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Andrew D. Friend BSc PhD

University Senior Lecturer in Environmental Science and Fellow of Clare College

Research interests focus on the use of numerical models to study vegetation-environment interactions, plant ecophysiology, and feedbacks between global change and biological processes at a wide range of scales

Biography

Career

• 2008-present: Fellow & Director of Studies, Clare College, University of Cambridge
• 2007-present: University Senior Lecturer in Environmental Science, Department of Geography, University of Cambridge
• 2003-2007: CNRS Chargé de Recherche de 1ére Classe, LSCE, Saclay, France
• 2002: Associate Research Scientist, Columbia University and NASA Goddard Institute for Space Studies, New York
• 1999-2001: Associate Research Professor, Rutgers University and NASA Goddard Institute for Space Studies, New York
• 1991-1999: Higher, then Senior Scientific Officer, Institute of Terrestrial Ecology, Edinburgh
• 1989-1991: Associate Research Scientist, Department of Environmental Sciences, University of Virginia
• 1989 Young Scientists' Summer Program, International Institute for Applied Systems Analysis, Laxenburg, Austria

Qualifications

• BSc (University College London)
• PhD (University of Cambridge)

Research

Andrew Friend's interests concern controls on terrestrial vegetation type, structure, and productivity over a wide range of time and space scales and the effects of vegetation on atmospheric processes through land surface energy partitioning and carbon fluxes. He develops numerical models in order to test our understanding of processes through the ability of these models to faithfully simulate real-world phenomena, as well as address concerns regarding the effects of global change on terrestrial ecosystems and potential future atmospheric feedbacks. He continues to develop an individual-based model of vegetation dynamics, HYBRID, with the aim of producing processed-based representations of land surface processes for coupling to global-scale atmospheric models. His current work is particularly concerned with the representation of physiological differences between plant types and species, the representation of competition, and the global-scale dynamics of biogeochemistry-climate interactions.

PhD supervision

I welcome the opportunity to supervise PhD students who wish to work on modelling and observations in the areas of plant physiology, ecosystem dynamics, global biogeochemical cycles (especially the global carbon cycle), and/or climate systems, especially where one or more of these elements are coupled.

Publications

Selected publications

2011

• Gerken T, Babel W, Hoffmann A, Biermann T, Herzog M, Friend AD, Li M, Ma Y, Foken T, Graf H-F. Submitted. Turbulent flux modelling with a simple 2-layer soil model and extrapolated surface temperature applied at Nam Co Lake basin on the Tibetan Plateau. Hydrology and Earth System Sciences Discussions, doi:10.5194/hessd-8-10275-2011
• Friend AD. 2011. Response of Earth's surface temperature to radiative forcing over AD 1-2009. Journal of Geophysical Research - Atmospheres 116, D13112, doi:10.1029/2010JD015143
• Zaehle S, Ciais P, Friend AD, Prieur V. 2011. Carbon benefits of anthropogenic reactive nitrogen offset by nitrous oxide emissions. Nature Geoscience 4, 601-605, doi:10.1038/ngeo1207
• Durant A, Le Quéré C, Hope C, Friend AD. 2011. Economic value of improved quantification in global sources and sinks of carbon dioxide. Philosophical Transactions of The Royal Society A 369, 1967-1979, doi: 10.1098/rsta.2011.0002

2010

• Friend AD. 2010. Terrestrial plant production and climate change. Journal of Experimental Botany 61, 1293-1309, doi: 10.1093/jxb/erq019
  
• Zaehle S, Friend AD 2010. Carbon and nitrogen cycle dynamics in the O-CN land surface model: 1. Model description, site-scale evaluation, and sensitivity to parameter estimates. Global Biogeochemical Cycles, 24, GB1005, doi:10.1029/2009GB003521.
• Zaehle S, Friedlingstein P, Friend AD. 2010. Terrestrial nitrogen feedbacks may accelerate future climate change. Geophysical Research Letters, 37, L01401, doi:10.1029/2009GL041345 ; see also Editor's Highlight
• Zaehle S, Friend AD, Friedlingstein P, Dentener F, Peylin P, Schulz M. 2010. Carbon and nitrogen cycle dynamics in the O-CN land surface model: 2. Role of the nitrogen cycle in the historical terrestrial carbon balance. Global Biogeochemical Cycles, 24, GB1006, doi:10.1029/2009GB003522.

