The effects of different fertilisation treatments with arbuscular mycorrhizal fungi (AMF) inocula... more The effects of different fertilisation treatments with arbuscular mycorrhizal fungi (AMF) inoculation on AMF root colonisation, fruit yield, nutrient and total phenol contents, volatile compound composition, and sensory attributes of tomato (Solanum lycopersicum L.) were investigated. Mineral, organic, and mineral + organic fertiliser application positively affected tomato yield (35%-50%) and phosphorus concentration (24%-29%) compared with controls. AMF application had a significant impact on the total nitrogen (+9%), manganese (+12%), and hydrophilic phenol (+8%) contents in the fruit. Volatile compounds were affected by the interactive effects of fertilisation and AMF application. The response of tomato fruit sensory quality indicators was relatively modest, with only a few sensory characteristics affected to a lesser extent. Although tomato showed susceptibility to field-native AMF, particular combinations of fertilisation and AMF inoculation were more effective at improving the quality parameters of tomatoes under field conditions applied in this study.
Forests, throughout the year, undergo different phenological stages. These seasonal phenology pat... more Forests, throughout the year, undergo different phenological stages. These seasonal phenology patterns, in deciduous, coniferous and/or mixed forests, should be considered in modelling studies of carbon, water, energy and biogenic volatile organic compound fluxes ...
Gaining knowledge emerged from a thesis on cherry trees and infestation, followed by a thesis on ... more Gaining knowledge emerged from a thesis on cherry trees and infestation, followed by a thesis on wetland chemistry, this PhD became a joint project on trees, chemistry, and infestations. Continuous gaining of experience and learning has been accumulated throughout these PhD years. Therefore, I am greatly indebted to my supervisors Prof. dr. ir. Kathy Steppe and dr. ir. Hans Verbeeck who have always been ready to explain, guide and supervise. Especially, I am very grateful to Prof. dr. ir. Kathy Steppe for having transmitted, hopefully, part of her way of scientific thinking. In addition, you provided criticism whenever possible offering solutions leading to this written manuscript. Dr. ir. Hans Verbeeck, thank you for always being there for scientific improvements. Thank you both with respect for all. Furthermore, I also do wish to thank you for using facilities of the Laboratory of Plant Ecology during the period of voluntary work. These months of voluntary work were a hard time, but my work flourished with a book that in now in front of you. I would like to thank the jury members Prof. dr. Reinhart Ceulemans, Prof. dr. Magda Claeys, Prof. dr. ir. Norbert De Kimpe, dr. ir. Bernard Heinesch, Prof. dr. ir. Monica Höfte, and Prof. dr. ir. Herman Van Langenhove for useful comments and advices. Prof. dr. em. Raoul Lemeur is gratefully acknowledged for his thorough help in the early work of this PhD and his life experience he shared with me. Additionally, I want to thank my supervisors in the early stages of this PhD, namely, to dr. ir. Karel Dhondt, Prof. dr. ir. Roeland Samson and dr. ir. Inge Vande Walle. Certainly, doing a PhD is not a work of your own but it involves assistance, advices, critics and comments to improve of many individuals. Prof. dr. ir. Herman Van Langenhove and dr. Crist Amelynck have not only acted as co-authors in my articles but also as instructors. Most sincere thanks for your patience and readiness. Prof. dr. ir. Herman Van Langenhove: the 'Grasshopper effect' is still active. Prof. dr. Marc Aubinet et dr. Bernard Heinesch sont grandement remerciés pour leurs commentaires scientifiques et pour leur l'aide. I really experienced a lot during the Vielsalm forest measurements in 2010. Ik zou graag dr. ir. Jeroen Staelens bedanken voor de wetenschappelijke ondersteuning. Proficiat met u dochter Mira! My sincere gratitude goes to Prof. dr. ir. Magda Claeys for useful technical and scientific tips.
