Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 12 2009 10.5194/bg-6-2779-2009 http://www.biogeosciences.net/6/2779/2009/ http://www.biogeosciences.net/6/2779/2009/bg-6-2779-2009.html http://www.biogeosciences.net/6/2779/2009/bg-6-2779-2009.pdf 2779 2797 2009-12-03 European emissions of isoprene and monoterpenes from the Last Glacial Maximum to present G. Schurgers guy.schurgers@nateko.lu.se T. Hickler P. A. Miller A. Arneth Lund University, Department of Physical Geography and Ecosystems Analysis, Sölvegatan 12, 223 62 Lund, Sweden University of Helsinki, Department of Physical Sciences, Helsinki, Finland Biogenic volatile organic compounds (BVOC), such as isoprene and monoterpenes, play an important role in atmospheric processes. BVOC species are oxidized in the atmosphere and influence levels of ozone. The less volatile amongst the BVOC and their oxidation products are important for the formation and growth of secondary biogenic aerosol. In this way, the Earth's radiation balance is affected. <br><br> Geographic distribution and temporal changes in BVOC emissions are highly uncertain. Here we assessed changes in emission patterns across Europe since the Last Glacial Maximum (LGM) with a dynamic vegetation model. This model reproduces European tree species distribution and includes a process-based algorithm for terpenoid production. In a set of simulations the model was driven with paleoclimate anomalies and reconstructed CO₂ concentrations. We quantified three main driving factors for the changes in emissions of isoprene and monoterpenes since the LGM: (1) the changes in climate, with temperature changes as the most important factor affecting plant physiology and terpenoid production in all plant species, (2) a change in species distribution related to the changes in climate, causing local shifts in emission characteristics of the vegetation, and (3) a change in CO₂ concentration, causing opposing effects on the availability of different substrates for terpenoid production. The effect of atmospheric CO₂ concentration is particularly uncertain, but sensitivity simulations showed an increase in European BVOC emissions in all sensitivity experiments irrespective of the use of a direct inhibition of terpenoid production by CO₂. The effects of climate change on physiology and terpenoid production resulted in an overall relatively uniform increase of emissions in Europe over the simulation period, but regionally the effect of changes in species distribution and the related changes in emission capacities resulted in changes of emissions that can dominate over the physiology effects. This may have consequences for regional atmospheric chemistry simulations for the past, that have to rely on suitable geographic patterns of forest emissions. Arneth, A., Miller, P., Scholze, M., Hickler, T., Schurgers, G., Smith, B., and Prentice, I.: CO₂ inhibition of global terrestrial isoprene emissions: Potential implications for atmospheric chemistry, Geophys. Res. Lett., 34, L18813, \doi10.1029/2007GL030615, 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 CO₂-isoprene interaction, Atmos. Chem. Phys., 7, 31–53, 2007b. Arneth, A., Monson, R. K., Schurgers, G., Niinemets, Ü., and Palmer, P. I.: Why are estimates of global terrestrial isoprene emissions so similar (and why is this not so for monoterpenes)?, Atmos. Chem. Phys., 8, 4605–4620, 2008a. Arneth, A., Schurgers, G., Hickler, T., and Miller, P.: Effects of species