BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-7-2203-2010 The emission factor of volatile isoprenoids: stress, acclimation, and developmental responses Niinemets Ü. 1 Arneth A. 2 Kuhn U. 3 Monson R. K. 4 Peñuelas J. 5 Staudt M. 6 Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51014, Estonia Division of Physical Geography and Ecosystem Analysis, Lund University, Sölvegatan 12, Lund, 22362, Sweden Federal Research Station Agroscope Reckenholz-Taenikon, ART, Zuerich, Switzerland Department of Ecology and Evolutionary Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309-0334, USA Global Ecology Unit CSIC-CEAB-CREAF, Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain Centre d'Ecologie Fonctionnelle et Evolutive (CEFE-CNRS), 1919 Route de Mende, Montpellier cedex 5, 34293, France 20 07 2010 7 7 2203 2223 Copyright: © 2010 Ü. Niinemets et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/7/2203/2010/bg-7-2203-2010.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/7/2203/2010/bg-7-2203-2010.pdf

The rate of constitutive isoprenoid emissions from plants is driven by plant emission capacity under specified environmental conditions (<i>E</i><sub>S</sub>, the emission factor) and by responsiveness of the emissions to instantaneous variations in environment. In models of isoprenoid emission, <i>E</i><sub>S</sub> has been often considered as intrinsic species-specific constant invariable in time and space. Here we analyze the variations in species-specific values of <i>E</i><sub>S</sub> under field conditions focusing on abiotic stresses, past environmental conditions and developmental processes. The reviewed studies highlight strong stress-driven, adaptive (previous temperature and light environment and growth CO<sub>2</sub> concentration) and developmental (leaf age) variations in <i>E</i><sub>S</sub> values operating at medium to long time scales. These biological factors can alter species-specific <i>E</i><sub>S</sub> values by more than an order of magnitude. While the majority of models based on early concepts still ignore these important sources of variation, recent models are including some of the medium- to long-term controls. However, conceptually different strategies are being used for incorporation of these longer-term controls with important practical implications for parameterization and application of these models. This analysis emphasizes the need to include more biological realism in the isoprenoid emission models and also highlights the gaps in knowledge that require further experimental work to reduce the model uncertainties associated with biological sources of variation.

 References Anderson, L. J., Harley, P. C., Monson, R. K., and Jackson, R. B.: Reduction of isoprene emissions from live oak (<i>Quercus fusiformis</i>) with oak wilt, Tree Physiol., 20, 1199–1203, 2000. Arneth, A., Miller, P. A., Scholze, M., Hickler, T., Schurgers, G., Smith, B., and Prentice, I. C.: CO<sub>2</sub> inhibition of global terrestrial isoprene emissions: potential implications for atmospheric chemistry, Geophys. Res. Lett., 34, L18813, https://doi.org/10.1029/2007GL030615, 2007a. Arneth, A., Niinemets, Ü., Pressley, S., Bäck, J., Hari, P., Karl, T., Noe, S., Prentice, I. C., Serça, D., Hickler, T., Wolf, A., and Smith, B.: Process-based estimates of terrestrial ecosystem isoprene emissions: incorporating the effects of a direct CO<sub>2</sub>-isoprene interaction, Atmos. Chem. Phys., 7, 31–53, https://doi.org/10.5194/acp-7-31-2007, 2007b. Arneth, A., Schurgers, G., Hickler, T., and Miller, P. A.: Effects of species composition, land surface cover, CO<sub>2</sub> concentration and climate on isoprene emissions from European forests, Plant Biol., 10, 150–152, 2008. Arneth, A. and Niinemets, Ü.: Induced BVOCs: how to bug our models?, Trends Plant Sci., 15, 118–125, 2010. Asner, G. P., Wessman, C. A., and Archer, S.: Scale dependence of absorption of photosynthetically active radiation in terrestrial ecosystems, Ecol. Appl., 8, 1003–1021, 1998. Augsburger, C. K. and Bartlett, E. A.: Differences in leaf phenology between juvenile and adult trees in a temperate deciduous forest, Tree Physiol., 23, 517–525, 2003. Baldocchi, D. D., Wilson, K. B., and Gu, L.: How the environment, canopy structure and canopy physiological functioning influence carbon, water and energy fluxes of a temperate broad-leaved deciduous forest – an assessment with the biophysical model CANOAK, Tree Physiol., 22, 1065–1077, 2002. Baraldi, R., Rapparini, F., Oechel, W. C., Hastings, S. J., Bryant, P., Cheng, Y. F., and Miglietta, F.: Monoterpene emission responses to elevated CO<sub>2</sub> in a Mediterranean-type ecosystem, New Phytol., 161, 17–21, 2004. Bargali, S. S. and Singh, R. P.: <i>Pinus patula</i> plantations in Kumaun Himalaya. I.&nbsp;Dry matter dynamics, J. Trop. For. Sci., 9, 526–535, 1997. Beauchamp, J., Wisthaler, A., Hansel, A., Kleist, E., Miebach, M., Niinemets, Ü., Schurr, U., and Wildt, J.: Ozone induced emissions of biogenic VOC from tobacco: relations between ozone uptake and emission of LOX products, Plant Cell Environ., 28, 1334-1343, 2005. Bertin, N. and Staudt, M.: Effect of water stress on monoterpene emissions from young potted holm oak (<i>Quercus ilex</i> L.) trees, Oecologia, 107, 456–462, 1996. Bertin, N., Staudt, M., Hansen, U., Seufert, G., Ciccioli, P., Foster, P., Fugit, J. L., and Torres, L.: Diurnal and seasonal course of monoterpene emissions from <i>Quercus ilex</i> (L.) under natural conditions – applications of light and temperature algorithms, Atmos. Environ., 31, 135–144, 1997. Blanch, J.-S., Peñuelas, J., and Llusià, J.: Sensitivity of terpene emissions to drought and fertilization in terpene-storing <i>Pinus halepensis</i> and non-storing <i>Quercus ilex</i>, Physiol. Plant., 131, 211–225, 2007. Blanch, J.