Changes in trace gases of the atmosphere, such as changes in biogenic volatile organic compounds ... more Changes in trace gases of the atmosphere, such as changes in biogenic volatile organic compounds (BVOCs) are assumed to be one of the main causes for the variation of the global climate during the last 150 years (Ludeke et al, 1994). These BVOCs contribute to tropospheric ozone formation having possible effect on air quality and, hence, on human health. This study will relate the BVOC emissions to some main ecophysiological plant processes (i.e. photosynthesis, internal water transport, stem diameter variations) for a potted beech tree (Fagus sylvatica L.) grown under controlled conditions, and subjected to drought stress. The impact of this drought stress on these relationships will be analysed.
Natural ecosystems, such as forests, are known to be important sources of non-methane volatile or... more Natural ecosystems, such as forests, are known to be important sources of non-methane volatile organic compounds (NMVOCs). Oxidation of these biogenic VOCs (BVOCs) in the presence of nitrogen oxides can result in net ozone formation and the low-volatility oxidation products may contribute to secondary organic aerosol formation and/or growth. As a result BVOC emissions can have a negative effect on air quality and human health. In the commonly used emission algorithms [Guenther et al., 1995], leaf temperature and photosynthetic photon flux density (PPFD) are the driving variables for BVOC emissions. However, in order to better explain the variability over time of BVOC emissions for a given tree species, the most recent emission algorithms, such as MEGAN [Guenther et al., 2006], also consider other driving variables such as phenology, temperature and light history. To validate these new emission algorithms, dynamic branch enclosure BVOC flux measurements have been performed on an adul...
Considerable attention has been focused on biogenic volatile organic compound (BVOC) emissions fr... more Considerable attention has been focused on biogenic volatile organic compound (BVOC) emissions from forest ecosystems because of their contribution to tropospheric oxidation processes and secondary aerosol formation [1, 2]. It became apparent that biogenic emissions show much more variation than previously assumed. In this poster we focus on the change in BVOC emission patterns from a four year old Fagus sylvatica L. during a growth chamber experiment (PAR, temperature controlled) lasting from March to November 2008. A dynamic branch enclosure system was used in our experiments. Ozone and VOC were removed from air entering the cuvette, as ozone level was found to be a critical parameter for degradation of the compounds [3]. Samples were collected on Tenax TA-Carbotrap solid phase adsorbent tubes and analyzed by TD-GC-MS. Measurements started before budburst of the tree and finished at the end of autumn. Over the entire period 33 samples have been analyzed, while 16 compounds were de...
Forest ecosystems are known to be important sources of Biogenic Volatile Organic Compounds (BVOC)... more Forest ecosystems are known to be important sources of Biogenic Volatile Organic Compounds (BVOC). Due to their large emissions and their high reactivity with the main oxidants (OH, O3, NO3) in the atmosphere, these BVOCs play an important role in atmospheric chemistry. In order to be able to quantify net formation of oxidants and aerosols from BVOCs, the physicochemical oxidation and aerosol formation and/or growth have to be well understood. Of equal importance, however, is that BVOC emissions need to be well characterized and quantified. Few experimental data are available on the effect of temperature and radiation history on emissions. Measurements are needed to determine the precise dependence of emissions upon radiation and leaf temperature for tree species commonly found in Belgium. The advent of new on-line, rapid and sensitive technologies such as the Proton Transfer Reaction Mass Spectrometer (PTR-MS) has opened new and exciting developments in BVOC emission research. As such direct eddy-covariance BVOC flux measurements at the level of a forest stand became possible. PTR-MS is also very useful to perform long-term continuous BVOC emission measurements from branch enclosures (e.g. leaf cuvettes).
