Professor Tjoelker's research focuses on the impacts of global environmental change on terrestrial ecosystems. His research spans savanna and forests in North America, Europe, and Australia.
As a physiological ecologist, he explores the linkages between plant traits and processes at the individual, stand, and ecosystem scales.
Research interests include climate change effects on respiration and carbon cycling, climatic adaptation in plant traits, and the biogeography of forest tree species. He and his students conduct basic and applied research in the laboratory and field in Australia and beyond.
A goal of his research is to advance fundamental knowledge of plant and ecosystem responses to environmental change and provide science-based information to inform policy choices.
He has authored more than 70 refereed journal articles and edited the book, The Biology and Ecology of Norway Spruce (Springer, 2007).
His published work is among the most cited (top 1%) in the refereed literature (ISI, Essential Science Indicators).
Professor Tjoelker has served grant advisory panels for the U.S. Department of Energy and other agencies and as an advisor to the U.S. Secretary of Agriculture through the Forestry Research Advisory Council. He serves on the editorial advisory board of Tree Physiology, is a Co-editor of New Phytologist, and Associate Editor for Functional Ecology.
In 2009, Dr. Tjoelker was a Visiting Fellow at the Australian National University.
Areas of Research / Teaching Expertise
Plant Biology, Ecological Impacts of Climate Change, Forestry Sciences, Forest Ecology, Ecosystem Function
Awards and Recognition
- Outstanding Graduate Professor Award, 2011
Department of Ecosystem Science and Management, Texas A&M University, chosen by graduate students
- Forestry Research Advisory Council to the US Secretary of Agriculture, 2010 – 2012
The 15-member Forestry Research Advisory Council was established to provide advice to the US Secretary of Agriculture on research and the US Forest Service research program.
- Student-Led Award for Teaching Excellence, 2009
Texas A&M University System, Chancellor's Office system-wide honor for excellence in undergraduate teaching, based on student responses to a voluntary survey.
- Outstanding Young Faculty Award, 2009
Molecular and Environmental Plant Sciences, Texas A&M University, award for excellence in teaching, research, and service.
- Highly Cited Researcher, 2002 – present
Ecology and Environment, 2003 – present, Plant and Animal Science, 2002 – present
Listed in the top 1% of scientists worldwide, based on number of citations in the primary scientific literature (3,771 citations, h-index = 33).
- Professor of the Year, 2002
Department of Ecosystem Science and Management, Texas A&M University, chosen by undergraduate students in Forestry.
- J. William Fulbright Fellowship, 1995
Environmental pollution and forest decline in Poland. This nationally competitive award was awarded to a dozen Ph.D. student scholars to conduct research in Poland.
- Journal Editorships and Advisory Boards
Co-Editor, New Phytologist, 2009 – present
Associate Editor, Functional Ecology, 2006 – present
Board of Advisors, New Phytologist, 2007 – 2009
Editorial Review Board, Tree Physiology 1999, 2001 – present
Editorial Board, Dendrobiology, 1999 – present
- Seminars and scientific conferences
Invited keynote, national and international seminars (>20) and presentations at scientific conferences (>50).
Grants / Current Projects
Is physiological flexibility of forest trees constrained by home climate in a rapidly warming world?
