Steven L. Voelker | Environmental and Forest Biology | SUNY-ESF
e s f home link - e s f college of environmental science and forestry
e s f home link - e s f college of environmental science and forestry

Steven L. VoelkerResearch Assistant Professor

Steven Voelker

246 Illick Hall
1 Forestry Drive
Syracuse, NY 13210

Title: Adjunct Assistant Professor

Research by Dr. Voelker focuses on forest health and forest responses to climate change. He primarily uses dendrochronology and stable isotope techniques, but also draws on a background in plant ecophysiology, disturbance ecology and paleoecology. His overarching goal is to determine how forests respond to environmental change that can support more accurate forecasts of climate change and other potential threats to forests and the ecosystem services they provide. For more information about Dr. Voelker's research you can visit his personal website at:

Office Location: 135 Illick Hall

Steven Voelker

Courses Taught at ESF

EFB 120: Global Environment and The Evolution of Human Society (Fall semesters)

EFB 340: Forest and Shade Tree Pathology (Spring Semesters)

Join the Dendro Team

The Dendro Team at ESF often has positions available for MS and/or PhD graduate students, as well as ungergrauate technicians or interns during the summer and/or school year. We may also have volunteer opportunities arise. Contact me at me email address above if you are interested in joining our team!

The Dendro Team involves many faculty and students at ESF who are interested in overlapping fields of dendroecology, dendroclimate, ecohydrology, disturbance ecology, ecophysiology and forest health.

The primary faculty members from the EFB Department include Dr. Steve Voelker, Dr. Gregory McGee and Dr. Melissa Fierke.

The primary faculty members from the SRM Department include Dr. John Stella, Dr. Julia Burton, Dr. Colin Beier, Dr. Eddie Bevilacqua and Dr. John Drake.

Position Announcements

Graduate student position: Dr Voelker seeks a motivated PhD student to start National Science Foundation-funded research at SUNY-ESF that addresses the intersecting fields of Dendroclimatology and Ecophysiology and Dendroecology. The prospective student will be responsible for producing the first robust winter-season temperature reconstruction for North America and associated past winter atmospheric circulation variability (i.e. Jet Stream Waviness) across North America. Field research will be based adjacent to Lake Superior, focused on tree-ring stable isotopes, and in conjunction with parallel tree-ring data collection in California. The prospective student will be advised by myself ( in collaboration with Dr. John Stella (, Dr. Simon Wang ( and Dr. Dan Griffin (

This position will be based at SUNY-ESF. Prospective students can plan to take part in the Graduate Program in Environmental Science ( and will include a full tuition waiver, stipend and benefits for a minimum of three years. We welcome applications from motivated, curious students with ecological research experience. Ideal candidates will have a MS in ecology, environmental science, or a related field; strong quantitative and writing skills; the ability to work in remote field settings; and interests in forest ecology, climate science and tree ecophysiology. This position would ideally start in January 2021, but later start dates may be considered.

Applications should include a brief statement of interest and experience, CV, transcripts, GRE scores, a research writing sample, if available and English proficiency scores for non-native language speakers. Send email inquiries to Steve Voelker (

Examples of Funded Research at ESF

Research is just getting underway for a funded proposal for from the National Science Foundation's Paleo Perspectives on Climate Change Program that awarded $504,000 to he and Dr. Simon Wang (Utah State University) and $190,287 to Dr. Dan Griffin (University of Minnesota).   The title of the project is "Collaborative Research: Winter Climate Anomalies across North America: Benchmarking Instrumental Trends and Model Projections with High Resolution Paleoclimatology". Link to the NSF award announcement:

Publications and Media

45. Lehman MM, Cormier M-A, P. Schuler, M. Leuenberg, SL Voelker. 2021. Hydrogen isotopic signature in trees: From source water to tree rings. Chapter 11 in Stable Isotopes in Tree Rings: inferring Physiological, Climate and Environmental Responses.  Book In Press. Eds: JS Roden, JR Brooks, RTW Siegwolf, M Saurer

44. Saurer M, SL Voelker. Intrinsic water-use efficiency derived from stable carbon isotopes of tree rings. 2021. Chapter 14 in Stable Isotopes in Tree Rings: inferring Physiological, Climate and Environmental Responses.  Book In Press. Eds: JS Roden, JR Brooks, RTW Siegwolf, M Saurer

​43. Siegwolf, RTW, M. Savard, T. Grams, SL Voelker. Impact of increasing CO2, and air pollutants (NOx, SO2, Ozone) on the C  and O isotope ratio in tree rings. 2021. Chapter 23 in Stable Isotopes in Tree Rings: inferring Physiological, Climate and Environmental Responses.  Book In Press. Eds: JS Roden, JR Brooks, RTW Siegwolf, M Saurer​

​42. Ulrich DEM, SL Voelker, JR Brooks, FC Meinzer. Insect and pathogen influences on tree-ring isotopes. 2021. Chapter 24 in Stable Isotopes in Tree Rings: inferring Physiological, Climate and Environmental Responses.  Book In Press. Eds: JS Roden, JR Brooks, RTW Siegwolf, M Saurer​

41. Keen RM, SL Voelker, BJ Bentz, S-Y S Wang and R. Ferrell. Stronger influence of growth rate than severity of drought stress on mortality of large ponderosa pines during the 2012-2015 California drought. In PressOecologia.

