Category Research 2.2 Shared project:

Direct funding is from non-IAI sources. The University of Arkansas Tree-Ring Laboratory has participated in the IAI-sponsored Treelines Project over the past year, with principal funding from the National Science Foundation Earth System History Program (grant number ATM 0400713).

3. Activities and Findings

3.1 Project activities

We have worked in collaboration with Dr. Jose Villanueva of INIFAP in Torreon, Mexico, and with Dr. Carlos Le Quesne of the Universidad Austral de Chile in Valdivia, Chile. Our field projects during the past year have included trips to the Sierra Madre Oriental of Puebla, Mexico, to extend the important Douglas-fir chronology for central Mexico, which is sensitive to precipitation, the timing of monsoon onset, and to maize yields in highland Mexico. On the same trip we made initial collections of Pinus montezumae on Popocatepetl and assisted a reporter from Discover magazine who is preparing an article about our collaborative tree ring, climate, and human impact research in Mexico.

Additional fieldwork during the past year included collections of millennium-old Montezuma baldcypress trees at Barrance de Amealco, Queretaro, and Los Peroles, San Luis Potosi, Mexico, with our colleagues Dr. Villanueva and Dr. Rodolfo Acuna Soto of the Departamento de Microbiologia y Parasitologia, UNAM, Mexico City. On a separate trip with the same colleagues we collected tree ring core samples from Cedrella mexicana found in a native forest at San Felipe de Bacalar, Quintana Roo.

3.2 Major findings

These involve climate (specifically precipitation) reconstructions for sites in Mexico and the United States. In collaboration with Dr Ed Cook and others we have put together a new, expanded, 286 grid network of PSDI reconstructions for North America including Mexico. We have also, in conjunction with Mexican colleagues, examined the evidence for historical droughts in Mexico, their impacts on society and their relationships to hemorrhagic disease

3.4 Training and Development

Dr. Le Quesne visited our Laboratory in Fayetteville in the summer of 2004 as part of his Post-Doctoral Fellowship to collaborate on a precipitation reconstruction for central Chile, and Dr. Stahle visited Valdivia and Dr. LeQuesne during December and January 2004-05 and helped finalize the manuscript which has been submitted to the Journal of Climate for publication.

3.5 Outreach Activities

With Dr. Henry Diaz (NOAA) we convened a conference in April 2005 at Akumal, Mexico, titled “Climate and Cultural History in the Americas” attended by an interdisciplinary group of climatologists, historical climatologists, paleoclimatologists, historians, archaeologists, ecologists, and epidemiologists, 30 participants from five countries. This meeting was held in conjunction with Final Annual Science Meeting of the IAI CRN03 Treelines Project, which provided a stimulating exchange of new research and suggested avenues of future collaboration. A report on the Climate and Cultural History in the Americas meeting has been prepared for publication, and selected papers will be submitted this fall for possible publication as a special issue of Climatic Change. Research involving our laboratory which has been published, or is in press or submitted during the past year is listed below.

5. Publications

5.1 Journal Publications

Submitted

Lequesne, C., D.W. Stahle, M.K. Cleaveland, M.D. Therrel, J.C. Aravena and J. Barichivich Ancient Cipres Tree-Ring Chronologies used to reconstruct Central Chile precipitation variability from A.D. 1200-2000. Submitted to Journal of Climate.

In Press

Acuna Soto, R., D.W. Stahle, R.D. Griffin, and M.D. Therrell, 2004. When half the population died: the epidemic of hemorrhagic fevers of 1576 in Mexico. FEMS Microbiology Letters (in press).

Acuna Soto, R., D.W. Stahle, M.D. Therrell, S. Gomez Chavez, M.K. Cleaveland, 2005. Drought, epidemic disease, and the fall of classic period cultures in Mesoamerica (AD 750-950), hemorrhagic fevers as a cause of massive population loss. Medical Hypotheses (in press).

Therrell, M.D., D.W. Stahle, M.K. Cleaveland, J. Villanueva-Diaz, E. Cornejo Oviedo, 2004. Tree-ring reconstructed maize yield in Central Mexico: 1474-2001. Climatic Change (in press).

Therrell, M. D. 2005. Tree rings and “El Año del Hambre” in Mexico. Dendrochronologia 22, (in press).

Published

Pohl, K., M. Therrell, J. Santiago-Blay, N. Ayotte, S. Bernal-Salazar, J. Cabrera-Hernandez, S. Castro-Diaz, A. Elvir, M. Gonzales-Elizondo, D. Opland, J. Park, G. Pederson, and L. Vazquez-Salem, D. Stahle, 2003, A Cool Season Precipitation Reconstruction for Saltillo, Mexico Tree-Ring Research 59, 11-20.

Fye, F.K., D.W. Stahle, and E .R. Cook, 2003, Paleoclimatic analogs to Twentieth-Century moisture regimes across the United States, Bulletin of the American Meteorological Society 84: 901-909.

Therrell, M.D., D.W. Stahle, R. Acuna Soto, 2004. Aztec drought and the curse of One Rabbit. Bulletin of the American Meteorological Society 85:1263-1272.

Stahle, D.W., 2004. Tree-ring analysis of ancient Douglas-fir at Guadalupe Mountains National Park, Texas. The Guadalupe Mountains Symposium, Proceedings of the 25th Anniversary Conference on Research and Resource Management in Guadalupe Mountains National Park, edited by F.R. Armstrong and K. KellerLynn, 205-207.

Fye, F.K., D.W. Stahle, and E.R. Cook, 2004. Sea surface temperature patterns witnessed during epic 20th century moisture regimes over the USA. Earth Interactions 8:22.

Cook, E.R., C. Woodhouse, C.M. Eakin, D.M. Meko, and D.W. Stahle, 2004. Long-term aridity changes in the western United States. Science 306:1015-1018.