Steve Leavitt

Professor

Dr. Leavitt’s research centers on past, present and future global change, variously using light stable-isotope analysis of tree rings, native plant leaves, crop plants, soils and geological materials. Recent publications below.

Leavitt’s involvement with the FACE (Free-Air CO2 Enrichment) experiments conducted at the Maricopa Agricultural Center has phased out. However, continued analysis of specific sorghum plant and soil compounds by PhD student Li Cheng (now Dr. Cheng), helped to assess the impact of CO2 fertilization on crop production and soil organic carbon pools. Furthermore, analysis of sour orange trees from Dr. Sherwood Idso’s long-lived sour orange tree CO2 experiment in Phoenix provided the opportunity to assess water-use efficiency using stable-carbon isotopes.

The investigation of water-use efficiency of trees has been further pursued by Leavitt through completion of an unsupported project by re-sampling a 14-site Southwestern pinyon pine between 1999 and 2003 in the US Southwest. This network had been developed in the mid-1980s with analysis of pentads, and stable-carbon isotope analysis has been completed to bring the chronologies up to 1999 with single-year analysis from 1985-99. These data are additionally being used to explore relationships with environmental moisture. Ponderosa pine and Douglas-fir isotope studies in the US Southwest have also been conducted associated with NSF Grants of PI Dr. Connie Woodhouse and PI Dr. Russ Monson.

Much of Leavitt’s efforts over the last decade have involved ongoing investigation of wood from ancient buried forests from around the Great Lakes area. The focus of the study is the Younger Dryas period, and Leavitt and Dr. Irina Panyushkina have collaborated to assemble a massive collection of ancient wood from the area spanning the period from about 4,000 to 15,000 years ago, representing ca. 15 different sites. Some of the wood had been previously collected by other researchers, but a large number of new pieces were collected in this effort. Standard ring-width techniques have been applied to develop floating chronologies, and stable isotopes have been used to further infer past environmental conditions. This study has involved collaborations with more than a dozen researchers, most of whom are located in the Midwest. The centerpiece of the project has been full tree-ring characterization of a Younger Dryas-age black spruce site from Indiana and a thousand-year ring-width chornology from the Bølling–Allerød period 14,000 years ago.
 

                                               Steven W. Leavitt
TITLE- Professor of Dendrochronology, Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ  85721
sleavitt@arizona.edu Phone 602-621-6468; FAX 602-621-8229; Orcid# 0000-0002-7291-208X

EDUCATION-
            May 1982         Ph.D. Geosciences.  University of Arizona, Tucson
(Dissertation title: Inference of past atmospheric δ13C and PCO2 from 13C/12C measurements in tree rings)

            Aug 1977          M.S. Environmental Sciences.  University of Virginia, Charlottesville
(Thesis title: Soil-plant relationships of nutrient and non-nutrient metals in Louisa Co., Virginia)

            June 1971         B.S. Geology.  University of Illinois, Urbana
(Thesis title: The geology and genesis of magmatic iron deposits at Kiruna and Gellivare, Sweden, and Iron Mountain, Missouri)

PROFESSIONAL BACKGROUND-

            Jan 2025 to Aug 2025      Acting Director, Laboratory of Tree-Ring Research 
            Aug 2015 to Aug 2016    Acting Director, Laboratory of Tree-Ring Research
             Jan 2008 to present         Associate Director, Laboratory of Tree-Ring Research
            Jul 1996 to present           Professor, University of Arizona
            Jul 1992 to Jul 1993         Acting Director, Laboratory of Tree-Ring Research
            Aug 1990 to Jun 1996     Associate Professor of Dendrochronology, University of Arizona
            Jul 1989 to Aug 1990      Associate Professor of Geology, University of Wisconsin-Parkside
            Aug 1984 to Jul 1989      Assistant Professor of Geology, University of Wisconsin-Parkside
            Jun 1982 to Jul 1984       Post-doc Research Assoc., University of Arizona, Dept. of  Geosciences


