Browsing by Person "Fangmeier, Andreas"

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Air pollution by particulate matter and ammonia at suburban and rural sites in the North China Plain
(2011) Kopsch, Jenny; Fangmeier, Andreas
The thesis presented here was conducted at the Institute of Landscape and Plant Ecology at the University of Hohenheim within the scope of the first Sino-German International Research Training Group (IRTG) ?Modeling Material Flows and Production Systems for Sustainable Resource Use in Intensified Crop Production in the North China Plain?. The project is jointly performed by the University of Hohenheim and the China Agricultural University (CAU) Beijing and financed by the German Research Foundation and the Chinese Ministry of Education. The present study was performed in the framework of subproject 1.3 of the IRTG which had the major aim to study air pollution and atmospheric nitrogen deposition in the North China Plain (NCP). For that purpose data on concentrations of atmospheric pollutants were required in order to assess the level of exposure to pollution of both population and environment in the NCP. This study represents the initial work in the NCP in 2005 and 2006 in order to monitor air pollution and dry nitrogen deposition and its effects. Within this work experiments were conducted to monitor concentrations of PM2.5, PM10, TSP, NOx and NH3 in the NCP. Ammonia monitoring and biomonitoring were synchronised in order to study the potential effects of nitrogen deposition on Molinia caerulea. Since there was no air monitoring network existing in the NCP at the onset of this study, one major part of the work consisted of setting up and testing of European measuring devices under the special conditions in the NCP. The measurements have been therefore the starting point of field observations in the NCP and especially the PM monitoring operated at the agricultural study site Dongbeiwang (DBW) was a key element of the field campaign in order to study pollutant concentrations in the NCP but also the influences of the nearby megacity Beijing. Sampling with the High Volume Sampler Digitel DHA 80 proved to be suitable for the conditions in the NCP. The levels of daily PM10 measured in this study exceeded European (50 µg m-3) and Chinese (150 µg m-3) thresholds by far. Also the EU standard for the number of tolerated daily exceedances (35 times per year) was not met in the Beijing area. Results of PM10 measurements at DBW showed 126 exceedances of the daily mean European threshold in only 128 days in 2005 and 43 exceedances in 44 days in 2006. The maximum daily mean of 412 µg m-3 also reflects the high PM10 peak concentrations in the study region. Results of daily PM2.5 measurements at DBW in 2005 and in 2006 showed exceedances of the U. S. daily average air quality standard of 35 µg m-3 for 99 % of the data (mean value in 2005: 222 µg m-3 and in 2006: 123 µg m-3). High daily PM2.5 peak concentrations were observed especially during the winter. Overall, only under extreme meteorological conditions such as heavy rainfalls PM levels of less than 50 µg m-3 were detected at DBW. Diurnal and hourly variations of PM levels were demonstrated. Glass fibre filters proved to be suitable for the collection of high PM loads whereas quartz fibre filters are much more suitable for the laboratory analysis of N species. Determination of particulate ammonium and nitrate on glass fibre filters of spring season was tested and showed averaged concentrations of 2.4 and 13.1 µg m-3 (TSP) and 8.0 and 11.6 µg m-3 (PM10), respectively. The mass spectrometric measurements were challenging due to the filter material and δ15N/14N ratios were found to be very heterogeneous ranging from -3.0 ? to 44.3 ?, referring to both filter types. The simple and low-cost passive sampling method used (Radiellos®) also proved to be an appropriate tool for evaluating ammonia exposure in the NCP. The seasonal ammonia levels were in the range from 9 to 43 µg m-3 at DBW, Wuqiao and Quzhou, which indicates intensive agricultural activity in the whole NCP. No relationship was found between atmospheric ammonia levels and plant growth parameters of Molinia caerulea and thus, growth of these test plants was not related to gaseous dry deposition of ammonia. The NOx measurements in NCP did not yield reliable data within given time. Overall, multiple sources are assumed to interplay at the study site namely, local dust (such as harvest), traffic, biomass burning, coal combustion, secondary aerosol and industrial emissions from Beijing area. Long-range transported air pollutants such as pollutants from Hebei and Shandong province or deserts as well as the weather pattern greatly influence the atmospheric pollution at DBW and NCP in general.