Over the past decades biogenic volatile organic compounds (BVOC) have been widely studied not onl... more Over the past decades biogenic volatile organic compounds (BVOC) have been widely studied not only for better understanding their functions, biosynthesis and regulation, but also because they have great impact on regional and global air quality [1]. Since all BVOCs react with hydroxyl radicals (OH●) and may also react with nitrate radicals (NO3●) and ozone (O3), they contribute to the formation of ozone and secondary organic aerosols. In this study we focus on Quercus robur which is a widely spread tree species in Europe and known as a strong isoprene emitter. We aimed to investigate seasonal patterns of BVOC emissions from Quercus robur under field conditions and to explore the intra-species variations within Quercus robur trees as both are of great importance for accurate modeling and regional inventories. Measurements were performed during a period from May till October 2009 at the campus of Ghent University (Belgium) using a dynamic branch enclosure system. Experiments were cond...
The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions st... more The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions stems from their importance in atmospheric chemistry. In order to compare the most frequently used BVOC measurement techniques, simultaneous on-line PTR-MS and off-line GC-MS data collection was performed on a 3 years old Fagus sylvatica L. tree placed in a growth chamber. Using an internal standard (deuterated toluene) and applying the selective ion mode (SIM) resulted in significant improvements of monoterpene (MT) quantification by TD-GC-MS. PTR-MS quantification of MTs was based on the ion signal at m/z 137. In the course of the experiments the relative contribution of linalool compared to that of MTs was found to be up to 84%. Since this compound has also a PTR-MS signature at m/z 137, quantification of MT emission rates by PTR-MS was disturbed. Comparison of GC-MS and PTR-MS data allowed an estimation of the ratio of the PTR-MS sensitivity for linalool to the one for MTs at m/z 137. This ratio of sensitivities, combined with the information of the relative contribution of linalool to the sum of linalool and MTs obtained by GC-MS, resulted in accurate derivation of the sum of emission rates of linalool and MTs by PTR-MS. The results indicate that fast and on-line PTR-MS measurements of BVOCs are best accompanied by off-line GC measurements to detect possible interferences or to use the additional information for properly quantifying the sum of emission rates of several compounds.
International Journal of Environmental Analytical Chemistry, 2011
Wyche et al.: Emissions of BVOCs and subsequent photochemical production of SOA ditions, although... more Wyche et al.: Emissions of BVOCs and subsequent photochemical production of SOA ditions, although instrumental and experimental constraints impose a level of caution in the interpretation of the results. Concomitant gas-and aerosol-phase composition measurements also provide a detailed overview of numerous key oxidation mechanisms at work within the systems studied, and their combined analysis provides insight into the nature of the SOA formed.
h i g h l i g h t s < Seasonal variation of BVOC emissions from Abies alba trees under ambient co... more h i g h l i g h t s < Seasonal variation of BVOC emissions from Abies alba trees under ambient conditions in Flanders (Belgium). < Isoprene was the main emitted compound (86e93% of the total BVOC emissions), which was never quantified. < Emission spectrum consisted of 27 compounds including 7 SQT.
Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of th... more Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of the plant's carbon (C) budget, they play an important role in atmospheric chemistry for example as a precursor of tropospheric ozone. We performed a study comparing BVOC emissions of European beech (Fagus sylvatica L.) in controlled and natural environmental conditions. A young and adult beech tree was exposed to short-term temperature variations in growth room conditions and in an experimental forest, respectively. This study attempts to clarify how short-term temperature variations between days influenced the ratio between monoterpenoid (MT) emissions and net photosynthesis (Pn). Within a temperature range of 17e27 C and 13e23 C, the MT/Pn carbon ratio increased 10e30 fold for the growth room and forest, respectively. An exponential increasing trend between MT/Pn C ratio and air temperature was observed in both conditions. Beech trees re-emitted a low fraction of the assimilated C back into the atmosphere as MT: 0.01e0.12% and 0.01e0.30% with a temperature rise from 17 to 27 C and 13e23 C in growth room and forest conditions, respectively. However, the data showed that the MT/Pn C ratio of young and adult beech trees responded significantly to changes in temperature.
