Atmospheric Chemistry and Physics
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10.5194/acp-7-31-2007
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2007-01-10
Process-based estimates of terrestrial ecosystem isoprene emissions: incorporating the effects of a direct CO<sub>2</sub>-isoprene interaction
A. Arneth
almut.arneth@nateko.lu.se
Ü. Niinemets
S. Pressley
J. Bäck
P. Hari
T. Karl
S. Noe
I. C. Prentice
D. Serça
T. Hickler
A. Wolf
B. Smith
Department of Physical Geography and Ecosystems Analysis, Geobiosphere Science Centre, Lund University, Sölvegatan 12, 223 62, Lund, Sweden
Department of Plant Physiology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, Tartu 51010, Estonia
Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 64, Tartu 51014, Estonia
Washington State University, Department of Civil and Environmental Engineering, USA
Department of Forest Ecology, University of Helsinki, Finland
Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado, USA
QUEST, Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
Laboratoire d'Aerologie, Toulouse, France
Forest Ecology, ETH Zürich, Switzerland
In recent years evidence has emerged that the amount of isoprene emitted
from a leaf is affected by the CO<sub>2</sub> growth environment. Many – though not
all – laboratory experiments indicate that emissions increase significantly
at below-ambient CO<sub>2</sub> concentrations and decrease when concentrations
are raised to above-ambient. A small number of process-based leaf isoprene
emission models can reproduce this CO<sub>2</sub> stimulation and inhibition.
These models are briefly reviewed, and their performance in standard
conditions compared with each other and to an empirical algorithm. One of
the models was judged particularly useful for incorporation into a dynamic
vegetation model framework, LPJ-GUESS, yielding a tool that allows the
interactive effects of climate and increasing CO<sub>2</sub> concentration on
vegetation distribution, productivity, and leaf and ecosystem isoprene
emissions to be explored. The coupled vegetation dynamics-isoprene model is
described and used here in a mode particularly suited for the ecosystem
scale, but it can be employed at the global level as well.
<br><br>
Annual and/or daily isoprene emissions simulated by the model were evaluated
against flux measurements (or model estimates that had previously been
evaluated with flux data) from a wide range of environments, and agreement
between modelled and simulated values was generally good. By using a dynamic
vegetation model, effects of canopy composition, disturbance history, or
trends in CO<sub>2</sub> concentration can be assessed. We show here for five
model test sites that the suggested CO<sub>2</sub>-inhibition of leaf-isoprene
metabolism can be large enough to offset increases in emissions due to
CO<sub>2</sub>-stimulation of vegetation productivity and leaf area growth. When
effects of climate change are considered atop the effects of atmospheric
composition the interactions between the relevant processes will become even
more complex. The CO<sub>2</sub>-isoprene inhibition may have the potential to
significantly dampen the expected steep increase of ecosystem isoprene
emission in a future, warmer atmosphere with higher CO<sub>2</sub> levels; this
effect raises important questions for projections of future atmospheric
chemistry, and its connection to the terrestrial vegetation and carbon
cycle.
Abbot, D., Palmer, P. I., Martin, R. V., Chance, K. V., Jacob, D., and Guenther, A.: Seasonal and interannual variability of North America isoprene emission as determined by formaldehyde column measurements from space, Geophys. Res. Lett., 30, 1886, doi:10.1029/2003GL017336, 2003.
Affek, H. P. and Yakir, D.: Natural abundance carbon isotope composition of isoprene reflects incomplete coupling between isoprene synthesis and photosynthetic carbon flow, Plant Physiol., 131, 1727–1736, 2003.
Andrews, T. J. and Kane, H. J.: Pyruvate is a by-product of catalysis of ribulosebisphosphate carboxylase/oxygenase, J. Biol. Chem., 266, 9447–9452, 1991.
Atkinson, R.: Atmospheric chemistry of VOCs and NO<sub>x</sub>, Atmos. Environ., 34, 2063–2101, 2000.
Atkinson, R. and Arey, J.: Gas-phase tropospheric chemistry of biogenic volatile organic compounds: a review, Atmos. Environ., 37, 197–219, 2003.
Bäck, J., Hari, P., Hakola, H., Juurola, E., and Kulmala, M.: Dynamics of monoterpene emissions in Pinus sylvestris during early spring, Boreal Environ. Res., 10, 409–424, 2005.
