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ISRN Atmospheric Sciences
Volume 2013 (2013), Article ID 786290, 27 pages
Biological and Chemical Diversity of Biogenic Volatile Organic Emissions into the Atmosphere
Atmospheric Chemistry Division, NCAR Earth System Laboratory, National Center for Atmospheric Research, 3090 Center Green, Boulder, CO 80301, USA
Received 13 March 2013; Accepted 20 May 2013
Academic Editors: P. Massoli, K. Schaefer, and E. Tagaris
Copyright © 2013 Alex Guenther. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Biogenic volatile organic compounds (BVOC) emitted by terrestrial ecosystems into the atmosphere play an important role in determining atmospheric constituents including the oxidants and aerosols that control air quality and climate. Accurate quantitative estimates of BVOC emissions are needed to understand the processes controlling the earth system and to develop effective air quality and climate management strategies. The large uncertainties associated with BVOC emission estimates must be reduced, but this is challenging due to the large number of compounds and biological sources. The information on the immense biological and chemical diversity of BVOC is reviewed with a focus on observations that have been incorporated into the MEGAN2.1 BVOC emission model. Strategies for improving current BVOC emission modeling approaches by better representations of this diversity are presented. The current gaps in the available data for parameterizing emission models and the priorities for future measurements are discussed.
Terrestrial ecosystems produce and emit many biogenic volatile organic compounds (BVOCs) into the air where they influence the chemistry and composition of the atmosphere including aerosols and oxidants [1–3]. These BVOCs are produced by a variety of sources in terrestrial ecosystems (e.g., flowers, stems, trunks, roots, leaf litter, soil microbes, insects, and animals), but most of the global total emission is from foliage [4–6]. The increasing awareness of the importance of these emissions for earth system modeling has resulted in numerical models of regional air quality and global climate that now routinely include BVOC emissions that are estimated as a function of landcover and environmental driving variables. This is a considerable challenge due to both the hundreds of different BVOC chemical species emitted into the atmosphere [7, 8] and the vast differences in the capacity of various plant species to produce and emit terpenoids and other BVOCs [9, 10]. Furthermore, an individual compound can be emitted by different ecosystem sources that are controlled by a variety of processes. Some compounds are stored in plant tissues that are isolated from the atmosphere and are emitted only if these tissues are damaged, while other compounds are stored in structures that are open to the atmosphere and are continuously being emitted . There are additional compounds that are not stored in tissues but instead are released immediately after production which may happen only in response to stress or specific environmental conditions .
Quantitative attempts to account for these BVOC emissions in models must consider all of the processes that control emission variability. Among the greatest of these challenges is characterizing the enormous diversity in BVOC emission types in ecosystems across the world. This paper provides an overview of our current understanding of the chemical and biological diversity of BVOC emissions into the atmosphere. Section 2 describes a compilation of observations in the scientific literature that have been used to quantify BVOC emissions in a widely used numerical model, the Model of Emissions of Gases and Aerosols from Nature (MEGAN) , and considers the suitability of these observations for characterizing regional to global BVOC emissions. The known chemical diversity of BVOC emissions is summarized in Section 3, and an approach for improving the representation of this diversity in numerical models is described. BVOC biological diversity is discussed in Section 4, and a framework for better representation of BVOC emission diversity types is presented. Section 5 presents the major conclusions of this summary of our current understanding of the chemical and biological diversity of BVOC emissions.
2. BVOC Emission Observations and Models
Quantitative estimation of global BVOC emissions into the atmosphere began with Went’s  seminal work that extrapolated measurements of a single group of compounds, monoterpenes, from a single plant species, Artemisia tridentata, to the entire earth. Rasmussen  recognized the great diversity in BVOC emission capacities of different plants species and introduced an approach for classifying the biosphere into different vegetation groups in order to quantify regional emissions. He noted that at least some vegetation types had “fingerprints” that could be used to represent the emission behavior of those plant species. He combined estimates of USA areas of different forest types (e.g., Loblolly-shortleaf pine forest, oak-gum-cypress forest) with observations of their representative emission rates in order to quantify total BVOC emissions on a USA national and on a global scale. Zimmerman  extended this approach using more comprehensive land cover data including broad natural vegetation types (e.g., shrub and brush rangeland, deciduous forest, and mixed forest), agricultural lands (e.g., crops, pasture, and orchards), and a category for residential areas. This approach was limited by the large differences in the emission rates of plant species in landscapes that, for example, are classified as deciduous forest or mixed forest because of the highly variable emission rates of these broad categories of vegetation. Zimmerman made additional progress towards accounting for this by collapsing USA forests into four types: high isoprene (e.g., oak) deciduous forest, low isoprene (e.g., sycamore) deciduous forest, no isoprene deciduous (e.g., maple), and coniferous forest (e.g., loblolly pine). Lamb and colleagues  refined this approach using higher resolution (county scale) landcover data that included land area planted with the major crop species. This approach was extended to the global scale [16, 17] by assigning emission factors to ecosystem types in global gridded databases. This was straightforward for categories dominated by a few species (e.g., paddy rice and mangrove) but not for most categories (e.g., farm/city-cool, temperate mixed, and dry evergreen) which did not represent a uniform BVOC emission type. For regions with detailed plant species data, the Biogenic Emission Inventory System 2 (BEIS2)  was developed to apply BVOC emission factors for individual tree genera and crop types. However, these data were only available for forests in some regions, and BEIS2 used broad categories for grassland and shrubland ecosystem types.
The MEGAN version 2.1 (MEGAN2.1)  BVOC emission model assigns emission factors and parameters to 19 BVOC chemical compound classes for each of the 15 plant functional types (PFTs) used for the Community Land Model (CLM4) . MEGAN2.1 can be run embedded in CLM4 and can also run offline using observations or variables from other models. BVOC emission rate measurements from about 300 studies were synthesized to estimate the emission factors used for MEGAN2.1 including data representative of the major global vegetation types. Measurements representing temperate landscapes are compiled in Table 1 [19–186]. Studies in tropical and boreal landscapes are summarized in Tables 2 [187–229] and 3 [230–268], respectively. Measurements characterizing BVOC emissions from agricultural crops are compiled in Table 4 [70, 269–282]. Terpenoid (e.g., isoprene, MBO, and monoterpene) emission factors were estimated for each of the 15 PFTs. For most of the other compounds, one or a few (e.g., one for woody PFTs and one for herbaceous PFTs) emission factors were used for all PFTs. Terpenoid emission factors are represented with a greater diversity in MEGAN2.1 both because of the greater actual diversity and because more observations have been reported.
Until recently, most BVOC emission measurements were conducted using enclosure techniques, but whole canopy flux measurements using micrometeorological approaches are now becoming more common . Characterizing BVOC emissions with enclosure measurements is challenging due to difficulties in accessing all parts of a mature forest canopy and because of the presence of storage structures which can be disturbed resulting in emissions at rates much higher than for undisturbed conditions . These issues resulted in BVOC emission factors reported by earlier studies that greatly underestimate isoprene emissions, because isoprene emission rates are lower for the shaded leaves in the more easily accessed portion of a forest canopy, and overestimate monoterpene emissions because of disturbances to terpenoid storage structures . The above-canopy flux measurements integrate over the entire canopy and landscape without disturbing emission rates . Capabilities for quantifying biogenic VOC fluxes have steadily improved over the past decades including recent analytical advances such as the time-of-flight proton-transfer reaction mass spectrometer (PTR-TOF-MS) that enables whole canopy measurement of a wide range of BVOC fluxes . Aircraft VOC flux systems have footprints of several km and can characterize fluxes over entire domains of hundreds of km and so are suitable for evaluating fluxes estimated by regional models . Tower-based VOC flux systems typically have a footprint of hundreds of meters and are well suited for quantifying diurnal, seasonal, and interannual variations. Biogenic VOC fluxes have been measured at more than 45 tower locations (Tables 1 to 4 and summarized in [287, 288]), but most of these studies were for a short period (a few weeks or less) of time. The availability of more than 500 above-canopy flux towers constructed for water, carbon, and energy flux studies provides an opportunity to add biogenic VOC measurements without the cost of basic site development . Measurements at a large number of sites can be accomplished with low-cost and low-power relaxed eddy accumulation measurements systems .
Figure 1 shows that there were relatively few BVOC emission rate observations reported in the 1960s and 1970s, and all but one of these studies were in temperate regions. Interest in the role of BVOC emissions in regional ozone pollution in the 1970s  stimulated publications on this topic by the early 1980s including some investigations of tropical, boreal, and agricultural ecosystems. This interest peaked in the mid-1980s and then declined as some researchers concluded that BVOC emissions did not have an important role in regional air quality . An improved understanding of the magnitude of BVOC emissions and the relatively high sensitivity of ozone to BVOC emissions demonstrated that this was not the case [291, 292] and led to a resurgence in BVOC emissions research in boreal, tropical, and agricultural ecosystems in the 1990s. Interest in tropical landscapes was driven by the recognition that the tropics are responsible for 80% of global emissions . There was initially little interest in BVOC from agricultural ecosystems because of the generally low terpenoid emissions from these plant species, but the discovery of substantial amounts of oxygenated VOC emissions from crops [102, 115] led to more studies. The annual publication rate decreased in the mid-2000s, but there has been a recent increase in the number of publications. This has likely been driven by the recognition of the important role of BVOC in secondary organic aerosol production [3, 293].
Figure 2 shows that temperate, tropical, and boreal ecosystems each cover 25 to 35% of the global vegetation-covered land surface with croplands covering the remaining 15%. This figure also shows that although the estimated global BVOC emission is dominated by tropical ecosystems, most studies have focused on temperate ecosystems. Needleleaf trees, broadleaf trees, shrubs, grass and crops each cover 10 to 30% of the global vegetation-covered land area but broadleaf trees are estimated to contribute nearly 80% of the emissions (Figure 3). Investigations of BVOC emission have generally focused on the important emission sources although broadleaf trees are somewhat understudied. Figure 2 shows that isoprene contributes about half of total emissions and was also investigated in about half of these studies. In contrast, other VOC are 36% of the estimated emissions and were examined in only ~20% of the studies. Recent studies provide some balance with relatively more investigations in the tropics and measurements of other VOC (Figure 1).
3. BVOC Chemical Diversity
Terrestrial ecosystems produce thousands of chemical species that can be emitted into the atmosphere  but only a few of these compounds are emitted at the rates required to have a significant impact on atmospheric composition . Most of these chemicals are organic compounds including some that contain oxygen, nitrogen, sulfur, or halogens. Biogenic emission models often reflect this dominance by including only a few major compounds, such as isoprene and α-pinene, and omitting the rest or including them as a generic undefined “other” category. More recently, the MEGAN2.1 biogenic emission model  was developed to estimate emissions of 147 compounds that were thought to be significant or potentially significant. This section describes BVOC chemical diversity and potential improvements over the MEGAN2.1 scheme.
3.1. Terpenoid Compounds
Terpenoid compounds have long been considered the dominant global BVOC . This incredibly diverse group includes thousands of chemical species that can be classified as hemiterpenoids (C5), monoterpenoids (C10), sesquiterpenoides (C15), homoterpenes (C11 and C16), diterpenoids (C20), and larger compounds with such low volatility that it is unlikely that they are emitted into the atmosphere in a gaseous form. Terpenoids include oxygenated terpenes such as the hemiterpenoid methylbutenol (MBO), the monoterpenoid linalool, and the sesquiterpenoid cedrol. These oxygenated terpenoids are a small portion of the global total terpenoid emission but may be important in some regions. About half of the 147 BVOC species included in MEGAN2.1 are terpenoid compounds including some that are major contributors to global BVOC emissions (e.g., isoprene, α-pinene) and others that are minor components.
Investigations of BVOC began centuries ago with interest in commercial applications for monoterpenes in the flavor and fragrance industries. These activities led to the development of diverse analytical techniques and a considerable body of the literature describing terpenoid production and distribution in the oleoresins stored within plant tissues. Very little of this information has been incorporated into BVOC emission models because the production of monoterpenes by plants and their release into the atmosphere are not always well correlated, and only a small fraction of the hundreds of monoterpene compounds identified in essential oils have been observed as significant atmospheric BVOC emissions. Some monoterpenoids are oxygenated compounds including some multifunctional oxygenates and acetylated compounds that may make a disproportionate contribution to secondary aerosol production. Early studies indicated that a few monoterpenes (α-pinene, β-pinene, limonene, sabinene, 3-carene, and myrcene) dominated the total monoterpene flux into the atmosphere . However, these studies typically did not attempt to measure all compounds, and some monoterpenes may have been reported more frequently simply because these were the only compounds targeted. It was initially thought that all monoterpenes emanated from storage pools and were controlled only by leaf temperature. The discovery of high emission rates of light-dependent monoterpene emissions, produced from recently synthesized carbon in a manner similar to isoprene, from European  and African  savannas, tropical forests , and boreal needleleaf trees  led to the introduction of multiple emission processes for an individual chemical species in BVOC emission models.
Organic chemists investigating monoterpenes in the late 1800s identified the hemiterpene, isoprene (2-methyl-1,3-butadiene), as the biochemical precursor of monoterpenes, but isoprene was thought to exist only within plant tissues . The discovery of substantial isoprene emissions from plants into the atmosphere was discovered more than 50 years ago and was initially controversial . Isoprene later became recognized as the dominant global BVOC emission into the atmosphere . Isoprene contributes about half of the total global BVOC flux, and so it is not surprising that it has been investigated more extensively than any other atmospheric BVOC.
Sesquiterpenes (SQTs) are a major component of essential oils stored by some plants, especially broadleaf trees, and can also be directly emitted without being stored . SQTs are emitted from numerous plant species including conifer and broadleaf trees, shrubs, and agricultural crops . While some sesquiterpenes, such as longifolene, have atmospheric oxidation lifetimes on the order of hours, similar to that of the dominant monoterpenes such as α-pinene, some of the most dominant sesquiterpenes emitted into the atmosphere (β-caryophyllene and farnesene) are much more reactive and have typical lifetimes of minutes . The low volatility, and in some cases high reactivity, of sesquiterpenes makes them considerably more difficult to detect and quantify. As a result, few studies considered sesquiterpene emission measurements since they were generally thought to be a minor contribution in comparison to monoterpenes. Efforts to quantify sesquiterpene emissions increased in the past decade with the growing interest in atmospheric secondary organic aerosol . Although sesquiterpenes are only a minor fraction of total BVOCs, they are recognized as important for the atmosphere due to their relatively high SOA yields .
Large emissions of an oxygenated hemiterpene, 2-methyl-3-buten-2-ol (referred to here as MBO) were observed from pine trees in the early 1990s although emissions of MBO from insects and flowers had been observed previously . MBO is emitted at high rates from some pine species, such as Pinus ponderosa, and low rates from other pines, including most Eurasian pines . The global MBO emission is less than 1% of the global total BVOC, but MBO is the dominant emission in ecosystems dominated by high MBO emitting pines including large areas of western USA forests. Recent studies suggest that MBO may be emitted from most isoprene emitting vegetation at a rate that is ~1% of the isoprene emission rate . This low level emission over a large part of global terrestrial ecosystems could be of the same magnitude as the localized emission from high MBO emitters.
The production of some terpenoid compounds is elevated in response to stress and is often observed as a light dependent, de-novo emission . These include monoterpenes (e.g., ocimene), oxygenated monoterpenes (e.g., linalool), sesquiterpenes (e.g., farnesene), the homoterpenes dimethyl-nonatriene (DMNT), and trimethyl-tridecatetraene (TMTT). Emissions of these compounds are not always present, but when they are observed they can exceed typical monoterpene or sesquiterpene emission rates. The large variability and limited knowledge of factors controlling stress-induced BVOC emissions result in high uncertainties associated with emissions of these compounds, but they may be a substantial component of total BVOC emissions into the atmosphere, and a better understanding is needed.