-S., Noe, S. M., Niinemets, Ü., and Peñuelas, J.: Control of plant monoterpene emissions by instantaneous and historical temperatures, J. Environ. Biol., in press, 2010. Boissard, C., Cao, X. L., Juan, C. Y., Hewitt, C. N., and Gallagher, M.: Seasonal variations in VOC emission rates from gorse (<i>Ulex europaeus</i>), Atmos. Environ., 35, 917–927, 2001. Boissard, C., Chervier, F., and Dutot, A. L.: Assessment of high (diurnal) to low (seasonal) frequency variations of isoprene emission rates using a neural network approach, Atmos. Chem. Phys., 8, 2089–2101, https://doi.org/10.5194/acp-8-2089-2008, 2008. Brilli, F., Barta, C., Fortunati, A., Lerdau, M., Loreto, F., and Centritto, M.: Response of isoprene emission and carbon metabolism to drought in white poplar (<i>Populus alba</i>) saplings, New Phytol., 175, 244–254, 2007. Brilli, F., Ciccioli, P., Frattoni, M., Prestininzi, M., Spanedda, A. F., and Loreto, F.: Constitutive and herbivore-induced monoterpenes emitted by <i>Populus x euroamericana</i> leaves are key volatiles that orient <i>Chrysomela populi</i> beetles, Plant Cell Environ., 32, 542–552, 2009. Brooks, J. R., Hinckley, T. M., and Sprugel, D. G.: Acclimation responses of mature <i>Abies amabilis</i> sun foliage to shading, Oecologia, 100, 316–324, 1994. Buckley, P. T.: Isoprene emissions from a Florida scrub oak species grown in ambient and elevated carbon dioxide, Atmos. Environ., 35, 631–634, 2001. 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. Chen, F., Al-Ahmad, H., Joyce, B., Zhao, N., Köllner, T. G., Degenhardt, J., and Stewart Jr., C. N.: Within-plant distribution and emission of sesquiterpenes from <i>Copaifera officinalis</i>, Plant Physiol. Bioch., 47, 1017–1023, 2009. Ciccioli, P., Fabozzi, C., Brancaleoni, E., Cecinato, A., Frattoni, M., Loreto, F., Kesselmeier, J., Schäfer, L., Bode, K., Torres, L., and Fugit, J.-L.: Use of the isoprene algorithm for predicting the monoterpene emission from the Mediterranean holm oak <i>Quercus ilex</i> L.: performance and limits of this approach, J. Geophys. Res., 102, 23319–23328, 1997. Ciccioli, P., Brancaleoni, E., Frattoni, M., Brachetti, A., Marta, S., Loreto, F., Seufert, G., Vitullo, M., Tirone, G., Manca, G., and Valentini, R.: Daily and seasonal variations of monoterpene emissions from an evergreen oak (<i>Quercus ilex</i> L.) forest of southern Europe, in: A changing atmosphere: Proceedings of the 8th European symposium on the physico-chemical behaviour of atmospheric pollutants, edited by: Raes, F., Angeletti, G., and Hjorth, J., European Commission, DG Research and Joint Research Center, Ispra, 5&nbsp;pp., 2001. Ciccioli, P., Brancaleoni, E., Frattoni, M., Marta, S., Brachetti, A., Vitullo, M., Tirone, G., and Valentini, R.: Relaxed eddy accumulation, a new technique for measuring emission and deposition fluxes of volatile organic compounds by capillary gas chromatography and mass spectrometry, J. Chromatogr. A, 985, 283–296, 2003. Cinege, G., Louis, S., Hänsch, R., and Schnitzler, J.-P.: Regulation of isoprene synthase promoter by environmental and internal factors, Plant Mol. Biol., 69, 593–604, 2009. 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. Constable, J. V. H., Litvak, M. E., Greenberg, J. P., and Monson, R. K.: Monoterpene emission from coniferous trees in response to elevated CO<sub>2</sub> concentration and climate warming, Global Change Biol., 5, 255–267, 1999. Curci, G., Beekmann, M., Vautard, R., Smiatek, G., Steinbrecher, R., Theloke, J., and Friedrich, R.: Modelling study of the impact of isoprene and terpene biogenic emissions on European ozone levels, Atmos. Environ., 43, 1444–1455, 2009. Dicke, M. and Baldwin, I. T.: The evolutionary context for herbivore-induced plant volatiles: beyond the "cry for help", Trends Plant Sci., 15, 167–175, 2010. Ekberg, A., Arneth, A., Hakola, H., Hayward, S., and Holst, T.: Isoprene emission from wetland sedges, Biogeosciences, 6, 601–613, https://doi.org/10.5194/bg-6-601-2009, 2009. Fall, R., Karl, T., Hansel, A., Jordan, A., and Lindinger, W.: Volatile organic compounds emitted after leaf wounding: on-line analysis by proton-transfer-reaction mass spectrometry, J. Geophys. Res., 104, 15963–15974, 1999. Fang, C., Monson, R. K., and Cowling, E. B.: Isoprene emission, photosynthesis, and growth in sweetgum (<i>Liquidambar styraciflua</i>) seedlings exposed to short- and long-term drying cycles, Tree Physiol., 16, 441–446, 1996. Fares, S., Barta, C., Brilli, F., Centritto, M., Ederli, L., Ferranti, F., Pasqualini, S., Reale, L., Tricoli, D., and Loreto, F.: Impact of high ozone on isoprene emission, photosynthesis and histology of developing <i>Populus alba</i> leaves directly or indirectly exposed to the pollutant, Physiol. Plant., 128, 456–465, 2006. Fares, S., Brilli, F., Noguès, I., Velikova, V., Tsonev, T., Dagli, S., and Loreto, F.: Isoprene emission and primary metabolism in <i>Phragmites australis</i> grown under different phosphorus levels, Plant Biol., 10, 38–43, 2008. 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. Farquhar, G. D. and von Caemmerer, S.: Modeling of photosynthetic response to environmental conditions, in: Physiological Plant Ecology, edited by: Lange, O. L., Nobel, P. S., Osmond, C. B., and Ziegler, H., Encyclopedia of plant physiology, 12B, Springer-Verlag, Berlin, 549–588, 1982. Fischbach, R. J., Staudt, M., Zimmer, I., Rambal, S., and Schnitzler, J. P.: Seasonal pattern of monoterpene synthase activities in leaves of the evergreen tree <i>Quercus ilex</i>, Physiol. Plant., 114, 354–360, 2002. Flexas, J. and Medrano, H.: Drought-inhibition of photosynthesis in C<sub>3</sub> plants: stomatal and non-stomatal limitations revisited, Ann. Bot., 89, 183–189, 2002. Fortunati, A., Barta, C., Brilli, F., Centritto, M., Zimmer, I., Schnitzler, J.