Partners/Funding Body: Australian Research Council
REU site proposal: Eco-hydrology of a tropical montane cloud forest
Co-Researchers: C Houser, T Cahill
Partner/Funding Body: National Science Foundation (US)
Leaf respiration under drought: A global perspective
Co-Researchers: OK Atkin, JR Evans, MG Tjoelker, SA Sitch, JJ Lloyd
Partner/Funding Body: Australian Research Council, Discovery Grant
A Graduate Program in Forest Resources: Developing Integrated Expertise in Forest Resource Management, Conservation, and Restoration
Co-Researchers: K Krutovsky, J Gan, U Kreuter, C Loopstra , P Merton, G Moore, S Popescu, W Rogers, R Washington-Allen, MG Tjoelker, B Wilcox, B Wu
Partner/Funding Body: US Department of Agriculture, National Institute of Food and Agriculture
Climate warming, respiration and the terrestrial carbon cycle: Comparative research and synthesis in Australia
Partner/Funding Body: Texas A&M University, International Programs Grant
Warming and rainfall redistribution effects on linkages between plant functional traits and ecosystem processes in oak savanna
Co-Researchers: MG Tjoelker, DD Briske, A Volder
Partner/Funding Body: US Department of Energy, National Institute for Climatic Change Research, Period: 2007 – 2010
Drake JE, Macdonald CA, Tjoelker MG, Reich PB, Singh BK, Anderson IC, Ellsworth DS, (2018) 'Three years of soil respiration in a mature eucalypt woodland exposed to atmospheric CO2 enrichment', Biogeochemistry, vol.139, no.1, pp 85-101
Drake JE, Tjoelker MG, Varhammar A, Medlyn BE, Reich PB, Leigh A, Pfautsch S, Blackman CJ, Lopez R, Aspinwall MJ, Crous KY, Duursma RA, Kumarathunge D, De Kauwe MG, Jiang M, Nicotra AB, Tissue DT, Choat B, Atkin OK, Barton CVM, (2018) 'Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance', Global Change Biology, vol.24, no.6, pp 2390-2402
Liang LL, Arcus VL, Heskel MA, O'Sullivan OS, Weerasinghe LK, Creek D, Egerton JJG, Tjoelker MG, Atkin OK, Schipper LA, (2018) 'Macromolecular rate theory (MMRT) provides a thermodynamics rationale to underpin the convergent temperature response in plant leaf respiration', Global Change Biology, vol.24, no.4, pp 1538-1547
Pfautsch S, Aspinwall MJ, Drake JE, Chacon-Doria L, Langelaan RJA, Tissue DT, Tjoelker MG, Lens F, (2018) 'Traits and trade-offs in whole-tree hydraulic architecture along the vertical axis of Eucalyptus grandis', Annals of Botany, vol.121, no.1, pp 129-141
Tjoelker MG, (2018) 'The role of thermal acclimation of plant respiration under climate warming: Putting the brakes on a runaway train?', Plant Cell and Environment, vol.41, no.3, pp 501-503
Zhang CJ, Delgado-Baquerizo M, Drake JE, Reich PB, Tjoelker MG, Tissue DT, Wang JT, He JZ, Singh BK, (2018) 'Intraspecies variation in a widely distributed tree species regulates the responses of soil microbiome to different temperature regimes', Environmental Microbiology Reports, vol.10, no.2, pp 167-178
Aspinwall MJ, Jacob VK, Blackman CJ, Smith RA, Tjoelker MG, Tissue DT, (2017) 'The temperature response of leaf dark respiration in 15 provenances of Eucalyptus grandis grown in ambient and elevated CO2', Functional Plant Biology, vol.44, no.11, pp 1075-1086
Aspinwall MJ, Varhammar A, Blackman CJ, Tjoelker MG, Ahrens C, Byrne M, Tissue DT, Rymer PD, (2017) 'Adaptation and acclimation both influence photosynthetic and respiratory temperature responses in Corymbia calophylla', Tree Physiology, vol.37, no.8, pp 1095-1112