3.2. Methanol and Acetone
Methanol and acetone are among the most abundant VOCs in the global atmosphere. High concentrations of atmospheric methanol and acetone observed by investigators in the 1960s were attributed primarily to the atmospheric oxidation of VOC with minor contributions from bacteria, biomass burning, and anthropogenic sources . In the early 1990s, high rates of methanol emissions were observed from vegetation foliage, especially young expanding leaves . Lower rates of acetone emissions were observed from conifer buds . A few years later, decaying leaf litter was found to be a smaller but significant abiotic source of methanol and acetone .
Jacob et al.  estimated that terrestrial ecosystems (biotic and abiotic) dominate global methanol emissions with 78% of the global annual production with the remainder being from atmospheric oxidation of VOC (15%), biomass burning (5%), and urban (2%) sources. Millet et al.  used additional in situ observations and concluded that oceans were responsible for 35% of the global methanol emission and assigned a contribution of 42% to terrestrial ecosystems. Stavrakou et al.  used both satellite and aircraft observations to constrain global methanol distributions and report annual emissions of 187 Tg per year with a contribution of 53% from vegetation. They also identified missing sources in arid and semiarid regions of Central Asia and Western USA.
An analysis of the global acetone budget by Jacob et al.  indicated contributions to total emissions from terrestrial ecosystems (37%), atmospheric oxidation of VOC (29%), ocean (28%), biomass burning (5%), and anthropogenic emissions (1%). A more recent analysis concluded that terrestrial ecosystems were responsible for only 22% and oceans contributed 55% .
3.3. Acetaldehyde, Formaldehyde, Ethanol, and Organic Acids
Kesselmeier  described both the atmospheric importance of short-chained oxygenated VOCs (e.g., acetaldehyde, formaldehyde, acetic acid, and formic acid) and the challenge of quantifying their atmospheric budgets. This includes the following challenges: (1) there are both natural and anthropogenic sources of these compounds, (2) there are primary and secondary (atmospheric oxidation) sources, (3) these compounds are difficult to measure, and (4) vegetation is both a source and a sink of these compounds. The strong bidirectional exchange exhibited by these compounds requires that both emission and deposition need to be considered. Accurate simulation of land-atmosphere fluxes of these compounds requires estimates of their atmospheric concentrations and the compensation point for each compound.
Alcoholic fermentation in the leaves and roots of plants produces ethanol which is converted to acetaldehyde in a pathway leading to acetate consumption . Millet et al.  identified the major sources of atmospheric acetaldehyde as oxidation of VOC (60%), ocean (27%), and terrestrial ecosystems (11%). Biomass burning and anthropogenic emissions contribute the remaining 2%. The introduction of the PTRMS technique has provided an increasing number of measurements of acetaldehyde emissions from vegetation, including whole canopy flux measurements, while there remain relatively few data for ethanol .
Substantial emissions of formaldehyde, and lesser amounts of formic and acetic acid, have been reported from studies using enclosure measurements to investigate various tree species [103, 309]. While emissions can be considerable, there is also the potential for a strong uptake of these compounds. These enclosure measurements suggest that the net flux of these compounds is a small emission into the atmosphere. Recent studies using above-canopy measurements have provided evidence that formaldehyde and formic acid emissions could be much larger. An analysis of satellite data suggests that formic acid emissions are two to three times higher than estimated from known sources  and that 90% of formic acid has a biogenic origin which includes direct emission and production from terpenoids. The first whole canopy fluxes of formaldehyde measured by eddy covariance have recently been reported . The above-canopy flux, a net emission, was much higher than predicted from enclosure measurements which may be because the flux included both primary emissions and within canopy production. Measurements to better constrain formic acid and formaldehyde fluxes are needed.
3.4. Stress Compounds
Environmental and biotic stresses are important factors controlling BVOC emissions . This includes BVOCs that are emitted at relatively low levels with unstressed conditions and then are elevated under stressed conditions (e.g., α-pinene) and compounds that are typically observed only when plants are stressed (e.g., methyl salicylate). BVOCs associated with pathogen or herbivore-induced stress include ethene, methanol, terpenoids, benzenoids, and green leaf volatiles [73, 128, 312–315]. The biochemical pathways and the defensive roles of these compounds have been the subject of many investigations , but there have been few attempts to quantify these emissions and they have not been integrated into regional BVOC emission models. The current limited understanding of the processes controlling stress-induced emissions makes any numerical approach for estimating stress BVOC emissions highly uncertain. Observations that provide an initial assessment of stress-induced emissions provide a first step towards assessing their contribution to total BVOC emissions and the need for accounting for these processes in BVOC emission models.
Ethene is an important phytohormone, and its emission rate from plants has been used as an indicator of stress . Sawada and Totsuka  estimated an annual global flux of 18 to 45 Tg of ethene with 74% released from natural sources. This was the first global emission estimate of a nonterpenoid BVOC and was based on an extrapolation of enclosure measurements that indicated widespread ethene production by plants in most landscapes. Canopy scale fluxes measured above a temperate deciduous forest confirmed that substantial amounts of ethene were released into the atmosphere from this landscape . The canopy scale fluxes are in reasonable agreement with the earlier enclosure measurements.
The green leaf volatiles are a major category of BVOC that is associated with plant response to herbivory and other stresses . These compounds are produced in plants from linoleic and linolenic acid which are unsaturated fatty acids. The most prominent of these with respect to emissions into the atmosphere are cis-3-hexenal, trans-2-hexenal, hexanal, 1-hexanol, and cis-3-hexenol . The compound methyl jasmonate is also produced from this pathway and has an important role in plant signaling .
3.5. Leaf Surface Compounds
Leaf surfaces are covered by a waxy material that serves as a barrier for keeping water in and pathogens out . Long-chain hydrocarbons, acids, alcohols, and esters are the dominant components of these leaf waxes, but there are a variety of other constituents . While these high molecular weight compounds have low volatility, a small fraction can volatilize into the gas phase, and this may be significant, especially with the high leaf temperatures (>40°C) that occur in hot deserts. A study by Matsunaga et al.  concluded that some compounds, including homosalate and 2-ethylhexyl salicylate, were emitted at significant rates from a wide variety of plants. These are sunscreen compounds that protect plant tissues from UV solar radiation . The estimated contribution to total emissions from most ecosystems was small, but a large contribution was estimated for desert regions dominated by mesquite (Prosopis spp.) which is an important component of large areas in the southwestern USA.
Another source of VOC emissions from vegetation is the oxidation of organics on the surface of leaves and other structures. Fruekilde et al.  fumigated leaves with ozone and reported elevated emissions of 6-methyl-5-hepten-2-one, acetone, geranyl acetone, and 4-oxopentanal and suggested that ozonolysis at vegetation surfaces could explain the widespread occurrence of these compounds in ambient air. Karl et al.  noted that elevated oxygenated VOC emission from foliage exposed to ozone could also be due to increased production of these compounds in leaves in response to stress or to gas phase oxidation (secondary compounds). They conducted experiments to isolate the mechanisms responsible for oxygenated VOC production and concluded that a substantial amount of oxygenated VOC was primary emissions, originating from reaction of ozone inside of the plant or on plant surfaces, although there were also some secondary products from gas phase reactions.
3.6. Organic Halides
Organic halides including methyl bromide, methyl chloride, and methyl iodide are produced by vegetation and emitted into the atmosphere. Emissions are controlled by environmental conditions including soil moisture and temperature . Even though methyl halide fluxes are small compared to terpenoid emissions, they are an important source of halogens in the stratosphere where they play a role in stratospheric ozone depletion . Quantifying fluxes of methyl halides is challenging because terrestrial ecosystems are both a source and a sink of these compounds [166, 323]. Stable isotopes are now being used to individually quantify gross emission and uptake rates to improve understanding of the processes driving net fluxes [322, 324].
3.7. Organic Sulfur Compounds
Biogenic organic sulfur emissions from marine and terrestrial ecosystems are an important source of atmospheric sulfur compounds in clean environments . Soil microbes and plants are both sources of compounds that include methyl mercaptan, dimethyl sulfide, and dimethyl disulfide. A more recent study  estimated that terrestrial ecosystems contribute about 15% of the global dimethyl sulfide flux with the remainder coming from oceans. Higher weight organic sulfur compounds such as diallyl disulfide, methyl propenyl disulfide, and propenylpropyldisulfide can be emitted in substantial amounts from a few plant species .
3.8. Alkanes (including Oxygenated Alkanes)
Zimmerman  reported that a variety of alkanes were a substantial fraction of the biogenic VOCs emitted from vegetation. This was based on gas chromatograph retention times, rather than identification by mass spectrometry, and later studies have found only very low level of emissions of alkanes including ethane , propane , pentane , hexane , heptane , C6 to C10 saturated aldehydes , alcohols , ketones , pyruvic acid , and methane . The potentially large source of methane  has been controversial as following studies found either much lower or no methane emission from living plants . Terrestrial ecosystems are, however, a major source of methane emission from soil microbes and termites .
3.9. Benzenoid Compounds
The extensive BVOCs emission surveys of Zimmerman  also indicated that benzenoid compounds were a substantial fraction of total BVOC emissions. As was the case for alkanes, later studies found much lower benzenoid emissions. However, it is widely recognized that there are many benzenoid compounds (e.g., benzaldehyde, anisole, and benzyl alcohol) emitted as floral scents . These floral benzenoid emissions are thought to make a small contribution to annual regional BVOC emissions  but can be a major emission at specific locations . At least some of these compounds (e.g., toluene and methyl salicylate) are associated with plant stress and have been observed at elevated rates from stressed plants [73, 88].
3.10. Other Alkenes (including Oxygenated Alkenes)
The terpenoids are not the only alkenes emitted into the atmosphere from terrestrial ecosystems. Propene and butene emissions have been observed in enclosures and confirmed by above-canopy flux measurements . Other longer-chain alkenes have only been observed using enclosure techniques. This includes 1-dodecene and 1-tetradecene . Oxygenated alkenes such as 1,3-octenol , neryl acetone , terpinyl acetate , and nonenal  have also been observed but are thought to be minor in comparison to terpenoid emissions.
3.11. Representing BVOC Chemical Diversity in Numerical Models
The first detailed biogenic VOC emission inventory  included estimates of just two compounds: isoprene and α-pinene. Several decades later, the USA EPA released the first widely available biogenic emission inventory approach, called BEIS . In addition to emission of isoprene and α-pinene, BEIS included lumped categories for “other monoterpenes” and an “unidentified” category. While this made the emission inventory more comprehensive, the “unidentified” category had limited use in atmospheric chemistry models because BVOCs have such varied atmospheric impacts (e.g., a wide range in aerosol yields and ozone production potential). In addition, some highly reactive BVOC may control the local atmospheric oxidizing capacity, while other less reactive compounds are transported long distances to remote areas or to the stratosphere where they can impact the chemistry of these pristine regions. An initial attempt to account for this was made  by using two “other” BVOC categories that included “other reactive VOC,” such as 232-MBO and “other VOC” which included less reactive compounds such as methanol and acetone. Emissions of 39 individual BVOCs were later estimated  in addition to three other categories: other terpenoids, other reactive NMVOCs, and other NMVOCs. The 39 identified compounds contributed about 94% of the total emission. MEGAN2.1  eliminated the use of any “unidentified” categories and estimated emissions of 149 known compounds.
Most atmospheric chemistry schemes include at most only a few BVOCs and may lump these together with other compounds which limits the advantages of a detailed emissions chemical speciation. The increased number of compounds is a disadvantage if there is a significant increase in the computational resources associated with emissions parameterization, processing inputs, and emission calculations. MEGAN2.1  uses a balanced approach that includes individual representations of 13 major BVOCs along with 5 additional categories for which an emission was calculated, and then the total was speciated into individual BVOC. This approach required the calculation of the emission activity of 18 BVOC types. The emission behavior of a compound, for example, the light dependent response, was treated the same for all vegetation types. This is reasonable for some compounds, such as isoprene, but not for others, such as α-pinene, which have different emission behavior in a tropical forest than in a temperate needleleaf forest . This approach can be improved by using a smaller number of compound types but allowing a different emission behavior for different vegetation types. The 18 BVOC categories used for MEGAN2.1  could be reduced to about half that number. For example, a nine BVOC category scheme could include hemiterpenes, light-dependent monoterpenes, light-independent monoterpenes, sesquiterpenes, methanol, acetone, bidirectional compounds, stress compounds, and other compounds. Each of these nine BVOC emission categories could have a different speciation profile for each vegetation type to simulate differences such as the contributions of individual monoterpenes to the total monoterpene flux from different landscapes.
4. BVOC Biological Diversity
Just as the scent of various flowers can be quite distinct, the total BVOC emission rates of various plants can differ. Some plants have total BVOC emission rates that are less than 0.01 μg per gram (dry weight) per hour (μg g−1 h−1), while others have rates that exceed 100 μg g−1 h−1. In addition to the three orders of magnitude variability in total emission, chemical composition can vary greatly with some plants dominated by isoprene, while emissions of other plants are dominated by other compounds such as α-pinene, MBO, or methanol. The BVOC emission rates of different terrestrial ecosystems vary by more than three orders of magnitude because the landscape average emission is determined both by the variability associated with plant-specific BVOC emission rates and the variability in vegetation cover fraction. In order to investigate BVOC emission variations associated with biological diversity, it is useful to define an emission factor for a set of standard conditions such as leaf age, growth environment, light, temperature, CO2 concentration, soil moisture, and others [5, 129]. While there are clear taxonomic patterns associated with BVOC emissions, with plants of the same species or genus tending to be more similar, there are also many exceptions [332, 333]. This is not unexpected since the taxonomic schemes used to classify plants are not based on their BVOC emissions characteristics. In addition, some BVOC emissions variability is expected within plant species. For example, pine trees emit a variety of monoterpenes that are used for chemical defense against many different pests . If all individuals of a pine species emit the same mix of monoterpenes, then a herbivore that manages to overcome this particular chemical mixture could devastate that pine species. If there are pine populations with different monoterpene emission types, then at least some pine tree individuals will survive.
Welter et al.  investigated BVOC emissions of an isoprene emitting oak species (Quercus canariensis), a monoterpene emitting oak species (Q. suber), and a species that is a hybrid of those two oak species (Q. afares). They found that Q. afares individuals were monoterpene emitters but at relatively low rates and with high variability. Geron et al.  examined isoprene emissions from Populus hybrids and found that their emission factors were a factor of two higher than their parents and that the second generation crosses had even higher emission factors. Bäck et al.  measured terpenoid emissions of individual Scots Pine (Pinus sylvestris) trees in a forest stand in Finland. They found that emissions of some trees were dominated by α-pinene, while others emitted primarily D3-carene, and still others emitted similar amounts of both. These studies demonstrate that there can be substantial within-species variation in terpenoid emissions for at least some plant species. Geron et al.  also considered whether there were significant interspecies differences in the isoprene emission factors of isoprene-emitting temperate broadleaf tree species and concluded that there was no clear evidence of this. Variability within and between species was similar suggesting that all temperate broadleaf trees could be divided into just two categories with respect to their isoprene emission: low emitters (<1 μg g−1 h−1) and high emitters (about 90 μg g−1 h−1). Isoprene emission factors for high emitting temperate needleleaf trees were much lower than broadleaf trees indicating a need to assign different isoprene emission factors to different PFTs.