-P., and Loreto, F.: Isoprene emission is not temperature-dependent during and after severe drought-stress: a physiological and biochemical analysis, Plant J., 55, 687–697, 2008. Fowler, D., Pilegaard, K., Sutton, M. A., Ambus, P., Raivonen, M., Duyzer, J., Simpson, D., Fagerli, H., Fuzzi, S., Schjoerring, J. K., Granier, C., Neftel, A., Isaksen, I. S. A., Laj, P., Maione, M., Monks, P. S., Burkhardt, J., Daemmgen, U., Neirynck, J., Personne, E., Wichink-Kruit, R., Butterbach-Bahl, K., Flechard, C., Tuovinen, J. P., Coyle, M., Gerosa, G., Loubet, B., Altimir, N., Gruenhage, L., Ammann, C., Cieslik, S., Paoletti, E., Mikkelsen, T. N., Ro-Poulsen, H., Cellier, P., Cape, J. N., Horváth, L., Loreto, F., Niinemets, Ü., Palmer, P. I., Rinne, J., Misztal, P., Nemitz, E., Nilsson, D., Pryor, S., Gallagher, M. W., Vesala, T., Skiba, U., Brüggemann, N., Zechmeister-Boltenstern, S., Williams, J., O'Dowd, C., Facchini, M. C., de Leeuw, G., Flossman, A., Chaumerliac, N., and Erisman, J. W.: Atmospheric composition change: ecosystems – atmosphere interactions, Atmos. Environ., 43, 5193–5267, 2009. Fracheboud, Y., Luquez, V., Björkén, L., Sjödin, A., Tuominen, H., and Jansson, S.: The control of autumn senescence in European aspens (<i>Populus tremula</i>), Plant Physiol., in press, 149, 1982–1991, https://doi.org/10.1104/pp.1108.133249, 2009. 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. Funk, J. L., Jones, C. G., and Lerdau, M. T.: Defoliation effects on isoprene emission from <i>Populus deltoides</i>, Oecologia, 118, 333–339, 1999. Funk, J. L., Jones, C. G., Baker, C. J., Fuller, H. M., Giardina, C. P., and Lerdau, M. T.: Diurnal variation in the basal emission rate of isoprene, Ecol. Appl., 13, 269–278, 2003. Geron, C., Guenther, A., Sharkey, T., and Arnts, R. R.: Temporal variability in basal isoprene emission factor, Tree Physiol., 20, 799–805, 2000. Gholz, H. L., Vogel, S. A., Cropper Jr., W. P., McKelvey, K., Ewel, K. C., Teskey, R. O., and Curran, P. J.: Dynamics of canopy structure and light interception in <i>Pinus elliottii</i> stands, North Florida, Ecol. Monogr., 61, 33–51, 1991. Grassi, G. and Magnani, F.: Stomatal, mesophyll conductance and biochemical limitations to photosynthesis as affected by drought and leaf ontogeny in ash and oak trees, Plant Cell Environ., 28, 834–849, 2005. Grassi, G., Vicinelli, E., Ponti, F., Cantoni, L., and Magnani, F.: Seasonal and interannual variability of photosynthetic capacity in relation to leaf nitrogen in a deciduous forest plantation in northern Italy, Tree Physiol., 25, 349–360, 2005. Gray, D. W., Goldstein, A. H., and Lerdau, M. T.: The influence of light environment on photosynthesis and basal methylbutenol emission from <i>Pinus ponderosa</i>, Plant Cell Environ., 28, 1463–1474, 2005. Gray, D. W., Goldstein, A. H., and Lerdau, M.: Thermal history regulates methylbutenol basal emission rate in <i>Pinus ponderosa</i>, Plant Cell Environ., 29, 1298–1308, 2006. Grinspoon, J., Bowman, W. D., and Fall, R.: Delayed onset of isoprene emission in developing velvet bean (<i>Mucuna</i> sp.) leaves, Plant Physiol., 97, 170–174, 1991. Grote, R., Mayrhofer, S., Fischbach, R. J., Steinbrecher, R., Staudt, M., and Schnitzler, J.-P.: Process-based modelling of isoprenoid emissions from evergreen leaves of <i>Quercus ilex</i> L., Atmos. Environ., 40, S152–S165, 2006. Grote, R., Lavoir, A.-V., Rambal, S., Staudt, M., Zimmer, I., and Schnitzler, J.-P.: Modelling the drought impact on monoterpene fluxes from an evergreen Mediterranean forest canopy, Oecologia, 160, 213–223, 2009. Grote, R., Keenan, T., Lavoir, A.-V., and Staudt, M.: Process-based simulation of seasonality and drought stress in monoterpene emission models, Biogeosciences, 7, 257–274, https://doi.org/10.5194/bg-7-257-2010, 2010. Guenther, A. B., Monson, R. K., and Fall, R.: Isoprene and monoterpene emission rate variability: observations with <i>Eucalyptus</i> and emission rate algorithm development, J. Geophys. Res., 96, 10799–10808, 1991. 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, 12609–12617, 1993. Guenther, A., Zimmerman, P. R., and Wildermuth, M.: Natural volatile organic compound emission rates for US&nbsp;woodland landscapes, Atmos. Environ., 28, 1197–1210, 1994. 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 Zimmerman, P.: A global model of natural volatile compound emissions, J. Geophys. Res., 100, 8873–8892, 1995. Guenther, A.: Modeling biogenic volatile organic compound emissions to the atmosphere, in: Reactive hydrocarbons in the atmosphere, edited by: Hewitt, C. N., Academic Press, San Diego, 41–94, 1999. Guenther, A., Baugh, B., Brasseur, G., Greenberg, J., Harley, P., Klinger, L., Serça, D., and Vierling, L.: Isoprene emission estimates and uncertainties for the Central African EXPRESSO study domain, J. Geophys. Res.-Atmos., 104, 30625–30639, 1999. Guenther, A., Geron, C., Pierce, T., Lamb, B., Harley, P., and Fall, R.: Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America, Atmos. Environ., 34, 2205–2230, 2000. 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, https://doi.org/10.5194/acp-6-3181-2006, 2006. Gutschick, V. P.: Plant acclimation to elevated CO<sub>2</sub> – from simple regularities to biogeographic chaos, Ecol. Model., 200, 433–451, 2007. Hall, A. E.: Breeding for heat tolerance, in: Blant breeding reviews, edited by: Janick, J., John Wiley & Sons, New York, 129–168, 1992. Hällgren, J.-E., Strand, M., and Lundmark, T.: Temperature stress, in: Physiology of trees, edited by: Raghavendra, A. S., John Wiley & Sons Inc., New-York, 301–335, 1991. Hamerlynck, E. P. and Knapp, A. K.: Leaf-level responses to light and temperature in two co-occurring <i>Quercus</i> (<i>Fagaceae</i>) species: implications for tree distribution patterns, Forest Ecol. Manage., 68, 149–159, 1994. Hanna, S. R., Russell, A. G., Wilkinson, J. G., Vukovich, J., and Hansen, D. A.: Monte Carlo estimation of uncertainties in BEIS3 emission outputs and their effects on uncertainties in chemical transport model predictions, J. Geophys. Res.-Atmos., 110, D01302, https://doi.org/10.1029/2004JD004986, 2005. 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, 2001a. Hanson, D. T. and Sharkey, T. D.: Effect of growth conditions on isoprene emission and other thermotolerance-enhancing compounds, Plant Cell Environ., 24, 929–936, 2001b. Hargreaves, P. R., Leidi, A., Grubb, H. J., Howe, M. T., and Mugglestone, M. A.: Local and seasonal variations in atmospheric nitrogen dioxide levels at Rothamsted, UK, and relationships with meteorological conditions, Atmos. Environ., 34, 843–853, 2000. Harley, P. C., Litvak, M. E., Sharkey, T. D., and Monson, R. K.: Isoprene emission from velvet bean leaves. Interactions among nitrogen availability, growth photon flux density, and leaf development, Plant Physiol., 105, 279–285, 1994. Harley, P. C. and Baldocchi, D. D.: Scaling carbon dioxide and water vapour exchange from leaf to canopy in a deciduous forest. I.