composition, land surface cover, CO₂ concentration and climate on isoprene emissions from European forests, Plant Biology, 10, 150–162, \doi10.1055/s-2007-965247, 2008b. Bäck, J., Hari, P., Hakola, H., Juurola, E., and Kulmala, M.: Dynamics of monoterpene emissions in \textitPinus sylvestris during early spring, Boreal Environ. Res., 10, 409–424, 2005. Baraldi, R., Rapparini, F., Oechel, W., Hastings, S., Bryant, P., Cheng, Y., and Miglietta, F.: Monoterpene emission responses to elevated CO₂ in a Mediterranean-type ecosystem, New Phytol., 161, 1–21, 2004. Berger, A.: Long-term variations of daily insolation and Quaternary climate changes, J. Atmos. Sci., 35, 2362–2367, 1978. 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 \textitQuercus ilex (L.) under natural conditions application of light and temperature algorithms, Atmos. Environ., 31, 135–144, \doi10.1016/S1352-2310(97)00080-0, 1997. Bohn, U. and Neuhäusl, R.: Map of the natural vegetation of Europe: Explanatory text with CD ROM, Tech. rep., German Federal Agency for Nature Conservation, 2003. Christensen, C S., Hummelshoj, P., Jensen, N O., Larsen, B., Lohse, C., Pilegaard, K., and Skov, H.: Determination of the terpene flux from orange species and Norway spruce by relaxed eddy accumulation, Atmos. Environ., 34, 3057–3067, 2000. Claeys, M., Graham, B., Vas, G., Wang, W., Vermeylen, R., Pashynska, V., Cafmeyer, J., Guyon, P., Andreae, M., Artaxo, P., and Maenhaut, W.: Formation of secondary organic aerosols through photooxidation of isoprene, Science, 303, 1173–1176, \doi10.1126/science.1092805, 2004. Claussen, M.: Late Quaternary vegetation-climate feedbacks, Clim. Past, 5, 203–216, 2009. Constable, J., Litvak, M., Greenberg, J., and Monson, R.: Monoterpene emission from coniferous trees in response to elevated CO₂ concentration and climate warming, Glob. Change Biol., 5, 255–267, 1999. Dindorf, T., Kuhn, U., Ganzeveld, L., Schebeske, G., Ciccioli, P., Holzke, C., Köble, R., Seufert, G., and Kesselmeier, J.: Significant light and temperature dependent monoterpene emissions from European beech (\textitFagus sylvatica L.) and their potential impact on the European volitile organic compound budget, J. Geophys. Res., 111, D16305, \doi10.1029/2005JD006751, 2006. Etheridge, D M., Steele, L P., Langenfelds, R L., Francey, R J., Barnola, J M., and Morgan, V I.: Natural and anthropogenic changes in atmospheric CO₂ over the last 1000 years from air in Antarctic ice and firn, J. Geophys. Res.-Atmos., 101, 4115–4128, 1996. Fletcher, W. and Sánchez-Goñi, M.: Orbital- and sub-orbital-scale climate impact on vegetation of the western Mediterranean basin over the last 48000 yr, Quaternary Res., 70, 451–464, \doi10.1016/j.yqres.2008.07.002, 2008. Friedli, H., Lötscher, H., Oeschger, H., Siegenthaler, U., and Stauffer, B.: Ice core record of the $^13$C/$^12$C ratio of atmospheric CO₂ in the past two centuries, Nature, 324, 237–238, 1986. Fuhrer, K. and Legrand, M.: Continental biogenic species in the Greenland Ice Core Project ice core: Tracing back the biomass history of the North American continent, J. Geophys. Res., 102, 26735–26745, 1997. 