Numerical land surface models typically classify terrestrial ecosystems as either a landcover type  or a mixture of PFTs . A savanna is an example of an ecosystem that is a mixture of grass and tree PFTs. Models based on a landcover classification have parameterizations that are intended to represent the weighted average for all of the vegetation species found in the biome. Plant functional types represent groups of vegetation species that are similar for at least some physiological and ecological traits. While it is possible for biome schemes to have very detailed classes, those used in global land surface models are simple approaches that provide a limited ability to represent BVOC emission diversity. A scheme with just five vegetation types (e.g., broadleaf forests, needleleaf forests, shrublands, grasslands, and croplands) was able to account for a significant part of BVOC emission diversity . A small to moderate number (5 to 25) of global PFTs provide a reasonable approach for estimating global isoprene emissions at coarse resolution but cannot represent the considerable within-biome emission diversity which results in large errors in local to regional isoprene emission estimates .
The MEGAN2.1  approach for simulating BVOC emission diversity is based on the Community Land Model version 4 PFT scheme . The CLM4 approach is typical of the PFT schemes used for the land surface component of global earth system models and includes 6 temperate, 5 boreal/arctic, 3 tropical, and 1 crop PFTs. Table 5 outlines a framework to improve BVOC emission model estimates by expanding the 15 CLM PFTs to 39 PFTs that can better represent the biological BVOC diversity in earth system models. This approach includes a representative “type” species for each of the PFTs listed in Table 5. The first step towards implementing this approach is to conduct an extensive and systematic quantification of the BVOC emission rates of each of these species. This can be accomplished with enclosure measurements  or above-canopy flux measurements above monospecific stands . Additional PFTs can be added when it can be demonstrated that their emission characteristics are substantially different from those on this list.
The three needleleaf tree PFTs included in CLM4 are temperate evergreen, boreal evergreen, and boreal deciduous. Figure 3 shows that needleleaf trees cover about 15% of the global vegetation covered land area but are estimated to contribute less than 5% of the total BVOC. Figure 3 also shows that nearly 25% of BVOC studies have targeted needleleaf trees indicating that they are relatively well studied. The studies summarized in Table 4 show that all three PFTs include a monoterpene emitting type. Both temperate and boreal evergreen species also include high isoprene  and high MBO  emitters, and there is some indication that there should be a low emission category for at least the temperate evergreen trees . It should be noted that the available data for characterizing emissions is limited, and the results of different studies are often conflicting. For example, a literature review  indicated that the Pseudotsuga menziesii (Douglas fir) monoterpene emission factor is a factor of 8 higher than that of Tsuga heterophylla (western hemlock). In contrast, another study  found that the western hemlock monoterpene emission factor is more than twice as high as the value for Douglas fir.
The CLM4 PFTs for broadleaf trees include tropical evergreen, tropical deciduous, temperate evergreen, temperate deciduous, and boreal deciduous trees. These broadleaf trees cover about a third of the vegetation-covered earth surface and are estimated to account for almost 80% of the global total BVOC emission (Figure 3). About half of the BVOC emission diversity studies in Tables 1 to 3 have focused on broadleaf trees resulting in a relatively good characterization of temperate and boreal species, but tropical broadleaf tree emissions have not received enough attention (Figure 2). Each of the five CLM4 broadleaf tree PFTs (Table 5) include a high isoprene emitting type. Some also include a high MT emission type [241, 339], a high isoprene and high monoterpene emission type , and a low emission type .
The CLM4 scheme includes just three shrub PFTs: broadleaf deciduous temperate, broadleaf evergreen temperate and broadleaf deciduous boreal. The two temperate shrub PFTs include high monoterpene, high isoprene, and low emitter categories [65, 138, 340, 341]. The boreal shrub PFT includes both high isoprene and low emitters .
The three CLM4 grass PFTs are C3 grass, C4 grass, and arctic C3 grass. All three PFTs are dominated by a low terpenoid emitting category, but the temperate and arctic C3 PFTs also include some isoprene emitting species [22, 49, 100, 233, 342]. The crop PFT is dominated by low terpenoid emitters, but there are some examples of high isoprene and high monoterpene emitters [275, 278, 280, 343].
This review summarizes the current understanding of BVOC chemical and biological diversity. There are hundreds of BVOCs emitted into the atmosphere, but a relatively few compounds (e.g., isoprene, methanol, α-pinene, acetone, and ethene) dominate the total flux. All BVOCs can influence atmospheric composition, if they are emitted at sufficient rates, but some BVOCs have a relatively high impact due to their reaction rates, products, ozone production potentials, organic aerosol yields, and other properties. As a result, there is a strong need to quantify the chemical diversity of BVOC emissions. On the other hand, a detailed numerical description of BVOC chemical speciation increases computational requirements and the personnel needed to process input variables. In addition, the large uncertainties associated with BVOC emission estimates do not justify an overly detailed parameterization of these compounds. An approach for accurately representing BVOC chemical diversity in emission models requires a balance between providing the appropriate level of details while also minimizing the complexity.
Global land surface models simulate regional variations in ecosystem-atmosphere carbon exchange by assigning values of the photosynthetic parameter Vc max to each PFT. This parameter describes the maximum rate of carboxylation by the photosynthetic enzyme Rubisco. The values of Vc max assigned to the 15 PFTs used by CLM4 vary from 52 μmol m−2 s−1 for grasses to 72 μmol m−2 s−1 for broadleaf evergreen trees and shrubs . In contrast, the isoprene emission factor, which describes the isoprene emission rate at a set of standard conditions, ranges from 1 μg m−2 h−1 for boreal deciduous needleleaf trees to 11000 μmol m−2 s−1 for broadleaf deciduous boreal trees . This comparison illustrates that there is a much greater range in the ability of plants to emit isoprene than there is for photosynthesis. Assigning BVOC emission factors to 15 PFTs is a good initial step towards characterizing BVOC biological diversity, but it is insufficient. A scheme with about 39 PFTs is proposed to improve regional to global BVOC emission estimates.
Reducing uncertainties in BVOC emission estimates will require additional observations. Measurements are especially needed for specific vegetation types (e.g., tropical broadleaf forest and crops) and some nonterpenoid compounds (e.g., ethene, propene, ethanol, ocimene, and hexenal). Leaf-level enclosure measurements are needed to improve representations of the processes controlling emission variations. Tower- and aircraft-based above-canopy flux measurements are also needed to quantify BVOC diversity on landscape to regional scales.
- T. Pierce, C. Geron, L. Bender, R. Dennis, G. Tonnesen, and A. Guenther, “Influence of increased isoprene emissions on regional ozone modeling,” Journal of Geophysical Research D, vol. 103, no. 19, pp. 25611–25629, 1998.
- A. G. Carlton, R. W. Pinder, P. V. Bhave, and G. A. Pouliot, “To what extent can biogenic SOA be controlled?” Environmental Science and Technology, vol. 44, no. 9, pp. 3376–3380, 2010.
- D. V. Spracklen, J. L. Jimenez, K. S. Carslaw et al., “Aerosol mass spectrometer constraint on the global secondary organic aerosol budget,” Atmospheric Chemistry and Physics, vol. 11, no. 23, pp. 12109–12136, 2011.
- R. Baghi, D. Helmig, A. Guenther, T. Duhl, and R. Daly, “Contribution of flowering trees to urban atmospheric biogenic volatile organic compound emissions,” Biogeosciences, vol. 9, pp. 3777–3785, 2012.
- A. B. Guenther, X. Jiang, C. L. Heald et al., “The model of emissions of gases and aerosols from nature version 2. 1 (MEGAN2. 1): an extended and updated framework for modeling biogenic emissions,” Geoscientific Model Development, vol. 5, no. 6, pp. 1471–1492, 2012.
- J. P. Greenberg, D. Asensio, A. Turnipseed, A. B. Guenther, T. Karl, and D. Gochis, “Contribution of leaf and needle litter to whole ecosystem BVOC fluxes,” Atmospheric Environment, vol. 59, pp. 302–311, 2012.
- T. E. Graedel, “Terpenoids in the atmosphere,” Reviews of Geophysics & Space Physics, vol. 17, no. 5, pp. 937–948, 1979.
- A. H. Goldstein and I. E. Galbally, “Known and unexplored organic constituents in the earth's atmosphere,” Environmental Science and Technology, vol. 41, no. 5, pp. 1514–1521, 2007.
- R. A. Rasmussen, “What do the hydrocarbons from trees contribute to air pollution?” Journal of the Air Pollution Control Association, vol. 22, no. 7, pp. 537–543, 1972.
- R. Singh, A. P. Singh, M. P. Singh, A. Kumar, and C. K. Varshney, “Emission of isoprene from common Indian plant species and its implications for regional air quality,” Environmental Monitoring and Assessment, vol. 144, no. 1–3, pp. 43–51, 2008.
- P. Ciccioli, E. Brancaleoni, M. Frattoni et al., “Emission of reactive terpene compounds from orange orchards and their removal by within-canopy processes,” Journal of Geophysical Research D, vol. 104, no. 7, pp. 8077–8094, 1999.
- N. Dudareva, F. Negre, D. A. Nagegowda, and I. Orlova, “Plant volatiles: recent advances and future perspectives,” Critical Reviews in Plant Sciences, vol. 25, no. 5, pp. 417–440, 2006.
- F. W. Went, “Blue hazes in the atmosphere,” Nature, vol. 187, no. 4738, pp. 641–643, 1960.
- P. Zimmerman, “Testing of hydrocarbon emissions from vegetastion, leaf litter and aquatic surfaces and devlopment of a method for compiling biogenic emission inventories,” Tech. Rep. EPA-450-4-70-004, U.S. Environmental Protection Agency, Research Triangle Park, calif, USA, 1979.
- B. Lamb, A. Guenther, D. Gay, and H. Westberg, “A national inventory of biogenic hydrocarbon emissions,” Atmospheric Environment, vol. 21, no. 8, pp. 1695–1705, 1987.
- J.-F. Muller, “Geographical distribution and seasonal variation of surface emissions and deposition velocities of atmospheric trace gases,” Journal of Geophysical Research, vol. 97, no. 4, pp. 3787–3804, 1992.
- A. Guenther, C. N. Hewitt, D. Erickson, et al., “A global model of natural volatile organic compound emissions,” Journal of geophysical research, vol. 100, no. 5, pp. 8873–8892, 1995.
- D. M. Lawrence, K. W. Oleson, M. G. Flanner, et al., “Parameterization improvements and functional and structural advances in version 4 of the community land model,” Journal of Advances in Modeling Earth Systems, vol. 3, 27 pages, 2011.
- E. C. Apel, D. D. Riemer, A. Hills et al., “Measurement and interpretation of isoprene fluxes isoprene, methacrolein, and methyl vinyl ketone mixing ratios at the PROPHET site during the 1998 intensive,” Journal of Geophysical Research D, vol. 107, no. 3, pp. 1–15, 2002.
- R. R. Arnts, W. B. Petersen, R. L. Seila, and B. W. Gay Jr., “Estimates of α-pinene emissions from a loblolly pine forest using an atmospheric diffusion model,” Atmospheric Environment, vol. 16, no. 9, pp. 2127–2137, 1982.
- G. P. Ayers and R. W. Gillett, “Isoprene emissions from vegetation and hydrocarbon emissions from bushfires in tropical Australia,” Journal of Atmospheric Chemistry, vol. 7, no. 2, pp. 177–190, 1988.
- J. Bai, B. Baker, B. Liang, J. Greenberg, and A. Guenther, “Isoprene and monoterpene emissions from an Inner Mongolia grassland,” Atmospheric Environment, vol. 40, no. 30, pp. 5753–5758, 2006.
- B. Baker, A. Guenther, J. Greenberg, A. Goldstein, and R. Fall, “Canopy fluxes of 2-methyl-3-buten-2-ol over a ponderosa pine forest by relaxed eddy accumulation: field data and model comparison,” Journal of Geophysical Research D, vol. 104, no. 21, pp. 26107–26114, 1999.
- B. Baker, A. Guenther, J. Greenberg, and R. Fall, “Canopy level fluxes of 2-methyl-3-buten-2-ol, acetone, and methanol by a portable relaxed eddy accumulation system,” Environmental Science and Technology, vol. 35, no. 9, pp. 1701–1708, 2001.
- I. Bamberger, L. Hörtnagl, T. M. Ruuskanen et al., “Deposition fluxes of terpenes over grassland,” Journal of Geophysical Research D, vol. 116, no. 14, Article ID D14305, 2011.
- J. N. Barney, J. P. Sparks, J. Greenberg, T. H. Whitlow, and A. Guenther, “Biogenic volatile organic compounds from an invasive species: impacts on plant-plant interactions,” Plant Ecology, vol. 203, no. 2, pp. 195–205, 2009.
- B. Bonsang, G. K. Moortgat, and C. A. Pio, “Overview of the FIELDVOC'94 experiment in a eucalyptus forest of Portugal,” Chemosphere, vol. 3, no. 3, pp. 211–226, 2001.
- J. W. Bottenheim and M. F. Shepherd, “C2-C6 hydrocarbon measurements at four rural locations across Canada,” Atmospheric Environment, vol. 29, no. 6, pp. 647–664, 1995.
- A. Bracho-Nunez, S. Welter, M. Staudt, and J. Kesselmeier, “Plant-specific volatile organic compound emission rates from young and mature leaves of Mediterranean vegetation,” Journal of Geophysical Research D, vol. 116, no. 16, Article ID D16304, 2011.
- P. T. Buckley, “Isoprene emissions from a Florida scrub oak species grown in ambient and elevated carbon dioxide,” Atmospheric Environment, vol. 35, no. 3, pp. 631–634, 2001.
- K. E. Burr, S. J. Wallner, and R. W. Tinus, “Ethylene and ethane evolution during cold acclimation and deacclimation of ponderosa pine,” Canadian Journal of Forestry Research, vol. 21, pp. 601–605, 1991.
- C. Calfapietra, G. Scarascia Mugnozza, D. F. Karnosky, F. Loreto, and T. D. Sharkey, “Isoprene emission rates under elevated CO2 and O3 in two field-grown aspen clones differing in their sensitivity to O3,” New Phytologist, vol. 179, no. 1, pp. 55–61, 2008.
- X.-L. Cao, C. Boissard, A. J. Juan, C. N. Hewitt, and M. Gallagher, “Biogenic emissions of volatile organic compounds from gorse (Ulex europaeus): diurnal emission fluxes at Kelling Heath, England,” Journal of Geophysical Research D, vol. 102, no. 15, pp. 18903–18915, 1997.
- J. Chang, Y. Ren, Y. Shi, et al., “An inventory of biogenic volatile organic compounds for a subtropical urban-rural complex,” Atmospheric Environment, vol. 56, pp. 115–123, 2012.
- P. Ciccioli, C. Fabozzi, E. Brancaleoni et al., “Biogenic emission from the Mediterranean Pseudosteppe ecosystem present in Castelporziano,” Atmospheric Environment, vol. 31, no. 1, pp. 167–175, 1997.
- S. B. Corchnoy, J. Arey, and R. Atkinson, “Hydrocarbon emissions from twelve urban shade trees of the Los Angeles, California, Air Basin,” Atmospheric Environment, vol. 26, no. 3, pp. 339–348, 1992.
- B. Davison, R. Taipale, B. Langford et al., “Concentrations and fluxes of biogenic volatile organic compounds above a Mediterranean Macchia ecosystem in western Italy,” Biogeosciences, vol. 6, no. 8, pp. 1655–1670, 2009.