PUBLICATIONS OF LAST 10 YEARS (of >160 in all categories/types since 1979)-

2025
Liu, Y., Song, H., An, Z., Li, Q., Leavitt, S.W., Büntgen, U., Cai, Q., Liu, R., Fang, C., Sun, C., Treydte, K., Ren, M., Mo, L., Song, Y., Cai, W., Zhang, Q., Zhou, W., Bräuning, A., Grießinger, J., Chen, D., Linderholm, H.W., Sinha, A., Cheng, H., Wang, L., Lei, Y., Sun, J., Gong, W., Li, X., Cui, L., Ning, L., Wan, L., Crowther, T.W., Zohner, C.M., 2025. Recent centennial drought on the Tibetan Plateau is outstanding within the past 3500 years. Nature Communications 16:1311. https://doi.org/10.1038/s41467-025-56687-z

Miller, A.E., Csank, A.Z., Hannam, M.P., Sherriff, R.L., Leavitt, S.W., 2025. Decoupling of temperature and growth of white spruce at western treeline, Alaska, is unrelated to intrinsic water stress. Ecology 106(7):e70147. https://doi.org/10.1002/ecy.70147

2024
Frank, D.C., Anchukaitis, K.J., Leavitt, S.W., 2024. Dendroclimatology Conference in Tucson, May 2023. Tree-Ring Research 80(1):19–22.

Chen, W., Li, J., Camarero, J.J., Ding, H., Fu, F., Li, Y., Zheng, X., Li, X., Shen, W., Sigdel, S.R., Leavitt, S.W., Liang, E., 2024. Facilitation drives tree seedling survival at alpine treelines. Journal of Plant Ecology 17(3) rtae033. doi.org/10.1093/jpe/rtae033

Zhang, H., Lu, H., Gu, Y., Lin, P., Shi, J., Shi, S., Liang, C., An, W., Ma, T., Leavitt, S.W., 2024. Testing and assessment of high-precision and high-accuracy AMS-radiocarbon measurements at Nanjing University, China. Radiocarbon 66(3):568-579. doi:10.1017/RDC.2024.70.

Wang, L., Liu, H., Shi, L., Zhang, X., Liang, B., Huang, R., Grießinger, J., Leavitt, S., Yue, Y., Wang, K., 2024. Water use strategies determine divergent growth trends of spruce and juniper on the southeastern Tibetan Plateau. Forest Ecosystems 11:100248, https://doi.org/10.1016/j.fecs.2024.100248.

2023
*Leavitt, S.W., 2023. Memorial to Allan Frank Schneider 1926–2023. Geological Society of America Memorials 52:9-12 (November 2023).

2022
Kimball, B.A., Thorp, K.R., Barnes, R.M., Choi, C.Y., Clarke, T.R., Colaizzi, P.D., Fitzgerald, G.J., Haberland, J.A., Hendrey, G., Hunsaker, D.J., Kostrzewski, M.A., LaMorte, R.L., Leavitt, S.W., Lewin, K., Mauney, J.R., Nagy, J., Pinter Jr., P.J., Waller, P.M., 2022. Cotton response to CO2, water, nitrogen, and plant density - A repository of FACE, AgIIS, and FISE experiment data. Open Data Journal for Agricultural Research (ODjAR) 27 July 2022. http://www.ordjar.org

Leavitt, S.W., Roden, J., 2022. Chapter 1. Isotope dendrochronology: Historical perspective. In Stable Isotopes in Tree Rings: Inferring Physiological, Climatic and Environmental Responses, edited by Rolf Siegwolf, J. Renée Brooks, John Roden, and Matthias Saurer, Springer.

Leavitt, S.W., Cheng, L., Williams, D.G., Brooks, T. Kimball, B.A., Pinter, P.J. Jr., Wall, G.W., Ottman, M.J., Matthias, A., Paul, E.A., Thompson, T., Adam, N. R., 2022.  Soil organic carbon isotope tracing in sorghum under ambient CO2 and Free-Air CO2 Enrichment (FACE), Land 11:309. https://doi.org/10.3390/land11020309. Data at https://doi.org/10.25422/azu.data.19216809.

Leavitt, S.W., Szejner, P., 2022. Intra-annual tree-ring isotope variations: Do they occur when environment remains constant? Trees 36:865–868 (editorial, 20 April 2022) https://doi.org/10.1007/s00468-022-02304-1.