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. Giesecke, T. and Bennett, K.: The Holocene spread of \textitPicea abies (L.) Karst. in Fennoscandia and adjacent areas, J. Biogeogr., 31, 1523–1548, 2004. Giesecke, T., Hickler, T., Kunkel, T., Sykes, M., and Bradshaw, R. H W.: Towards the understanding of the Holocene distribution of \textitFagus sylvatica L., J. Biogeogr., 34, 118–131, 2007. Grabmer, W., Kreuzwieser, J., Wisthaler, A., Cojocariu, C., Graus, M., Rennenberg, M., Steigner, D., Steinbrecher, R., and Hansel, A.: VOC emissions from Norway spruce (\textitPicea abies L. [Karst]) twigs in the field - Results of a dynamic enclosure study, Atmos. Environ., 40, S128–S137, 2006. Guenther, A., Hewitt, C., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., McKay, W., Pierce, T., Scholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., and Zimmerman, P.: A global model of natural volatile organic compound emissions, J. Geophys. Res., 100, 8873–8892, 1995. Hakola, H., Rinne, J., and Laurila, T.: The hydrocarbon emission rates of Tea-leafed willow (\textitSalix phylicifolia), Silver birch (\textitBetula pendula) and European aspen (\textitPopulus tremula), Atmos. Environ., 32, 1825–1833, 1998. Hakola, H., Laurila, T., Lindfors, V., Hellen, H., Gaman, A., and Rinne, J.: Variation of the VOC emission rates of birch species during the growing season, Boreal Environ. Res., 6, 237–249, 2001. Hakola, H., Tarvainen, V., Bäck, J., Ranta, H., Bonn, B., Rinne, J., and Kulmala, M.: Seasonal variation of mono- and sesquiterpene emission rates of Scots pine, Biogeosciences, 3, 93–101, 2006. Hansen, U. and Seufert, G.: The terpenoid emission pattern of \textitQuercus coccifera L. coincides with the emission pattern found with \textitQuercus ilex L., in: Proceedings of EUROTRAC Symposium '96: Transport and transformation of poluttants in the troposphere, edited by: Borrell, P., Borrell, P., Kelly, K., Cvitaš, T., and Seiler, W., vol. 2: Emissions, deposition, laboratory work and instrumentation, 1996. Hansen, U., Van~Eijk, J., Bertin, N., Staudt, M., Kotzias, D., Seufert, G., Fugit, J L., Torres, L., Cecinato, A., Brancaleoni, E., Ciccioli, P., and Bomboi, T.: Biogenic emissions and CO₂ gas exchange investigated on four Mediterranean shrubs, Atmos. Environ., 31, 157–166, 1997. Heald, C., Wilkinson, M J., Monson, R., Alo, C., Wang, G., and Guenther, A.: Response of isoprene emission to ambient CO₂ changes and implications for global budgets, Glob. Change Biol., 15, 1127–1140, \doi10.1111/j.1365-2486.2008.01803.x, 2009. Hewitt, C., Stewart, H., Street, R., and Scholefield, P.: Isoprene and monoterpene-emitting species survey 1997, online available at: http://www.es.lancs.ac.uk/cnhgroup/download.html, 1997. Hewitt, C N. and Street, R A.: A qualitative assessment of the emission of nonmethane hydrocarbon compounds from the biosphere to the atmosphere in the Uk - Present knowledge and uncertainties, Atmos. Environ. A, 26, 3069–3077, 1992. Hickler, T., Smith, B., Sykes, M., Davis, M., Sugita, S., and Walker, K.: Using a generalized vegetation model to simulate vegetation dynamics in Northeastern USA, Ecology, 85, 519–530, 2004. Hickler, T., Fronzek, S., Araújo, M., Schweiger, O., Thuiller, W., and Sykes, M.: An ecosystem model-based estimate of changes in water availability differs from water proxies that are commonly used in species distribution models, Global Ecol.Biogeogr., 18, 304–313, \doi10.1111/j.1466-8238.2009.00455.x, 2009a. Hickler, T., Vohland, K., Miller, P., Smith, B., Costa, L., Feehan, J., Giesecke, T., Fronzek, S., Carter, T., Cramer, W., Kühn, I., and Sykes, M.: Climate-driven changes in European potential natural vegetation in relation to the Natura 2000 protected area network, Global Ecol. Biogeogr., submitted, 