- W. A. Dement, B. J. Tyson, and H. A. Mooney, “Mechanism of monoterpene volatilization in Salvia mellifera,” Phytochemistry, vol. 14, no. 12, pp. 2555–2557, 1975.
- J. P. Digangi, E. S. Boyle, T. Karl et al., “First direct measurements of formaldehyde flux via eddy covariance: implications for missing in-canopy formaldehyde sources,” Atmospheric Chemistry and Physics, vol. 11, no. 20, pp. 10565–10578, 2011.
- T. Dindorf, U. Kuhn, L. Ganzeveld et al., “Significant light and temperature dependent monoterpene emissions from European beech (Fagus sylvatica L.) and their potential impact on the European volatile organic compound budget,” Journal of Geophysical Research D, vol. 111, no. 16, Article ID D16305, 2006.
- P. Dominguez-Taylor, L. G. Ruiz-Suarez, I. Rosas-Perez, J. M. Hernández-Solis, and R. Steinbrecher, “Monoterpene and isoprene emissions from typical tree species in forests around Mexico City,” Atmospheric Environment, vol. 41, no. 13, pp. 2780–2790, 2007.
- P. V. Doskey and W. Gao, “Vertical mixing and chemistry of isoprene in the atmospheric boundary layer: aircraft-based measurements and numerical modeling,” Journal of Geophysical Research D, vol. 104, no. 17, pp. 21263–21274, 1999.
- R. C. Evans, D. T. Tingey, M. L. Gumpertz, and W. F. Burns, “Estimates of isoprene and monoterpene emission rates in plants,” Botanical Gazette, vol. 143, no. 3, pp. 304–310, 1982.
- S. Fares, J. H. Park, D. R. Gentner et al., “Seasonal cycles of biogenic volatile organic compound fluxes and concentrations in a California citrus orchard,” Atmospheric Chemistry and Physics, vol. 12, no. 20, pp. 9865–9880, 2012.
- P. Fruekilde, J. Hjorth, N. R. Jensen, D. Kotzias, and B. Larsen, “Ozonolysis at vegetation surfaces: a source of acetone, 4-oxopentanal, 6-methyl-5-hepten-2-one, and geranyl acetone in the troposphere,” Atmospheric Environment, vol. 32, no. 11, pp. 1893–1902, 1998.
- J. D. Fuentes, D. Wang, G. Den Hartog, H. H. Neumann, T. F. Dann, and K. J. Puckett, “Modelled and field measurements of biogenic hydrocarbon emissions from a Canadian deciduous forest,” Atmospheric Environment, vol. 29, no. 21, pp. 3003–3017, 1995.
- J. D. Fuentes, D. Wang, H. H. Neumann, T. J. Gillespie, G. Den Hartog, and T. F. Dann, “Ambient biogenic hydrocarbons and isoprene emissions from a mixed deciduous forest,” Journal of Atmospheric Chemistry, vol. 25, no. 1, pp. 67–95, 1996.
- J. D. Fuentes and D. Wang, “On the seasonality of isoprene emissions from a mixed temperate forest,” Ecological Applications, vol. 9, no. 4, pp. 1118–1131, 1999.
- Y. Fukui and P. V. Doskey, “Air-surface exchange of nonmethane organic compounds at a grassland site: seasonal variations and stressed emissions,” Journal of Geophysical Research D, vol. 103, no. 11, pp. 13153–13168, 1998.
- F. Geng, X. Tie, A. Guenther, G. Li, J. Cao, and P. Harley, “Effect of isoprene emissions from major forests on ozone formation in the city of Shanghai, China,” Atmospheric Chemistry and Physics, vol. 11, no. 20, pp. 10449–10459, 2011.
- C. D. Geron, D. Nie, R. R. Arnts et al., “Biogenic isoprene emission: model evaluation in a southeastern United States bottomland deciduous forest,” Journal of Geophysical Research D, vol. 102, no. 15, pp. 18889–18901, 1997.
- C. Geron, A. Guenther, T. Sharkey, and R. R. Arnts, “Temporal variability in basal isoprene emission factor,” Tree Physiology, vol. 20, no. 12, pp. 799–805, 2000.
- C. Geron, R. Rasmussen, R. R. Arnts, and A. Guenther, “A review and synthesis of monoterpene speciation from forests in the United States,” Atmospheric Environment, vol. 34, no. 11, pp. 1761–1781, 2000.
- C. Geron, P. Harley, and A. Guenther, “Isoprene emission capacity for US tree species,” Atmospheric Environment, vol. 35, no. 19, pp. 3341–3352, 2001.
- P. D. Goldan, W. C. Kuster, F. C. Fehsenfield, and S. A. Montzka, “The observation of a C5 alcohol emission in a north American pine forest,” Geophysical Research Letters, vol. 20, no. 11, pp. 1039–1042, 1993.
- A. H. Goldstein, S. M. Fan, M. L. Goulden, J. W. Munger, and S. C. Wofsy, “Emissions of ethene, propene, and 1-butene by a midlatitude forest,” Journal of Geophysical Research D, vol. 101, no. 4 D, pp. 9149–9157, 1996.
- A. H. Goldstein, M. L. Goulden, J. W. Munger, S. C. Wofsy, and C. D. Geron, “Seasonal course of isoprene emissions from a midlatitude deciduous forest,” Journal of Geophysical Research D, vol. 103, no. 23, pp. 31045–31056, 1998.
- J. P. Greenberg, A. Guenther, P. Zimmerman et al., “Tethered balloon measurements of biogenic VOCs in the atmospheric boundary layer,” Atmospheric Environment, vol. 33, no. 6, pp. 855–867, 1999.
- A. B. Guenther, R. K. Monson, and R. Fall, “Isoprene and monoterpene emission rate variability: observations with eucalyptus and emission rate algorithm development,” Journal of Geophysical Research, vol. 96, no. 6, pp. 10799–10808, 1991.
- A. B. Guenther, P. R. Zimmerman, P. C. Harley, R. K. Monson, and R. Fall, “Isoprene and monoterpene emission rate variability: model evaluations and sensitivity analyses,” Journal of Geophysical Research, vol. 98, no. 7, pp. 12–617, 1993.
- A. B. Guenther and A. J. Hills, “Eddy covariance measurement of isoprene fluxes,” Journal of Geophysical Research D, vol. 103, no. 11, pp. 13145–13152, 1998.
- A. Guenther, J. Greenberg, P. Harley et al., “Leaf, branch, stand and landscape scale measurements of volatile organic compound fluxes from U.S. woodlands,” Tree Physiology, vol. 16, no. 1-2, pp. 17–24, 1996.
- A. Guenther, P. Zimmerman, L. Klinger, et al., “Estimates of regional natural volatile organic compound fluxes from enclosure and ambient measurements,” Journal of Geophysical Research, vol. 101, no. 1, pp. 1345–1359, 1966.
- A. Guenther, W. Baugh, K. Davis et al., “Isoprene fluxes measured by enclosure, relaxed eddy accumulation, surface layer gradient, mixed layer gradient, and mixed layer mass balance techniques,” Journal of Geophysical Research D, vol. 101, no. 13, pp. 18555–18567, 1996.
- A. Guenther, S. Archer, J. Greenberg et al., “Biogenic hydrocarbon emissions and landcover/climate change in a subtropical savanna,” Physics and Chemistry of the Earth B, vol. 24, no. 6, pp. 659–667, 1999.
- P. Harley, A. Guenther, and P. Zimmerman, “Effects of light, temperature and canopy position on net photosynthesis and isoprene emission from sweetgum (Liquidambar styraciflua) leaves,” Tree Physiology, vol. 16, no. 1-2, pp. 25–32, 1996.
- P. Harley, A. Guenther, and P. Zimmerman, “Environmental controls over isoprene emission in deciduous oak canopies,” Tree Physiology, vol. 17, no. 11, pp. 705–714, 1997.
- P. Harley, V. Fridd-Stroud, J. Greenberg, A. Guenther, and P. Vasconcellos, “Emission of 2-methyl-3-buten-2-ol by pines: a potentially large natural source of reactive carbon to the atmosphere,” Journal of Geophysical Research D, vol. 103, no. 19, pp. 25479–25486, 1998.
- P. Harley, L. Otter, A. Guenther, and J. Greenberg, “Micrometeorological and leaf-level measurements of isoprene emissions from a southern African savanna,” Journal of Geophysical Research, vol. 108, no. 13, 2003.
- P. Harley, J. Greenberg, Ü. Niinemets, and A. Guenther, “Environmental controls over methanol emission from leaves,” Biogeosciences, vol. 4, no. 6, pp. 1083–1099, 2007.
- D. Harrison, M. C. Hunter, A. C. Lewis, P. W. Seakins, T. V. Nunes, and C. A. Pio, “Isoprene and monoterpene emission from the coniferous species Abies Borisii-regis: implications for regional air chemistry in Greece,” Atmospheric Environment, vol. 35, no. 27, pp. 4687–4698, 2001.
- C. He, F. Murray, and T. Lyons, “Seasonal variations in monoterpene emissions from Eucalyptus species,” Chemosphere, vol. 2, no. 1, pp. 65–76, 2000.
- A. C. Heiden, T. Hoffmann, J. Kahl et al., “Emission of volatile organic compounds from ozone-exposed plants,” Ecological Applications, vol. 9, no. 4, pp. 1160–1167, 1999.
- D. Helmig, L. F. Klinger, A. Guenther, L. Vierling, C. Geron, and P. Zimmerman, “Biogenic volatile organic compound emissions (BVOCs). I. Identifications from three continental sites in the U.S,” Chemosphere, vol. 38, no. 9, pp. 2163–2187, 1999.
- D. Helmig, J. Ortega, A. Guenther, J. D. Herrick, and C. Geron, “Sesquiterpene emissions from loblolly pine and their potential contribution to biogenic aerosol formation in the Southeastern US,” Atmospheric Environment, vol. 40, no. 22, pp. 4150–4157, 2006.
- D. Helmig, J. Ortega, T. Duhl et al., “Sesquiterpene emissions from pine trees: identifications, emission rates and flux estimates for the contiguous United States,” Environmental Science and Technology, vol. 41, no. 5, pp. 1545–1553, 2007.
- M. W. Holdren, H. H. Westberg, and P. R. Zimmerman, “Analysis of monoterpene hydrocarbons in rural atmosphere,” Journal of Geophysical Research, vol. 84, no. 8, pp. 5083–5088, 1979.
- R. Holzinger, A. Lee, M. McKay, and A. H. Goldstein, “Seasonal variability of monoterpene emission factors for a Ponderosa pine plantation in California,” Atmospheric Chemistry and Physics, vol. 6, no. 5, pp. 1267–1274, 2006.
- C. Holzke, T. Dindorf, J. Kesselmeier, U. Kuhn, and R. Koppmann, “Terpene emissions from European beech (Fagus sylvatica L.): pattern and emission behaviour over two vegetation periods,” Journal of Atmospheric Chemistry, vol. 55, no. 1, pp. 81–102, 2006.
- A.-K. Huang, N. Li, A. Guenther et al., “Investigation on emission properties of biogenic VOCs of landscape plants in Shenzhen,” Huanjing Kexue/Environmental Science, vol. 32, no. 12, pp. 3555–3559, 2011.
- J. G. Isebrands, A. B. Guenther, P. Harley et al., “Volatile organic compound emission rates from mixed deciduous and coniferous forests in Northern Wisconsin, USA,” Atmospheric Environment, vol. 33, no. 16, pp. 2527–2536, 1999.
- V. A. Isidorov, I. G. Zenkevich, and B. V. Ioffe, “Volatile organic compounds in the atmosphere of forests,” Atmospheric Environment, vol. 19, no. 1, pp. 1–8, 1985.
- K. Jardine, T. Karl, M. Lerdau, P. Harley, A. Guenther, and J. E. Mak, “Carbon isotope analysis of acetaldehyde emitted from leaves following mechanical stress and anoxia,” Plant Biology, vol. 11, no. 4, pp. 591–597, 2009.
- K. Jardine, P. Harley, T. Karl, A. Guenther, M. Lerdau, and J. E. Mak, “Plant physiological and environmental controls over the exchange of acetaldehyde between forest canopies and the atmosphere,” Biogeosciences, vol. 5, no. 6, pp. 1559–1572, 2008.
- K. J. Jardine, E. D. Sommer, S. R. Saleska, T. E. Huxman, P. C. Harley, and L. Abrell, “Gas phase measurements of pyruvic acid and its volatile metabolites,” Environmental Science and Technology, vol. 44, no. 7, pp. 2454–2460, 2010.
- T. G. Karl, C. Spirig, J. Rinne et al., “Virtual disjunct eddy covariance measurements of organic compound fluxes from a subalpine forest using proton transfer reaction mass spectrometry,” Atmospheric Chemistry and Physics, vol. 2, no. 4, pp. 279–291, 2002.
- T. Karl, A. Guenther, C. Spirig, A. Hansel, and R. Fall, “Seasonal variation of biogenic VOC emissions above a mixed hardwood forest in northern Michigan,” Geophysical Research Letters, vol. 30, no. 23, pp. 4–19, 2003.
- T. Karl, A. Guenther, A. Turnipseed, E. G. Patton, and K. Jardine, “Chemical sensing of plant stress at the ecosystem scale,” Biogeosciences, vol. 5, no. 5, pp. 1287–1294, 2008.
- J. F. Karlik and A. M. Winer, “Measured isoprene emission rates of plants in California landscapes: comparison to estimates from taxonomic relationships,” Atmospheric Environment, vol. 35, no. 6, pp. 1123–1131, 2001.
- J. Kesselmeier, L. Schäfer, P. Ciccioli et al., “Emission of monoterpenes and isoprene from a Mediterranean oak species Quercus ilex L. measured within the BEMA (Biogenic Emissions in the Mediterranean Area) project,” Atmospheric Environment, vol. 30, no. 10-11, pp. 1841–1850, 1996.
- J. Kesselmeier, K. Bode, U. Hofmann et al., “Emission of short chained organic acids, aldehydes and monoterpenes from Quercus ilex L. and Pinus pinea L. in relation to physiological activities, carbon budget and emission algorithms,” Atmospheric Environment, vol. 31, no. 1, pp. 119–133, 1997.
- J. Kesselmeier, K. Bode, L. Schafer et al., “Simultaneous field measurements of terpene and isoprene emissions from two dominant Mediterranean oak species in relation to a North American species,” Atmospheric Environment, vol. 32, no. 11, pp. 1947–1953, 1998.
- J. Kesselmeier, K. Bode, C. Gerlach, and E.-M. Jork, “Exchange of atmospheric formic and acetic acids with trees and crop plants under controlled chamber and purified air conditions,” Atmospheric Environment, vol. 32, no. 10, pp. 1765–1775, 1998.
- J.-C. Kim, “Factors controlling natural VOC emissions in a southeastern US pine forest,” Atmospheric Environment, vol. 35, no. 19, pp. 3279–3292, 2001.
- J.-C. Kim, K.-J. Kim, D.-S. Kim, and J.-S. Han, “Seasonal variations of monoterpene emissions from coniferous trees of different ages in Korea,” Chemosphere, vol. 59, no. 11, pp. 1685–1696, 2005.
- S. Kim, T. Karl, D. Helmig, R. Daly, R. Rasmussen, and A. Guenther, “Measurement of atmospheric sesquiterpenes by proton transfer reaction-mass spectrometry (PTR-MS),” Atmospheric Measurement Techniques, vol. 2, no. 1, pp. 99–112, 2009.