&nbsp;Leaf model parametrization, Plant Cell Environ., 18, 1146–1156, 1995. Harley, P., Guenther, A., and Zimmerman, P.: Effects of light, temperature and canopy position on net photosynthesis and isoprene emission from sweetgum (<i>Liquidambar styraciflua</i>) leaves, Tree Physiol., 16, 25–32, 1996. Harley, P., Guenther, A., and Zimmerman, P.: Environmental controls over isoprene emission in deciduous oak canopies, Tree Physiol., 17, 705–714, 1997. Heald, C. L., Henze, D. K., Horowitz, L. W., Feddema, J., Lamarque, J.-F., Guenther, A., Hess, P. G., Vitt, F., Seinfeld, J. H., Goldstein, A. H., and Fung, I.: Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land use change, J. Geophys. Res.-Atmos., 113, D05211, https://doi.org/10.1029/2007JD009092, 2008. Heald, C. L., Wilkinson, M. J., Monson, R. K., Alo, C. A., Wang, G., and Guenther, A.: Response of isoprene emission to ambient CO<sub>2</sub> changes and implications for global budgets, Global Change Biol., 15, 1127–1140, 2009. Heiden, A. C., Kobel, K., Langebartels, C., Schuh-Thomas, G., and Wildt, J.: Emissions of oxygenated volatile organic compounds from plants. Part&nbsp;I: Emissions from lipoxygenase activity, J. Atmos. Chem., 45, 143–172, 2003. Holopainen, J. K. and Gershenzon, J.: Multiple stress factors and the emission of plant VOCs, Trends Plant Sci., 15, 176–184, 2010. Huber, D. P. W., Philippe, R. N., Godard, K.-A., Sturrock, R. N., and Böhlmann, J.: Characterization of four terpene synthase cDNAs from methyl jasmonate-induced Douglas-fin, <i>Pseudotsuga menziesii</i>, Phytochemistry, 66, 1427–1439, 2005. Juuti, S., Arey, J., and Atkinson, R.: Monoterpene emission rate measurements from a Monterey pine, J. Geophys. Res., 95, 7515–7519, 1990. Kanakidou, M., Seinfeld, J. H., Pandis, S. N., Barnes, I., Dentener, F. J., Facchini, M. C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C. J., Swietlicki, E., Putaud, J. P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G. K., Winterhalter, R., Myhre, C. E. L., Tsigaridis, K., Vignati, E., Stephanou, E. G., and Wilson, J.: Organic aerosol and global climate modelling: a review, Atmos. Chem. Phys., 5, 1053–1123, https://doi.org/10.5194/acp-5-1053-2005, 2005. Karl, T., Guenther, A., Turnipseed, A., Patton, E. G., and Jardine, K.: Chemical sensing of plant stress at the ecosystem scale, Biogeosciences, 5, 1287–1294, https://doi.org/10.5194/bg-5-1287-2008, 2008. Karl, M., Guenther, A., Köble, R., Leip, A., and Seufert, G.: A new European plant-specific emission inventory of biogenic volatile organic compounds for use in atmospheric transport models, Biogeosciences, 6, 1059–1087, https://doi.org/10.5194/bg-6-1059-2009, 2009. Keenan, T., Niinemets, Ü., Sabate, S., Gracia, C., and Peñuelas, J.: Seasonality of monoterpene emission potentials in <i>Quercus ilex</i> and <i>Pinus pinea</i>: Implications for regional BVOC emissions modelling, J. Geophys. Res.-Atmos., 114, D22202, https://doi.org/10.1029/2009JD011904, 2009. Keskitalo, J., Bergquist, G., Gardeström, P., and Jansson, S.: A cellular timetable of autumn senescence, Plant Physiol., 139, 1635–1648, 2005. Kesselmeier, J., Bode, K., Hofmann, U., Müller, H., Schäfer, L., Wolf, A., Ciccioli, P., Brancaleoni, E., Cecinato, A., Frattoni, M., Foster, P., Ferrari, C., Jacob, V., Fugit, J. L., Dutaur, L., Simon, V., and Torres, L.: Emission of short chained organic acids, aldehydes and monoterpenes from <i>Quercus ilex</i> L.&nbsp;and <i>Pinus pinea</i> L.&nbsp;in relation to physiological activities, carbon budget and emission algorithms, Atmos. Environ., 31, 119–133, 1997. Kesselmeier, J., Bode, K., Schäfer, L., Schebeske, G., Wolf, A., Brancaleoni, E., Cecinato, A., Ciccioli, P., Frattoni, M., Dutaur, L., Fugit, J. L., Simon, V., and Torres, L.: Simultaneous field measurements of terpene and isoprene emissions from two dominant Mediterranean oak species in relation to a north American species, Atmos. Environ., 32, 1947–1953, 1998. Kim, J. C.: Factors controlling natural VOC emissions in a southeastern US&nbsp;pine forest, Atmos. Environ., 35, 3279–3292, 2001. 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 <i>Hymenaea courbaril</i> with fundamental changes in volatile organic compounds emission composition during early leaf development, Plant Cell Environ., 27, 1469-1485, 2004. Kull, O.: Acclimation of photosynthesis in canopies: models and limitations, Oecologia, 133, 267–279, 2002. Kulmala, M., Suni, T., Lehtinen, K. E. J., Dal Maso, M., Boy, M., Reissell, A., Rannik, Ü., Aalto, P., Keronen, P., Hakola, H., Bäck, J., Hoffmann, T., Vesala, T., and Hari, P.: A new feedback mechanism linking forests, aerosols, and climate, Atmos. Chem. Phys., 4, 557–562, https://doi.org/10.5194/acp-4-557-2004, 2004. Lamb, B., Gay, D., Westberg, H., and Pierce, T.: A biogenic hydrocarbon emission inventory for the USA using a simple forest canopy model, Atmos. Environ., 27A, 1673–1690, 1993. Lavoir, A.