Walker AP, MG De Kauwe, A Bastos, S Belmecheri, K Georgiou, R. Keeling, S McMahon, BE Medlyn, DJO Moore, RJ Norby, S Zaehle, KJ Anderson-Texiera, G. Battipaglia, RJW Brienen, K Cabugao, M Cailleret, E Campbell, P Canadell, P Ciais, ME Craig, D Ellsworth, G Farquhar, S Fatichi, JB Fischer, D Frank, H Graven, L Gu, V Haverd, K Heilmann, BA Hungate, C Iversen, F Joos, M Jiang, TF Keenan, J Knauer, WK Smith, C Korner, VO Leshyk, S Leuzinger, Y Liu, N Macbean, Y Malhi, T McVicar, J Penuelas, J Pongratz, AS Powell, T Riutta, MEB Sabot, J Schleucher, S Sitch, B Sulman, B Taylor, C Terrer, M Torn, K Treseder, AT Trugman, S Trumbore, PJ van Mantgem, SL Voelker, M Whelan and PA Zuidema. Tansley Review: Integrating evidence for a terrestrial carbon sink caused by increasing atmospheric CO2. New Phytologist doi:10.1111/nph.16866 

Brienen RJW, L Caldwell, L Duchesne, SL Voelker, J Barichivich, M Baliva, G Ceccantini, A Di Filippo, S Helama, G Locoselli, L Lopez, G Piovesan, J Schoengart, R. Villalba  and E Gloor. 2020. Forest carbon sink neutralized by pervasive growth-lifespan tradeoffs. Nature Communications 11: 4241.

Press releases related to this research are available here:

The lead author of the paper penned some long-form Science Communication journalism available here:
The Conversation: Across the world trees are growing faster and dying younger and will soon store less carbon

Media: More than 120 news stories covered this research spanning the globe. Here are some examples:  

38. Pettit JM, SL Voelker, RJ DeRose RJ and JI Burton. 2020. Spruce beetle outbreak was not driven by drought stress: evidence from a tree-ring iso-demographic approach indicate temperatures were more important. Global Change Biology. 

37. Chien Y-T, S-YS Wang, Y Chikamoto, SL Voelker, J Meyer and J-H Yoon. 2019. North American winter dipole: Observed and simulated changes in circulation modes. Atmosphere 10: 793.

36. Lavergne A, SL Voelker, AM Csank, H Graven, HJ de Boer, V Daux, I Robertson, I Dorado-Liñán, E Martinez-Sancho, G Battipaglia, KJ Bloomfield, FC Meinzer, JJ Camarero, R Clisby, Y Fang, A Menzel, CJ Still, RM Keen, JS Roden, TE Dawson, IC Prentice. 2019. Historical trends in the stomatal limitation of photosynthesis: empirical support for an optimality principle. New Phytologist 225: 2484-2495.

35. Pettit JM, JI Burton , RJ DeRose RJ, JN Long and SL Voelker. 2019. Epidemic spruce beetle outbreak modifies drivers of Engelmann spruce seedling establishment.  Ecosphere 10: eo2912.

34. Lee CA, S Voelker and P Angwin. Investigating causes of Bishop pine decline on California's North Coast. 2019.  pp. 145-152 In: Forest Health Monitoring: National Status, Trends, and Analysis 2018. USDA Forest Service General Technical report SRS-233.

33. Jiang Y, CJ Still, GFM Page, B Rastogi, S Wharton, FC Meinzer, SL Voelker and JB Kim. 2019. Trend and control in water use efficiency of an old-growth coniferous forest in the Pacific Northwest.  Environmental Research Letters 14: 070429. 

32. Voelker SL, S-Y Wang, TE Dawson, JS Roden, CJ Still, FJ Longstaffe and A. Ayalon. 2019. Tree-ring isotopes adjacent to Lake Superior reveal cold winter anomalies for the Great Lakes region of North America. Scientific Reports 9: 4412.