- S. Kim, T. Karl, A. Guenther et al., “Emissions and ambient distributions of Biogenic Volatile Organic Compounds (BVOC) in a ponderosa pine ecosystem: interpretation of PTR-MS mass spectra,” Atmospheric Chemistry and Physics, vol. 10, no. 4, pp. 1759–1771, 2010.
- S. Kim, A. Guenther, T. Karl, and J. Greenberg, “Contributions of primary and secondary biogenic VOC tototal OH reactivity during the CABINEX (Community Atmosphere-Biosphere INteractions Experiments)-09 field campaign,” Atmospheric Chemistry and Physics, vol. 11, no. 16, pp. 8613–8623, 2011.
- S. Y. Kim, X. Y. Jiang, M. Lee, et al., “Impact of biogenic volatile organic compounds on ozone production at the Taehwa Research Forest near Seoul, South Korea,” Atmospheric Environment, vol. 70, pp. 447–453, 2013.
- W. Kirstine, I. Galbally, Y. Ye, and M. Hooper, “Emissions of volatile organic compounds (primarily oxygenated species) from pasture,” Journal of Geophysical Research D, vol. 103, no. 3339, pp. 10605–10619, 1998.
- L. F. Klinger, Q. J. Li, A. B. Guenther, J. P. Greenberg, B. Baker, and J. H. Bai, “Assessment of volatile organic compound emissions from ecosystems of China,” Journal of Geophysical Research, vol. 107, no. 21, 2002.
- G. Konig, M. Brunda, H. Puxbaum, C. N. Hewitt, S. C. Duckham, and J. Rudolph, “Relative contribution of oxygenated hydrocarbons to the total biogenic VOC emissions of selected mid-European agricultural and natural plant species,” Atmospheric Environment, vol. 29, no. 8, pp. 861–874, 1995.
- J. Kreuzwieser, J.-P. Schnitzler, and R. Steinbrecher, “Biosynthesis of organic compounds emitted by plants,” Plant Biology, vol. 1, no. 2, pp. 149–159, 1999.
- J. Kreuzwieser, H. Rennenberg, and R. Steinbrecher, “Impact of short-term and long-term elevated CO2 on emission of carbonyls from adult Quercus petraea and Carpinus betulus trees,” Environmental Pollution, vol. 142, no. 2, pp. 246–253, 2006.
- B. Lamb, H. Westberg, and G. Allwine, “Biogenic hydrocarbon emissions from deciduous and coniferous trees in the United States,” Journal of Geophysical Research, vol. 90, no. 1, pp. 2380–2390, 1985.
- B. Lamb, H. Westberg, and G. Allwine, “Isoprene emission fluxes determined by an atmospheric tracer technique,” Atmospheric Environment, vol. 20, no. 1, pp. 1–8, 1986.
- M. Lerdau, S. B. Dilts, H. Westberg, B. K. Lamb, and E. J. Allwine, “Monoterpene emission from ponderosa pine,” Journal of Geophysical Research, vol. 99, no. 8, pp. 16–615, 1994.
- M. Lerdau, P. Matson, R. Fall, and R. Monson, “Ecological controls over monoterpene emissions from douglas-fir (Pseudotsuga menziesii),” Ecology, vol. 76, no. 8, pp. 2640–2647, 1995.
- D. W. Li, Y. Shi, X. Y. He, W. Chen, and X. Chen, “Volatile organic compound emissions from urban trees in Shenyang, China,” Botanical Studies, vol. 49, no. 1, pp. 67–72, 2008.
- Y.-J. Lim, A. Armendariz, Y.-S. Son, and J.-C. Kim, “Seasonal variations of isoprene emissions from five oak tree species in East Asia,” Atmospheric Environment, vol. 45, no. 13, pp. 2202–2210, 2011.
- M. E. Litvak, F. Loreto, P. C. Harley, T. D. Sharkey, and R. K. Monson, “The response of isoprene emission rate and photosynthetic rate to photon flux and nitrogen supply in aspen and white oak trees,” Plant, Cell and Environment, vol. 19, no. 5, pp. 549–559, 1996.
- J. Llusia, J. Penuelas, R. Seco, and I. Filella, “Seasonal changes in the daily emission rates of terpenes by Quercus ilex and the atmospheric concentrations of terpenes in the natural park of Montseny, NE Spain,” Journal of Atmospheric Chemistry, vol. 69, no. 3, pp. 215–230, 2012.
- H. W. Loescher, Non-methane hydrocarbon fluxes from Pinus elliottii and Sereonoa repens: comparing enclosure and above-canopy measurements [Doctoral dissertation], University of Florida, 1997.
- F. Loreto and T. D. Sharkey, “A gas-exchange study of photosynthesis and isoprene emission in Quercus rubra L,” Planta, vol. 182, no. 4, pp. 523–531, 1990.
- R. C. MacDonald and R. Fall, “Detection of substantial emissions of methanol from plants to the atmosphere,” Atmospheric Environment, vol. 27, no. 11, pp. 1709–1713, 1993.
- R. C. MacDonald and R. Fall, “Acetone emission from conifer buds,” Phytochemistry, vol. 34, no. 4, pp. 991–994, 1993.
- M. B. Madronich, J. P. Greenberg, C. A. Wessman, and A. B. Guenther, “Monoterpene emissions from an understory species, Pteridium aquilinum,” Atmospheric Environment, vol. 54, pp. 308–312, 2012.
- R. S. Martin, H. Westberg, E. Allwine, L. Ashman, J. C. Farmer, and B. Lamb, “Measurement of isoprene and its atmospheric oxidation products in a central Pennsylvania deciduous forest,” Journal of Atmospheric Chemistry, vol. 13, no. 1, pp. 1–32, 1991.
- R. S. Martin, I. Villanueva, J. Zhang, and C. J. Popp, “Nonmethane hydrocarbon, monocarboxylic acid, and low molecular weight aldehyde and ketone emissions from vegetation in central New Mexico,” Environmental Science and Technology, vol. 33, no. 13, pp. 2186–2192, 1999.
- S. N. Matsunaga, A. B. Guenther, M. J. Potosnak, and E. C. Apel, “Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation,” Atmospheric Chemistry and Physics, vol. 8, no. 24, pp. 7367–7371, 2008.
- S. N. Matsunaga, A. B. Guenther, J. P. Greenberg et al., “Leaf level emission measurement of sesquiterpenes and oxygenated sesquiterpenes from desert shrubs and temperate forest trees using a liquid extraction technique,” Geochemical Journal, vol. 43, no. 3, pp. 179–189, 2009.
- S. N. Matsunaga, S. Chatani, S. Nakatsuka et al., “Determination and potential importance of diterpene (kaur-16-ene) emitted from dominant coniferous trees in Japan,” Chemosphere, vol. 87, no. 8, pp. 886–893, 2012.
- S. N. Matsunaga, O. Muller, S. Chatani, M. Nakamura, T. Nakaji, and T. Hiura, “Seasonal variation of isoprene basal emission in mature Quercus crispula trees under experimental warming of roots and branches,” Geochemical Journal, vol. 46, no. 2, pp. 163–167, 2012.
- K. A. McKinney, B. H. Lee, A. Vasta, T. V. Pho, and J. W. Munger, “Emissions of isoprenoids and oxygenated biogenic volatile organic compounds from a New England mixed forest,” Atmospheric Chemistry and Physics, vol. 11, no. 10, pp. 4807–4831, 2011.
- R. K. Monson and R. Fall, “Isoprene Emission from Aspen Leaves: influence of Environment and Relation to Photosynthesis and Photorespiration,” Plant Physiology, vol. 90, no. 1, pp. 267–274, 1989.
- R. K. Monson, P. C. Harley, M. E. Litvak et al., “Environmental and developmental controls over the seasonal pattern of isoprene emission from aspen leaves,” Oecologia, vol. 99, no. 3-4, pp. 260–270, 1994.
- S. Moukhtar, B. Bessagnet, L. Rouil, and V. Simon, “Monoterpene emissions from Beech (Fagus sylvatica) in a French forest and impact on secondary pollutants formation at regional scale,” Atmospheric Environment, vol. 39, no. 19, pp. 3535–3547, 2005.
- Ü. Niinemets, “Mild versus severe stress and BVOCs: thresholds, priming and consequences,” Trends in Plant Science, vol. 15, no. 3, pp. 145–153, 2010.
- Ü. Niinemets, U. Kuhn, P. C. Harley et al., “Estimations of isoprenoid emission capacity from enclosure studies: measurements, data processing, quality and standardized measurement protocols,” Biogeosciences, vol. 8, no. 8, pp. 2209–2246, 2011.
- T. V. Nunes and C. A. Pio, “Emission of volatile organic compounds from Portuguese eucalyptus forests,” Chemosphere, vol. 3, no. 3, pp. 239–248, 2001.
- K. Ohta, “Diurnal and seasonal variation in isoprene emission from live oak,” Geochemical Journal, vol. 19, pp. 269–274, 1986.
- E. Ormeño, C. Fernandez, A. Bousquet-Mélou et al., “Monoterpene and sesquiterpene emissions of three Mediterranean species through calcareous and siliceous soils in natural conditions,” Atmospheric Environment, vol. 41, no. 3, pp. 629–639, 2007.
- J. Ortega, D. Helmig, A. Guenther, P. Harley, S. Pressley, and C. Vogel, “Flux estimates and OH reaction potential of reactive biogenic volatile organic compounds (BVOCs) from a mixed northern hardwood forest,” Atmospheric Environment, vol. 41, no. 26, pp. 5479–5495, 2007.
- J. Ortega, D. Helmig, R. W. Daly, D. M. Tanner, A. B. Guenther, and J. D. Herrick, “Approaches for quantifying reactive and low-volatility biogenic organic compound emissions by vegetation enclosure techniques. Part B: applications,” Chemosphere, vol. 72, no. 3, pp. 365–380, 2008.
- L. B. Otter, A. Guenther, and J. Greenberg, “Seasonal and spatial variations in biogenic hydrocarbon emissions from southern African savannas and woodlands,” Atmospheric Environment, vol. 36, no. 26, pp. 4265–4275, 2002.
- S. Owen, C. Boissard, R. A. Street, S. C. Duckham, O. Csiky, and C. N. Hewitt, “Screening of 18 Mediterranean plant species for volatile organic compound emissions,” Atmospheric Environment, vol. 31, no. 1, pp. 101–117, 1997.
- S. M. Owen, C. Boissard, B. Hagenlocher, and C. N. Hewitt, “Field studies of isoprene emissions from vegetation in the Northwest Mediterranean region,” Journal of Geophysical Research D, vol. 103, no. 19, pp. 25499–25511, 1998.
- M. R. Papiez, M. J. Potosnak, W. S. Goliff, A. B. Guenther, S. N. Matsunaga, and W. R. Stockwell, “The impacts of reactive terpene emissions from plants on air quality in Las Vegas, Nevada,” Atmospheric Environment, vol. 43, no. 27, pp. 4109–4123, 2009.
- E. Pegoraro, A. Rey, J. Greenberg et al., “Effect of drought on isoprene emission rates from leaves of Quercus virginiana Mill,” Atmospheric Environment, vol. 38, no. 36, pp. 6149–6156, 2004.
- D. Pérez-Rial, J. Peñuelas, P. López-Mahía, and J. Llusià, “Terpenoid emissions from Quercus robur. A case study of Galicia (NW Spain),” Journal of Environmental Monitoring, vol. 11, no. 6, pp. 1268–1275, 2009.
- G. Pétron, P. Harley, J. Greenberg, and A. Guenther, “Seasonal temperature variations influence isoprene emission,” Geophysical Research Letters, vol. 28, no. 9, pp. 1707–1710, 2001.
- P. A. Pier, “Isoprene emission rates from northern red oak using a whole-tree chamber,” Atmospheric Environment, vol. 29, no. 12, pp. 1347–1353, 1995.
- P. A. Pier and C. McDuffie Jr., “Seasonal isoprene emission rates and model comparisons using whole-tree emissions from white oak,” Journal of Geophysical Research D, vol. 102, no. 20, pp. 23963–23971, 1997.
- C. A. Pio and A. A. Valente, “Atmospheric fluxes and concentrations of monoterpenes in resin-tapped pine forests,” Atmospheric Environment, vol. 32, no. 4, pp. 683–691, 1998.
- O. Pokorska, J. Dewulf, C. Amelynck et al., “Isoprene and terpenoid emissions from Abies alba: identification and emission rates under ambient conditions,” Atmospheric Environment, vol. 59, pp. 501–508, 2012.
- O. Pokorska, J. Dewulf, C. Amelynck et al., “Emissions of biogenic volatile organic compounds from Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium),” International Journal of Environmental Analytical Chemistry, vol. 92, no. 15, pp. 1729–1741, 2012.
- S. Pressley, B. Lamb, H. Westberg, A. Guenther, J. Chen, and E. Allwine, “Monoterpene emissions from a Pacific Northwest Old-Growth Forest and impact on regional biogenic VOC emission estimates,” Atmospheric Environment, vol. 38, no. 19, pp. 3089–3098, 2004.
- S. Pressley, B. Lamb, H. Westberg, J. Flaherty, J. Chen, and C. Vogel, “Long-term isoprene flux measurements above a northern hardwood forest,” Journal of Geophysical Research D, vol. 110, no. 7, Article ID D07301, pp. 1–12, 2005.
- H. Puxbaum and G. König, “Observation of dipropenyldisulfide and other organic sulfur compounds in the atmosphere of a beech forest with Allium ursinum ground cover,” Atmospheric Environment, vol. 31, no. 2, pp. 291–294, 1997.
- F. Rapparini, R. Baraldi, F. Miglietta, and F. Loreto, “Isoprenoid emission in trees of Quercus pubescens and Quercus ilex with lifetime exposure to naturally high CO2 environment,” Plant, Cell and Environment, vol. 27, no. 4, pp. 381–391, 2004.
- R. A. Rasmussen, “Isoprene: identified as a forest-type emission to the atmosphere,” Environmental Science and Technology, vol. 4, no. 8, pp. 667–671, 1970.
- R. A. Rasmussen and F. Went, “Volatile organic material of plant origin in the atmosphere,” Proceedings of the National Academy of Sciences, vol. 53, pp. 215–220, 1965.
- R. C. Rhew, B. R. Miller, and R. F. Welss, “Natural methyl bromide and methyl chloride emissions from coastal salt marshes,” Nature, vol. 403, no. 6767, pp. 292–295, 2000.
- J. M. Roberts, F. C. Fehsenfeld, D. L. Albritton, and R. E. Sievers, “Measurement of monoterpene hydrocarbons at Niwot Ridge, Colorado,” Journal of Geophysical Research, vol. 88, no. 15, pp. 10.667–10.678, 1983.
- J. M. Roberts, C. J. Hahn, F. C. Fehsenfeld, J. M. Warnock, D. L. Albritton, and R. E. Sievers, “Monoterpene hydrocarbons in the nighttime troposphere,” Environmental Science and Technology, vol. 19, no. 4, pp. 364–369, 1985.
- G. Sanadze, “The nature of gaseous substances emitted by leaves of Robinia pseudoacacia,” Soobshcheniya Akademi Nauk Gruzinskoj, vol. 27, pp. 747–750, 1957.
- T. J. Savage, M. K. Hristova, and R. Croteau, “Evidence for an elongation/reduction/C1-elimination pathway in the biosynthesis of n-heptane in xylem of Jeffrey pine,” Plant Physiology, vol. 111, no. 4, pp. 1263–1269, 1996.
- S. Sawada and T. Totsuka, “Natural and anthropogenic sources and fate of atmospheric ethylene,” Atmospheric Environment, vol. 20, no. 5, pp. 821–832, 1986.