Panyushkina, I.P, Leavitt, S.W., Meko, D.M., Black, B.A., Jull, A.J.T., Van de Water, P., Squire, J., Testa, N.R., 2022. Douglas fir multiproxy tree-ring data glimpse MIS 5 environment in the U.S. Pacific Northwest. Forests 13:2161. https://doi.org/10.3390/f13122161. [available at https://www.mdpi.com/2073-445X/11/2/309]

Sass Klaassen, U., Ważny, T., Čufar, K., Krause, C., Kuniholm, P., Dean, J. S., Liang, E., Liu, Y., Pumijumnong, N., Seo, J.-W., Leavitt, S. W., 2022. Bridging people, countries and continents to promote dendrochronology: IN MEMORIAM− Dieter Eckstein. Tree-Ring Research 78(2):156–162.

Wang, L., Liu, H., Chen, D., Zhang, P., Leavitt, S.W., Liu, Y., Fang, C., Sun, C., Cai, Q., Gui, Z., Liang, B., Shi, L., Liu, F., Zheng, Y., Cherubini, P., Grießinger, J., 2022 The 1820s marks a significant shift towards hotter-drier summers in West Europe since 1360. Geophysical Research Letters 49: e2022GL099692.

Zhang, J., Li, X., Ren, P., Leavitt, S.W., Liang, E., 2022. Terminal bud size, spring and summer temperatures regulate the timing of height-growth cessation of Smith fir on the southeastern Tibetan Plateau. Agricultural and Forest Meteorology 316, 108883 DOI: 10.1016/j.agrformet.2022.108883.

Zhang, J., Li, X., Ren, P., Chai, C., Camarero, J., Leavitt, S.W., Rossi, S., Liang, E., 2022. Lengthening height-growth duration in Smith fir as onset becomes more synchronous across elevations under climate warming scenarios. Agricultural and Forest Meteorology 326, 109193. https://doi.org/10.1016/j.agrformet.2022.109193.

2021
Kimball, B.A., Ottman, M.J., Pinter Jr., P.J., Wall, G.W., Leavitt, S.W., Cheng, L., Conley, M.M., LaMorte, R.L., Triggs, J.M., and Gleadow, R., 2021. Data from the Arizona FACE (Free-Air CO2 Enrichment) experiments on sorghum at ample and limiting Levels of Water. Open Data Journal for Agricultural Research (ODjAR.org) 7:1–10

Leavitt, S.W., 2021. IN MEMORIAM— Minze Stuiver. Tree-Ring Research 77(1):38-40.

Pearson, C.L., Leavitt, S.W., Kromer, B., Solanki, S., Usoskin, I., 2022. Dendrochronology and radiocarbon dating. Radiocarbon 64(3), 569-588. https://doi.org/10.1017/RDC.2021.97

Sigdel, S.R., Pandey, J., Liang, E., Muhammad, S., Babst, F., Leavitt, S., Shen, M., Zhu, H., Salerno, F., Piao, S., Camarero, J.J., Peñuelas, J., 2021. No benefits from warming even for subnival vegetation in the Himalayas. Science Bulletin 66:1825–1829.

Wang, L., Liu, H., Liu, Y., Leavitt, S., Cressey, E. L., Quine, T. A., Shi, J., Shi, S., 2021. Tree-ring δ18O identifies similarity in timing but differences in depth of soil water uptake by trees in mesic and arid climates. Agricultural and Forest Meteorology 308/309:108569. https://doi.org/10.1016/j.agrformet.2021.108569.

2020
Gutiérrez-García, G., Leavitt, S.W., Trouet V., Carriquiry-Beltrán, J.D., 2020. Tree ring-based historic hydroclimatic variability of the Baja California Peninsula. Journal of Geophysical Research Atmospheres 125, e2020JD032675. https://doi.org/10.1029/2020JD032675.

Leavitt, S.W., 2020. IN MEMORIAM— Wallace S. Broecker. Tree-Ring Research 76(1):59-60.

Liu, Y., Song, H., An, Z., Sun, C., Trouet, V., Cai, Q., Liu, R., Leavitt, S.W., Song, Y., Li, Q., Zhou, W., Fang, C., Yang, Y., Jin, Z., Wang, Y., Sun, J., Mu, X., Lei, Y., Wang, L., Li, X., Ren, M., Cui, L., Zen, X., 2020. Recent anthropogenic curtailing of Yellow River runoff and sediment load is unprecedented over the past 500 years. PNAS 117(31):18251-18257, doi/10.1073/pnas.1922349117.