Baldocchi, D. D., Fuentes, J. D., Bowling, D. R., Turnipseed, A. A., and Monson, R. K.: Scaling isoprene fluxes from leaves to canopies: Test cases over a boreal aspen and a mixed species temperate forest, J. Appl. Meteorol., 38, 885–898, 1999.
Benjamin, M. T., Sudol, M., Bloch, L., and Winer, A. M.: Low-emitting urban forests: a taxonomic methodology for assigning isoprene and monoterpene emission rates, Atmos. Environ., 30, 1437–1452, 1996.
Brüggemann, N. and Schnitzler, J. P.: Relationship of isopentyl diphosphate (IDP) isomerase activity to isoprene emission of oak leaves, Tree Physiology, 22, 1011–1018, 2002.
Buckley, P. T.: Isoprene emissions from a Florida scrub oak species grown in ambient and elevated carbon dioxide, Atmos. Environ., 35, 631–634, 2001.
Campbell, G. S. and Norman, J. M.: Introduction to Environmental Biophysics, Springer Verlag, New York, 1998.
Centritto, M., Nascetti, P., Petrilli, L., Raschi, A., and Loreto, F.: Profiles of isoprene emission and photosynthetic parameters in hybrid poplars exposed to free-air CO<sub>2</sub> enrichment, Plant. Cell. Environ., 27, 403–412, 2004.
Claeys, M., Graham, B., Vas, G., Wang, W., Vermeylen, R., Pashynska, V., Cafmeyer, J., Guyon, P., Andreae, M. O., Artaxo, P., and Maenhaut, W.: Formation of secondary organic aerosols through photooxidation of Isoprene, Science, 303, 1173–1176, 2004.
Collatz, G. J., Ball, J. T., Grivet, C., and Berry, J. A.: Physiological and Environmental regulation of stomatal conductance, photosynthesis and transpiration: A model that includes a laminar boundary layer, Agric. Forest Meteorol., 54, 107–136, 1991.
Cowan, I. R.: Regulation of water use in relation to carbon gain in higher plants, in: Physiological Plant Ecology II. Water Relations and Carbon Assimilation, edited by: Lange, O. L., Nobel, P. S., Osmond, C. B., and Ziegler, H., Springer, Berlin, 589–613, 1982.
Curtis, P. S., Hanson, P. J., Bolstad, P., Barford, C., Randolph, J. C., Schmid, H. P., and Wilson, K. B.: Biometric and eddy-covariance based estimates of annual carbon storage in five eastern North American deciduous forests, Agric. Forest Meteorol., 113, 3–19, 2001.
Curtis, P. S., Vogel, C. S., Gough, C. M., Schmid, H. P., Su, H. B., and Bovard, B. D.: Respiratory carbon losses and the carbon-use efficiency of a northern hardwood forest, 1999–2003, New Phytol., 167, 437–456, 2005.
Delwiche, C. F. and Sharkey, T. D.: Rappid appearance of $^13$C in biogenic isoprene when $^13$C-CO<sub>2</sub> is fed into intact leaves, Plant, Cell Environ., 16, 587–591, 1993.
Eisenreich, W., Rohdich, F., and Bacher, A.: Deoxyxylulose phosphate pathway to terpenoids, Trends in Plant Science, 6, 78–84, 2001.
Fall, R. and Monson, R. K.: Isoprene emission rate and intercellular isoprene concentration as influenced by stomatal distribution and conductance, Plant Physiol., 100, 987–992, 1992.
Farquhar, G. D.: Models of integrated photosynthesis of cells and leaves, Philosophical Transactions of the Royal Society of London, B 323, 357–367, 1989.
Farquhar, G. D., von Caemmerer, S., and Berry, J. A.: A biochemical model of photosynthetic CO<sub>2</sub> assimilation in leaves of C<sub>3</sub> species, Planta, 149, 78–90, 1980.
Friend, A., Arneth, A., Kiang, N. Y., Lomas, M. R., Ogéé, J. C. R., Running, S. W., Santaren, J. D., Sitch, S., Viovy, N., and Woodward, F. I.: FLUXNET and global carbon modelling, Global Change Biol., doi:10.1111/j.1365-2486.2006.01223.x, 2006.
Fuentes, J. D., Lerdau, M., Atkinson, R., Baldocchi, D., Bottenheim, J. W., Ciccioli, P., Lamb, B., Geron, C., Gu, L., Guenther, A., Sharkey, T. D., and Stockwell, W.: Biogenic hydrocarbons in the atmospheric boundary layer: A review, Bull. Am. Meteorol. Soc., 81, 1537–1575, 2000.