- G. W. Schade and A. H. Goldstein, “Fluxes of oxygenated volatile organic compounds from a ponderosa pine plantation,” Journal of Geophysical Research D, vol. 106, no. 3, pp. 3111–3123, 2001.
- R. Seco, I. Filella, J. Llusià, and J. Peñuelas, “Methanol as a signal triggering isoprenoid emissions and photosynthetic performance in Quercus ilex,” Acta Physiologiae Plantarum, vol. 33, no. 6, pp. 2413–2422, 2011.
- T. D. Sharkey, E. L. Singsaas, P. J. Vanderveer, and C. Geron, “Field measurements of isoprene emission from trees in response to temperature and light,” Tree Physiology, vol. 16, no. 7, pp. 649–654, 1996.
- T. D. Sharkey, E. L. Singsaas, M. T. Lerdau, and C. D. Geron, “Weather effects on isoprene emission capacity and applications in emissions algorithms,” Ecological Applications, vol. 9, no. 4, pp. 1132–1137, 1999.
- U. K. Sharma, Y. Kajii, and H. Akimoto, “Characterization of NMHCs in downtown urban center Kathmandu and rural site Nagarkot in Nepal,” Atmospheric Environment, vol. 34, no. 20, pp. 3297–3307, 2000.
- R. W. Shaw Jr., A. L. Crittenden, R. K. Stevens, D. R. Cronn, and V. S. Titov, “Ambient concentrations of hydrocarbons from conifers in atmospheric gases and aerosol particles measured in Soviet Georgia,” Environmental Science and Technology, vol. 17, no. 7, pp. 389–395, 1983.
- M. Šimpraga, H. Verbeeck, M. Demarcke et al., “Clear link between drought stress, photosynthesis and biogenic volatile organic compounds in Fagus sylvatica L,” Atmospheric Environment, vol. 45, no. 30, pp. 5254–5259, 2011.
- B. C. Sive, R. K. Varner, H. Mao, D. R. Blake, O. W. Wingenter, and R. Talbot, “A large terrestrial source of methyl iodide,” Geophysical Research Letters, vol. 34, no. 17, Article ID L17808, 2007.
- C. Spirig, A. Neftel, C. Ammann et al., “Eddy covariance flux measurements of biogenic VOCs during ECHO 2003 using proton transfer reaction mass spectrometry,” Atmospheric Chemistry and Physics, vol. 5, no. 2, pp. 465–481, 2005.
- M. Staudt, A. Ennajah, F. Mouillot, and R. Joffre, “Do volatile organic compound emissions of Tunisian cork oak populations originating from contrasting climatic conditions differ in their responses to summer drought?” Canadian Journal of Forest Research, vol. 38, no. 12, pp. 2965–2975, 2008.
- R. Steinbrecher, M. Klauer, K. Hauff et al., “Biogenic and anthropogenic fluxes of non-methane hydrocarbons over an urban-impacted forest, Frankfurter Stadtwald, Germany,” Atmospheric Environment, vol. 34, no. 22, pp. 3779–3788, 2000.
- A. Tani and Y. Kawawata, “Isoprene emission from the major native Quercus spp. in Japan,” Atmospheric Environment, vol. 42, no. 19, pp. 4540–4550, 2008.
- A. Tani, S. Nozoe, M. Aoki, and C. N. Hewitt, “Monoterpene fluxes measured above a Japanese red pine forest at Oshiba plateau, Japan,” Atmospheric Environment, vol. 36, no. 21, pp. 3391–3402, 2002.
- D. T. Tingey, M. Manning, L. C. Grothaus, and W. F. Burns, “Influence of light and temperature on isoprene emission rates from live Oak,” Physiologia Plantarum, vol. 47, no. 2, pp. 112–118, 1979.
- D. T. Tingey, M. Manning, L. C. Grothaus, and W. F. Burns, “Influence of light and temperature on monoterpene emission rates from slash pine,” Plant Physiology, vol. 65, no. 5, pp. 797–801, 1980.
- J. K.-Y. Tsui, A. Guenther, W.-K. Yip, and F. Chen, “A biogenic volatile organic compound emission inventory for Hong Kong,” Atmospheric Environment, vol. 43, no. 40, pp. 6442–6448, 2009.
- H. J. Wang, J. Y. Xia, Y. J. Mu, L. Nie, X. G. Han, and S. Q. Wan, “BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition,” Atmospheric Chemistry and Physics, vol. 12, no. 8, pp. 3809–3819, 2012.
- C. Warneke, J. A. de Gouw, L. Del Negro et al., “Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories,” Journal of Geophysical Research D, vol. 115, no. 5, Article ID D00F18, 2010.
- S. Welter, A. Bracho-Nunez, C. Mir et al., “The diversification of terpene emissions in Mediterranean oaks: iessons from a study of Quercus suber , Quercus canariensis and its hybrid Quercus afares,” Tree Physiology, vol. 32, no. 9, pp. 1082–1091, 2012.
- H. Westberg, B. Lamb, R. Hafer, A. Hills, P. Shepson, and C. Vogel, “Measurement of isoprene fluxes at the PROPHET site,” Journal of Geophysical Research D, vol. 106, no. 20, pp. 24347–24358, 2001.
- C. Wiedinmyer, S. Friedfeld, W. Baugh et al., “Measurement and analysis of atmospheric concentrations of isoprene and its reaction products in central Texas,” Atmospheric Environment, vol. 35, no. 6, pp. 1001–1013, 2001.
- C. Wiedinmyer, J. Greenberg, A. Guenther et al., “Ozarks Isoprene Experiment (OZIE): measurements and modeling of the ‘isoprene volcano’,” Journal of Geophysical Research D, vol. 110, no. 18, Article ID D18307, pp. 1–17, 2005.
- A. J. Winters, M. A. Adams, T. M. Bleby et al., “Emissions of isoprene, monoterpene and short-chained carbonyl compounds from Eucalyptus spp. in southern Australia,” Atmospheric Environment, vol. 43, no. 19, pp. 3035–3043, 2009.
- Z. Xiaoshan, M. Yujing, S. Wenzhi, and Z. Yahui, “Seasonal variations of isoprene emissions from deciduous trees,” Atmospheric Environment, vol. 34, no. 18, pp. 3027–3032, 2000.
- A. Yani, G. Pauly, M. Faye, F. Salin, and M. Gleizes, “The effect of a long-term water stress on the metabolism and emission of terpenes of the foliage of Cupressus sempervirens,” Plant, Cell and Environment, vol. 16, no. 8, pp. 975–981, 1993.
- Y. Yokouchi, M. Okaniwa, Y. Ambe, and K. Fuwa, “Seasonal variation of monoterpenes in the atmosphere of a pine forest,” Atmospheric Environment, vol. 17, no. 4, pp. 743–750, 1983.
- Y. Yokouchi, A. Hijikata, and Y. Ambe, “Seasonal variation of monoterpene emission rate in a pine forest,” Chemosphere, vol. 13, no. 2, pp. 255–259, 1984.
- Y. Yokouchi and Y. Ambe, “Factors affecting the emission of monoterpenes from red pine (Pinus densiflora),” Plant Physiology, vol. 75, no. 4, pp. 1009–1012, 1984.
- B. Baker, J.-H. Bai, C. Johnson et al., “Wet and dry season ecosystem level fluxes of isoprene and monoterpenes from a southeast Asian secondary forest and rubber tree plantation,” Atmospheric Environment, vol. 39, no. 2, pp. 381–390, 2005.
- D. R. Cronn and W. Nutmagul, “Analysis of atmospheric hydrocarbons during winter MONEX (Borneo),” Tellus, vol. 34, no. 2, pp. 159–165, 1982.
- P. Crutzen, M. Coffey, A. Delany et al., “Observations of air composition in Brazil between the equator and 20°S during the dry season,” Acta Amazonica, vol. 15, pp. 77–119, 1985.
- L. Donoso, R. Romero, A. Rondón, E. Fernandez, P. Oyola, and E. Sanhueza, “Natural and anthropogenic C2 to C6 hydrocarbons in the Central-Eastern Venezuelan atmosphere during the rainy season,” Journal of Atmospheric Chemistry, vol. 25, no. 2, pp. 201–214, 1996.
- C. Geron, A. Guenther, J. Greenberg, H. W. Loescher, D. Clark, and B. Baker, “Biogenic volatile organic compound emissions from a lowland tropical wet forest in Costa Rica,” Atmospheric Environment, vol. 36, no. 23, pp. 3793–3802, 2002.
- J. P. Greenberg, P. R. Zimmerman, L. Heidt, and W. Pollock, “Hydrocarbon and carbon monoxide emissions from biomass burning in Brazil,” Journal of Geophysical Research, vol. 89, no. 1, pp. 1350–1354, 1984.
- J. P. Greenberg, “Biogenic volatile organic compound emissions in central Africa during the Experiment for the Regional Sources and Sinks of Oxidants (EXPRESSO) biomass burning season,” Journal of Geophysical Research D, vol. 104, no. 23, pp. 30659–30671, 1999.
- J. P. Greenberg, A. Guenther, P. Harley et al., “Eddy flux and leaf-level measurements of biogenic VOC emissions from mopane woodland of Botswana,” Journal of Geophysical Research D, vol. 108, no. 13, pp. 2–9, 2003.
- J. P. Greenberg, A. B. Guenther, G. Pétron et al., “Biogenic VOC emissions from forested Amazonian landscapes,” Global Change Biology, vol. 10, no. 5, pp. 651–662, 2004.
- G. Gregory, R. Harriss, R. Talbot et al., “Air chemistry over the tropical forest of Guyana,” Journal of Geophysical Research, vol. 91, pp. 8603–8612, 1986.
- A. Guenther, L. Otter, P. Zimmerman, J. Greenberg, R. Scholes, and M. Scholes, “Biogenic hydrocarbon emissions from southern African savannas,” Journal of Geophysical Research D, vol. 101, no. 20, pp. 25859–25865, 1996.
- P. Harley, P. Vasconcellos, L. Vierling et al., “Variation in potential for isoprene emissions among Neotropical forest sites,” Global Change Biology, vol. 10, no. 5, pp. 630–650, 2004.
- D. Helmig, B. Balsley, K. Davis et al., “Vertical profiling and determination of landscape fluxes of biogenic nonmethane hydrocarbons within the planetary boundary layer in the Peruvian Amazon,” Journal of Geophysical Research D, vol. 103, no. 19, pp. 25519–25532, 1998.
- R. Holzinger, E. Sanhueza, R. von Kuhlmann, B. Kleiss, L. Donoso, and P. J. Crutzen, “Diurnal cycles and seasonal variation of isoprene and its oxidation products in the tropical savanna atmosphere,” Global Biogeochemical Cycles, vol. 16, no. 4, pp. 22–1, 2002.
- T. Karl, M. Potosnak, A. Guenther et al., “Exchange processes of volatile organic compounds above a tropical rain forest: implications for modeling tropospheric chemistry above dense vegetation,” Journal of Geophysical Research D, vol. 109, no. 18, pp. D18306–19, 2004.
- T. Karl, A. Guenther, R. J. Yokelson et al., “The tropical forest and fire emissions experiment: emission, chemistry, and transport of biogenic volatile organic compounds in the lower atmosphere over Amazonia,” Journal of Geophysical Research D, vol. 112, no. 18, Article ID D18302, 2007.
- T. Karl, A. Guenther, A. Turnipseed, G. Tyndall, P. Artaxo, and S. Martin, “Rapid formation of isoprene photo-oxidation products observed in Amazonia,” Atmospheric Chemistry and Physics, vol. 9, no. 20, pp. 7753–7767, 2009.
- M. Keller and M. Lerdau, “Isoprene emission from tropical forest canopy leaves,” Global Biogeochemical Cycles, vol. 13, no. 1, pp. 19–29, 1999.
- J. Kesselmeier, U. Kuhn, A. Wolf et al., “Atmospheric volatile organic compounds (VOC) at a remote tropical forest site in central Amazonia,” Atmospheric Environment, vol. 34, no. 24, pp. 4063–4072, 2000.
- J. Kesselmeier, U. Kuhn, S. Rottenberger et al., “Concentrations and species composition of atmospheric volatile organic compounds (VOCs) as observed during the wet and dry season in Rondônia (Amazonia),” Journal of Geophysical Research D, vol. 107, no. 20, pp. 1–20, 2002.
- L. F. Klinger, “Patterns in volatile organic compound emissions along a savanna-rainforest gradient in central Africa,” Journal of Geophysical Research D, vol. 103, no. 1, pp. 1443–1454, 1998.
- U. Kuhn, S. Rottenberger, T. Biesenthal et al., “Isoprene and monoterpene emissions of Amazonian tree species during the wet season: direct and indirect investigations on controlling environmental functions,” Journal of Geophysical Research D, vol. 107, no. 20, pp. XCXLIII–XCXLIV, 2002.
- U. Kuhn, S. Rottenberger, T. Biesenthal et al., “Seasonal differences in isoprene and light-dependent monoterpene emission by Amazonian tree species,” Global Change Biology, vol. 10, no. 5, pp. 663–682, 2004.
- U. Kuhn, M. O. Andreae, C. Ammann et al., “Isoprene and monoterpene fluxes from Central Amazonian rainforest inferred from tower-based and airborne measurements, and implications on the atmospheric chemistry and the local carbon budget,” Atmospheric Chemistry and Physics, vol. 7, no. 11, pp. 2855–2879, 2007.
- C. E. Jones, J. R. Hopkins, and A. C. Lewis, “In situ measurements of isoprene and monoterpenes within a south-east Asian tropical rainforest,” Atmospheric Chemistry and Physics, vol. 11, no. 14, pp. 6971–6984, 2011.
- B. Langford, P. K. Misztal, E. Nemitz et al., “Fluxes and concentrations of volatile organic compounds from a South-East Asian tropical rainforest,” Atmospheric Chemistry and Physics, vol. 10, no. 17, pp. 8391–8412, 2010.
- D. Y. C. Leung, P. Wong, B. K. H. Cheung, and A. Guenther, “Improved land cover and emission factors for modeling biogenic volatile organic compounds emissions from Hong Kong,” Atmospheric Environment, vol. 44, no. 11, pp. 1456–1468, 2010.
- P. K. Misztal, S. M. Owen, A. B. Guenther et al., “Large estragole fluxes from oil palms in Borneo,” Atmospheric Chemistry and Physics, vol. 10, no. 9, pp. 4343–4358, 2010.
- P. K. Misztal, E. Nemitz, B. Langford et al., “Direct ecosystem fluxes of volatile organic compounds from oil palms in South-East Asia,” Atmospheric Chemistry and Physics, vol. 11, no. 17, pp. 8995–9017, 2011.
- J.-F. Müller, T. Stavrakou, S. Wallens et al., “Global isoprene emissions estimated using MEGAN, ECMWF analyses and a detailed canopy environment model,” Atmospheric Chemistry and Physics, vol. 8, no. 5, pp. 1329–1341, 2008.
- H. Oku, M. Fukuta, H. Iwasaki, P. Tambunan, and S. Baba, “Modification of the isoprene emission model G93 for tropical tree Ficus virgata,” Atmospheric Environment, vol. 42, no. 38, pp. 8747–8754, 2008.
- P. K. Padhy and C. K. Varshney, “Isoprene emission from tropical tree species,” Environmental Pollution, vol. 135, no. 1, pp. 101–109, 2005.
- R. A. Rasmussen and M. A. K. Khalil, “Isoprene over the Amazon Basin,” Journal of Geophysical Research, vol. 93, no. 2, pp. 1417–1421, 1988.