Shi, S., Shi, J., Xu, C., Leavitt, S.W., Wright, W.E., Cai, Z., Zhang, H., Sun, X., Zhao, Y., Ma, X., Zhang, W., Lu, H., 2020. Tree-ring δ18O from Southeast China reveals regional monsoon precipitation and ENSO variability. Palaeogeography, Palaeoclimatology, Palaeoecology 558: 109954. https://doi.org/10.1016/j.palaeo.2020.109954 [online]

2019
Leavitt, S.W., Hughes, M.K., Cook, E.R, 2019.  IN MEMORIAM— Harold C. Fritts, Tree-Ring Research 75(2):167-169.

Liu, Y., Cai, W., Sun, C., Song, H., Cobb, K. M., Li, J., Leavitt, S.W., Wu, L., Cai, Q., Liu, R., Ng, B., Cherubini, P., Büntgen, U., Song, Y., Wang, G., Lei, Y., Yan, L., Li, Q., Ma, Y., Fang, C., Sun, J., Li, X., Chen, D., Linderholm, H.W., 2019. Anthropogenic aerosols cause recent pronounced weakening of Asian Summer Monsoon relative to last four centuries.  Geophysical Research Letters 46(10): 5469-5479, https://doi.org/10.1029/2019GL082497.

Lu, X., Liang, E. Wang, Y., Babst, F., Leavitt, S.W., Camarero, J.J., 2019. Past the climate optimum: Recruitment is declining at the world’s highest juniper shrublines in the Tibetan Plateau. Bulletin of the Ecological Society of America 100(1):e01497. https://doi.org/10.1002/bes2.1497.

2018
Kassie, B.T., Kimball, B.A., Jamieson, P.D., Bowden, J.W. Sayre, K.D., Groot, J.J.R., Pinter, P.P, LaMorte, R.L., Hunsaker, D.J., Wall, G.W., Leavitt, S.W., White, J.W., Asseng, S., 2018. Field experimental data for crop modeling of wheat growth response to nitrogen fertilizer, elevated CO2, water stress, and high temperature.  Open Data Journal for Agricultural Research 4:9-15.

Liu, S., Li, X., Rossi, S., Wang, L., Li, W., Liang, E., Leavitt, S.W., 2018.  Differences in xylogenesis between dominant and suppressed trees. American Journal of Botany, 105(5):950-956. https://doi.org/10.1002/ajb2.1089.

Lu, X., Liang, E. Wang, Y., Babst, F., Leavitt, S. W., Camarero, J. J., 2018. Past the climate optimum: Recruitment is declining at the world’s highest juniper shrublines on the Tibetan Plateau. Ecology. https://doi.org/10.1002/ecy.2557.

Luczaj, J., Leavitt, S.W., Csank, A.Z., Panyushkina, I.P., Wright, W.E., accepted. Comment on “Non-Mineralized Fossil Wood” by George E. Mustoe.  Geosciences 8(12):462, https://doi.org/10.3390/geosciences8120462.

Sigdel, S.T., Dawadi, B., Camarero, J.J., Liang, E., Leavitt, S.W., 2018. Moisture-limited tree growth for the subtropical Himalayan conifer forest, western Nepal. Forests: 9(6), 340. https://doi.org/10.3390/f9060340

Szejner, P., Wright, W. E., Belmecheri, S., Meko, D. M., Leavitt, S. W., Ehleringer, J. R., & Monson, R. K., 2018. Disentangling seasonal and interannual lags from inferred patterns of forest water and carbon cycling using tree-ring stable isotopes. Global Change Biology 218:1-16. https://doi.org/10.1111/gcb.14395

Webber, H., White, J.W., Kimball, B.A., Ewert, F., Asseng, S., Rezaei, E., Pinter Jr., P.J., Hatfield, J., Reynolds, M., Ababaei, B., Bindi, M., Doltra, J., Ferrise, R., Kage, H., Kassie, B., Kersebaum, K.-C., Luig, A., Olesen, J.E., Semenov, M.A., Stratonovitch, P., Ratjen, A., LaMorte, R.L., Leavitt, S.W., Hunsaker, D.J., Wall, G.W., Martre, P., 2018. Physical robustness of canopy temperature models for crop heat stress simulation across environments and production conditions. Field Crops Research 216:75-88.