2009

• Friend AD, Geider RJ, Behrenfeld MJ, Still CJ. 2009. Photosynthesis in Global-Scale Models. In: Photosynthesis in silico: Understanding Complexity from Molecules to Ecosystems. Laisk A, Nedbal L, Govindjee (Eds). Springer Series "Advances in Photosynthesis and Respiration". Vol 29. Springer (Dordrecht, The Netherlands). pp. 465-497.
• Keenan T, García R, Friend AD, Zaehle S, Gracia C, Sabate S. 2009. Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO₂ and water fluxes through combined in situ measurements and ecosystem modelling. Biogeosciences 6, 1423-1444. www.biogeosciences.net/6/1423/2009/
• Zaehle S, Friend AD, Friedlingstein P. 2009. Consequences of simulating terrestrial N dynamics for projecting future terrestrial C storage. Geophysical Research Abstracts 11, EGU2009-12404.

2008

• Friend AD, GREENCYCLES Project Members. 2008. Biogenic feedbacks on the atmospheric concentrations of greenhouse gases: overview of the GREENCYCLES network. Geophysical Research Abstracts 10, EGU2008-A-07827.
• Friend AD. 2008. Quantifying the global dynamics of terrestrial photosynthesis, 1900-2100. Eos Transactions, AGU, 89(53), Fall Meeting Supplement, Abstract B51E-0443.
• Garcia R, Keenan T, Zaehle S, Friend A, Gracia C, Sabate S. 2008. Ecophysiological responses to drought in Mediterranean forest ecosystems: data analysis and the evaluation of model predictions in drought prone ecosystems. Geophysical Research Abstracts 10, EGU2008-A-06420.
• van der Merwe H, Friend AD. 2008. Quantifying the effect of biogeochemical feedbacks on global climate change. Geophysical Research Abstracts 10, EGU2008-A-09045.
• Zaehle S, Friend AD, Friedlingstein P. 2008. Terrestrial N cycling and C ctorage: Some insights from a process-based land surface model. Eos Transactions, AGU, 89(53), Fall Meeting Supplement, Abstract B51E-0440.
• Zaehle S, Friend AD, Friedlingstein P, Schulz M. 2008. Modelling ecosystem nitrogen dynamics to simulate historical and future terrestrial greenhouse gas budgets. Geophysical Research Abstracts 10, EGU2008-A-06373.

2007

• Demarty, J., Chevallier, F., Friend, A.D., Viovy, N., Piao, S., and Ciais, P. 2007. Assimilation of global MODIS leaf area index retrievals within a terrestrial biosphere model. Geophysical Research Letters 34, L15402, doi:10.1029/2007GL030014.
• Friend, A.D., Arneth, A., Kiang, N.Y., Lomas, M., Ogée, J., Rödenbeck, C., Running, S.W., Santaren, D., Sitch, S., Viovy, N., Woodward, F.I., and Zaehle, S. 2007. Fluxnet and modelling the global carbon cycle. Global Change Biology 13, 610-633, doi:10.1111/j.1365-2486.2006.01223.x.
• Hansen, J., Sato, Mki., Ruedy, R., Kharecha, P., Lacis, A., Miller, R.L., Nazarenko, K., Lo, K., Schmidt, G.A., Russell, G., Aleinov, I., Bauer, S., Baum, E., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Cohen, A., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., and 25 co-authors. 2007. Climate simulations for 1880-2003 with GISS modelE. Climate Dynamics 29, 661-696. doi:10.1007/s00382-007-0255-8.
• Hansen, J., Sato, Mki., Ruedy, R., Kharecha, P., Lacis, A., Miller, R.L., Nazarenko, L., Lo, K., Schmidt, G.A., Russell, G., Aleinov, I., Bauer, S., Baum, E., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Cohen, A., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., and 25 co-authors. 2007. Dangerous human-made interference with climate: A GISS modelE study. Atmospheric Chemistry and Physics 7, 2287-2312, www.atmos-chem-phys.net/7/2287/2007/

2006

• Schmidt, G. A., Ruedy, R., Hansen, J. E., Aleinov, I., Bell, N., Bauer, M., Bauer, S., Cairns, B., Cheng, Y., DelGenio, A., Faluvegi, G., Friend, A.D., and 23 co-authors. 2006. Present day atmospheric simulations using GISS ModelE: Comparison to in-situ, satellite and reanalysis data. Journal of Climate 19, 153-192, doi:10.1175/JCLI3612.1.