-V., Staudt, M., Schnitzler, J. P., Landais, D., Massol, F., Rocheteau, A., Rodriguez, R., Zimmer, I., and Rambal, S.: Drought reduced monoterpene emissions from the evergreen Mediterranean oak <i>Quercus ilex</i>: results from a throughfall displacement experiment, Biogeosciences, 6, 1167–1180, https://doi.org/10.5194/bg-6-1167-2009, 2009. Lechowicz, M. J.: Why do temperate deciduous trees leaf out at different times? Adaptations and ecology of forest communities, Am. Nat., 124, 821–842, 1984. Lehning, A., Zimmer, W., Zimmer, I., and Schnitzler, J. P.: Modeling of annual variations of oak (<i>Quercus robur</i> L.) isoprene synthase activity to predict isoprene emission rates, J. Geophys. Res., 106, 3157–3166, 2001. Lenz, R., Selige, T., and Seufert, G.: Scaling up the biogenic emissions from test sites at Castelporziano, Atmos. Environ., 31, 239–250, 1997. Lerdau, M., Litvak, M., and Monson, R.: Monoterpenes and the growth-differentiation balance hypothesis, Tree, 9, 58–61, 1994. Lerdau, M., Matson, P., Fall, R., and Monson, R.: Ecological controls over monoterpene emissions from Douglas-fir (<i>Pseudotsuga</i> menziesii), Ecology, 76, 2640–2647, 1995. Li, D., Chen, Y., Shi, Y., He, X., and Chen, X.: Impact of elevated CO<sub>2</sub> and O<sub>3</sub> concentrations on biogenic volatile organic compounds emissions from <i>Ginkgo biloba</i>, B. Environ. Contam. Tox., 82, 473–477, 2009. Litvak, M. E., Loreto, F., Harley, P. C., Sharkey, T. D., and Monson, R. K.: The response of isoprene emission rate and photosynthetic rate to photon flux and nitrogen supply in aspen and white oak trees, Plant Cell Environ., 19, 549–559, 1996. Litvak, M. E. and Monson, R. K.: Patterns of induced and constitutive monoterpene production in conifer needles in relation to insect herbivory, Oecologia, 114, 531–540, 1998. Litvak, M. E., Constable, J. V. H., and Monson, R. K.: Supply and demand processes as controls over needle monoterpene synthesis and concentration in Douglas fir [<i>Pseudotsuga menziesii</i> (Mirb.) Franco], Oecologia, 132, 382–391, 2002. Llorens, L., Llusià, J., Murchie, E. H., Peñuelas, J., and Beerling, D. J.: Monoterpene emissions and photoinhibition of "living fossil" trees grown under CO<sub>2</sub> enrichment in a simulated Cretaceous polar environment, J. Geophys. Res.-Biogeo., 114, G01005, https://doi.org/10.1029/2008JG000802, 2009. Llusià, J. and Peñuelas, J.: Changes in terpene content and emission in potted Mediterranean woody plants under severe drought, Can. J. Bot., 76, 1366–1373, 1998. Llusià, J. and Peñuelas, J.: Seasonal patterns of terpene content and emission from seven Mediterranean woody species in field conditions, Am. J. Bot., 87, 133–140, 2000. Llusià, J., Peñuelas, J., and Gimeno, B. S.: Seasonal and species-specific response of VOC emissions by Mediterranean woody plant to elevated ozone concentrations, Atmos. Environ., 36, 3931–3938 2002. Llusià, J., Peñuelas, J., Alessio, G. A., and Ogaya, R.: Species-specific, seasonal and inter-annual changes in foliar terpene emission rates in <i>Phillyrea latifolia</i> L.&nbsp;and <i>Quercus ilex</i> L.&nbsp;submitted to rain exclusion in the Prades mountains (Catalonia), Russ. J. Plant. Physiol., in press, 2010. Loivamäki, M., Louis, S., Cinege, G., Zimmer, I., Fischbach, R. J., and Schnitzler, J.-P.: Circadian rhythms of isoprene biosynthesis in grey poplar leaves, Plant Physiol., 143, 540–551, 2007. Loreto, F. and Sharkey, T. D.: Isoprene emission by plants is affected by transmissible wound signals, Plant Cell Environ., 16, 563–570, 1993. Loreto, F., Förster, A., Dürr, M., Csiky, O., and Seufert, G.: On the monoterpene emission under heat stress and on the increased thermotolerance of leaves of <i>Quercus ilex</i> L.&nbsp;fumigated with selected monoterpenes, Plant Cell Environ., 21, 101–107, 1998. Loreto, F., Nascetti, P., Graverini, A., and Mannozzi, M.: Emission and content of monoterpenes in intact and wounded needles of the Mediterranean pine, <i>Pinus pinea</i>, Funct. Ecol., 14, 589–595, 2000. Loreto, F., Fischbach, R. J., Schnitzler, J. P., Ciccioli, P., Brancaleoni, E., Calfapietra, C., and Seufert, G.: Monoterpene emission and monoterpene synthase activities in the Mediterranean evergreen oak <i>Quercus ilex</i> L.&nbsp;grown at elevated CO<sub>2</sub>, Global Change Biol., 7, 709–717, 2001. Loreto, F. and Velikova, V.: Isoprene produced by leaves protects the photosynthetic apparatus against ozone damage, quenches ozone products, and reduces lipid peroxidation of cellular membranes, Plant Physiol., 127, 1781–1787, 2001. Loreto, F., Pinelli, P., Manes, F., and Kollist, H.: Impact of ozone on monoterpene emissions and evidence for an isoprene-like antioxidant action of monoterpenes emitted by <i>Quercus ilex</i> leaves, Tree Physiol., 24, 361–367 2004. Loreto, F., Barta, C., Brilli, F., and Nogues, I.: On the induction of volatile organic compound emissions by plants as consequence of wounding or fluctuations of light and temperature, Plant Cell Environ., 29, 1820–1828, 2006. Loreto, F. and Schnitzler, J.-P.: Abiotic stresses and induced BVOCs, Trends Plant Sci., 15, 154–166, 2010. 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. Model., 131, 161–174, 2000. Mayrhofer, S., Teuber, M., Zimmer, I., Louis, S., Fischbach, R. J., and Schnitzler, J.-P.: Diurnal and seasonal variation of isoprene biosynthesis-related genes in grey poplar leaves, Plant Physiol., 139, 474–484, 2005. McMurtrie, R. E. and Comins, H. N.: The temporal response of forest ecosystems to doubled atmospheric CO<sub>2</sub> concentration, Global Change Biol., 2, 49–57, 1996. Medrano, H., Escalona, J. M., Bota, J., Gulias, J., and Flexas, J.: Regulation of photosynthesis of C<sub>3</sub> plants in response to progressive drought: Stomatal conductance as a reference parameter, Ann. Bot., 89, 895–905, 2002. Mentel, Th. F., Wildt, J., Kiendler-Scharr, A., Kleist, E., Tillmann, R., Dal Maso, M., Fisseha, R., Hohaus, Th., Spahn, H., Uerlings, R., Wegener, R., Griffiths, P. T., Dinar, E., Rudich, Y., and Wahner, A.: Photochemical production of aerosols from real plant emissions, Atmos. Chem. Phys., 9, 4387–4406, https://doi.org/10.5194/acp-9-4387-2009, 2009. Monson, R. K., Harley, P. C., Litvak, M. E., Wildermuth, M., Guenther, A. B., 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., Trahan, N., Rosenstiel, T. N., Veres, P., Moore, D., Wilkinson, M., Norby, R. J., Volder, A., Tjoelker, M. G., Briske, D. D., Karnosky, D. F., and Fall, R.: Isoprene emission from terrestrial ecosystems in response to global change: minding the gap between models and observations, Philos. T. Roy. Soc. Lond.