring chronologies in the Upper Colorado River basin were developed from samples taken almost entirely from living trees, and the longest chronology extended to AD 1126. The average chronology start date is AD 1375. At many of the collection sites, there is remnant woodl (stumps, logs, standing dead trees) which has been well-preserved due to the arid climate. Sampling of this remnant wood provided ring-width data to extend the chronologies back an additional 200-400 years or more. The objectives in extending the chronologies were twofold: (1) to provide longer overlap with high-resolution lake sediment records collected by USGS reseachers, and (2) to permit longer reconstructions of Upper Colorado streamflow.

In August 2005, we collected remnant material at 11 sites in western Colorado. At each site, 5 to 20 cross-sections were collected, and at four sites, 6-10 living trees were cored to update chronologies that did not already end in 2002 or later. In August 2006, we collected remnant wood at 2 additional sites and collected more wood at 3 sites sampled in 2005. All of the chronologies at these sites have been extended back an additional 100-900 years using the remnant wood. At 5 sites, the chronologies extend back before AD 800, with the longest chronology beginning in 203, or over 1800 years long.

In 2007 and 2008, the project focus turned upwards to treeline environments in Colorado, where we pursued the dual goals of developing long tree-ring chronologies (mainly bristlecone pine) and examining the potential influence of climate on stand dynamics at treeline over the past 2-3 millennia.

Funding: USGS Earth Surface Processes Group
PIs: Connie Woodhouse

Regional vs. local controls of pinyon-juniper expansion on the Colorado Plateau (2006-2007)

Both natural climate variability and anthropogenic effects such as livestock grazing and changes in historical fire regimes have been identified as key factors in pinyon-juniper woodland expansion across the western United States. This research program examined the importance of regional versus local controls on pinyon-juniper woodland expansion at two national park units on the northern Colorado Plateau: Grand Staircase-Escalante National Monument and Canyonlands National Park. Climate affects plant communities on regional and global scales, whereas changes in livestock grazing patterns and fire regimes occur at more local scales. Dendrochronological techniques were used to compare regional (between park) versus local (within park) pinyon-juniper stand structure to better understand the role of natural and anthropogenic change in pinyon-juniper woodlands on the Colorado Plateau.

Funding: National Parks Ecological Research Fellowship
PI: Nichole Barger


Riparian forest age structure and past hydroclimatic variability, Sand Creek Massacre NHS (2005)

Sand Creek Massacre National Historic Site in southeastern Colorado was created to preserve, protect, interpret, and memorialize the site of a large Cheyenne and Arapaho village that was attacked by troops of the Colorado Cavalry, on November 29, 1864. The riparian cottonwood forests at Sand Creek were, and remain, a critical element of the landscape, providing shelter, timber, firewood, forage, and wildlife habitat. In addition, individual cottonwood trees along Sand Creek, both living and dead, have cultural and spiritual significance because of their association with the Indian encampments and the massacre itself.

These riparian ecosystems appear to have changed significantly over the 140 years since the massacre. Photographs of Sand Creek as late as the 1930s show many fewer trees than are now present. Management of the riparian ecosystems at Sand Creek will require better understanding of the site’s environmental history, current conditions, changes that have occurred over time, and possible causes of those changes. Thus, the main objectives of the research were (1) to describe the age structure of the cottonwood stands, targeting in particular trees that may have been alive in 1864 and (2) to identify the hydroclimatic factors (e.g. floods, drought) that have influenced development of the stands. By providing information on the ages of the trees, particularly the very oldest ones, the research will assist the park in managing the trees as a cultural resource, including the gathering and use of ceremonial firewood from the site, implementing culturally and environmentally appropriate fuel reduction strategies, and other issues.

Funding: National Park Service
PIs: Connie Woodhouse, Jeff Lukas


Collaborative Research: Reconstructions of Drought and Streamflow over the Coterminous United States from Tree Rings, with extensions into Mexico and Canada (2000-2004)

The goals of this collaborative research project were to 1) update and improve PDSI reconstructions for the U.S., Canada, and Mexico and to 2) explore new methods and metrics of hydroclimatic reconstructions. New methods developed with project co-PIs include quantile regression and Bayesian-based reconstructions approaches. Hydroclimatic metrics investigated for reconstructions include n-day low flow and snow water equivalent (SWE). Our studies have focused on hydroclimatic reconstructions of the S. Platte, Arkansas, Colorado main stem, and the Gunnison River basins.

Funding: National Science Foundation, Earth Systems History
PIs: Edward Cook, Upmanu Lall, David Meko, and Connie Woodhouse
Sept. 2000 to Aug. 2003, with an extension to Aug. 2004

Woodhouse, C.A. 2003. A 431-year reconstruction of western Colorado snowpack. Journal of Climate, 16, 1551-1561.

Jain, S., C.A. Woodhouse, M.P.Hoerling. 2002. Multidecadal streamflow regimes in the interior western United States: implications for the vulnerability of water resources. Geophysical Research Letters 29, 2036-2039.

Great Plains and Central Rocky Mountains Drought (1999-2002)

The objectives of this project were to (1) reconstruct spatial and temporal patterns of drought in the central Rocky Mountains and central High Plains and 2) examine relationships between atmospheric circulation patterns that have accompanied droughts over the past centuries. The Great Plains have represented the largest spatial gap in the distribution of tree-ring chronologies across the U.S. By systematically searching for isolated stands of ponderosa pine, Douglas-fir, and junipers growing on scattered outcrops and uplands in the Great Plains, this gap was narrowed considerably. About two-dozen such stands were sampled for this project, with most of the sites developed into full chronologies. Much of the wood collected was from trees cut by settlers in the late 1800s. Specific products of this research include a new reconstruction of PDSI (1552-1995) for eastern Colorado, and a detailed spatiotemporal analysis of the 1845-56 drought--longer and more severe than the 1930s Dust Bowl--which centered on eastern Colorado.

Funding: National Science Foundation Atmospheric Sciences (ATM-97299571)
PIs: Connie Woodhouse, Peter Brown
May 1998 – May 2001, extended to May 2002

Woodhouse, C.A., J.J. Lukas, and P.M. Brown. 2002. Drought in the Western Great Plains, 1845-56: Impacts and Implications. Bulletin of the American Meteorological Society, 83, 1485-1493.

Woodhouse, C.A. and P. M. Brown. 2001. Tree-ring evidence for Great Plains drought. Tree-Ring Research, 57, 89-103.

Temperature Variability since AD 1000 in the Western US (1999-2002)

The objectives of this project were to collect new millennial-length chronologies from a variety of species in the Northern Rockies and the Northwest, and develop long tree-ring based temperature reconstructions. This work complements collections in the Great Basin and western Canada, and contributes to a network of western North American millennial-length temperature sensitive tree-ring chronologies. Summer temperature reconstructions from this network allow the examination of spatiotemporal patterns of temperature variation, and the placing of the fluctuations of the last century into a longer perspective. About 20 new temperature-sensitive chronologies were collected, with several exceeding 1000 years in length.

Funding: National Science Foundation, Earth Systems History (subcontract under U of AZ, Y501756)
PIs: Malcolm Hughes, Connie Woodhouse, Peter Brown
Oct. 1998 - Sept. 2001, extended to Sept. 2002

Woodhouse, C. A., Brown, P., Hughes, M.K., and Salzer, M. 2001. Patterns of temperature variability over the western U.S. for the past 700-1000 years. Proceedings of the 18th Annual Pacific Climate (PACLIM) Workshop. Technical Report 68, Interagency Ecological Program for the San Francisco Estuary, 203 pp.



last updated: February 10, 2011