Fuentes, J. D. and Wang, D.: On the seasonality of isoprene emissions from a mixed temperate forest, Ecol. Appl., 9, 1118–1131, 1999.
Fuentes, J. D., Wang, D., and Gu, L.: Seasonal variations in isoprene emissions from a boreal aspen forest, J. Appl. Meteorol., 38, 855–869, 1999.
Gedney, N., Cox, P. M., and Huntingford, C.: Climate feedback from wetland methane emissions, Geophys. Res. Lett., 31, L20503, doi:10.1029/2004GL020919, 2004.
Geron, C., Guenther, A., Greenberg, J., Loescher, H. W., Clark, D., and Baker, B.: Biogenic volatile organic compound emissions from a lowland tropical wet forest in Costa Rica, Atmos. Environ., 36, 3793–3802, 2002.
Geron, C., Guenther, A., Sharkey, T. D., and Arnts, R. R.: Temporal variability in basal isoprene emission factor, Tree Physiology, 20, 799–805, 2000.
Geron, C., Harley, P., and Guenther, A.: Isoprene emission capacity for US tree species, Atmos. Environ., 35, 3341–3352, 2001.
Geron, C. D., Guenther, A. B., and Pierce, T. E.: An improved model for estimating emissions of volatile organic-compounds from forests in the eastern United-States, J. Geophys. Res., 99, 12 773–12 791, 1994.
Geron, C. D., Nie, D., Arnts, R. R., Sharkey, T. D., Singsaas, E. L., Vanderveer, P. J., Guenther, A., Sickles, J. E., and Kleindienst, T. E.: Biogenic isoprene emission: Model evaluation in a southeastern United States bottomland deciduous forest, J. Geophys. Res., 102, 18 889–18 901, 1997.
Gerten, D., Lucht, W., Schaphoff, S., Cramer, W., and Wagner, W.: Hydrologic resilience of the terrestrial biosphere, Geophys. Res. Lett., 32, L21408, doi:10.1029/2005GL024247, 2005.
Gerten, D., Schaphoff, S., Haberlandt, U., Lucht, W., and Sitch, S.: Terrestrial vegetation and water balance – hydrological evaluation of a dynamic global vegetation model, J. Hydrol., 286, 249–270, 2004.
Goldstein, A. H., Goulden, M. L., Munger, J. W., Wofsy, S. C., and Geron, C. D.: Seasonal course of isoprene emissions from a midlatitude deciduous forest, J. Geophys. Res., 103, 31 045–31 056, 1998.
Guenther, A.: Seasonal and spatial variations in natural volatile organic compound emissions, Ecol. Appl., 7, 34–45, 1997.
Guenther, A., Hewitt, C. N., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., McKay, W. A., Pierce, T., Scholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., and Zimmermann, P.: A global model of natural volatile organic compound emissions, J. Geophys. Res., 100, 8873–8892, 1995.
Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181–3210, 2006.
Guenther, A., Zimmerman, P., Klinger, L., Greenberg, J., Ennis, C., Davis, K., Pollock, W., Westberg, H., Allwine, E., and Geron, C.: Estimates of regional natural volatile organic compound fluxes from enclosure and ambient measurements, J. Geophys. Res., 101, 1345–1359, 1996.
Guenther, A. B., Zimmerman, P. R., Harley, P. C., Monson, R. K., and Fall, R.: Isoprene and monoterpene emission rate variability – Model evaluations and sensitivity analyses, J. Geophys. Res., 98, 12 609–12 617, 1993.
Hakola, H., Rinne, J., and Laurila, T.: The hydrocarbon emission rates of tea-leafed willow (Salix phylicifolia), silver birch (Betula pendula) and European aspen (Populus tremula), Atmos. Environ., 32, 1825–1833, 1998.
Hanson, D. T. and Sharkey, T. D.: Rate of acclimation of the capacity for isoprene emission in response to light and temperature, Plant, Cell Environ., 24, 937–946, 2001.
Hari, P. and Mäkelä, A.: Annual pattern of photosynthesis in Scots pine in the boreal zone, Tree Physiology, 2, 169–175, 2003.
Harley, P., Vasconcellos, P., Vierling, L., Pinheiro, C. C. D., Greenberg, J., Guenther, A., Klinger, L., De Almeida, S. S., Neill, D., Baker, T., Phillips, O., and Malhi, Y.: Variation in potential for isoprene emissions among Neotropical forest sites, Global Change Biol., 10, 630–650, 2004.