&nbsp;A, 365, 1677–1695, 2007. Niinemets, Ü., 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 <i>Liquidambar</i> and <i>Quercus</i>, Plant Cell Environ., 22, 1319–1336, 1999. Niinemets, Ü., Hauff, K., Bertin, N., Tenhunen, J. D., Steinbrecher, R., and Seufert, G.: Monoterpene emissions in relation to foliar photosynthetic and structural variables in Mediterranean evergreen <i>Quercus</i> species, New Phytol., 153, 243–256, 2002a. Niinemets, Ü., Seufert, G., Steinbrecher, R., and Tenhunen, J. D.: A model coupling foliar monoterpene emissions to leaf photosynthetic characteristics in Mediterranean evergreen <i>Quercus</i> species, New Phytol., 153, 257–276, 2002b. Niinemets, Ü., Kull, O., and Tenhunen, J. D.: Within canopy variation in the rate of development of photosynthetic capacity is proportional to integrated quantum flux density in temperate deciduous trees, Plant Cell Environ., 27, 293–313, 2004. Niinemets, Ü. and Valladares, F.: Photosynthetic acclimation to simultaneous and interacting environmental stresses along natural light gradients: optimality and constraints, Plant Biol., 6, 254–268, 2004. Niinemets, Ü., Cescatti, A., Rodeghiero, M., and Tosens, T.: Complex adjustments of photosynthetic capacity and internal mesophyll conductance to current and previous light availabilities and leaf age in Mediterranean evergreen species <i>Quercus ilex</i>, Plant Cell Environ., 29, 1159–1178, 2006. Niinemets, Ü.: Photosynthesis and resource distribution through plant canopies, Plant Cell Environ., 30, 1052–1071, 2007. Niinemets, Ü. and Valladares, F.: Environmental tolerance, in: Encyclopedia of Ecology, edited by: Jørgensen, S. E. and Fath, B. D., Elsevier, Oxford, 1370–1376, 2008. Niinemets, Ü. and Anten, N. P. R.: Packing photosynthesis machinery: from leaf to canopy, in: Photosynthesis in silico: understanding complexity from molecules to ecosystems, 29&nbsp;edition, edited by: Laisk, A., Nedbal, L., and Govindjee, Advances in photosynthesis and respiration, Springer Verlag, Berlin, 363–399, 2009. Niinemets, Ü.: Mild versus severe stress and BVOCs: thresholds, priming and consequences, Trends Plant Sci., 15, 145–153, 2010. Niinemets, Ü., García-Plazaola, J. I., and Tosens, T.: Photosynthesis during leaf development and ageing, in: Terrestrial photosynthesis in a changing environment, The molecular, physiological and ecological bases of photosynthesis driving its response to the environmental changes, edited by: Flexas, J., Loreto, F., and Medrano, H., Cambridge University Press, Cambridge, in press, 2010a. Niinemets, Ü., Monson, R. K., Arneth, A., Ciccioli, P., Kesselmeier, J., Kuhn, U., Noe, S. M., Peñuelas, J., and Staudt, M.: The leaf-level emission factor of volatile isoprenoids: caveats, model algorithms, response shapes and scaling, Biogeosciences, 7, 1809–1832, https://doi.org/10.5194/bg-7-1809-2010, 2010b. Ortega, J. and Helmig, D.: Approaches for quantifying reactive and low-volatility biogenic organic compound emissions by vegetation enclosure techniques – Part&nbsp;A, Chemosphere, 72, 343–364, 2008. Ortega, J., Helmig, D., Daly, R. W., Tanner, D. M., Guenther, A. B., and Herrick, J. D.: Approaches for quantifying reactive and low-volatility biogenic organic compound emissions by vegetation enclosure techniques – Part&nbsp;B: applications, Chemosphere, 72, 365–380, 2008. Owen, S., Boissard, C., Street, R. A., Duckham, S. C., Csiky, O., and Hewitt, C. N.: Screening of 18&nbsp;Mediterranean plant species for volatile organic compound emissions, Atmos. Environ., 31, 101–117, 1997. Pegoraro, E., Rey, A., Bobich, E. G., Barron-Gafford, G. A., Grieve, K. A., Malhi, Y., and Murthy, R.: Effect of elevated CO<sub>2</sub> concentration and vapor pressure deficit on isoprene emission from leaves of <i>Populus deltoides</i> during drought, Funct. Plant Biol., 31, 1137–1147, 2004a. Pegoraro, E., Rey, A., Greenberg, J., Harley, P., Grace, J., Malhi, Y., and Guenther, A.: Effect of drought on isoprene emission rates from leaves of <i>Quercus virginiana</i> Mill., Atmos. Environ., 38, 6149–6156, 2004b. Pegoraro, E., Rey, A., Barron-Gafford, G., Monson, R., Malh, 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, 2005. Peñuelas, J. and Llusià, J.: Effects of carbon dioxide, water supply, and seasonality on terpene content and emission by <i>Rosmarinus officinalis</i>, J. Chem. Ecol., 23, 979–993, 1997. Peñuelas, J. and Estiarte, M.: Can elevated CO<sub>2</sub> affect secondary metabolism and ecosystem functioning?, Tree, 13, 20–24, 1998. Peñuelas, J. and Llusià, J.: BVOCs: plant defense against climatic warming?, Trends Plant Sci., 8, 105–109, 2003. Peñuelas, J., Filella, I., Stefanescu, C., and Llusià, J.: Caterpillars of <i>Euphydryas aurinia</i> (Lepidoptera: Nymphalidae) feeding on <i>Succisa pratensis</i> leaves induce large foliar emissions of methanol, New Phytol., 167, 851–857, 2005. Peñuelas, J., Filella, I., Seco, R., and Llusià, J.: Increase in isoprene and monoterpene emissions after re-watering of droughted <i>Quercus ilex</i> seedlings, Biol. Plant., 53, 351–354, 2009. Peñuelas, J. and Staudt, M.: BVOCs and global change, Trends Plant Sci., 15, 133–144, 2010. Pétron, G., Harley, P., Greenberg, J., and Guenther, A.: Seasonal temperature variations influence isoprene emission, Geophys. Res. Lett., 28, 1707–1710, 2001. Pook, E. W.: Canopy dynamics of <i>Eucalyptus maculata</i> Hook, I.&nbsp;Distribution and dynamics of leaf populations, Aust. J. Bot., 32, 387–403, 1984. Porcar-Castell, A., Peñuelas, J., Owen, S. M., Llusià, J., Munné-Bosch, S., and Bäck, J.: Leaf carotenoid concentrations and monoterpene emission capacity under acclimation of the light reactions of photosynthesis, Boreal Environ. Res., 14, 794–806, 2009. Possell, M., Heath, J., Hewitt, C. N., Ayres, E., and Kerstiens, G.: Interactive effects of elevated CO<sub>2</sub> and soil fertility on isoprene emissions from <i>Quercus robur</i>, Global Change Biol., 10, 1835–1843, 2004. Possell, M., Hewitt, C. N., 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. Priemé, A., Knudsen, T. B., Glasius, M., and Christensen, S.: Herbivory by the weevil, <i>Strophosoma melanogrammum</i>, causes severalfold increase in emission of monoterpenes from young Norway spruce (<i>Picea abies</i>), Atmos. Environ., 34, 711–718, 2000. Räisänen, T., Ryyppö, A., Julkunen-Tiitto, R., and Kellomäki, S.: Effects of elevated CO<sub>2</sub> and temperature on secondary compounds in the needles of Scots pine (<i>Pinus sylvestris</i> L.), Trees, 22, 121–135, 2008a. Räisänen, T., Ryyppö, A., and Kellomäki, S.: Effects of elevated CO<sub>2</sub> and temperature on monoterpene emission of Scots pine (<i>Pinus sylvestris</i> L.), Atmos. Environ., 42, 4160–4171, 2008b. Rapparini, F., Baraldi, R., Miglietta, F., and Loreto, F.: Isoprenoid emission in trees of <i>Quercus pubescens</i> and <i>Quercus ilex</i> with lifetime exposure to naturally high CO<sub>2</sub> environment, Plant Cell Environ., 27, 381–391, 2004. Reynolds, J. F., Kemp, P. R., Acock, B., Chen, J.