2009b. Hoffmann, T., Odum, J R., Bowman, F., Collins, D., Klockow, D., Flagan, R C., and Seinfeld, J H.: Formation of organic aerosols from the oxidation of biogenic hydrocarbons, J. Atmos. Chem., 26, 189–222, 1997. Holzke, C., Dindorf, T., Kesselmeier, J., Kuhn, U., and Koppmann, R.: Terpene emissions from European beech (\textitFagus sylvatica L.): Pattern and emission behaviour over two vegetation periods, J. Atmos. Chem., 55, 81–102, 2006. Huntley, B.: Vegetation history, chap. Europe, Kluwer Academic Publishers, 341~pp., 1988. Indermühle, A., Stocker, T., Joos, F., Fischer, H., Smith, H., Wahlen, M., Deck, B., Mastroianni, D., Tschumi, J., Blunier, T., Meyer, R., and Stauffer, B.: Holocene carbon-cycle dynamics based on CO₂ trapped in ice at Taylor Dome, Antarctica, Nature, 398, 121–126, 1999. Isebrands, J., Guenther, A., Harley, P., Helmig, D., Klinger, L., Vierling, L., Zimmerman, P., and Geron, C.: Volatile organic compound emission rates from mixed deciduous and coniferous forests in Northern Wisconsin, USA, Atmos. Environ., 33, 2527–2536, 1999. Isidorov, V., Zenkevich, I., and Ioffe, B.: Volatile organic compounds in the atmosphere of forests, Atmos. Environ., 19, 1–8, 1985. Janson, R.: Monoterpene emissions from Scots pine and Norwegian spruce, J. Geophys. Res.-Atmos., 98, 2839–2850, 1993. Janson, R. and de~Serves, C.: Acetone and monoterpene emissions from the boreal forest in northern Europe, Atmos. Environ., 35, 4629–4637, 2001. Janson, R., De~Serves, C., and Romero, R.: Emission of isoprene and carbonyl compounds from a boreal forest and wetland in Sweden, Agr. Forest Meteorol., 98-9, 671–681, 1999. Kaplan, J., Folberth, G., and Hauglustaine, D.: Role of methane and biogenic volatile organic compound sources in late glacial and Holocene fluctuations of atmospheric methane concentrations, Global Biogeochem. Cy., 20, GB2016, \doi10.1029/2005GB002590, 2006. 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, 2009. Keeling, C D., Whorf, T P., Wahlen, M., and Vanderplicht, J.: Interannual Extremes In The Rate Of Rise Of Atmospheric Carbon-Dioxide Since 1980, Nature, 375, 666–670, 1995. Kellomaki, S., Rouvinen, I., Peltola, H., Strandman, H., and Steinbrecher, R.: Impact of global warming on the tree species composition of boreal forests in Finland and effects on emissions of isoprenoids, Glob. Change Biol., 7, 531–544, 2001. Kesselmeier, J. and Staudt, M.: Biogenic volatile organic compounds (VOC): An overview on emission, physiology and ecology, J. Atmos. Chem., 33, 23–88, 1999. Kesselmeier, J., Bode, K., Schafer, 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, \doi10.1016/S1352-2310(97)00500-1, 1998. Koca, D., Smith, B., and Sykes, M.: Modelling regional climate change effects on potential natural ecosystems in Sweden, Climatic Change, 78, 381–406, 2006. Komenda, M. and Koppmann, R.: Monoterpene emissions from Scots pine (\textitPinus sylvestris): Field studies of emission rate variabilities, J. Geophys. Res.