Chmura DJ, Modrzynski J, Chmielarz P, Tjoelker MG, (2017) 'Plasticity in seedling morphology, biomass allocation and physiology among ten temperate tree species in response to shade is related to shade tolerance and not leaf habit', Plant Biology, vol.19, no.2, pp 172-182
de Dios VR, Gessler A, Ferrio JP, Alday JG, Bahn M, del Castillo J, Devidal S, Garcia-Munoz S, Kayler Z, Landais D, Martin-Gomez P, Milcu A, Piel C, Pirhofer-Walzl K, Ravel O, Salekin S, Tissue DT, Tjoelker MG, Voltas J, Roy J, (2017) 'Circadian rhythms regulate the environmental responses of net CO2 exchange in bean and cotton canopies', Agricultural and Forest Meteorology, vol.239, pp 185-191
Drake JE, Power SA, Duursma RA, Medlyn BE, Aspinwall MJ, Choat B, Creek D, Eamus D, Maier C, Pfautsch S, Smith RA, Tjoelker MG, Tissue DT, (2017) 'Stomatal and non-stomatal limitations of photosynthesis for four tree species under drought: A comparison of model formulations', Agricultural and Forest Meteorology, vol.247, pp 454-466
Drake JE, Varhammar A, Kumarathunge D, Medlyn BE, Pfautsch S, Reich PB, Tissue DT, Ghannoum O, Tjoelker MG, (2017) 'A common thermal niche among geographically diverse populations of the widely distributed tree species Eucalyptus tereticornis: No evidence for adaptation to climate-of-origin', Global Change Biology, vol.23, no.12, pp 5069-5082
Ellsworth DS, Anderson IC, Crous KY, Cooke J, Drake JE, Gherlenda AN, Gimeno TE, Macdonald CA, Medlyn BE, Powell JR, Tjoelker MG, Reich PB, (2017) 'Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil', Nature Climate Change, vol.7, no.4, pp 279-282
Freschet GT, Valverde-Barrantes OJ, Tucker CM, Craine JM, McCormack ML, Violle C, Fort F, Blackwood CB, Urban-Mead KR, Iversen CM, Bonis A, Comas LH, Cornelissen JHC, Dong M, Guo DL, Hobbie SE, Holdaway RJ, Kembel SW, Makita N, Onipchenko VG, Picon-Cochard C, Reich PB, de la Riva EG, Smith SW, Soudzilovskaia NA, Tjoelker MG, Wardle DA, Roumet C, (2017) 'Climate, soil and plant functional types as drivers of global fine-root trait variation',Journal of Ecology, vol.105, no.5, pp 1182-1196
Gessler A, Roy J, Kayler Z, Ferrio JP, Alday JG, Bahn M, del Castillo J, Devidal S, García-Muñoz S, Landais D, Martín-Gomez P, Milcu A, Piel C, Pirhofer-Walzl K, Galiano L, Schaub M, Haeni M, Ravel O, Salekin S, Tissue DT, Tjoelker MG, Voltas J, Hoch G, Resco de Dios V, (2017) 'Night and day – Circadian regulation of night-time dark respiration and light-enhanced dark respiration in plant leaves and canopies', Environmental and Experimental Botany, vol.137, pp 14-25
Huntingford C, Atkin OK, Martinez-de la Torre A, Mercado LM, Heskel MA, Harper AB, Bloomfield KJ, O'Sullivan OS, Reich PB, Wythers KR, Butler EE, Chen M, Griffin KL, Meir P, Tjoelker MG, Turnbull MH, Sitch S, Wiltshire A, Malhi Y, (2017) 'Implications of improved representations of plant respiration in a changing climate', Nature Communications, vol.8, Article no.1602
Ochoa-Hueso R, Hughes J, Delgado-Baquerizo M, Drake JE, Tjoelker MG, Pineiro J, Power SA, (2017) 'Rhizosphere-driven increase in nitrogen and phosphorus availability under elevated atmospheric CO2 in a mature Eucalyptus woodland', Plant and Soil, vol.416, no.s 1-2, pp 283-295
O'Sullivan OS, Heskel MA, Reich PB, Tjoelker MG, Weerasinghe LK, Penillard A, Zhu LL, Egerton JJG, Bloomfield KJ, Creek D, Bahar NHA, Griffin KL, Hurry V, Meir P, Turnbull MH, Atkin OK, (2017) 'Thermal limits of leaf metabolism across biomes', Global Change Biology, vol.23, no.1, pp 209-223