- H. J. I. Rinne, A. B. Guenther, J. P. Greenberg, and P. C. Harley, “Isoprene and monoterpene fluxes measured above Amazonian rainforest and their dependence on light and temperature,” Atmospheric Environment, vol. 36, no. 14, pp. 2421–2426, 2002.
- T. Saito, Y. Yokouchi, Y. Kosugi, M. Tani, E. Philip, and T. Okuda, “Methyl chloride and isoprene emissions from tropical rain forest in Southeast Asia,” Geophysical Research Letters, vol. 35, no. 19, Article ID L19812, 2008.
- E. Sanhueza, M. Santana, D. Trapp et al., “Field measurement evidence for an atmospheric chemical source of formic and acetic acids in the tropic,” Geophysical Research Letters, vol. 23, no. 9, pp. 1045–1048, 1996.
- J. E. Saxton, A. C. Lewis, J. H. Kettlewell et al., “Isoprene and monoterpene measurements in a secondary forest in northern Benin,” Atmospheric Chemistry and Physics, vol. 7, no. 15, pp. 4095–4106, 2007.
- D. Sercanda, A. Guenther, L. Klinger et al., “EXPRESSO flux measurements at upland and lowland Congo tropical forest site,” Tellus B, vol. 53, no. 3, pp. 220–234, 2001.
- R. W. Talbot, M. O. Andreae, H. Berresheim, D. J. Jacob, and K. M. Beecher, “Sources and sinks of formic, acetic, and pyruvic acids over central Amazonia. 2. Wet season,” Journal of Geophysical Research, vol. 95, no. 10, pp. 16–811, 1990.
- C. K. Varshney and A. P. Singh, “Isoprene emission from Indian trees,” Journal of Geophysical Research D, vol. 108, no. 24, pp. 24–7, 2003.
- C. Warneke, S. L. Luxembourg, J. A. de Gouw, H. J. I. Rinne, A. B. Guenther, and R. Fall, “Disjunct eddy covariance measurements of oxygenated volatile organic compounds fluxes from an alfalfa field before and after cutting,” Journal of Geophysical Research D, vol. 107, no. 7-8, pp. 6–1, 2002.
- J. Williams, U. Pöschl, P. J. Crutzen et al., “An atmospheric chemistry interpretation of mass scans obtained from a proton transfer mass spectrometer flown over the tropical rainforest of Surinam,” Journal of Atmospheric Chemistry, vol. 38, no. 2, pp. 133–166, 2001.
- P. R. Zimmerman, J. P. Greenberg, and C. E. Westberg, “Measurements of atmospheric hydrocarbons and biogenic emission fluxes in the Amazon Boundary Layer,” Journal of Geophysical Research, vol. 93, no. 2, pp. 1407–1416, 1988.
- J. Bäck, J. Aalto, M. Henriksson, H. Hakola, Q. He, and M. Boy, “Chemodiversity in terpene emissions at a boreal Scots pine stand,” Biogeosciences Discussions, vol. 8, no. 5, pp. 10577–10615, 2011.
- J. Bai, F. Lin, X. Wan, A. Guenther, A. Turnipseed, and T. Duhl, “Volatile organic compound emission fluxes from a temperate forest in Changbai Mountain,” Acta Scientiae Circumstantiae, vol. 32, no. 3, pp. 545–554, 2012.
- A. Ekberg, A. Arneth, H. Hakola, S. Hayward, and T. Holst, “Isoprene emission from wetland sedges,” Biogeosciences, vol. 6, no. 4, pp. 601–613, 2009.
- A. Ekberg, A. Arneth, and T. Holst, “Isoprene emission from Sphagnum species occupying different growth positions above the water table,” Boreal Environment Research, vol. 16, no. 1, pp. 47–59, 2011.
- P. Faubert, P. Tiiva, Å. Rinnan, A. Michelsen, J. K. Holopainen, and R. Rinnan, “Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming,” New Phytologist, vol. 187, no. 1, pp. 199–208, 2010.
- I. Filella, M. J. Wilkinson, J. Llusià, C. N. Hewitt, and J. Peñuelas, “Volatile organic compounds emissions in Norway spruce (Picea abies) in response to temperature changes,” Physiologia Plantarum, vol. 130, no. 1, pp. 58–66, 2007.
- J. D. Fuentes, D. Wang, and L. Gu, “Seasonal variations in isoprene emissions from a boreal aspen forest,” Journal of Applied Meteorology, vol. 38, no. 7, pp. 855–869, 1999.
- A. Ghirardo, K. Koch, R. Taipale, I. Zimmer, J.-P. Schnitzler, and J. Rinne, “Determination of de novo and pool emissions of terpenes from four common boreal/alpine trees by 13CO2 labelling and PTR-MS analysis,” Plant, Cell and Environment, vol. 33, no. 5, pp. 781–792, 2010.
- S. Haapanala, J. Rinne, K.-H. Pystynen, H. Hellén, H. Hakola, and T. Riutta, “Measurements of hydrocarbon emissions from a boreal fen using the REA technique,” Biogeosciences, vol. 3, no. 1, pp. 103–112, 2006.
- H. Hakola, J. Rinne, and T. Laurila, “The hydrocarbon emission rates of tea-leafed willow (Salix phylicifolia), silver birch (Betula pendula) and European aspen (Populus tremula),” Atmospheric Environment, vol. 32, no. 10, pp. 1825–1833, 1998.
- H. Hakola, T. Laurila, J. Rinne, and K. Puhto, “The ambient concentrations of biogenic hydrocarbons at a northern European, boreal site,” Atmospheric Environment, vol. 34, no. 29-30, pp. 4971–4982, 2000.
- H. Hakola, T. Laurila, V. Lindfors, H. Hellén, A. Gaman, and J. Rinne, “Variation of the VOC emission rates of birch species during the growing season,” Boreal Environment Research, vol. 6, no. 3, pp. 237–249, 2001.
- H. Hakola, V. Tarvainen, J. Bäck et al., “Seasonal variation of mono- and sesquiterpene emission rates of Scots pine,” Biogeosciences, vol. 3, no. 1, pp. 93–101, 2006.
- D. T. Hanson, S. Swanson, L. E. Graham, and T. D. Sharkey, “Evolutionary significance of isoprene emission from mosses,” The American Journal of Botany, vol. 86, no. 5, pp. 634–639, 1999.
- H. Hellén, H. Hakola, K.-H. Pystynen, J. Rinne, and S. Haapanala, “C2-C10 hydrocarbon emissions from a boreal wetland and forest floor,” Biogeosciences, vol. 3, no. 2, pp. 167–174, 2006.
- T. Holst, A. Arneth, S. Hayward et al., “BVOC ecosystem flux measurements at a high latitude wetland site,” Atmospheric Chemistry and Physics, vol. 10, no. 4, pp. 1617–1634, 2010.
- O. Hov, J. Schjoldager, and B. M. Wathne, “Measurement and modeling of the concentrations of terpenes in coniferous forest air (Norway),” Journal of Geophysical Research, vol. 88, no. 15, pp. 10679–10688, 1983.
- R. Janson, “Monoterpene concentrations in and above a forest of Scots pine,” Journal of Atmospheric Chemistry, vol. 14, no. 1–4, pp. 385–394, 1992.
- R. Janson and C. de Serves, “Isoprene emissions from boreal wetlands in Scandinavia,” Journal of Geophysical Research D, vol. 103, no. 19, pp. 25513–25517, 1998.
- R. Janson, C. de Serves, and R. Romero, “Emission of isoprene and carbonyl compounds from a boreal forest and wetland in Sweden,” Agricultural and Forest Meteorology, vol. 98-99, pp. 671–681, 1999.
- B. T. Jobson, Z. Wu, H. Niki, and L. A. Barrie, “Seasonal trends of isoprene, C2-C5 alkanes, and acetylene at a remote boreal site in Canada,” Journal of Geophysical Research, vol. 99, pp. 1589–1599, 1994.
- K. Kempf, E. Allwine, H. Westberg, C. Claiborn, and B. Lamb, “Hydrocarbon emissions from spruce species using environmental chamber and branch enclosure methods,” Atmospheric Environment, vol. 30, no. 9, pp. 1381–1389, 1996.
- L. F. Klinger, P. R. Zimmerman, J. P. Greenberg, L. E. Heidt, and A. B. Guenther, “Carbon trace gas fluxes along a successional gradient in the Hudson-Bay Lowland,” Journal of Geophysical Research, vol. 99, no. 1, pp. 1469–1494, 1994.
- D. M. Martin, J. Gershenzon, and J. Bohlmann, “Induction of volatile terpene biosynthesis and diurnal emission by methyl jasmonate in foliage of Norway spruce,” Plant Physiology, vol. 132, no. 3, pp. 1586–1599, 2003.
- E. Pattey, R. L. Desjardins, H. Westberg, B. Lamb, and T. Zhu, “Measurement of isoprene emissions over a black spruce stand using a tower-based relaxed eddy-accumulation system,” Journal of Applied Meteorology, vol. 38, no. 7, pp. 870–877, 1999.
- G. Petersson, “High ambient concentrations of monoterpenes in a Scandinavian pine forest,” Atmospheric Environment, vol. 22, no. 11, pp. 2617–2619, 1988.
- M. J. Potosnak, B. Baker, L. LeStourgeon et al., “Isoprene emissions from a tundra ecosystem,” Biogeosciences, vol. 10, pp. 871–889, 2013.
- T. Räisänen, A. Ryyppö, and S. Kellomäki, “Monoterpene emission of a boreal Scots pine (Pinus sylvestris L.) forest,” Agricultural and Forest Meteorology, vol. 149, no. 5, pp. 808–819, 2009.
- J. Rinne, H. Hakola, and T. Laurila, “Vertical fluxes of monoterpenes above a Scots pine stand in the boreal vegetation zone,” Physics and Chemistry of the Earth B, vol. 24, no. 6, pp. 711–715, 1999.
- J. Rinne, H. Hakola, T. Laurila, and Ü. Rannik, “Canopy scale monoterpene emissions of Pinus sylvestris dominated forests,” Atmospheric Environment, vol. 34, no. 7, pp. 1099–1107, 2000.
- J. Rinne, R. Taipale, T. Markkanen et al., “Hydrocarbon fluxes above a Scots pine forest canopy: measurements and modeling,” Atmospheric Chemistry and Physics, vol. 7, no. 12, pp. 3361–3372, 2007.
- T. M. Ruuskanen, H. Hakola, M. K. Kajos, H. Hellén, V. Tarvainen, and J. Rinne, “Volatile organic compound emissions from Siberian larch,” Atmospheric Environment, vol. 41, no. 27, pp. 5807–5812, 2007.
- C. Spirig, A. Guenther, J. P. Greenberg, P. Calanca, and V. Tarvainen, “Tethered balloon measurements of biogenic volatile organic compounds at a Boreal forest site,” Atmospheric Chemistry and Physics, vol. 4, no. 1, pp. 215–229, 2004.
- V. Tarvainen, H. Hakola, H. Hellén, J. Bäck, P. Hari, and M. Kulmala, “Temperature and light dependence of the VOC emissions of Scots pine,” Atmospheric Chemistry and Physics, vol. 5, no. 4, pp. 989–998, 2005.
- P. Tiiva, R. Rinnan, T. Holopainen, S. K. Mörsky, and J. K. Holopainen, “Isoprene emissions from boreal peatland microcosms; effects of elevated ozone concentration in an open field experiment,” Atmospheric Environment, vol. 41, no. 18, pp. 3819–3828, 2007.
- P. Tiiva, P. Faubert, A. Michelsen, T. Holopainen, J. K. Holopainen, and R. Rinnan, “Climatic warming increases isoprene emission from a subarctic heath,” New Phytologist, vol. 180, no. 4, pp. 853–863, 2008.
- T. Vuorinen, A.-M. Nerg, E. Vapaavuori, and J. K. Holopainen, “Emission of volatile organic compounds from two silver birch (Betula pendula Roth) clones grown under ambient and elevated CO2 and different O3 concentrations,” Atmospheric Environment, vol. 39, no. 7, pp. 1185–1197, 2005.
- Q.-H. Zhang, F. Schlyter, and P. Anderson, “Green leaf volatiles interrupt pheromone response of spruce bark beetle, Ips typographus,” Journal of Chemical Ecology, vol. 25, no. 12, pp. 2847–2861, 1999.
- T. Zhu, D. Wang, R. L. Desjardins, and J. I. Macpherson, “Aircraft-based volatile organic compounds flux measurements with relaxed eddy accumulation,” Atmospheric Environment, vol. 33, no. 12, pp. 1969–1979, 1999.
- N. G. Agelopoulos, K. Chamberlain, and J. A. Pickett, “Factors affecting volatile emissions of intact potato plants, Solanum tuberosum: variability of quantities and stability of ratios,” Journal of Chemical Ecology, vol. 26, no. 2, pp. 497–511, 2000.
- J. Arey, “Terpenes emitted from agricultural species found in California's Central Valley,” Journal of Geophysical Research, vol. 96, no. 5, pp. 9329–9336, 1991.
- J. Arey, A. M. Winer, R. Atkinson, S. M. Aschmann, W. D. Long, and C. L. Morrison, “The emission of (Z)-3-hexen-1-ol, (Z)-3-hexenylacetate and other oxygenated hydrocarbons from agricultural plant species,” Atmospheric Environment, vol. 25, no. 5-6, pp. 1063–1075, 1991.
- J. Arey, D. E. Crowley, M. Crowley, M. Resketo, and J. Lester, “Hydrocarbon emissions from natural vegetation in California's South Coast Air Basin,” Atmospheric Environment, vol. 29, no. 21, pp. 2977–2988, 1995.
- N. Copeland, J. N. Cape, and M. R. Heal, “Volatile organic compound emissions from Miscanthus and short rotation coppice willow bioenergy crops,” Atmospheric Environment, vol. 60, pp. 327–335, 2012.
- C. M. de Moraes, M. C. Mescher, and J. H. Tumlinson, “Caterpillar-induced nocturnal plant volatiles repel conspecific females,” Nature, vol. 410, no. 6828, pp. 577–579, 2001.
- A. S. D. Eller, K. Sekimoto, J. B. Gilman et al., “Volatile organic compound emissions from switchgrass cultivars used as biofuel crops,” Atmospheric Environment, vol. 45, no. 19, pp. 3333–3337, 2011.
- S. P. Gouinguené and T. C. J. Turlings, “The effects of abiotic factors on induced volatile emissions in corn plants,” Plant Physiology, vol. 129, no. 3, pp. 1296–1307, 2002.
- C. N. Hewitt, R. K. Monson, and R. Fall, “Isoprene emissions from the grass Arundo donax L. are not linked to photorespiration,” Plant Science, vol. 66, no. 2, pp. 139–144, 1990.
- F. Loreto and T. D. Sharkey, “Isoprene emission by plants is affected by transmissible wound signals,” Plant Cell and Environment, vol. 16, no. 5, pp. 563–570, 1993.
- J. Ruther and S. Kleier, “Plant-plant signaling: ethylene synergizes volatile emission in Zea mays induced by exposure to (Z)-3-hexen-1-ol,” Journal of Chemical Ecology, vol. 31, no. 9, pp. 2217–2222, 2005.
- G. Schuh, A. C. Heiden, T. Hoffmann et al., “Emissions of volatile organic compounds from sunflower and beech: dependence on temperature and light intensity,” Journal of Atmospheric Chemistry, vol. 27, no. 3, pp. 291–318, 1997.