2005

• Ciais, P., Reichstein, M, Viovy, N., Granier, A., Ogée, J., Allard, V., Aubinet, M., Buchmann, N., Bernhofer, Chr., Carrara, A., Chevallier, F., De Noblet, N., Friend, A.D., and 20 co-authors. 2005. European-wide reduction in primary productivity caused by heat and drought in 2003. Nature 437, 529-533. doi:10.1038/nature03972.
• Friend, A.D. and Kiang, N.Y. 2005. Land-surface model development for the GISS GCM: Effects of improved canopy physiology on simulated climate. Journal of Climate 18, 2883-2902, doi:10.1175/JCLI3425.1.
• Hansen, J., Sato, Mki., Ruedy, R., Nazarenko, L., Lacis, A., Schmidt, G.A., Russell, G., Aleinov, A., Bauer, M., Bauer, S., Bell, N., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Del Genio, T., Faluvegi, G., Fleming, E., Friend, A., and 26 co-authors. 2005. Efficacy of climate forcings. Journal of Geophysical Research 110, D18104, doi:1029/2005JD005776.
• Lathière, J., Hauglustaine, D.A., Friend, A.D., De Noblet-Ducoudré, N., Viovy, N., Folberth, G. 2005. Impact of climate variability and land use change on global biogenic volatile organic compounds emissions. Atmospheric Chemistry and Physics 6, 2129-2146, www.atmos-chem-phys.net/6/2129/2006/

2004

• Levy, P.E., Friend, A.D., White, A., and Cannell, M.G.R. 2004. The influence of land use change on global-scale fluxes of carbon from terrestrial ecosystems. Climatic Change 67(2-3), 185-209, doi:10.1007/s10584-004-2849-z.
• Levy, P.E., Cannell, M.G.R., and Friend, A.D. 2004. Modelling the impact of future changes in climate, CO₂ concentration and land use on natural ecosystems and the terrestrial carbon sink. Global Environmental Change 14(1), 21-30, doi:10.1016/j.gloenvcha.2003.10.005.

2001

• Ciais, P., Friedlingstein, P., Friend, A., and Schimel, D.S. 2001. Integrating global models of terrestrial primary productivity. In: Terrestrial Global Productivity. Roy, J. et al. (Eds). Academic Press, San Diego. pp. 449-478.
• Cramer, W., Bondeau, A., Woodward, F.I., Prentice, I.C., Betts, R.A., Brovkin, V., Cox, P.M., Fisher, V., Foley, J., Friend, A.D., and 7 co-authors. 2001. Global response of terrestrial ecosystem structure and function to CO₂ and climate change: results from six dynamic global vegetation models. Global Change Biology 7, 357-373, doi:10.1046/j.1365-2486.2001.00383.x.
• Friend, A.D. 2001. Modelling canopy CO₂ fluxes: are 'big-leaf' simplifications justified? Global Ecology and Biogeography 10, 603-619, 10.1046/j.1466-822x.2001.00268.x.
• Wullschleger, S.D., Jackson, R.B., Currie, W.S., Friend, A.D., Luo, Y., Mouillot, F., Pan, Y., Shao, G. 2001. Below-ground processes in gap models for simulating forest response to global change. Climatic Change 51, 449-473, 10.1023/A:1012570821241.