Harley, P. C., Thomas, R. B., Reynolds, J. F., and Strain, B. R.: Modeling photosynthesis of cotton grown in elevated CO<sub>2</sub>, Plant, Cell Environ., 15, 271–282, 1992.
Haxeltine, A., Prentice, I. C., and Creswell, D. I.: A coupled carbon and water flux model to predict vegetation structure, J. Veg. Sci., 7, 651–666, 1996.
Henze, D. and Seinfeld, J. H.: Global secondary organic aerosol from isoprene oxidation, Geophys. Res. Lett., 33, L09812, doi:10.1029/2006GL025976, 2006.
Hewitt, C. N. and Street, R. A.: A qualitative assessment of the emission of non-methane hydrocarbon compounds from the biosphere to the atmosphere in the UK: present knowledge and uncertainties, Atmos. Environ., 26A, 3069–3077, 1992.
Hickler, T., Smith, B., Sykes, M. T., Davis, M. B., Sugita, S., and Walker, K.: Using a generalized vegetation model to simulate vegetation dynamics in northeastern USA, Ecology, 85, 519–530, 2004.
Huber, L., Laville, P., and Fuentes, J. D.: Uncertainties in Isoprene Emissions from a Mixed Deciduous Forest Estimated Using a Canopy Microclimate Model, J. Appl. Meteorol., 38, 899–912, 1999.
Karl, T., Potosnak, M., Guenther, A., Clark, D., Walker, J., Herrick, J. D., and Geron, C.: Exchange processes of volatile organic compounds above a tropical rain forest: Implications for modeling tropospheric chemistry above dense vegetation, J. Geophys. Res., 109, D18306, doi:10.1029/2004JD004738, 2004.
Kelliher, F. M., Leuning, R., and Schulze, E.-D.: Evaporation and canopy characteristics of coniferous forests and grasslands, Oecologia, 95, 153–163, 1993.
Kesselmeier, J., Ciccioli, P., Kuhn, U., Stefani, P., Biesenthal, T., Rottenberger, S., Wolf, A., Vitullo, M., Valentini, R., Nobre, A., Kabat, P., and Andreae, M. O.: Volatile organic compound emissions in relation to plant carbon fixation and the terrestrial carbon budget, Global Biogeochem. Cycles, 16, 73/1–73/9, 2002.
Kesselmeier, J. and Staudt, M.: Biogenic volatile organic compounds (VOC): An overview on emission, physiology and ecology, J. Atmos. Chem., 33, 23–88, 1999.
Kirschbaum, M. U. F., Kueppers, M., Schneider, H., Giersch, C., and Noe, S.: Modelling photosynthesis in fluctuating light with inclusion of stomatal conductance, biochemical activation and pools of key photosynthetic intermediates, Planta, 204, 16–26, doi:10.1007/s004250050225, 1997.
Koca, D., Smith, B., and Sykes, M. T.: Modelling regional climate change effects on potential natural ecosystems in Sweden, Clim. Change, 78, 381–406, doi:10.1007/s10584-005-9030-1, 2006.
Kourtchev, I., Ruuskanen, T., Maenhaut, W., Kulmala, M., and Claeys, M.: Observation of 2-methyltetrols and related photo-oxidation products of isoprene in boreal forest aerosols from Hyytiälä, Finland, Atmos. Chem. Phys., 5, 2761–2770, 2005.
Krinner, G., Viovy, N., de Noblet-Ducoudré, N., Ogéé, J., Polcher, J., Friedlingstein, P., Ciais, P., Sitch, S., and Prentice, I. C.: A dynamic global vegetation model for studies of the coupled atmosphere-biosphere system, Global Biogeochem. Cycles, 19, GB1015, doi:10.1029/2003GB002199, 2005.
Kuhn, U., Rottenberger, S., Biesenthal, T., Wolf, A., Schebeske, G., Ciccioli, P., and Kesselmeier, J.: Strong correlation between isoprene emission and gross photosynthetic capacity during leaf phenology of the tropical tree species Hymenaea courbaril with fundamental changes in volatile organic compounds emission composition during early leaf development, Plant, Cell Environ., 27, 1469–1485, 2004.
Kuzma, J. and Fall, R.: Leaf isoprene emission rate is dependent on leaf development and the level of isoprene synthase, Plant Physiol., 101, 435–440, 1993.