The effects of different fertilisation treatments with arbuscular mycorrhizal fungi (AMF) inocula... more The effects of different fertilisation treatments with arbuscular mycorrhizal fungi (AMF) inoculation on AMF root colonisation, fruit yield, nutrient and total phenol contents, volatile compound composition, and sensory attributes of tomato (Solanum lycopersicum L.) were investigated. Mineral, organic, and mineral + organic fertiliser application positively affected tomato yield (35%-50%) and phosphorus concentration (24%-29%) compared with controls. AMF application had a significant impact on the total nitrogen (+9%), manganese (+12%), and hydrophilic phenol (+8%) contents in the fruit. Volatile compounds were affected by the interactive effects of fertilisation and AMF application. The response of tomato fruit sensory quality indicators was relatively modest, with only a few sensory characteristics affected to a lesser extent. Although tomato showed susceptibility to field-native AMF, particular combinations of fertilisation and AMF inoculation were more effective at improving the quality parameters of tomatoes under field conditions applied in this study.
Forests, throughout the year, undergo different phenological stages. These seasonal phenology pat... more Forests, throughout the year, undergo different phenological stages. These seasonal phenology patterns, in deciduous, coniferous and/or mixed forests, should be considered in modelling studies of carbon, water, energy and biogenic volatile organic compound fluxes ...
Gaining knowledge emerged from a thesis on cherry trees and infestation, followed by a thesis on ... more Gaining knowledge emerged from a thesis on cherry trees and infestation, followed by a thesis on wetland chemistry, this PhD became a joint project on trees, chemistry, and infestations. Continuous gaining of experience and learning has been accumulated throughout these PhD years. Therefore, I am greatly indebted to my supervisors Prof. dr. ir. Kathy Steppe and dr. ir. Hans Verbeeck who have always been ready to explain, guide and supervise. Especially, I am very grateful to Prof. dr. ir. Kathy Steppe for having transmitted, hopefully, part of her way of scientific thinking. In addition, you provided criticism whenever possible offering solutions leading to this written manuscript. Dr. ir. Hans Verbeeck, thank you for always being there for scientific improvements. Thank you both with respect for all. Furthermore, I also do wish to thank you for using facilities of the Laboratory of Plant Ecology during the period of voluntary work. These months of voluntary work were a hard time, but my work flourished with a book that in now in front of you. I would like to thank the jury members Prof. dr. Reinhart Ceulemans, Prof. dr. Magda Claeys, Prof. dr. ir. Norbert De Kimpe, dr. ir. Bernard Heinesch, Prof. dr. ir. Monica Höfte, and Prof. dr. ir. Herman Van Langenhove for useful comments and advices. Prof. dr. em. Raoul Lemeur is gratefully acknowledged for his thorough help in the early work of this PhD and his life experience he shared with me. Additionally, I want to thank my supervisors in the early stages of this PhD, namely, to dr. ir. Karel Dhondt, Prof. dr. ir. Roeland Samson and dr. ir. Inge Vande Walle. Certainly, doing a PhD is not a work of your own but it involves assistance, advices, critics and comments to improve of many individuals. Prof. dr. ir. Herman Van Langenhove and dr. Crist Amelynck have not only acted as co-authors in my articles but also as instructors. Most sincere thanks for your patience and readiness. Prof. dr. ir. Herman Van Langenhove: the 'Grasshopper effect' is still active. Prof. dr. Marc Aubinet et dr. Bernard Heinesch sont grandement remerciés pour leurs commentaires scientifiques et pour leur l'aide. I really experienced a lot during the Vielsalm forest measurements in 2010. Ik zou graag dr. ir. Jeroen Staelens bedanken voor de wetenschappelijke ondersteuning. Proficiat met u dochter Mira! My sincere gratitude goes to Prof. dr. ir. Magda Claeys for useful technical and scientific tips.