Resco de Dios V, Gessler A, Ferrio JP, Alday J, Bahn M, del Castillo J, Devidal S, García-Muñoz S, Kayler Z, Landais D, Martín-Gómez P, Milcu A, Piel C, Pirhofer-Walzl K, Ravel O, Salekin S, Tissue D, Tjoelker M, Voltas J, Roy J, (2017) 'Circadian rhythms regulate the environmental responses of net CO2 exchange in bean and cotton canopies', Agricultural and Forest Meteorology, vol.239, pp 185-191
Aspinwall MJ, Drake JE, Campany C, Vårhammar A, Ghannoum O, Tissue DT, Reich PB, Tjoelker MG, (2016) 'Convergent acclimation of leaf photosynthesis and respiration to prevailing ambient temperatures under current and warmer climates in Eucalyptus tereticornis', New Phytologist, vol.212, no.2, pp 354-367
Campany CE, Tjoelker MG, von Caemmerer S, Duursma RA, (2016) 'Coupled response of stomatal and mesophyll conductance to light enhances photosynthesis of shade leaves under sunflecks', Plant Cell and Environment, vol.39, no.12, pp 2762-2773
de Dios VR, Gessler A, Ferrio JP, Alday JG, Bahn M, del Castillo J, Devidal S, Garcia-Munoz S, Kayler Z, Landais D, Martin-Gomez P, Milcu A, Piel C, Pirhofer-Walzl K, Ravel O, Salekin S, Tissue DT, Tjoelker MG, Voltas J, Roy J, (2016) 'Circadian rhythms have significant effects on leaf-to-canopy scale gas exchange under field conditions', Gigascience, vol.5, Article no.43
Drake JE, Macdonald CA, Tjoelker MG, Crous KY, Gimeno TE, Singh BK, Reich PB, Anderson IC, Ellsworth DS, (2016) 'Short-term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration', Global Change Biology, vol.22, no.1, pp 380-390
Drake JE, Tjoelker MG, Aspinwall MJ, Reich PB, Barton CVM, Medlyn BE, Duursma RA, (2016) 'Does physiological acclimation to climate warming stabilize the ratio of canopy respiration to photosynthesis?' New Phytologist, vol.211, no.3, pp 850-863
Duursma RA, Gimeno TE, Boer MM, Crous KY, Tjoelker MG, Ellsworth DS, (2016) 'Canopy leaf area of a mature evergreen Eucalyptus woodland does not respond to elevated atmospheric [CO2] but tracks water availability', Global Change Biology, vol.22, no.4, pp 1666-1676
Heskel MA, Atkin OK, O'Sullivan OS, Reich P, Tjoelker MG, Weerasinghe LK, Penillard A, Egerton JJG, Creek D, Bloomfield KJ, Xiang J, Sinca F, Stangl ZR, Martinez-De La Torre A, Griffin KL, Huntingford C, Hurry V, Meir P, Turnbull MH, (2016) 'Empirical versus process-based approaches to modeling temperature responses of leaf respiration', Proceedings of the National Academy of Sciences of the United States of America, vol.113, no.41, pp E5996-E5997
Heskel MA, O'Sullivan OS, Reich PB, Tjoelker MG, Weerasinghe LK, Penillard A, Egerton JJG, Creek D, Bloomfield KJ, Xiang J, Sinca F, Stangl ZR, Martinez-De La Torre A, Griffin KL, Huntingford C, Hurry V, Meir P, Turnbull MH, Atkin OK, (2016) 'Convergence in the temperature response of leaf respiration across biomes and plant functional types', Proceedings of the National Academy of Sciences of the United States of America, vol.113, no.14, pp 3832-3837
Medlyn BE, De Kauwe MG, Zaehle S, Walker AP, Duursma RA, Luus K, Mishurov M, Pak B, Smith B, Wang Y-P, Yang X, Crous KY, Drake JE, Gimeno TE, Macdonald CA, Norby RJ, Power SA, Tjoelker MG, Ellsworth DS, (2016) 'Using models to guide field experiments: a priori predictions for the CO2 response of a nutrient- and water-limited native Eucalypt woodland', Global Change Biology, vol.22, no.8, pp 2834-2851