-L., and Moorhead, D. L.: Progress, limitations, and challenges in modeling the effects of elevated CO<sub>2</sub> on plants and ecosystems, in: Carbon dioxide and terrestrial ecosystems, edited by: Koch, G. W. and Mooney, H. A., Academic Press, Inc., San Diego, 347–380, 1996. 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. Rosenthal, S. I. and Camm, E. L.: Effects of air temperature, photoperiod and leaf age on foliar senescence of western larch (<i>Larix occidentalis</i> Nutt.) in environmentally controlled chambers, Plant Cell Environ., 19, 1057–1065, 1996. Rosenthal, S. I. and Camm, E. L.: Photosynthetic decline and pigment loss during autumn foliar senescence in western larch (<i>Larix occidentalis</i>), Tree Physiol., 17, 767–775, 1997. Sabillón, D. and Cremades, L. V.: Diurnal and seasonal variation of monoterpene emission rates for typical Mediterranean species (<i>Pinus pinea</i> and <i>Quercus ilex</i>) from field measurements – relationship with temperature and PAR, Atmos. Environ., 35, 4419–4431, 2001. Schade, G. W. and Goldstein, A. H.: Increase of monoterpene emissions from a pine plantation as a result of mechanical disturbances, Geophys. Res. Lett., 30, 1380, https://doi.org/10.1029/2002GL016138, 2003. Schnitzler, J. P., Lehning, A., and Steinbrecher, R.: Seasonal pattern of isoprene synthase activity in <i>Quercus robur</i> leaves and its significance for modeling isoprene emission rates, Bot. Acta, 110, 240–243, 1997. Scholefield, P. A., Doick, K. J., Herbert, B., Hewitt, C. N., Schnitzler, J. P., Pinelli, P., and Loreto, F.: Impact of rising CO<sub>2</sub> on VOC emissions: isoprene emission from <i>Phragmites australis</i> growing at elevated CO<sub>2</sub> in a natural carbon dioxide spring, Plant Cell Environ., 27, 393–401, 2004. Sharkey, T. D. and Seemann, J. R.: Mild water stress effects on carbon-reduction-cycle intermediates, ribulose bisphosphate carboxylase activity, and spatial homogeneity of photosynthesis in intact leaves, Plant Physiol., 89, 1060–1065, 1989. 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, 1991. 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, 1993. Sharkey, T. D., Singsaas, E. L., Vanderveer, P. J., and Geron, C.: Field measurements of isoprene emission from trees in response to temperature and light, Tree Physiol., 16, 649–654, 1996. Sharkey, T. D., Singsaas, E. L., Lerdau, M. T., and Geron, C. D.: Weather effects on isoprene emission capacity and applications in emissions algorithms, Ecol. Appl., 9, 1132–1137, 1999. Sharkey, T. D.: Effects of moderate heat stress on photosynthesis: importance of thylakoid reactions, rubisco deactivation, reactive oxygen species, and thermotolerance provided by isoprene, Plant Cell Environ., 28, 269–277, 2005. Shesták, Z., Tichá, I., Chatsky, J., Solárová, J., Pospíshilová, J., and Hodánová, D.: Integration of photosynthetic characteristics during leaf development, in: Photosynthesis during leaf development, edited by: Shesták, Z., Tasks for vegetation science, 11, Dr.&nbsp;W.&nbsp;Junk Publishers, Dordrecht - Boston - Lancaster, 263–286, 1985. Simon, E., Kuhn, U., Rottenberger, S., Meixner, F. X., and Kesselmeier, J.: Coupling isoprene and monoterpene emissions from Amazonian tree species with physiological and environmental parameters using a neural network approach, Plant Cell Environ., 28, 287–301, 2005. Simpson, D., Guenther, A., Hewitt, C. N., and Steinbrecher, R.: Biogenic emissions in Europe. 1.&nbsp;Estimates and uncertainties, J. Geophys. Res., 100, 22875–22890, 1995. 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. E., Puxbaum, H., Shearer, M., Skiba, U., Steinbrecher, R., Tarrasón, L., and Öquist, M. G.: Inventorying emissions from nature in Europe, J. Geophys. Res.-Atmos., 104, 8113–8152, 1999. Singsaas, E. L., Laporte, M. M., Shi, J.-Z., Monson, R. K., Bowling, D. R., Johnson, K., Lerdau, M., Jasentuliytana, A., and Sharkey, T. D.: Kinetics of leaf temperature fluctuation affect isoprene emission from red oak (<i>Quercus rubra</i>) leaves, Tree Physiol., 19, 917–924, 1999. Singsaas, E. L. and Sharkey, T. D.: The effects of high temperature on isoprene synthesis in oak leaves, Plant Cell Environ., 23, 751–757, 2000. Snow, M. D., Bard, R. R., Olszyk, D. M., Minster, L. M., Hager, A. N., and Tingey, D. T.: Monoterpene levels in needles of Douglas fir exposed to elevated CO<sub>2</sub> and temperature, Physiol. Plant., 117, 352–358, 2003. Spracklen, D. V., Bonn, B., and Carslaw, K. S.: Boreal forests, aerosols and the impacts on clouds and climate, Philos. T. Roy. Soc. Lond.&nbsp;A, 366, 4613–4626, 2008. Staudt, M. and Bertin, N.: Light and temperature dependence of the emission of cyclic and acyclic monoterpenes from holm oak (<i>Quercus ilex</i> L.) leaves, Plant Cell Environ., 21, 385–395, 1998. Staudt, M., Bertin, N., Frenzel, B., and Seufert, G.: Seasonal variation in amount and composition of monoterpenes emitted by young <i>Pinus pinea</i> trees – implications for emission modeling, J. Atmos. Chem., 35, 77–99, 2000. Staudt, M., Joffre, R., Rambal, S., and Kesselmeier, J.: Effect of elevated CO<sub>2</sub> on monoterpene emission of young <i>Quercus ilex</i> trees and its relation to structural and ecophysiological parameters, Tree Physiol., 21, 437–445, 2001. Staudt, M., Rambal, S., Joffre, R., and Kesselmeier, J.: Impact of drought on seasonal monoterpene emissions from <i>Quercus ilex</i> in southern France, J. Geophys. Res., D107, 4602, https://doi.org/10.1029/2001JD002043, 2002. Staudt, M., Joffre, R., and Rambal, S.: How growth conditions affect the capacity of <i>Quercus ilex</i> leaves to emit monoterpenes, New Phytol., 158, 61–73, 2003. Staudt, M., Mir, C., Joffre, R., Rambal, S., Bonin, A., Landais, D., and Lumaret, R.: Isoprenoid emissions of <i>Quercus</i> spp.