2017
Liu, Y., Cobb, K.M., Song, H., Li, Q., Li, C.Y., Nakatsuka, T., An, Z., Zhou, W., Cai, Q., Li, J., Leavitt, S.W., Sun, C., Mei, R., Shen, C.-C., Chan, M.-H., Sun, J., Yan, L., Lei, Y., Ma, Y., Li, X., Chen, D., Linderholm, H.W., 2017.  Recent enhancement of central Pacific El Niño variability relative to last eight centuries.  Nature Communications 8, doi:10.1038/ncomms15386.

Johnson, J.E., Hamann, L., Dettman, D.L., Kim-Hak, D., Leavitt, S.W., Monson, R.K., Papuga, S.A., 2017. Performance of induction module-cavity ring-down spectroscopy (IM-CRDS) for measuring δ18O and δ2H values of soil, stem, and leaf waters. Rapid Communications in Mass Spectrometry 31(6):547-560.

Panyushkina I.P., Leavitt S.W., Mode, W.N., 2017. A long Bølling-Allerød tree-ring record from the U.S. Great Lakes. Tree-Ring Research 73(2):102-112.

2016
Voelker, S.L., Brooks, J.R., Meinzer, F.C., Anderson, R., Bader, M.K.-F., Battipaglia, G., Becklin, K.M., Beerling, D., Bert, D., Betancourt, J.L., Dawson, T.E., Domec, J.C., Guyette, R.P., Körner, C., Leavitt, S.W., Linder, S., Marshall, J.D., Mildner, M., Ogée J., Panyushkina, I., Plumpton, H.J., Pregitzer, K.S., Saurer, M., Smith, A.R., Siegwolf, R.T.W., Stambaugh, M.C., Talhelm, A.F., Tardif, J.C., Van de Water, P.K., Ward, J.K., Wingate, L., 2016. A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: Evidence from carbon isotope discrimination in paleo and CO2 enrichment studies.  Global Change Biology 22(2):889-902. doi: 10.1111/gcb.13102.

Gleadow, R.M., Ottman, M.J., Kimball, B.A., Wall, G.W., Pinter, Jr., P.J., LaMorte, R.L., and Leavitt, S.W., 2016.  Drought-induced changes in nitrogen partitioning between cyanide and nitrate in leaves and stems of sorghum grown at elevated CO2 are age dependent. Field Crops Research 185:97–102.

Panyushkina, I. P., Shishov, V. V., Grachev, A. M., Knorre, A. A., Kirdyanov, A. V., Leavitt, S. W., Vaganov, E. A., Chebykin, E. P., Zhuchenko, N. A., Hughes, M. K., 2016.  Trends in elemental concentrations of tree rings from the Siberian Arctic.  Tree-Ring Research 72(2):67-77. doi: 0.3959/1536-1098-72.02.XX (Supplementary Material PDF)

Szejner, P., Wright, W. E., Babst, F., Belmecheri, S., Trouet, V., Leavitt, S. W., Ehleringer, J. R., Monson, R. K., 2016.  Latitudinal gradients in tree-ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon System. Journal of Geophysical Research: Biogeosciences.  121(7):1978-1991. doi: 10.1002/2016JG003460

Hatton, P.-J. F., Chatterjee, S., Filley, T. R., Dastmalchi, K., Plante, A. F., Abiven, S., Gao, X., Masiello, C. A., Leavitt, S. W., Nadelhoffer, K. J., Stark, R. E., Bird, J. A., 2016.  Tree taxa and pyrolysis temperature interact to control the efficacy of pyrogenic organic matter formation. Biogeochemistry 130(1-2):103-116. DOI 10.1007/s10533-016-0245-1.

2015
Voelker, S.L., Stambaugh, M.C., Guyette, R.P., Feng, X., Grimley, D.A., Leavitt, S.W., Panyushkina, I., Grimm.E., Jeremiah P. Marsicek, J.P., Shuman, B., Curry, B., 2015. Deglacial hydroclimate for midcontinental North America. Quaternary Research 83: 336-344 http://dx.doi.org/10.1016/j.yqres.2015.01.001.