2000

• Friend, A.D. and White, A. 2000. Evaluation and analysis of a dynamic terrestrial ecosystem model under preindustrial conditions at the global scale. Global Biogeochemical Cycles 14(4), 1173-1190.
• Murray, M.B., Smith, R.I., Friend, A., and Jarvis, P.G. 2000. Effect of elevated [CO₂] and varying nutrient application rates on physiology and biomass accumulation of Sitka spruce (Picea sitchensis). Tree Physiology 20(7), 421-434.
• White, A., Cannell, M.G.R., and Friend, A.D. 2000. CO₂ stabilization, climate change and the terrestrial carbon sink. Global Change Biology 6, 817-833, doi:10.1046/j.1365-2486.2000.00358.x.
• White, A., Cannell, M.G.R., and Friend, A.D. 2000. The high-latitude terrestrial carbon sink: a model analysis. Global Change Biology 6, 227-245, doi:10.1046/j.1365-2486.2000.00302.x.

1999

• Cannell, M.G.R., Mobbs, D.C., Friend, A.D., and Ågren, G.I. 1999. Air chemistry and effects on tree growth as indicated by preliminary modelling results. In: Relationships Between Recent Changes of Growth and Nutrition of Norway Spruce, Scots Pine, and European Beech Forests in Europe - RECOGNITION - . EFI Working Paper 19. Rehfuess, K.-E., Ågren, G.I., Andersson, F., Cannell, M.G.R., Friend, A., Hunter, I., Kahle, H.-P., Prietzel, J., and Spiecker, H. pp. 27-53.
• White, A., Cannell, M.G.R., and Friend, A.D. 1999. Climate change impacts on ecosystems and the terrestrial carbon sink: a new assessment. Global Environmental Change 9, S21-S30.

1998

• Cannell, M.G.R., Thornley, J.H.M., Mobbs, D.C., Friend, A.D. 1998. UK conifer forests may be growing faster in response to increased N deposition, atmospheric CO₂ and temperature. Forestry 71, 277-296.
• Friend, A.D. 1998. Biochemical modelling of leaf photosynthesis. In: European forests and global change: the likely impact of rising CO₂ and temperature. P. G. Jarvis (Ed). Cambridge, Cambridge University Press. pp. 335-346.
• Friend, A.D. 1998. Parameterisation of a global daily weather generator for terrestrial ecosystem and biogeochemical modelling. Ecological Modelling 109, 121-140.
• Friend, A., Kellomäki, S., and Kruijt, B. 1998. Modelling leaf, tree and forest responses to increasing CO₂ and temperature. In: European forests and global change: the likely impacts of rising CO₂ and temperature. P. G. Jarvis (Ed). Cambridge, Cambridge University Press. pp. 293-334.
• Mobbs, D.C., Cannell, M.G.R., Crout, N.M.J., Lawson, G.J., Friend, A.D., and Arah, J. 1998. Complementarity of light and water use in tropical agroforests. I. Theoretical model outline, performance and sensitivity. Forest Ecology and Management, 102, 259-274.

1997

• Friend, A.D., Stevens, A. K., Knox, R. G., and Cannell, M. G. R. 1997. A process-based, terrestrial biosphere model of ecosystem dynamics (Hybrid v3.0). Ecological Modelling 95, 249-287.
• White, A., Friend, A.D., and Cannell, M.G.R. 1997. The impact of climate change on natural vegetation. In: Climate Change and its Impacts: a Global Perspective. UK Department of the Environment, Transport and Regions, UK Met. Office, Bracknell, 16pp.

1996

• Kramer, K., Friend, A.D. and Leinonen, I. 1996. Modelling comparison to evaluate the importance of phenology and spring frost damage for the effects of climate change on growth of mixed temperate zone deciduous forests. Climate Research, 7, 31-41.
• Melillo, J.M., et al., (inc. Friend, A.D.) 1996. Terrestrial biotic responses to environmental change and feedbacks to climate. In: Climate change 1995: the science of climate change. J.T. Houghton, L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg, and K. Maskell (Eds). Cambridge: Cambridge University Press. pp. 445-481.
• Ryan, M.G., Hunt, E.R., McMurtrie, R.E., Ågren, G.I., Aber, J.D., Friend, A.D., Rastetter, E.B., Pulliam, W.M., Raison, R.J., and Linder, S. 1996. Comparing models of ecosystem function for coniferous forests. I. Model description and validation. In: Global Change: Effects on Coniferous Forests and Grasslands. SCOPE 56. J.M. Melillo, G.I. Ågren, and A. Breymeyer (Eds). John Wiley and Sons, New York. pp. 313-362.
• Ryan, M.G., McMurtrie, R.E., Hunt, E.R., Friend, A.D., Pulliam, W.M., Ågren, G.I., Aber, J.D., and Rastetter, E.B. 1996. Comparing models of ecosystem function for coniferous forests. II. Simulations of the effect of climate change. In: Global Change: Effects on Coniferous Forests and Grasslands. SCOPE 56. J.M. Melillo, G.I. Ågren, and A. Breymeyer (Eds). John Wiley and Sons, New York. pp. 363-387.