-Atmos., 107, 4161, doi:10.1029/2001JD000691, 2002. König, G., Brunda, M., Puxbaum, H., Hewitt, C., Duckham, S., and Rudolph, J.: Relative contribution of oxygenated hydrocarbons to the total biogenic VOC emissions of selected mid-European agricultural and natural plant species, Atmos. Environ., 29, 861–874, 1995. Kroll, J H., Ng, N L., Murphy, S M., Flagan, R C., and Seinfeld, J H.: Secondary organic aerosol formation from isoprene photooxidation under high-NO_x conditions, Geophys. Res. Lett., 32, L18808, \doi10.1029/2005GL023637, 2005. Lang, G.: Quartäre Vegetationsgeschichte Europas, Gustav Fischer Verlag, 1994. Lathiére, J., Hauglustaine, D. A., Friend, A. D., De Noblet-Ducoudré, N., Viovy, N., and Folberth, G. A.: Impact of climate variability and land use changes on global biogenic volatile organic compound emissions, Atmos. Chem. Phys., 6, 2129–2146, 2006. Legrand, M. and De~Angelis, M.: Origins and variations of light carboxylic acids in polar precipitation, J. Geophys. Res., 100, 1445–1462, 1995. Legrand, M., Preunkert, S., Wagenbach, D., Cachier, H., and Puxbaum, H.: A historical record of formate and acetate from a high-elevation Alpine glacier: Implications for their natural versus anthropogenic budgets at the European scale, J. Geophys. Res., 108, 4788, \doi10.1029/2003JD003594, 2003. Lehning, A., Zimmer, I., Steinbrecher, R., Bruggemann, N., and Schnitzler, J P.: Isoprene synthase activity and its relation to isoprene emission in Quercus robur L-leaves, Plant Cell Environ., 22, 495–504, 1999. Levis, S., Wiedinmyer, C., Bonan, G., and Guenther, A.: Simulating biogenic volatile organic compound emissions in the Community Climate System Model, J. Geophys. Res., 108, 4659, \doi10.1029/2002JD003203, 2003. Llorens, L., Llusià, J., Murchie, E., Peñuelas, J., and Beerling, D J.: Monoterpene emissions and photoinhibition of "living fossil" trees grown under CO₂ enrichment in a simulated Cretaceous polar environment, J. Geophys. Res., 114, G01005, \doi10.1029/2008JG000802, 2009. Llusia, J. and Penuelas, J.: Seasonal patterns of terpene content and emission from seven Mediterranean woody species in field conditions, Am. J. Bot., 87, 133–140, 2000. Loreto, F., Mannozzi, M., Maris, C., Nascetti, P., Ferranti, F., and Pasqualini, S.: Ozone quenching properties of isoprene and its antioxidant role in leaves, Plant Physiol., 126, 993–1000, 2001. Mikolajewicz, U., Groger, M., Maier-Reimer, E., Schurgers, G., Vizcaino, M., and Winguth, A. M E.: Long-term effects of anthropogenic CO2 emissions simulated with a complex earth system model, Clim. Dynam., 28, 599–631, 2007. Miller, P A., Giesecke, T., Hickler, T., Bradshaw, R. H W., Smith, B., Seppä, H., Valdes, P J., and Sykes, M T.: Exploring climatic and biotic controls on Holocene vegetation change in Fennoscandia, J. Ecol., 96, 247–259, \doi10.1111/j.1365-2745.2007.01342.x, 2008. Mitchell, T D. and Jones, P D.: An improved method of constructing a database of monthly climate observations and associated high-resolution grids, Int. J. Climatol., 25, 693–712, 2005. 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 Ogee, J.: Comparing and evaluating process-based ecosystem model predictions of carbon and water fluxes in major European forest biomes, Glob. Change Biol., 11, 2211–2233, \doi10.1111/j.1365-2486.2005.01036.x, 2005. Moukhtar, S., Bessagnet, B., Rouil, L., and Simon, V.: Monoterpene emissions from Beech (Fagus sylvatica) in a French forest and impact on secondary pollutants formation at regional scale, Atmos. Environ., 39, 3535–3547, 2005. Moukhtar, S., Couret, C., Rouil, L., and Simon, V.: Biogenic Volatile Organic Compounds (BVOCs) emissions from Abies alba in a French forest, Sci. Total Environ., 354, 232–245, 2006. Naik, V., Delire, C., and Wuebbles, D.: Sensitivity of global biogenic isoprenoid emissions to climate variability and atmospheric CO₂, J. Geophys. Res., 109, D06301, \doi10.1029/2002JD003203, 2004. New, M., Hulme, M., and