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Southern Oregon University


Sciences RM 226

1250 Sisikiyou Blvd.

Ashland, OR  97520

(541) 552-6798





Ph.D., Botany, University of California, Davis. 1992

M.S., Botany, University of California, Davis. 1989.

B.S., Forest Management, University of Washington. 1987.


Plant Physiology, (Bi 331)

Principles of Biology, (Bi211)

Forest Ecology and Management (Bi386)

Biogeochemistry (Bi346)

Plant Form and Function (Bi434/534)

Introductory Ecology Lab (Bi340L)

Stable Isotope Ecology and Biogeochemistry (summer course, University of Utah) 


Research Interests

My fundamental interests are in Plant Physiological Ecology and Biogeochemistry with special reference to trees and forest ecosystems. The theme that binds my interests together is an interest in how the microenvironment of a plant influences its form and function. In particular, I have been interested in how plants acclimate and adapt to environmental heterogeneity with an emphasis on how those physiological and morphological characteristics affect survival and growth. Recent projects have included stable isotopes in tree ring cellulose as indicators of plant water use and climate change, the effects of wind and leaf movements (leaf flutter) on canopy light dynamics and its impact on photosynthesis, the effects of elevated CO2 and temperature extreme events (global change) on tree seedling physiology.

I am the faculty supervisor of the Southern Oregon University Stable Isotope Facility (SOUSIF), where we measure the stable isotopes of C, O and N from organic matter samples. Stable isotopes have numerous applications in biology and ecology and we have run samples for many different labs and investigators. Recently we had major NSF funded projects looking at the stable isotope variation in coast redwood trees as a proxy for climate variation over the last millennium.  




Roden, J.S. (2008) Cross-dating of tree ring d18O and d13C time series. Chemical Geology. 252: 72-79. doi:10.1016/j.chemgeo.2008.01.007

Roden, J.S. Johnstone J., Dawson TE (2009) Intra-annual variation in the stable oxygen and carbon isotope ratios of cellulose in tree rings of coast redwood (Sequoia sempervirens). The Holocene. 19:189-197.

Roden, JS, Canny, MJ, Huang CX and Ball, MC (2009) Frost tolerance and ice formation in Pinus radiata needles: ice management by the endodermis and transfusion tissues. Functional Plant Biology. 36:180–189.

Roden, J.S. Johnstone J.A. and T.E. Dawson (2011) Regional and watershed coherence in the stable oxygen and carbon isotope ratio time-series in tree rings of coast redwood (Sequoia sempervirens). Tree Ring Research. 67:71-86.

Roden, JS and GD Farquhar (2012) A controlled test of the dual isotope approach for interpretation of stable carbon and oxygen isotope ratio variation in tree-rings. Tree Physiology. 32:490-503. doi:10.1093/treephys/tbs019.

Roden, JS and R. Siegwolf (2012) Is the dual isotope conceptual model fully operational? Tree Physiology 32:1179-1182.

Johnstone JA, J Roden, and TE Dawson (2013) Oxygen and carbon stable isotopes in coast redwood tree rings respond to spring and summer climate signals. Journal of Geophysical Research: Biogeosciences 118:1438-1450.

Voelker SL, JR Brooks, FC Meinzer, J Roden, A Pazdur, S Pawelczyk, P Hartsough,K Snyder, L Plavcova and J Šantrůček (2014) Reconstructing relative humidity from plant δ18O and δD as deuterium deviations from the global meteoric water line. Ecological Applications 24:960-975.

Babst, F, Alexander R, Szejner P, Bouriaud O, Klesse S, Roden J, Ciais P, Poulter B, Frank D, Moore D and Trouet V. (2014) A tree-ring perspective on the terrestrial carbon cycle. Oecologia 176: 307-322. doi:10.1007/s00442-014-3031-6

Tipple BJ, Berke MA, Hambach, B, Roden JS and JR Ehleringer (2015) Predicting leaf wax n-alkane 2H/1H ratios: controlled water source and humidity experiments with hydroponically grown trees confirm predictions of Craig–Gordon model. Plant Cell and Environment 38:1035-1047. Doi:10.1111/pce.12457.

Roden JS, Kahmen A, Buchmann N and R Siegwolf  (2015) The enigma of effective pathlength for 18O enrichment in leaf water of conifers. Plant Cell and Environment 38:2551-2565. doi:10.1111/pce.12568.

Churakova (Sidorova) O, Shashkin A, Launois T, Siegwolf R, Saurer M, Vaganov E, Bryukhanova M, Spahni R, Peylin P, Masson-Delmotte V and J Roden. Application of eco-physiological models to tree-ring parameters. Dendrochronologia (in press).