Lamb, B., Pierce, T., Baldocchi, D., Allwine, E., Dilts, S., Westberg, H., Geron, C., Guenther, A., Klinger, L., Harley, P., and Zimmerman, P.: Evaluation of forest canopy models for estimating isoprene emissions, J. Geophys. Res., 101, 22 787–22 797, 1996.
Lathière, J., Hauglustaine, D. A., and De Noblet-Ducoudré, N.: Past and future changes in biogenic volatile organic compound emissions simulated with a global dynamic vegetation model, Geophys. Res. Lett., 32, L20818, doi:10.1029/2005GL024164, 2005.
Lathiere, J., Hauglustaine, D. A., Friend, A., De Noblet-Ducoudré, N., Viovy, N., and Folberth, G.: Impact of climate variability and land use changes on global biogenic volatile organic compound emissions, Atmos. Chem. Phys., 6, 2199–2146, 2005.
Lehning, A., Zimmer, W., Zimmer, I., and Schnitzler, J.-P.: Modeling of annual variations of oak (\textitQuercus robur) isoprene synthase activity to predict isoprene emission rates, J. Geophys. Res., 106, 3157–3166, 2001.
Lerdau, M. and Gray, D.: Ecology and evolution of light-dependent and light-independent phytogenic volatile organic carbon, New Phytol., 157, 199–211, 2003.
Levis, S., Wiedinmyer, C., Bonan, G. B., and Guenther, A.: Simulating biogenic volatile organic compound emissions in the Community Climate System Model, J. Geophys. Res., 108, 4659, doi:10.1029/2002JD003203, 2003.
Lichtenthaler, H. K.: The 1-deoxy-D-xylulose-5-phosphate pathway of isoprenoid biosynthesis in plants, Ann. Rev. Plant Physiol. Plant Molecular Biol., 50, 47–65, 1999.
Lindfors, V. and Laurila, T.: Biogenic volatile organic compound (VOC) emissions from forests in Finland, Boreal Env. Res., 5, 95–113, 2000.
Long, S. P.: Modification of the response of photosynthetic productivity to rising temperature by atmospheric CO<sub>2</sub> concentrations: Has its importance been underestimated? Plant, Cell Environ., 14, 729–739, 1991.
Loreto, F. and Sharkey, T.: A gas-exchange study of photosynthesis and isoprene emission in \textitQuercus rubra L, Planta, 182, 523–531, 1990.
Loreto, F., and Sharkey, T. D.: On the relationship between isoprene emission and photosynthetic metabolites under different environmental conditions, Planta, 189, 410–424, 1993.
Martin, M. J.: Models of the interactive effect of rising ozone, carbon dioxide and temperature on canopy carbon dioxide exchange and isoprene emission. Pages 220, Biological and Chemical Sciences, University of Essex, Essex, 1997.
Martin, M. J., Stirling, C. M., Humphries, S. W., and Long, S. P.: A process-based model to predict the effects of climatic change on leaf isoprene emission rates, Ecol. Modell., 131, 161–174, 2000. %
%Matsunaga, S. N., Wiedinmyer, C., Guenther, A., Orlando, J. J., Karl, T., %Toohey, d. W., Greenberg, J. P., and Kajii, Y.: Isoprene oxidation products %are a significant atmospheric aerosol component, Atmos. Chem. Phys. Discuss., 5, 11 143–11 156, 2005. %\blackbox\bf Please check if this reference can be updated to "Atmos. Chem. %Phys."
Monson, R., Harley, P., Litvak, M. E., Wildermuth, M., Guenther, A., Zimmerman, P. R., and Fall, R.: Environmental and developmental controls over the seasonal pattern of isoprene emission from aspen leaves, Oecologia, 99, 260–270, 1994.
Monson, R. K. and Fall, R.: Isoprene emission from aspen leaves: Influence of environment and relation to photosynthesis and photorespiration, Plant Physiol., 90, 267–274, 1989a.
Monson, R. K. and Fall, R.: Isoprene emissions from aspen leaves. Influence of environment and relation to photosynthesis, Plant Physiol., 90, 267–274, 1989b.
Monson, R. K. and Holland, E.: Biospheric trace gas fluxes and their control over tropospheric chemistry, Ann. Rev. Ecol. Syst., 32, 547–576, 2001.