Pfautsch S, Harbusch M, Wesolowski A, Smith R, Macfarlane C, Tjoelker MG, Reich PB, Adams MA, (2016) 'Climate determines vascular traits in the ecologically diverse genus Eucalyptus', Ecology Letters, vol.19, no.3, pp 240-248
Aspinwall MJ, Loik ME, de Dios VR, Tjoelker MG, Payton PR, Tissue DT, (2015) 'Utilizing intraspecific variation in phenotypic plasticity to bolster agricultural and forest productivity under climate change', Plant Cell and Environment, vol.38, no.9, pp 1752-1764, SI
Atkin OK, Bloomfield KJ, Reich PB, Tjoelker MG, Asner GP, Bonal D, Bönisch G, Bradford MG, Cernusak LA, Cosio EG, Creek D, Crous KY, Domingues TF, Dukes JS, Egerton JJG, Evans JR, Farquhar GD, Fyllas NM, Gauthier PPG, Gloor E, Gimeno TE, Griffin KL, Guerrieri R, Heskel MA, Huntingford C, Ishida FY, Kattge J, Lambers H, Liddell MJ, Lloyd J, Lusk CH, Martin RE, Maksimov AP, Maximov TC, Malhi Y, Medlyn BE, Meir P, Mercado LM, Mirotchnick N, Ng D, Niinemets U, O'Sullivan OS, Phillips OL, Poorter L, Poot P, Prentice IC, Salinas N, Rowland LM, Ryan MG, Sitch S, Slot M, Smith NG, Turnbull MH, Vanderwel MC, Valladares F, Veneklaas EJ, Weerasinghe LK, Wirth C, Wright IJ, Wythers KR, Xiang J, Xiang S, Zaragoza-Castells J, (2015) 'Global variability in leaf respiration in relation to climate, plant functional types and leaf traits', New Phytologist, vol.206, no.2, pp 614-636
Drake JE, Aspinwall MJ, Pfautsch S, Rymer PD, Reich PB, Smith RA, Crous KY, Tissue DT, Ghannoum O, Tjoelker MG, (2015) 'The capacity to cope with climate warming declines from temperate to tropical latitudes in two widely distributed Eucalyptus species', Global Change Biology, vol.21, no.1, pp 459-472
Modrzyński J, Chmura DJ, Tjoelker MG, Thomas S, (2015) 'Seedling growth and biomass allocation in relation to leaf habit and shade tolerance among 10 temperate tree species', Tree Physiology, vol.35, no.8, pp 879-893
Pfautsch S, Renard J, Tjoelker MG, Salih A, (2015) 'Phloem as capacitor: Radial transfer of water into xylem of tree stems occurs via symplastic transport in ray parenchyma', Plant Physiology, vol.167, no.3, pp 963-971
Vanderwel MC, Slot M, Lichstein JW, Reich PB, Kattge J, Atkin OK, Bloomfield KJ, Tjoelker MG, Kitajima K, (2015) 'Global convergence in leaf respiration from estimates of thermal acclimation across time and space', New Phytologist, vol.207, no.4, pp 1026-1037
Dickie IA, Tjoelker MG, (2014) 'Changing ecology', New Phytologist, vol.202, no.4, pp 1118-1121
Gauthier PPG, Crous KY, Ayub G, Duan H, Weerasinghe LK, Ellsworth DS, Tjoelker MG, Evans JR, Tissue DT, Atkin OK, (2014) 'Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature', Journal of Experimental Botany, vol.65, no.22, pp 6471-6485
O'Sullivan OS, Weerasinghe KWLK, Evans JR, Egerton JJG, Tjoelker MG, Atkin OK, (2013) 'High-resolution temperature responses of leaf respiration in snow gum (Eucalyptus pauciflora) reveal high-temperature limits to respiratory function', Plant, Cell and Environment, vol.36, no.7, pp 1268-1284
Pfautsch S, Aspinwall M, Drake J, Choat B, Tissue D, Burykin T, Tjoelker M, (2013) 'Putting the puzzle together: Investigating hydraulic functioning and water transport at high spatial resolution in tall trees', Acta Horticulturae, vol.991, pp 245-252