Changes in trace gases of the atmosphere, such as changes in biogenic volatile organic compounds ... more Changes in trace gases of the atmosphere, such as changes in biogenic volatile organic compounds (BVOCs) are assumed to be one of the main causes for the variation of the global climate during the last 150 years (Ludeke et al, 1994). These BVOCs contribute to tropospheric ozone formation having possible effect on air quality and, hence, on human health. This study will relate the BVOC emissions to some main ecophysiological plant processes (i.e. photosynthesis, internal water transport, stem diameter variations) for a potted beech tree (Fagus sylvatica L.) grown under controlled conditions, and subjected to drought stress. The impact of this drought stress on these relationships will be analysed.
Natural ecosystems, such as forests, are known to be important sources of non-methane volatile or... more Natural ecosystems, such as forests, are known to be important sources of non-methane volatile organic compounds (NMVOCs). Oxidation of these biogenic VOCs (BVOCs) in the presence of nitrogen oxides can result in net ozone formation and the low-volatility oxidation products may contribute to secondary organic aerosol formation and/or growth. As a result BVOC emissions can have a negative effect on air quality and human health. In the commonly used emission algorithms [Guenther et al., 1995], leaf temperature and photosynthetic photon flux density (PPFD) are the driving variables for BVOC emissions. However, in order to better explain the variability over time of BVOC emissions for a given tree species, the most recent emission algorithms, such as MEGAN [Guenther et al., 2006], also consider other driving variables such as phenology, temperature and light history. To validate these new emission algorithms, dynamic branch enclosure BVOC flux measurements have been performed on an adul...
Considerable attention has been focused on biogenic volatile organic compound (BVOC) emissions fr... more Considerable attention has been focused on biogenic volatile organic compound (BVOC) emissions from forest ecosystems because of their contribution to tropospheric oxidation processes and secondary aerosol formation [1, 2]. It became apparent that biogenic emissions show much more variation than previously assumed. In this poster we focus on the change in BVOC emission patterns from a four year old Fagus sylvatica L. during a growth chamber experiment (PAR, temperature controlled) lasting from March to November 2008. A dynamic branch enclosure system was used in our experiments. Ozone and VOC were removed from air entering the cuvette, as ozone level was found to be a critical parameter for degradation of the compounds [3]. Samples were collected on Tenax TA-Carbotrap solid phase adsorbent tubes and analyzed by TD-GC-MS. Measurements started before budburst of the tree and finished at the end of autumn. Over the entire period 33 samples have been analyzed, while 16 compounds were de...
Forest ecosystems are known to be important sources of Biogenic Volatile Organic Compounds (BVOC)... more Forest ecosystems are known to be important sources of Biogenic Volatile Organic Compounds (BVOC). Due to their large emissions and their high reactivity with the main oxidants (OH, O3, NO3) in the atmosphere, these BVOCs play an important role in atmospheric chemistry. In order to be able to quantify net formation of oxidants and aerosols from BVOCs, the physicochemical oxidation and aerosol formation and/or growth have to be well understood. Of equal importance, however, is that BVOC emissions need to be well characterized and quantified. Few experimental data are available on the effect of temperature and radiation history on emissions. Measurements are needed to determine the precise dependence of emissions upon radiation and leaf temperature for tree species commonly found in Belgium. The advent of new on-line, rapid and sensitive technologies such as the Proton Transfer Reaction Mass Spectrometer (PTR-MS) has opened new and exciting developments in BVOC emission research. As such direct eddy-covariance BVOC flux measurements at the level of a forest stand became possible. PTR-MS is also very useful to perform long-term continuous BVOC emission measurements from branch enclosures (e.g. leaf cuvettes).