Panyushkina, I.P. and Leavitt, S.W., 2015.  Tree-ring investigation of Holocene flood-deposited wood from the Oneida Lake watershed, New York State. Tree-Ring Research 71(2):83-94.

Liu, Y., Wang, Y., Li, Q., Song, H., Linderhlom, H.W., Leavitt. S.W., Wang, R., An, Z., 2015. Corrigendum to "Tree-ring stable carbon isotope-based May-July temperature reconstruction over Nanwutai, China, for the past century and its record of 20th century warming" [Quat. Sci. Rev. 93 (2014) 67-76] doi: 10.1016/j.quascirev.2014.03.023. Quaternary Science Reviews 117:164.

 

SELECTED RECENT CONFERENCE/WORKSHOP PRESENTATIONS (*=Invited)

2019
Michaletz, S., Duran, S., Leavitt, S., McDowell, N., Saleska, S.R., van Haren, J., Troch, P.A., Enquist, B. J., 2019. Re-evaluating a stable isotope (δ18O) approach for estimating the temperature of photosynthesis. 11–16 August 2019, Ecological Society of America meeting. Louisville, Kentucky.

2018
*Leavitt, S.W., Panyushkina, I.P., Gutierrez, G., 2018.  Tree, tree-ring and isotope prospects for identifying Holocene abrupt climate change in North America.  18-21 June 2018, Holocene Abrupt Climatic Events and the Environmental Effects Workshop, Institute of Earth Environment, CAS, Xi'an, China.

2017
Panyushkina, I., Leavitt, S.W., Mode, W., 2017.  Late Pleistocene millennium-scale tree-ring record from North America.  The 14th International Conference on Accelerator Mass Spectrometry, IntCal and Dendrochronology Workshop, 14-18 August 2017, University of Ottawa, Canada.

2016
Michael L. Detizio, John M. Zawiskie, Irina P. Panyushkina, Steven W. Leavitt, 2016. New AMS radiocarbon bone and tusk dates for Late Pleistocene mastodons in southeast Michigan. Michigan Academy of Science Arts & Letters Conference, 4 March 2016, Saginaw Valley State University.

Panyushkina, I.P., Livina, V.N., Leavitt, S.W., 2016. Climate variability of Late Pleistocene deglaciation in the North American midcontinent derived from tree rings. European Geosciences Union (EGU) General Assembly 2016, 17–22 April 2016, Vienna, Austria.

*Leavitt, S.W., 2016. Global Change in the Great Lakes Region 14ka to 6ka from the Annals of Ancient Wood.  Geology Department, University of Wisconsin-Oshkosh, 12 April 2016, Oshkosh, Wisconsin.

Leavitt, S.W. and Panyushkina, I.P., 2016.  The stable-isotopic view of tree-ring series from the Great Lakes area between ca. 12 ka and 13.8 ka.  Geological Society of America, North-Central Section - 50th Annual Meeting, 18 to 19 April 2016, Champaign, IL.

*Panyushkina, I.P., Leavitt, S.W., Zawiskie, J., 2016. Annually-Resolved Environmental proxies in the Great Lakes Area, 14 ka to 10 ka BP:  A Time of Rising Human Population and Mega-Fauna Extinction. Society for American Archaeology (SAA) 81st Annual Meeting, 6-10 April 2016, Orlando, Florida.

Paul, S., Wright, William E., Leavitt, S., Monson, Russell K., 2016.  Using stable isotopes in tree-rings to understand tree performance.  Tropical Ecology and tree ring Isotope Seminar, Georg-August-University, Göttingen, Germany.

Hamann, L., Johnson, J. E., Dettman, D., K.-H., D., Leavitt, Steven W., Monson, R. K., Pope, A., Papuga, S. A., 2016.  Quantifying differences between cryogenic distillation and induction methods for stable isotope analysis:  Implications for understanding plant-water dynamics.  Earth Week, University of Arizona.

Gutierrez Garcia, G., Carriquiry-Beltran, J.D., Leavitt, S., Trouet, V., 2016. Hydroclimatic variability of the Baja California Peninsula reconstructed from tree-rings of Pinus lagunae and Pinus monophylla. Third American Dendrochronology Conference (AmeriDendro) March 28 - April 1, 2016, Mendoza, Argentina.