Monson, R. K., Jaeger, C. H., Adams, W. W. I., Driggers, E. M., Silver, G. M., and Fall, R.: Relationship among isoprene emission rate, photosynthesis, and isoprene synthase activity as influenced by temperature, Plant Physiol., 98, 1175–1180, 1992.
Monson, R. K., Lerdau, M. T., Sharkey, T. D., Schimel, D. S., and Fall, R.: Biological aspects of constructing volatile organic compound emission inventories, Atmos. Environ., 29, 2989–3002, 1995.
Morales, P., Sykes, M. T., Prentice, I. C., Smith, P., Smith, B., Bugmann, H., Zierl, B., Friedlingstein, P., Viovy, N., Sabaté, S., Sánchez, A., Pla, E., Gracia, C. A., Sitch, S., Arneth, A., and Ogéé, J.: Comparing and evaluating process-based ecosystem model predictions of carbon and water fluxes in major European forest biomes, Global Change Biol., 11, 2211–2233, doi:10.1111/j.1365–2486.2005.01036.x, 2005.
Naik, V., Delire, C., and Wuebbles, D. J.: Sensitivity of global biogenic isoprenoid emissions to climate variability and atmospheric CO<sub>2</sub>, J. Geophys. Res., 109, D06301, doi:10.1029/2003JD004236, 2004.
Niinemets, Ü.: Costs of production and physiology of emission of volatile leaf isoprenoids, pages 241–278 in Hemantaranjan, ed. Advances in Plant Physiology, Scientific Publishers, Jodhpur, 2004.
Niinemets, U. and Reichstein, M.: Controls on the emission of plant volatiles through stomata: A sensitivity analysis, J. Geophys. Res., 108, 4211, doi:10.1029/2002JD002626, 2003.
Niinemets, U., Tenhunen, J. D., Harley, P. C., and Steinbrecher, R.: A model of isoprene emission based on energetic requirements for isoprene synthesis and leaf photosynthetic properties for \textitLiquidambar and \textitQuercus, Plant, Cell Environ., 22, 1319–1335, 1999.
Pegoraro, E., Abrell, L., Van Haren, J., Barron-Gafford, G., Grieve, K. A., Malhi, Y., Murthy, R., and Lin, G.: The effect of elevated atmospheric CO<sub>2</sub> and drought on sources and sinks of isoprene in a temperate and tropical rainforest mesocosm, Global Change Biol., 11, 1234–1246, 2005a.
Pegoraro, E., Rey, A., Barron-Gafford, G., Monson, R., Malhi, Y., and Murthy, R.: The interacting effects of elevated atmospheric CO<sub>2</sub> concentration, drought and leaf-to-air vapour pressure deficit on ecosystem isoprene fluxes, Oecologia, 146, 120–129, 2005b.
Pegoraro, E., Rey, A., Bobich, E. G., Barron-Gafford, G., Grieve, K. A., Malhi, Y., and Murthy, R.: Effect of elevated CO<sub>2</sub> concentration and vapour pressure deficit on isoprene emission from leaves of Populus deltoides during drought, Functional Plant Biol., 31, 1137–1147, 2004.
Pétron, G., Harley, P., Greenberg, J., and Guenther, A.: Seasonal temperature variations influence isoprene emission, Geophys. Res. Lett., 28, 1707–1710, 2001.
Poisson, N., Kanakidou, M., and Crutzen, P. J.: Impact of non-methane hydrocarbons on tropospheric chemistry and the oxidizing power of the global troposphere: 3-dimensional modelling results, J. Atmos. Chem., 36, 157–203, doi:10.1023/A:1006300616544, 2000.
Possell, M., Heath, J., Hewitt, N. C., Ayres, E., and Kerstiens, G.: Interactive effects of elevated CO<sub>2</sub> and soil fertility on isoprene emissions from \textitQuercus robur, Global Change Biol., 10, 1835–1843, 2004.
Possell, M., Nicholas Hewitt, C., and Beerling, D. J.: The effects of glacial atmospheric CO<sub>2</sub> concentrations and climate on isoprene emissions by vascular plants, Global Change Biol., 11, 60–69, 2005.
Pressley, S., Lamb, B., Westberg, H., Flaherty, J., Chen, J., and Vogel, C.: Long-term isoprene flux measurements above a northern hardwood forest, J. Geophys. Res., 110, D07301, doi:10.1029/2004JD005523, 2005.