Over the past decades biogenic volatile organic compounds (BVOC) have been widely studied not onl... more Over the past decades biogenic volatile organic compounds (BVOC) have been widely studied not only for better understanding their functions, biosynthesis and regulation, but also because they have great impact on regional and global air quality [1]. Since all BVOCs react with hydroxyl radicals (OH●) and may also react with nitrate radicals (NO3●) and ozone (O3), they contribute to the formation of ozone and secondary organic aerosols. In this study we focus on Quercus robur which is a widely spread tree species in Europe and known as a strong isoprene emitter. We aimed to investigate seasonal patterns of BVOC emissions from Quercus robur under field conditions and to explore the intra-species variations within Quercus robur trees as both are of great importance for accurate modeling and regional inventories. Measurements were performed during a period from May till October 2009 at the campus of Ghent University (Belgium) using a dynamic branch enclosure system. Experiments were cond...
The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions st... more The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions stems from their importance in atmospheric chemistry. In order to compare the most frequently used BVOC measurement techniques, simultaneous on-line PTR-MS and off-line GC-MS data collection was performed on a 3 years old Fagus sylvatica L. tree placed in a growth chamber. Using an internal standard (deuterated toluene) and applying the selective ion mode (SIM) resulted in significant improvements of monoterpene (MT) quantification by TD-GC-MS. PTR-MS quantification of MTs was based on the ion signal at m/z 137. In the course of the experiments the relative contribution of linalool compared to that of MTs was found to be up to 84%. Since this compound has also a PTR-MS signature at m/z 137, quantification of MT emission rates by PTR-MS was disturbed. Comparison of GC-MS and PTR-MS data allowed an estimation of the ratio of the PTR-MS sensitivity for linalool to the one for MTs at m/z 137. This ratio of sensitivities, combined with the information of the relative contribution of linalool to the sum of linalool and MTs obtained by GC-MS, resulted in accurate derivation of the sum of emission rates of linalool and MTs by PTR-MS. The results indicate that fast and on-line PTR-MS measurements of BVOCs are best accompanied by off-line GC measurements to detect possible interferences or to use the additional information for properly quantifying the sum of emission rates of several compounds.
International Journal of Environmental Analytical Chemistry, 2011
Wyche et al.: Emissions of BVOCs and subsequent photochemical production of SOA ditions, although... more Wyche et al.: Emissions of BVOCs and subsequent photochemical production of SOA ditions, although instrumental and experimental constraints impose a level of caution in the interpretation of the results. Concomitant gas-and aerosol-phase composition measurements also provide a detailed overview of numerous key oxidation mechanisms at work within the systems studied, and their combined analysis provides insight into the nature of the SOA formed.
h i g h l i g h t s < Seasonal variation of BVOC emissions from Abies alba trees under ambient co... more h i g h l i g h t s < Seasonal variation of BVOC emissions from Abies alba trees under ambient conditions in Flanders (Belgium). < Isoprene was the main emitted compound (86e93% of the total BVOC emissions), which was never quantified. < Emission spectrum consisted of 27 compounds including 7 SQT.
Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of th... more Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of the plant's carbon (C) budget, they play an important role in atmospheric chemistry for example as a precursor of tropospheric ozone. We performed a study comparing BVOC emissions of European beech (Fagus sylvatica L.) in controlled and natural environmental conditions. A young and adult beech tree was exposed to short-term temperature variations in growth room conditions and in an experimental forest, respectively. This study attempts to clarify how short-term temperature variations between days influenced the ratio between monoterpenoid (MT) emissions and net photosynthesis (Pn). Within a temperature range of 17e27 C and 13e23 C, the MT/Pn carbon ratio increased 10e30 fold for the growth room and forest, respectively. An exponential increasing trend between MT/Pn C ratio and air temperature was observed in both conditions. Beech trees re-emitted a low fraction of the assimilated C back into the atmosphere as MT: 0.01e0.12% and 0.01e0.30% with a temperature rise from 17 to 27 C and 13e23 C in growth room and forest conditions, respectively. However, the data showed that the MT/Pn C ratio of young and adult beech trees responded significantly to changes in temperature.
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