&nbsp;(<i>Q.&nbsp;suber</i> and <i>Q.&nbsp;ilex</i>) in mixed stands contrasting in interspecific genetic introgression, New Phytol., 163, 573–584, 2004. Staudt, M. and Lhoutellier, L.: Volatile organic compound emission from holm oak infested by gypsy moth larvae: evidence for distinct responses in damaged and undamaged leaves, Tree Physiol., 27, 1433–1440, 2007. Staudt, M., Ennajah, A., Mouillot, F., and Joffre, R.: Do volatile organic compound emissions of Tunisian cork oak populations originating from contrasting climatic conditions differ in their responses to summer drought?, Can. J. Forest Res., 38, 2965–2975, 2008. Steinbrecher, R., Smiatek, G., Köble, R., Seufert, G., Theloke, J., Hauff, K., Ciccioli, P., Vautard, R., and Curci, G.: Intra- and inter-annual variability of VOC emissions from natural and semi-natural vegetation in Europe and neighbouring countries, Atmos. Environ., 43, 1380–1391, 2009. Steindel, F., Beauchamp, J., Hansel, A., Kesselmeier, J., Kleist, E., Kuhn, U., Wisthaler, A., and Wildt, J.: Stress induced VOC emissions from mildew infested oak, Geophys. Res. Abstracts, 7, EGU05-A-03010, 2005. Stolwijk, A. M., Straatman, H., and Zielhuis, G. A.: Studying seasonality by using sine and cosine functions in regression analysis, J. Epidemiol. Commun. H., 53, 235–238, 1999. Street, R. A., Owen, S., Duckham, S. C., Boissard, C., and Hewitt, C. N.: Effect of habitat and age on variations in volatile organic compound (VOC) emissions from <i>Quercus ilex</i> and <i>Pinus pinea</i>, Atmos. Environ., 31, 89–100, 1997. Sun, Z., Niinemets, Ü., and Copolovici, L.: Foliar isoprene emission during autumn senescence in aspen (<i>Populus tremula</i>), Geochim. Cosmochim. Ac., 73, A1295, https://doi.org/10.1016/j.gcq.2009.05.015, 2009. Tingey, D. T., Turner, D. P., and Weber, J. A.: Factors controlling the emissions of monoterpenes and other volatile organic compounds, in: Trace gas emissions by plants, edited by: Sharkey, T. D., Holland, E. A., and Mooney, H. A., Physiological ecology, A series of monographs, texts, and treatises, Academic Press, Inc., San Diego/New York/Boston/London/Sydney/Tokyo/Toronto, 93–119, 1991. Tognetti, R., Johnson, J. D., Michelozzi, M., and Raschi, A.: Response of foliar metabolism in mature trees of <i>Quercus pubescens</i> and <i>Quercus ilex</i> to long-term elevated CO<sub>2</sub>, Environ. Exp. Bot., 39, 233–245, 1998. Valladares, F. and Niinemets, Ü.: The architecture of plant crowns: from design rules to light capture and performance, in: Handbook of functional plant ecology, 2nd&nbsp;edition, edited by: Pugnaire, F. I. and Valladares, F., CRC Press, Boca Raton, 101–149, 2007. van Doorn, W. G. and Woltering, E. J.: Senescence and programmed cell death: substance or semantics?, J. Exp. Bot., 55, 2147–2153, 2004. 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 Physiol., 25, 1523–1532, 2005. Vickers, C. E., Gershenzon, J., Lerdau, M. T., and Loreto, F.: A unified mechanism of action for volatile isoprenoids in plant abiotic stress, Nat. Chem. Biol., 5, 283–291, 2009. 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. Wiberley, A. E., Donohue, A. R., Meier, M. E., Westphal, M. M., and Sharkey, T. D.: Regulation of isoprene emission in <i>Populus trichocarpa</i> leaves subjected to changing growth temperature, Plant Cell Environ., 31, 258–267, 2008. Wiedinmyer, C., Greenberg, J., Guenther, A., Hopkins, B., Baker, K., Geron, C., Palmer, P. I., Long, B. P., Turner, J. R., Pétron, G., Harley, P., Pierce, T. E., Lamb, B., Westberg, H., Baugh, W., Koerber, M., and Janssen, M.: Ozarks Isoprene Experiment (OZIE): measurements and modeling of the "isoprene volcano", J. Geophys. Res.-Atmos., 110, D18307, https://doi.org/10.1029/2005JD005800, 2005. Wilkinson, M. J., Owen, S. M., Possell, M., Hartwell, J., Gould, P., Hall, A., Vickers, C., and Hewitt, C. N.: Circadian control of isoprene emissions from oil palm (<i>Elaeis guineensis</i>), Plant J., 47, 960–968, 2006. Wilkinson, M. J., Monson, R. K., Trahan, N., Lee, S., Brown, E., Jackson, R. B., Polley, H. W., Fay, P. A., and Fall, R.: Leaf isoprene emission rate as a function of atmospheric CO<sub>2</sub> concentration, Global Change Biol., 15, 1189–1200, 2009. Wilson, K. B., Baldocchi, D. D., and Hanson, P. J.: Quantifying stomatal and non-stomatal limitations to carbon assimilation resulting from leaf aging and drought in mature deciduous tree species, Tree Physiol., 20, 787–797, 2000a. Wilson, K. B., Baldocchi, D. D., and Hanson, P. J.: Spatial and seasonal variability of photosynthetic parameters and their relationship to leaf nitrogen in a deciduous forest, Tree Physiol., 20, 565–578, 2000b. Wilson, K. B., Baldocchi, D. D., and Hanson, P. J.: Leaf age affects the seasonal pattern of photosynthetic capacity and net ecosystem exchange of carbon in a deciduous forest, Plant Cell Environ., 24, 571–583, 2001. Yani, A., Pauly, G., Faye, M., Salin, F., and Gleizes, M.: The effect of a long-term water stress on the metabolism and emission of terpenes of the foliage of <i>Cupressus sempervirens</i>, Plant Cell Environ., 16, 975–981, 1993. Young, P. J., Arneth, A., Schurgers, G., Zeng, G., and Pyle, J. A.: The CO<sub>2</sub> inhibition of terrestrial isoprene emission significantly affects future ozone projections, Atmos. Chem. Phys., 9, 2793–2803, https://doi.org/10.5194/acp-9-2793-2009, 2009. Zhang, R., Cruz, J. A., Kramer, D. M., Magallanes-Lundback, M. E., DellaPenna, D., and Sharkey, T. D.: Moderate heat stress reduces the pH component of the transthylakoid proton motive force in light-adapted, intact tobacco leaves, Plant Cell Environ., 32, 1538–1547, 2009. Zhang, R. and Sharkey, T. D.: Photosynthetic electron transport and proton flux under moderate heat stress, Photosynth. Res., 100, 29–43, 2009. Zimmer, W., Brüggemann, 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.