Jones, P.: Representing twentieth-century space-time climate variability. Part II: Development of 1901-96 monthly grids of terrestrial surface climate, J. Climate, 13, 2217–2238, 2000. Niinemets, Ü., Tenhunen, J., Harley, P., 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. Niinemets, Ü., Seufert, G., Steinbrecher, R., and Tenhunen, J.: A model coupling foliar monoterpene emissions to leaf photosynthetic characteristics in Mediterranean evergreen \textitQuercus species, New Phytol., 153, 257–275, 2002. Owen, S., Boissard, C., Street, R., Duckham, S., Csiky, O., and Hewitt, C.: Screening of 18 mediterranean plant species for volatile organic compound emissions, Atmos. Environ., 31, 101–117, 1997. Owen, S., Boissard, C., Hagenlocher, B., and Hewitt, C.: Field studies of isoprene emissions from vegetation in the Northwest Mediterranean region, J. Geophys. Res., 103, 25499–25511, 1998. Owen, S., Harley, P., Guenther, A., and Hewitt, C.: Light dependency of VOC emissions from selected Mediterranean plants, Atmos. Environ., 36, 3147–3159, 2002. Peñuelas, J. and Llusià, J.: Short-term response of terpene emission rates to experimental changes of PFD in \textitPinus halepensis and \textitQuercus ilex in summer field conditions, Environ. Exp. Botany, 42, 61–68, 1999. Peltier, W.: Ice age paleotopography, Science, 265, 195–201, 1994. Plaza, J., Nunez, L., Pujadas, M., Perrez-Pastor, R., Bermejo, V., Garcia-Alonso, S., and Elvira, S.: Field monoterpene emission of Mediterranean oak (\textitQuercus ilex) in the central Iberian Peninsula measured by enclosure and micrometeorological techniques: Observation of drought stress effect, J. Geophys. Res.-Atmos., 110, D03303, doi:10.1029/2004JD005168, 2005. Pope, V D., Gallani, M L., Rowntree, P R., and Stratton, R A.: The impact of new physical parametrizations in the Hadley Centre climate model: HadAM3, Clim. Dynam., 16, 123–146, \doi10.1007/s003820050009, 2000. Possell, M., Heath, J., Nicholas~Hewitt, C., Ayres, E., and Kerstiens, G.: Interactive effects of elevated CO₂ and soil fertility on isoprene emissions from \textitQuercus robur, Glob. Change Biol., 10, 1835–1843, 2004. Possell, M., Hewitt, C N., and Beerling, D J.: The effects of glacial atmospheric CO₂ concentrations and climate on isoprene emissions by vascular plants, Glob. Change Biol., 11, 60–69, 2005. Ramankutty, N., Evan, A T., Monfreda, C., and Foley, J A.: Farming the planet: 1. Geographic distribution of global agricultural lands in the year 2000, Global Biogeochem. Cy., 22, GB1003, doi:10.1029/2007GB002952, 2008. Rinne, J., Hakola, H., Laurila, T., and Rannik, U.: Canopy scale monoterpene emissions of \textitPinus sylvestris dominated forests, Atmos. Environ., 34, 1099–1107, 2000. Rosenstiel, T N., Potosnak, M J., Griffin, K L., Fall, R., and Monson, R K.: Increased CO₂ uncouples growth from isoprene emission in an agriforest ecosystem, Nature, 421, 256–259, 2003. Ruddiman, W F.: The challenge of modeling interglacial CO₂ and CH₄ trends, Quaternary Sci. Rev., 27, 445–448, \doi10.1016/j.quascirev.2007.11.007, 2008. Savarino, J. and Legrand, M.: High northern latitude forest fires and vegetation emissions over the last millennium inferred from the chemistry of a central Greenland ice core, J. Geophys. Res., 103, 8267–8279, 1998. Schurgers, G., Mikolajewicz, U., Gröger, M., Maier-Reimer, E., Vizcaíno, M., and Winguth, A.: Dynamics of the terrestrial biosphere, climate and atmospheric CO₂ concentration during interglacials: a comparison between Eemian and Holocene, Clim. Past, 2, 205–220, 2006. Schurgers, G., Arneth, A., Holzinger, R., and Goldstein, A. H.: Process-based modelling of biogenic monoterpene emissions combining production and release from storage, Atmos. Chem. Phys., 9, 3409–3423, 2009. Simon, E., Kuhn, U., Rottenberger, S., Meixner, F., and Kesselmeier, J.: Coupling isoprene and monoterpene emissions from Amazonian tree species with physiological 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. Estimates and uncertainties, J. Geophys. Res.-Atmos., 100, 22875–22890, 1995. Simpson, D., Winiwarter, W., Borjesson, 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., Tarrason, L., and Oquist, M G.: Inventorying emissions from nature in Europe, J. Geophys. Res.-Atmos., 104, 8113–8152, 1999. Sitch, S., Smith, B., Prentice, I., Arneth, A., Bondeau, A., Cramer, W., Kaplan, J., Levis, S., Lucht, W., Sykes, M., Thonicke, K., and Venevsky, S.: Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ Dynamic Global Vegetation Model, Glob. Change Biol., 9, 161–185, 2003. Sitch, S., Cox, P., Collins, W., and Huntingford, C.: Indirect radiative forcing of climate change through ozone effects on the land-carbon sink, Nature, 448, 791–794, \doi10.1038/nature06059, 2007. Smiatek, G. and Steinbrecher, R.: Temporal and spatial variation of forest VOC emissions in Germany in the decade 1994–2003, Atmos. Environ., 40, S166–S177, 2006. Smith, B., Prentice, I., and Sykes, M.: Representation of vegetation dynamics in the modelling of terrestrial ecosystems: comparing two contrasting approaches within European climate space, Glob. Ecol. Biogeogr., 10, 621–637, 2001. Snow, M., Bard, R., Olszyk, D., Minster, L., Hager, A., and Tingey, D.: Monoterpene levels in needles of Douglas fir exposed to elevated CO₂ and temperature, Physiologia Plantarum, 117, 352–358, 2003. Staudt, M., Joffre, R., Rambal, S., and Kesselmeier, J.: Effect of elevated CO₂ on monoterpene emission of young \textitQuercus ilex trees and its relation to structural and ecophysiological parameters, Tree Physiol., 21, 437–445, 2001. Steinbrecher, R., Hauff, K., Rabong, R., and Steinbrecher, J.: Isoprenoid emission of Oak species typical for the Mediterranean area: source strength and controlling variables, Atmos. Environ., 31, 79–88, 1997. 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, \doi10.1016/j.atmosenv.2008.09.072, 2009. Tarvainen, V., Hakola, H., Hellén, H., Bäck, J., Hari, P., and Kulmala, M.: Temperature and light dependence of the VOC emissions of Scots pine, Atmos. Chem. Phys., 5, 989–998, 2005. Tollsten, L. and Muller, P M.: Volatile organic compounds emitted from beech leaves, Phytochemistry, 43, 759–762, 1996. Valdes, P., Beerling, D J., and Johnson, C.: The ice age methane budget, Geophys. Res. Lett., 32, L02704, doi:10.1029/2004GL021004, 2005. Wiedinmyer, C., Guenther, A., Harley, P., Hewitt, C., Geron, C., Artaxo, P., Steinbrecher, R., and Rasmussen, R.: Global organic emissions from vegetation, Kluwer Academic Publishers, 115–170, online available at: http://bai.acd.ucar.edu/Data/BVOC/index.shtml, 2004. Wilkinson, M J., Monson, R., Trahan, N., Lee, S., Brown, E., Jackson, R., Polley, H., Fay, P., and Fall, R.: Leaf isoprene emission rate as a function of atmospheric CO₂ concentration, Glob. Change Biol., 15, 1189–1200, \doi10.1111/j.1365-2486.2008.01803.x, 2009. 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.