Media: Our research, on winter climate reconstruction, was written up by Utah State Today:
Media: Dr. Voelker conducted an interview with Utah Public Radio about this research:

31. Voelker SL, AG Merschel, FC Meinzer, CJ Still, DE Ulrich and TA Spies. 2019. Fire deficits have increased drought-sensitivity in dry conifer forests; fire frequency and tree-ring carbon isotope evidence from Central Oregon. Global Change Biology 25: 1247-1262.

Media: Our research, on fire deficits and drought sensitivity was written up by Oregon State Today:
Media: The OSU article was picked up by numerous other media outlets -- below is a selection:

30. Liu X, L Zhao, SL Voelker, G Xu, X Zeng, X Zhang, L Zhang, W Sun, Q Zhang, G Wu and X. Li. 2018. Warming and CO2 enrichment modified the ecophysiological responses of Dahurian larch and Mongolia pine during the past century in the permafrost region of northeastern China. Tree Physiology 39: 88-103. 

29. Ratcliff CJ, SL Voelker and AW Nolin.  2018. Tree-ring carbon isotope records from the western Oregon Cascade Mountains primarily record summer maximum temperatures. Tree-Ring Research 74: 185-195.

28. Voelker SL, JS Roden, and TE Dawson.  2018. Millennial-scale tree-ring isotope chronologies from coastal redwoods provide insights on controls over California hydroclimate variability. Oecologia 187: 897-909.

Media: Our research, along with that from other groups was featured in an article on redwood tree-rings published in Bay Nature:
Media: Dr. Voelker conducted an interview with Utah Public Radio once the research was published:

​27. Voelker SL, RJ DeRose, MF Bekker, C Sriladda N Leksungnoen and RK Kjelgren. 2018Anisohydric behavior links growing season evaporative demand to ring-width increment. Trees - Structure and Function 32: 745-749.

26. Voelker SL and FC Meinzer. 2017. Where and when does stem cellulose δ18O reflect a leaf water enrichment signal? Tree Physiology 37: 551-553

25. Voelker SL, MC Stambaugh, JR Brooks, FC Meinzer, B Lachenbruch and RP Guyette. 2017. Evidence that higher CO2  increases tree growth sensitivity to temperature: a comparison of modern and paleo oaks. Oecologia 183: 1183-1195.

24. Cornejo-Oviedo, SL Voelker, DB Mainwaring, DA Maguire, FC Meinzer and JR Brooks. 2017. Basal area growth, carbon isotope discrimination, and intrinsic water use efficiency after fertilization of Douglas-fir in the Oregon Coast Range. Forest Ecology and Management 389: 289-295.

23. Voelker SL, JR Brooks, FC Meinzer, R Anderson, M K.-F. Bader, G Battipaglia, KM Becklin, D Beerling, D Bert, JL Betancourt, TE Dawson, JC Domec, RP Guyette, C Körner, SW Leavitt, S Linder, JD Marshall, M Mildner, J Ogée, I Panyushkina, HJ Plumpton, KS Pregitzer, M Saurer, AR Smith, RTW Siegwolf, MC Stambaugh, AF Talhelm, JC Tardif, PK Van de Water, JK Ward and L Wingate. 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: 899-902.

22. Voelker SL, MC Stambaugh, RP Guyette, X Feng, DA Grimley, SW Leavitt, IP Panyushkina, D Grimm, JP Marsicek, B Shuman and BB Curry. 2015. Deglacial hydroclimate of mid-continental North America. Quaternary Research 83: 336-344.

21. Lee C, SL Voelker, RM Holdo and RM Muzika. 2014. Tree architecture as a predictor of growth and mortality after an episode of red oak decline in the Ozark Highlands of Missouri, U.S.A. Canadian Journal of Forest Research 44: 1005-1012.

20. Marias DE, FC Meinzer, DC Shaw, DR Woodruff, SL Voelker and B Lachenbruch. 2014. Effect of hemlock dwarf mistletoe on the physiology of host western hemlock using tree ring 13C and 18O. Tree Physiology 34: 595-607.

19. Voelker SL, JR Brooks, FC Meinzer, JS Roden, A Pazdur, S Pawelczyk, P Hartsough, K Snyder, L Plavcová, J Šantrůček. 2014. Isolating relative humidity: dual isotopes δ18O and δD as deuterium deviations from the global meteoric water line. Ecological Applications 24: 960-975.

18. Saffell BJ, FC Meinzer, SL Voelker, DC Shaw, JR Brooks, B Lachenbruch, J McKay. 2014. Tree-ring isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas-fir. Plant, Cell & Environment 37: 1536-1547.

17. Saffell BJ, FC Meinzer, DR Woodruff, DC Shaw, SL Voelker and B Lachenbruch. 2014. Impact of Swiss needle cast infection on tree carbohydrate reserves. Tree Physiology 34: 218-228.