Panyushkina, I.P., Livina, V.N., Leavitt, S.W., Mode, W.N., 2016.  Tree-ring evidence of climate variability of Late Pleistocene deglaciation in the North American midcontinent.  Geol. Soc. Of America national meeting, 25-28 September 2016. Abstract #278227

Szejner, P., Wright, W. E., Babst, F., Belmecheri, S., Trouet, V., Leavitt, S. W., Ehleringer, J. R., Monson, R. K., 2016.  Latitudinal gradients in tree ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon system. AGU Fall Meeting, 12-16 December 2016, San Francisco.  ID#142441

Meixner, T., Leavitt, S., Morino, K., 2016. Water sources over time for a semi-arid river- Implications for water resources.  AGU Fall Meeting, 12-16 December 2016, San Francisco.  ID# 161011

Johnson, J.E., Tipple, B.J., Betancourt, J.L., Ehleringer, J.R., Leavitt, S.W., Monson, R.K., 2016. Variation in the apparent biosynthetic fractionation for N-alkane δD among terrestrial plants: Patterns, mechanisms, and implications. AGU Fall Meeting, 12-16 December 2016, San Francisco.  ID# 197064

2015
*Leavitt, S.W., 2015. 25 years of stable isotope research at LTRR.  A talk to LTRR Docents, 10 January 2015, Tucson, AZ.

*Leavitt, S.W., 2015. Radiocarbon dating at LTRR and the birth of calibration.  Workshop- A Comprehensive Guide to Bayesian Modeling of Radiocarbon Dates using OxCal. 25-26 April 2015, Tucson, AZ.

*Leavitt, S.W., 2015. Tree rings and the tales they tell of drought, floods, fires, and times gone by.  Cochise College, High Desert Gardening Workshop, 13 March 2015, Sierra Vista, AZ.

Panyushkina, I.P., and Leavitt, S.W., 2015.  Climatic signals in tree-ring stable isotope records from the U.S. Great Lakes subfossil wood network: Successes and limitations.  European Geoscience Union General Assembly, 12-17 April 2015, Vienna, Austria.

*Leavitt, S.W., 2015. Long tree-ring isotope chronologies in the U.S. Southwest and North American Monsoon hydroclimate.  North American Forest Ecology Workshop (NAFEW), 14-18 June 2015, Veracruz, Mexico.

Leavitt, S.W. and Panyushkina, I.P., 2015.  Tree-ring evidence of non-stationary environment in the U.S. Great Lakes area between 15ka-7ka: A time of human transcontinental migrations and mega-fauna extinctions.  XIX INQUA Congress (Quaternary Perspectives on Climate Change, Natural Hazards and Civilization), 26 July to 2 August 2015, Nagoya, Japan.

Panyushkina, I.P., and Leavitt, S.W., Lara, A., Roig, F., Palmer, J., Turney, C.S.M., Jull, T., Van de Water, P.K., 2015. Pan-Pacific tree-ring records in excess of 50 ka.  XIX INQUA Congress (Quaternary Perspectives on Climate Change, Natural Hazards and Civilization), 26 July to 2 August 2015, Nagoya, Japan.

*Leavitt, S.W., 2015. Connecting Trees and Space: The A.E. Douglass Story.  Moon Tree Celebration, 30 October 2015, Space Sciences Building, Campus.

Gutiérrez García, Genaro, Carriquiry Beltrán, José D., Leavitt, Steven W., Trouet, Valerie, 2015. Ariabilidad hidroclimática de la península de Baja California reconstruida a partir de anillos de crecimiento de Pinus lagunae y Pinus monophylla.  Reunión Anual 2015 de la Unión Geofísica Mexicana, 2-7 November, 2015, Puerto Vallarta, Jalisco, México.

Johnson, J.E., Tipple, B.J., Betancourt, J.L., Ehleringer, J.R., Leavitt, S.W., Monson, R.K., 2015. Do interspecific differences in the stable hydrogen isotopic composition of n-alkanes reflect variation in plant water sources or in biosynthetic fractionation?  AGU Fall Meeting, 14-18 December 2015, San Francisco.