1995

• Friend, A.D. 1995. PGEN - an integrated model of leaf photosynthesis, transpiration, and conductance. Ecological Modelling 77, 233-255.
• Friend, A.D. and Cox, P.M. 1995. Modelling the effects of atmospheric CO₂ on vegetation-atmosphere interactions. Agricultural and Forest Meteorology 73, 285-295.

1994

• Murray, M.B., Friend, A.D., and Leith, I.D. 1994. Effects of elevated CO₂ on Sitka spruce (Picea sitchensis (Bong.) Carr). March 1994. In: Carbon sequestration by vegetation in the UK. UK Department of the Environment. 23 pp.
• Murray, M.B., Smith, R.I., Leith, I.D., Fowler, D., Lee, H.S.J., Friend, A.D., and Jarvis, P. 1994. Effects of elevated CO₂, nutrition and climatic warming on bud phonology in Sitka spruce (Picea sitchensis (Bong.) Carr) and its impact on frost tolerance. Tree Physiology 14, 691-706.

1993

• Friend, A.D. 1993. Final report on modelling in the EPOC-13 Project. In: An investigation of the impact of elevated CO₂ on the responses of European forests. Commission of the European Communities.
• Friend, A.D. 1993. The prediction and physiological significance of tree height. In: Vegetation Dynamics and Global Change. A.M. Solomon and H.H. Shugart (Eds). New York: Chapman and Hall. pp. 101-115.
• Friend, A.D., Murray, M.B., and Leith, I.D. 1993. Effects of elevated CO₂ on the growth, phenology, and physiology of Picea sitchensis. In: Carbon sequestration by vegetation in the UK. UK Department of the Environment.
• Friend, A.D., Shugart, H.H., and Running, S.W. 1993. A physiology-based gap model of forest dynamics. Ecology 74, 792-797.

1992

• Friend, A.D., Cox, P. and Dewar, R.C. 1992. Modelling the fluxes of water and carbon from plant canopies. In: Proceedings of the Scientific Conference on Biospheric Aspects of the Hydrological Cycle, Toulouse.
• Friend, A.D., Murray, M.B., and Leith, I.D. 1992. Effects of elevated CO₂ on the growth, phenology, and physiology of Picea sitchensis. In: Carbon sequestration by vegetation in the UK. Department of the Environment.

1991

• Friend, A.D. 1991. Use of a model of photosynthesis and leaf microenvironment to predict optimal stomatal conductance and leaf nitrogen partitioning. Plant, Cell and Environment 14, 895-905.

1990

• Friend, A.D. and Woodward, F.I. 1990. Evolutionary and ecophysiological responses of mountain plants to the growing season environment. Advances in Ecological Research 20, 59-124.

1989

• Friend, A.D., Woodward, F.I. and Switsur, V.R. 1989. Field measurements of photosynthesis, stomatal conductance, leaf nitrogen and δ¹³C along altitudinal gradients in Scotland. Functional Ecology 3, 117-122.

1988

• Woodward, F.I. and Friend, A.D. 1988. Controlled environment studies on the temperature responses of leaf extension in species of Poa with diverse altitudinal ranges. Journal of Experimental Botany 39, 411-420.

Teaching

• Undergraduate: Biogeography (second year); Earth System Processes and Feedbacks (third year); Atmospheric Chemistry and Global Change (Part III Chemistry)
• Postgraduate: Research Design for Environmental Science; MPhil in Environmental Science; PhD viva

External activities

• American Geophysical Union (member)
• European Geosciences Union (member)