16. Voelker SL, FC Meinzer, B Lachenbruch, JR Brooks and RP Guyette. 2014. Drivers of radial growth and carbon isotope discrimination of bur oak (Quercus macrocarpa Michx.) across continental gradients in precipitation, vapor pressure deficit and irradiance. Plant, Cell & Environment 37: 766-779

15. Voelker SL, P-E Noirot-Cosson, MC Stambaugh, ER McMurry, FC Meinzer, B Lachenbruch and RP Guyette. 2012. Spring temperature responses of oaks are synchronous with North Atlantic conditions during the last deglaciation. Ecological Monographs 82: 169-187.

14. McCulloh KA, DM Johnson, FC Meinzer, SL Voelker, B Lachenbruch and J-C Domec. 2012. Hydraulic architecture of two species differing in wood density: opposing strategies in co-occurring tropical pioneer trees. Plant, Cell & Environment 35: 116-125

13. Voelker, SL. 2011. Age-dependent changes in environmental influences on tree growth and their implications for forest responses to climate change. In Size- and age-related changes in tree structure and function, FC Meinzer, T Dawson and B Lachenbruch (eds.). pp. 455-479, DOI: 10.1007/978-94-007-1242-3_17.

12. McCulloh KA, FC Meinzer, JS Sperry, B Lachenbruch, SL Voelker, DR Woodruff and J-C Domec. 2011. Comparative hydraulic architecture of tropical tree species representing a range of successional status and wood density. Oecologia 167: 27-37.

11. Voelker SL, B Lachenbruch, FC Meinzer and SH Strauss. 2011. Reduced wood stiffness and strength, and altered stem form, in young antisense 4CL transgenic poplar with reduced lignin contents. New Phytologist 189: 1096-1109.

10. Voelker SL, B Lachenbruch, FC Meinzer, P Kitin and SH Strauss. 2011. Transgenic poplars with reduced lignin show impaired xylem conductivity, growth efficiency and survival. Plant, Cell & Environment 34: 655-668.

9. Voelker SL, B Lachenbruch, FC Meinzer, M Jourdes, C Ki, AM Patten, LB Davin, NG Lewis, GA Tuskan, L Gunter, SR Decker, MJ Selig, R Sykes, ME Himmel, P Kitin, O Shevchencko and SH Strauss.  2010. Antisense down-regulation of 4CL expression alters lignification, tree growth and saccharification potential of field-grown poplar. Plant Physiology 154: 874-886.

8. Kitin P, SL Voelker B Lachenbruch, FC Meinzer and SH Strauss. 2010. Tyloses and phenolic deposits in xylem vessels impede water transport in low-lignin transgenic poplars: a study by cryo-fluorescence microscopy. Plant Physiology 154: 887-898.

7. McCulloh K, JS Sperry, B Lachenbruch, FC Meinzer, PB Reich and SL Voelker. 2010. Moving water well: comparing hydraulic efficiency in twigs and trunks of coniferous, ring-porous, and diffuse-porous saplings from temperate and tropical forests. New Phytologist 186: 439-450.

6. Lachenbruch B, SL Voelker, FC Meinzer and SH Strauss. 2010. Structural and functional differences among transgenic hybrid poplar lines with varying lignin contents. Proceedings of the 6th Plant Biomechanics Conference, Cayenne, French Guiana, Nov. 16-21, 2009.

5. Voelker SL, RM Muzika and RP Guyette. 2008. Individual tree and stand level influences on the growth, vigor
and decline of red oaks in the Ozarks. Forest Science 54: 8-20

4. Taylor AM, JR Brooks, B Lachenbruch, JJ Morell and SL Voelker. 2008. Correlation of carbon isotope ratios in the cellulose and wood extractives of Douglas-fir. Dendrochronologia 26: 125-131.

3. Parke JL, E Oh, SL Voelker, EM Hansen, G Buckles, and B Lachenbruch. 2007. Phytopthora ramorum colonizes tanoak xylem and is associated with reduced stem water transport. Phytopathology 97: 1558-1567.

2. Guyette RP, RM Muzika, and SL Voelker. 2007. The historical ecology of fire, climate, and the decline of shortleaf pine in the Ozarks. In JM Kabrick, DC Dey, D Gwaze (eds.). Shortleaf pine restoration and ecology in the Ozarks: proceedings of a symposium, USDA For. Serv. GTR-NRS-P-15, pp. 8-18.

1. Voelker SL, RM Muzika, RP Guyette and MC Stambaugh. 2006. Historical CO2 growth enhancement declines
with age in Quercus and Pinus. Ecological Monographs 76: 549-564.