Rapparini, F., Baraldi, R., Miglietta, F., and Loreto, F.: Isoprenoid emission in trees of \textitQuercus pubescens and \textitQuercus ilex with lifetime exposure to naturally high CO<sub>2</sub> environment, Plant Cell Env., 27, 381–391, 2004.
Rasmussen, R.: Isoprene: Identified as a forest-type emission to the atmosphere, Environ. Sci. Technol., 4, 667–671, 1970.
Rohdich, F., Kis, K., Bacher, A., and Eisenreich, W.: The non-mevalonate pathway of isoprenoids: genes, enzymes and intermediates, Current Opinion in Chemical Biol., 5, 535–540, 2001.
Rosenstiel, T. N., Ebbets, A. L., Khatri, W. C., Fall, R., and Monson, R. K.: Induction of Poplar leaf nitrate reductase: A test of extrachloroplastic control of Isoprene emission rate, Plant Biol., 6, 12–21, 2004.
Rosenstiel, T. N., Potosnak, M. J., Griffin, K. L., Fall, R., and Monson, R. K.: Increased CO<sub>2</sub> uncouples growth from isoprene emission in an agriforest ecosystem, Nature, 421, 256–259, 2003.
Sanderson, M. G., Jones, C. D., Collins, W. J., Johnson, C. E., and Derwent, R. G.: Effect of climate change on isoprene emissions and surface ozone levels, Geophys. Res. Lett., 30, 1936, doi:10.1029/2003GL017642, 2003.
Schnitzler, J. P., Lehning, A., and Steinbrecher, R.: Seasonal pattern of isoprene synthase activity in \textitQuercus robur leaves and its significance for modeling isoprene emission rates, Botanica Acta, 110, 240–243, 1997.
Scholefield, P. A., Doick, K. J., Herbert, B. M. J., Hewitt, C. N. S., Schnitzler, J. P., Pinelli, P., and Loreto, F.: Impact of rising CO<sub>2</sub> on emissions of volatile organic compounds: isoprene emission from \textitPhragmites australis growing at elevated CO<sub>2</sub> in a natural carbon dioxide spring, 27, 393–401, 2004.
Sharkey, T. D. and Loreto, F.: Water stress, temperature, and light effects on the capacity for isoprene emission and photosynthesis of kudzu leaves, Oecologia, 95, 328–333, doi:10.1007/BF00320984, 1993.
Sharkey, T. D., Loreto, F., and Delwiche, C. F.: The biochemistry of isoprene emission from leaves during photosynthesis, in: Trace Gas Emissions by Plants, edited by: Sharkey, T. D., Holland, E. A., and Mooney, H. A., Academic Press, San Diego, 153–184, 1991a.
Sharkey, T. D., Loreto, F., and Delwiche, C. F.: High-carbon dioxide and sun shade effects on Isoprene emission from oak and aspen tree leaves, Plant Cell Environ., 14, 333–338, 1991b.
Sharkey, T. D., Singsaas, E. L., Lerdau, M., and Geron, C. D.: Weather effects in isoprene emission capacity and applications in emissions algorithms, Ecol. Appl., 9, 1132–1137, 1999.
Sharkey, T. D. and Yeh, S.: Isoprene emission from plants, Ann. Rev. Plant Physiol. Plant Molecular Biol., 52, 407–436, 2001.
Shindell, D. T., Walter, B. P., and Faluvegi, G.: Impacts of climate change on methane emissions from wetlands, Geophys. Res. Lett., 31, L21202, doi:10.1029/2004GL021009, 2004.
Simpson, D., Winiwarter, W., Börjesson, G., Cinderby, S., Ferreiro, A., Guenther, A., Hewitt, C. N., Janson, R., Khalil, M. A. K., Owen, S., Pierce, T., Puxbaum, H., Shearer, M., Skiba, U., Steinbrecher, R., Tarrasón, L., and Öquist, M. G.: Inventorying emissions from nature in Europe, J. Geophys. Res., 104, 8113–8152, 1999.
Singsaas, E. L., Laporte, M. M., Shi, J.-Z., Monson, R. K., Browling, D. R., Johnson, K., Lerdau, M., Jasentuliytana, A., and Sharkey, T. D.: Kinetics of leaf temperature fluctiation affect isoprene emission from red oak (\textitQuercus rubra) leaves, Tree Physiology, 19, 917–924, 1999. %
%Sitch, S., McGuire, A. D., Kimball, J., Gedney, N., Gamno, J., Engstrom, R., %Wolf, A., Zhuang, Q., and Clein, J.: Assessing the circumpolar carbon %balance of arctic tundra with remote sensing and process/based modelling %approaches, Ecol. Appl., in press, 2007.\blackbox\bf not cited in the text!