- A. Tava, N. Berardo, C. Cunico, M. Romani, and M. Odoardi, “Cultivar differences and seasonal changes of primary metabolites and flavor constituents in tall fescue in relation to palatability,” Journal of Agricultural and Food Chemistry, vol. 43, no. 1, pp. 98–101, 1995.
- C. Warneke, S. L. Luxembourg, J. A. de Gouw, H. J. I. Rinne, A. B. Guenther, and R. Fall, “Disjunct eddy covariance measurements of oxygenated volatile organic compounds fluxes from an alfalfa field before and after cutting,” Journal of Geophysical Research D, vol. 107, no. 7-8, pp. 6–1, 2002.
- S. Juuti, J. Arey, and R. Atkinson, “Monoterpene emission rate measurements from a monterey pine,” Journal of Geophysical Research, vol. 95, no. 6, pp. 7515–7519, 1990.
- A. Guenther, P. Zimmerman, and M. Wildermuth, “Natural volatile organic compound emission rate estimates for U.S. woodland landscapes,” Atmospheric Environment, vol. 28, no. 6, pp. 1197–1210, 1994.
- S. Kim, A. Guenther, and E. Apel, “Quantitative and qualitative sensing techniques for biogenic volatile organic compounds and their oxidation products,” Environmental Science, 2013.
- T. Karl, E. Apell, A. Hodzic, D. D. Riemer, D. R. Blake, and C. Wiedinmyer, “Emissions of volatile organic compounds inferred from airborne flux measurements over a megacity,” Atmospheric Chemistry and Physics, vol. 9, no. 1, pp. 271–285, 2009.
- A. Guenther, C. Geron, T. Pierce, B. Lamb, P. Harley, and R. Fall, “Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America,” Atmospheric Environment, vol. 34, no. 12–14, pp. 2205–2230, 2000.
- J. Kesselmeier, A. Guenther, T. Hoffmann, M. T. Piedade, and J. Warnke, “Natural volatile organic compound emissions from plants and their roles in oxidant balance and particle formation,” in Amazonia and Global Change, M. Keller, Ed., Geophysical Monograph Series, 2009.
- A. Guenther, M. Kulmala, A. Turnipseed, J. Rinne, T. Suni, and A. Reissell, “Integrated land ecosystem-atmosphere processes study (iLEAPS) assessment of global observational networks,” Boreal Environment Research, vol. 16, no. 4, pp. 321–336, 2011.
- A. P. Altshuller, “Review: natural volatile organic substances and their effect on air quality in the United States,” Atmospheric Environment, vol. 17, no. 11, pp. 2131–2165, 1983.
- M. Trainer, “Models and observations of the impact of natural hydrocarbons on rural ozone,” Nature, vol. 329, no. 6141, pp. 705–707, 1987.
- W. L. Chameides, R. W. Lindsay, J. Richardson, and C. S. Kiang, “The role of biogenic hydrocarbons in urban photochemical smog: atlanta as a case study,” Science, vol. 241, no. 4872, pp. 1473–1475, 1988.
- C. R. Hoyle, M. Boy, N. M. Donahue et al., “A review of the anthropogenic influence on biogenic secondary organic aerosol,” Atmospheric Chemistry and Physics, vol. 11, no. 1, pp. 321–343, 2011.
- J. T. Knudsen, R. Eriksson, J. Gershenzon, and B. Ståhl, “Diversity and distribution of floral scent,” Botanical Review, vol. 72, no. 1, pp. 1–120, 2006.
- J. H. Langenheim, “Higher plant terpenoids: a phytocentric overview of their ecological roles,” Journal of Chemical Ecology, vol. 20, no. 6, pp. 1223–1280, 1994.
- T. R. Duhl, D. Helmig, and A. Guenther, “Sesquiterpene emissions from vegetation: a review,” Biogeosciences, vol. 5, no. 3, pp. 761–777, 2008.
- N. C. Bouvier-Brown, A. H. Goldstein, J. B. Gilman, W. C. Kuster, and J. A. de Gouw, “In-situ ambient quantification of monoterpenes, sesquiterpenes and related oxygenated compounds during BEARPEX 2007: implications for gas- and particle-phase chemistry,” Atmospheric Chemistry and Physics, vol. 9, no. 15, pp. 5505–5518, 2009.
- T. Sakulyanontvittaya, A. Guenther, D. Helmig, J. Milford, and C. Wiedinmyer, “Secondary organic aerosol from sesquiterpene and monoterpene emissions in the United States,” Environmental Science and Technology, vol. 42, no. 23, pp. 8784–8790, 2008.
- D. W. Gray, M. T. Lerdau, and A. H. Goldstein, “Influences of temperature history, water stress, and needle age on methylbutenol emissions,” Ecology, vol. 84, no. 3, pp. 765–776, 2003.
- D. W. Gray, S. R. Breneman, L. A. Topper, and T. D. Sharkey, “Biochemical characterization and homology modeling of methylbutenol synthase and implications for understanding hemiterpene synthase evolution in plants,” Journal of Biological Chemistry, vol. 286, no. 23, pp. 20582–20590, 2011.
- G.-I. Arimura, K. Matsui, and J. Takabayashi, “Chemical and molecular ecology of herbivore-induced plant volatiles: proximate factors and their ultimate functions,” Plant and Cell Physiology, vol. 50, no. 5, pp. 911–923, 2009.
- J. R. Snider and G. A. Dawson, “Tropospheric light alcohols, carbonyls, and acetonitrile: concentrations in the southwestern United States and Henry’s law data,” Journal of Geophysical Research, vol. 90, pp. 3797–3805, 1985.
- C. Warneke, T. Karl, H. Judmaier et al., “Acetone, methanol, and other partially oxidized volatile organic emissions from dead plant matter by abiological processes: significance for atmospheric HO(X) chemistry,” Global Biogeochemical Cycles, vol. 13, no. 1, pp. 9–17, 1999.
- D. J. Jacob, B. D. Field, Q. Li et al., “Global budget of methanol: constraints from atmospheric observations,” Journal of Geophysical Research D, vol. 110, no. 8, pp. 1–17, 2005.
- D. B. Millet, D. J. Jacob, T. G. Custer et al., “New constraints on terrestrial and oceanic sources of atmospheric methanol,” Atmospheric Chemistry and Physics, vol. 8, no. 23, pp. 6887–6905, 2008.
- T. Stavrakou, A. Guenther, A. Razavi et al., “First space-based derivation of the global atmospheric methanol emission fluxes,” Atmospheric Chemistry and Physics, vol. 11, no. 10, pp. 4873–4898, 2011.
- D. J. Jacob, B. D. Field, E. M. Jin et al., “Atmospheric budget of acetone,” Journal of Geophysical Research D, vol. 107, no. 9-10, pp. 5–1, 2002.
- E. V. Fischer, D. J. Jacob, D. B. Millet, R. M. Yantosca, and J. Mao, “The role of the ocean in the global atmospheric budget of acetone,” Geophysical Research Letters, vol. 39, no. 1, Article ID L01807, 2012.
- J. Kesselmeier, “Exchange of short-chain oxygenated volatile organic compounds (VOCs) between plants and the atmosphere: a compilation of field and laboratory studies,” Journal of Atmospheric Chemistry, vol. 39, no. 3, pp. 219–233, 2001.
- D. B. Millet, A. Guenther, D. Siegel et al., “Global atmospheric budget of acetaldehyde: 3-D model analysis and constraints from in-situ and satellite observations,” Atmospheric Chemistry and Physics, vol. 10, no. 7, pp. 3405–3425, 2010.
- T. Stavrakou, J.-F. Müller, J. Peeters et al., “Satellite evidence for a large source of formic acid from boreal and tropical forests,” Nature Geoscience, vol. 5, no. 1, pp. 26–30, 2012.
- J. Engelberth, H. T. Alborn, E. A. Schmelz, and J. H. Tumlinson, “Airborne signals prime plants against insect herbivore attack,” Proceedings of the National Academy of Sciences of the United States of America, vol. 101, no. 6, pp. 1781–1785, 2004.
- T. C. Turlings and J. Ton, “Exploiting scents of distress: the prospect of manipulating herbivore-induced plant odours to enhance the control of agricultural pests,” Current Opinion in Plant Biology, vol. 9, no. 4, pp. 421–427, 2006.
- C. C. Von Dahl, M. Hävecker, R. Schlögl, and I. T. Baldwin, “Caterpillar-elicited methanol emission: a new signal in plant-herbivore interactions?” Plant Journal, vol. 46, no. 6, pp. 948–960, 2006.
- K. Hüve, M. M. Christ, E. Kleist et al., “Simultaneous growth and emission measurements demonstrate an interactive control of methanol release by leaf expansion and stomata,” Journal of Experimental Botany, vol. 58, no. 7, pp. 1783–1793, 2007.
- M. R. Kant, P. M. Bleeker, M. V. Wijk, R. C. Schuurink, and M. A. Haring, “Plant volatiles in defence,” Advances in Botanical Research, vol. 51, pp. 613–666, 2009.
- F. A. M. Wellburn and A. R. Wellburn, “Variable patterns of antioxidant protection but similar ethene emission differences in several ozone-sensitive and ozone-tolerant plant selections,” Plant, Cell and Environment, vol. 19, no. 6, pp. 754–760, 1996.
- J. Browse and G. A. Howe, “New weapons and a rapid response against insect attack,” Plant physiology, vol. 146, no. 3, pp. 832–838, 2008.
- A. Hansjakob, M. Riederer, and U. Hildebrandt, “Wax matters: absence of very-long-chain aldehydes from the leaf cuticular wax of the glossy11 mutant of maize compromises the prepenetration processes of Blumeria graminis,” Plant Pathology, vol. 60, no. 6, pp. 1151–1161, 2011.
- D. Chachalis, K. N. Reddy, and C. D. Elmore, “Characterization of leaf surface, wax composition, and control of redvine and trumpetcreeper with glyphosate,” Weed Science, vol. 49, no. 2, pp. 156–163, 2001.
- T. Karl, P. Harley, A. Guenther et al., “The bi-directional exchange of oxygenated VOCs between a loblolly pine (Pinus taeda) plantation and the atmosphere,” Atmospheric Chemistry and Physics, vol. 5, no. 11, pp. 3015–3031, 2005.
- M. A. H. Khan, M. E. Whelan, and R. C. Rhew, “Effects of temperature and soil moisture on methyl halide and chloroform fluxes from drained peatland pasture soils,” Journal of Environmental Monitoring, vol. 14, no. 1, pp. 241–249, 2012.
- Y. Yoshida, Y. Wang, C. Shim, D. Cunnold, D. R. Blake, and G. S. Dutton, “Inverse modeling of the global methyl chloride sources,” Journal of Geophysical Research D, vol. 111, no. 16, Article ID D16307, 2006.
- R. C. Rhew, “Sources and sinks of methyl bromide and methyl chloride in the tallgrass prairie: applying a stable isotope tracer technique over highly variable gross fluxes,” Journal of Geophysical Research G, vol. 116, no. 3, Article ID G03026, 2011.
- T. S. Bates, B. K. Lamb, A. Guenther, J. Dignon, and R. E. Stoiber, “Sulfur emissions to the atmosphere from natural sources,” Journal of Atmospheric Chemistry, vol. 14, no. 1–4, pp. 315–337, 1992.
- S. F. Watts, “The mass budgets of carbonyl sulfide, dimethyl sulfide, carbon disulfide and hydrogen sulfide,” Atmospheric Environment, vol. 34, no. 5, pp. 761–779, 2000.
- J. Wildt, K. Kobel, G. Schuh-Thomas, and A. C. Heiden, “Emissions of oxygenated volatile organic compounds from plants part II: emissions of saturated aldehydes,” Journal of Atmospheric Chemistry, vol. 45, no. 2, pp. 173–196, 2003.
- F. Keppler, J. T. G. Hamilton, M. Braß, and T. Röckmann, “Methane emissions from terrestrial plants under aerobic conditions,” Nature, vol. 439, no. 7073, pp. 187–191, 2006.
- T. A. Dueck, R. de Visser, H. Poorter et al., “No evidence for substantial aerobic methane emission by terrestrial plants: a 13C-labelling approach,” New Phytologist, vol. 175, no. 1, pp. 29–35, 2007.
- S.-L. Steenhuisen, R. A. Raguso, A. Jürgens, and S. D. Johnson, “Variation in scent emission among floral parts and inflorescence developmental stages in beetle-pollinated Protea species (Proteaceae),” South African Journal of Botany, vol. 76, no. 4, pp. 779–787, 2010.
- T. E. Pierce and P. S. Waldruff, “PC-BEIS: a personal computer version of the Biogenic Emissions Inventory System,” Journal of the Air and Waste Management Association, vol. 41, no. 7, pp. 937–941, 1991.
- M. T. Benjamin and A. M. Winer, “Estimating the ozone-forming potential of urban trees and shrubs,” Atmospheric Environment, vol. 32, no. 1, pp. 53–68, 1998.
- P. C. Harley, R. K. Monson, and M. T. Lerdau, “Ecological and evolutionary aspects of isoprene emission from plants,” Oecologia, vol. 118, no. 2, pp. 109–123, 1999.
- R. G. Latta, Y. B. Linhart, M. A. Snyder, and L. Lundquist, “Patterns of variation and correlation in the monoterpene composition of xylem oleoresin within populations of ponderosa pine,” Biochemical Systematics and Ecology, vol. 31, no. 5, pp. 451–465, 2003.
- E. Sertel, A. Robock, and C. Ormeci, “Impacts of land cover data quality on regional climate simulations,” International Journal of Climatology, vol. 30, no. 13, pp. 1942–1953, 2010.
- G. B. Bonan, S. Levis, L. Kergoat, and K. W. Oleson, “Landscapes as patches of plant functional types: an integrating concept for climate and ecosystem models,” Global Biogeochemical Cycles, vol. 16, no. 2, pp. 5–1, 2002.
- A. Guenther, T. Karl, P. Harley, C. Wiedinmyer, P. I. Palmer, and C. Geron, “Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature),” Atmospheric Chemistry and Physics, vol. 6, no. 11, pp. 3181–3210, 2006.
- G. B. Bonan, P. J. Lawrence, K. W. Oleson et al., “Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data,” Journal of Geophysical Research, vol. 116, no. G02, 2011.
- B. Clement, M. L. Riba, R. Leduc, M. Haziza, and L. Torres, “Concentration of monoterpenes in a maple forest in Quebec,” Atmospheric Environment, vol. 24, no. 9, pp. 2513–2516, 1990.
- C. Geron, A. Guenther, J. Greenberg, T. Karl, and R. Rasmussen, “Biogenic volatile organic compound emissions from desert vegetation of the southwestern US,” Atmospheric Environment, vol. 40, no. 9, pp. 1645–1660, 2006.
- K. Jardine, L. Abrell, S. A. Kurc, T. Huxman, J. Ortega, and A. Guenther, “Volatile organic compound emissions from Larrea tridentata (creosotebush),” Atmospheric Chemistry and Physics, vol. 10, no. 24, pp. 12191–12206, 2010.
- D. A. Exton, D. J. Suggett, M. Steinke, and T. J. McGenity, “Spatial and temporal variability of biogenic isoprene emissions from a temperate estuary,” Global Biogeochemical Cycles, vol. 26, 2012.
- E. Ormeño, D. R. Gentner, S. Fares, J. Karlik, J. H. Park, and A. H. Goldstein, “Sesquiterpenoid emissions from agricultural crops: correlations to monoterpenoid emissions and leaf terpene content,” Environmental Science and Technology, vol. 44, no. 10, pp. 3758–3764, 2010.