Volder A, Briske DD, Tjoelker MG, (2013) 'Climate warming and precipitation redistribution modify tree-grass interactions and tree species establishment in a warm-temperate savanna', Global Change Biology, vol.19, no.3, pp 843-857
Brzostek ER, Blair JM, Dukes JS, Frey SD, Hobbie SE, Melillo JM, Mitchell RJ, Pendall E, Reich PB, Shaver GR, Stefanski A, Tjoelker MG, Finzi AC, (2012) 'The effect of experimental warming and precipitation change on proteolytic enzyme activity: Positive feedbacks to nitrogen availability are not universal', Global Change Biology, vol.18, no.8, pp 2617-2625
Crous K, Zaragoza-Castells J, Löw M, Ellsworth DS, Tissue D, Tjoelker MG, Barton C, Gimeno T, Atkin OK, (2011), 'Seasonal acclimation of leaf respiration in Eucalyptus saligna trees: impacts of elevated atmospheric CO2 and summer drought', Global Change Biology, vol.17, no.4, pp 1560-1576
Luo Y, Melillo JM, Niu S, Beier C, Clark JS, Classen AT, Davidson E, Dukes JS, Evans RD, Field CB, Czimczik CI, Keller M, Kimball BA, Kueppers LM, Norby RJ, Pelini SL, Pendall E, Rastetter E, Six J, Smith M, Tjoelker MG, Torn MS, (2011) 'Coordinated approaches to quantify long-term ecosystem dynamics in response to global change', Global Change Biology, vol.17, no.2, pp 843–854
Volder A, Tjoelker MG, Briske DD, (2010), 'Contrasting physiological responsiveness of establishing trees and a C4 grass to rainfall events, intensified summer drought, and warming in oak savanna', Global Change Biology, vol.16, no.12, pp 3349–3362
Tjoelker MG, Oleksyn J, Lorenc-Plucinska G, Reich PB, (2009), 'Acclimation of respiratory temperature responses in northern and southern populations of Pinus banksiana', New Phytologist, vol.181, no.1, pp 218-229
Reich PB, Tjoelker MG, Pregitzer KS, Wright IJ, Oleksyn O, Machado J-L, (2008), 'Scaling of respiration to nitrogen in leaves, stems and roots of higher land plants', Ecology Letters, vol.11, no. 8, pp 793-801
Tjoelker MG, Oleksyn J, Reich PB, Zytkowiak R, (2008), 'Coupling of respiration, nitrogen, and sugars underlies convergent temperature acclimation in Pinus banksiana across wide-ranging sites and populations', Global Change Biology, vol.14, no.4, pp 782-797
Chmura DJ, Tjoelker MG, (2008), 'Leaf traits in relation to crown development, light interception, and growth of elite families of loblolly and slash pine', Tree Physiology, vol.28, no.5, pp 729-742
Reich PB, Tjoelker MG, Machado J-L, Oleksyn J, (2006), 'Universal scaling of respiratory metabolism, size and nitrogen in plants', Nature, vol.439, no.7075, pp 457-461
Tjoelker MG, Craine JM, Wedin DA, Reich PB, Tilman DG, (2005), 'Linking leaf and root trait syndromes among 39 grassland and savannah species', New Phytologist, vol.167, no.2, pp 493-508
Wright IJ, Reich PB, Westoby M, Ackerly DD, Baruch Z, Bongers F, Cavender-Bares J, Chapin T, Cornelissen JHC, Diemer M, Flexas J, Garnier E, Groom PK, Gulias J, Hikosaka K, Lamont BB, Lee T, Lee W, Lusk C, Midgley JJ, Navas M-L, Niinemets Ü, Oleksyn J, Osada N, Poorter H, Poot P, Prior L, Pyankov VI, Roumet C, Thomas SC, Tjoelker MG, Veneklaas EJ, Villar R, (2004), 'The world-wide leaf economics spectrum', Nature, vol. 428, no.6985, pp 821-827
Atkin OK, Tjoelker MG, (2003), 'Thermal acclimation and the dynamic response of plant respiration to temperature', Trends in Plant Science, vol.8, no.7, pp 343-351
Tjoelker MG, Oleksyn J, Reich PB, (2001), 'Modeling respiration of vegetation: evidence for a general temperature-dependent Q10 ', Global Change Biology, vol.7, no.2, pp 223-230