Sitch, S., Smith, B., Prentice, I. C., Arneth, A., Bondeau, A., Cramer, W., Kaplan, J. O., Levis, S., Lucht, W., Sykes, M. T., Thonicke, K., and Venevsky, S.: Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model, Global Change Biol., 9, 161–185, 2003.
Smith, B., Prentice, I. C., and Sykes, M. T.: Representation of vegetation dynamics in the modelling of terrestrial ecosystems: comparing two contrasting approaches within European climate space, Global Ecol. Biogeogr., 10, 621–637, 2001.
Stitt, M.: Rising CO<sub>2</sub> levels and their potential significance for carbon flow in photosynthetic cells, Plant, Cell Environ., 14, 741–762, 1991.
Stitt, M. and Krapp, A.: The interaction between elevated carbon dioxide and nitrogen nutrition: the physiological and molecular background, Plant, Cell Environ., 22, 583–621, 1999.
Tingey, D. T., Evans, R., and Gumpertz, M.: Effects of environmental conditions on isoprene emission from live oak, Planta, 152, 565–570, 1981.
Tognetti, R., Johnson, J. D., Michelozzi, M., and Raschi, A.: Response of foliar metabolism in mature trees of \textitQuercus pubescens and \textitQuercus ilex to long-term elevated CO<sub>2</sub>, Environmental and Experimental Botany, 39, 233–245, 1998.
Valdes, P. J., Beerling, D. J., and Johnson, D. E.: The ice age methane budget, Geophys. Res. Lett., 32, L02704, doi:10.1029/2004GL021004, 2005.
Velikova, V., Tsonev, T., Pinelli, P., Alessio, G. A., and Loreto, F.: Localized ozone fumigation system for studying ozone effects on photosynthesis, respiration, electron transport rate and isoprene emission in field-grown Mediterranean oak species, Tree Physiology, 25, 1523–1532, 2005.
Wang, K. Y. and Shallcross, D. E.: Modelling terrestrial biogenic isoprene fluxes and their potential impact on global chemical species using a coupled LSM-CTM model, Atmos. Environ., 34, 2909–2925, 2000.
Waring, R. H., Landsberg, J. J., and Williams, M.: Net primary production of forests: a constant fraction of gross primary production?, Tree Physiology, 18, 129–134, 1998.
Wiberley, A. E., Linskey, A. R., Falbel, T. G., and Sharkey, T. D.: Development of the capacity for isoprene emission in kudzu, Plant, Cell Environ., 28, 898–905, 2005.
Wiedinmyer, C., Guenther, A., Harley, P., Hewitt, C., Geron, C., Artaxo, P., Steinbrecher, R., and Rasmussen, R.: Global Organic Emissions from Vegetation, in: Emissions of Atmospheric Trace Compounds, edited by: Granier, C., Kluwer Publishing, Dordrecht, 121–182, 2004.
Wolfertz, M., Sharkey, T. D., Boland, W., Kuhnemann, F., Yeh, S., and Weise, S. E.: Biochemical regulation of isoprene emission, Plant Cell Environ., 26, 1357–1364, 2003.
Wolff, M., Seemann, M., Tse Sum Bui, B., Frapart, Y., Tritsch, D., Garcia Estrabot, A., Rodríguez-Concepción, M., Boronat, A., Marquet, A., and Rohmer, M.: Isoprenoid biosynthesis via the methylerythritol phosphate pathway: the (E)-4-hydroxy-3-methylbut-2-enyl diphosphate reductase (LytB/IspH) from Escherichia coli is a [4Fe-4S] protein, FEBS Lett., 541, 115–120, 2003.
Zimmer, W., Bruggemann, N., Emeis, S., Giersch, C., Lehning, A., Steinbrecher, R., and Schnitzler, J.-P.: Process-based modelling of isoprene emission by oak leaves, Plant, Cell Environ., 23, 585–595, 2000.
Zimmer, W., Steinbrecher, R., Körner, C., and Schnitzler, J.-P.: The process-based SIM-BIM model: towards more realistic prediction of isoprenen emissions from adult \textitQuercus petrea forest trees, Atmos. Environ., 37, 1665–1671, 2003.