Biomonitoring of ammonia deposition by means of higher plants
(2013) Ilogu Chibuzo Franklin; Fangmeier, Andreas
Atmospheric nitrogen deposition emanating from oxidized or reduced nitrogen sources has been influenced immensely by human activities. This is as a result of the need to improve and meet the ever changing demands of an increasing growth in global population. The benefits accrued from such activities however, have not been without some negative effects on several ecosystems, plants, air quality and human health. This is due to the emission of reactive nitrogen species and its contribution to the level of atmospheric nitrogen pollution in the environment as well as nitrogen deposition afterwards. Atmospheric ammonia (NH3) arguably is an important source of nitrogen deposition. Its major source is from agricultural activities involving various aspects of crop production including, fertilizer and manure applications among others and also importantly from livestock management. It is pertinent therefore, to conduct continuous monitoring studies in order to ascertain the prevailing ambient NH3 concentration in an area, so as to identify periods when threshold values are exceeded and also to determine how certain plants would respond when exposed to NH3 pollution. This necessitated the need to investigate in this thesis, through active biomonitoring, the interaction of NH3 pollution on selected indicator species namely, Italian ryegrass (Lolium multiflorum L.), barnyard grass (Echinochloa crus-galli L.), stinging nettle (Urtica dioica L.) and common lambsquarters (Chenopodium album L.). The influence of nitrogen deposition, arising from NH3 pollution on the selected indicator species were examined by the responses of the free amino acids and above ground biomass accumulation of the various plants studied, as an indicator of nitrogen accumulation. In order to execute plant and atmospheric NH3 interactions, two different experiments were conducted. The first experiment was a field study carried out around a livestock farm as a source of NH3 pollution and nitrogen deposition. Plant materials were exposed alongside passive diffusion tube samplers at three selected distances from the stable along a transect of 804m. The three different sites were selected with increasing distance from the stable, in order to enable a comparison between the plants exposed in close proximity to the source NH3 emission and those further away. The ambient NH3 concentration at each site was measured with the passive diffusion tube samplers exposed at each location. This measurement was conducted with a view to determine the ambient NH3 concentration exposed to the plant materials at each site and also to observe the influence of increasing distance on NH3 pollution and its exposure on the plants, from a point source of NH3 pollution. Furthermore, two fumigation experiments were conducted under controlled greenhouse conditions. In the fumigation study, only Lolium multiflorum and Echinochloa crus-galli, plants were used for this experiment and exposed to three treatment levels of gaseous NH3 fumigations in different growth chambers. The plants were exposed to the following treatments, non-filtered air (NFA), non-filtered air with low NH3 concentration (NFA+) and non-filtered air with high NH3 concentration (NFA++) in both fumigation experiments. In the field experiment, the ambient NH3 concentration measured at each location from the stable, decreased with increasing distance from the point of NH3 emission. This decrease in concentration of NH3 clearly demonstrates the impact of livestock management as a source of NH3 pollution. The free amino acid concentrations and compositions investigated in the various plants studied in the field experiments showed a significant response to NH3 exposure. Several fold increases in the free amino acid concentrations and changes in composition were observed in plant materials exposed to increasing NH3 concentrations at closer proximity to the stable. Observations made from this study showed that an increase in NH3 concentration with closer distance to the source of NH3 pollution influenced remarkably, the percentage increases of low carbon to nitrogen compounds such as Glutamine (Gln) in Lolium multiflorum and Chenopodium album, Asparagine (Asn) in Echinochloa crus-galli and Arginine (Arg) in Urtica dioica. The increases and alterations observed in the free amino acid compositions of the plants studied, demonstrates the uptake and sensitivity of the various plants to NH3 pollution and nitrogen deposition by inducing changes in its free amino acid metabolism. The effects of nitrogen deposition on the above ground biomass of the plants in the field study, indicated a significant effect of the ambient NH3 concentrations on Lolium multiflorum, Echinochloa crus-galli and Urtica dioica. These findings demonstrate a positive influence of NH3 pollution as a nitrogen source on growth and biomass accumulation in the plants. Considering the results obtained in this study based on the responses of the plants to atmospheric NH3 pollution in the field and in the fumigation studies, it is obvious NH3 had an influence over the growth and metabolism of the plants studied. This influence indicates the plants were able to detect changes in the ambient NH3 concentrations in the environment and responded by exhibiting changes in biomass production and alterations in free amino acid compositions, thus indicating they have good potentials as biomonitors of ammonia deposition.
Biomonitoring von Fluorwasserstoff : neue Ansätze zum Einsatz Höherer Pflanzen als Akkumulationsindikatoren
(2009) Blanckart, Peter; Fangmeier, Andreas
The standardised grass culture as described in VDI guideline 3957 sheet 2 has successfully been used for years to identify pollution related effects and to assess pollution load with hydrogen fluoride. At the moment, two directives are in preparation for the evaluation of the results from the exposure of standardised grass cultures which provide scales for judging and values for orientation on the basis of detailed studies. The directives will be published as VDI 3857 sheet 1 and sheet 2 as green print in 2009. The directive VDI 2310 sheet 3 is being revised as well. Its publication (green print) is also expected for 2009. According to no. 5.3 of the directive VDI 3957 sheet 2, samples with less than 2 g of dry substance have to be rejected. However, the rejection of these samples leads to a time gap for assessing of 14 days or even of 4 weeks. In this context it should be tested how the accumulation of fluoride after exposure with air containing hydrogen fluoride would be affected at lower growth rates. It should also be tested if samples of exposed grass with a minimum weight of less than the required 2 g of dry substance can be used for determining the pollution situation. To evaluate these problems, exposures were performed with standardised grass cultures and with modified methodology in an area ? the city of Ransbach-Baumbach ? which is highly contaminated by fluorides. Parallel to bioindication, the fluoride concentration in the air was assessed with radial symmetric passive samplers as a physicochemical method. By this means a direct comparison of the concentration of air pollutants with the pollutant concentration in the grass could be performed. The tests confirmed that the study area is indeed quite contaminated with fluoride from anthropogenic sources. The area around Ransbach-Baumbach can be considered as a hot-spot for higher fluoride concentrations within Germany. The results confirm that fluoride pollution in Central Europe is still an ongoing problem, even though the pollution is mostly scattered and small scale limited. Therefore, evaluation fundamentals for bioindication methods for fluoride (passive and active) should be worked out for the future, although fluoride accumulations are no longer regularly determined in large scale bioindication monitoring networks. The application of Deschampsia flexuosa (L.) Trin. as an accumulation indicator as a possible alternative to Lolium multiflorum Lam. could not be confirmed in this study; the deviations of fluoride concentrations in Deschampsia flexuosa (L.) Trin. and in Lolium multiflorum Lam. were too large in the spatiotemporal comparison. The measurements performed with radialsymmetric passive samplers did not show a good relationship between the hydrogen fluoride concentration in the air and the fluoride concentration F- [µg g-1 ds] in the Lolium grass cultures. There were only very low correlations between the fluoride concentration and the increase of biomass as raw and dry weight of Lolium multiflorum Lam. (R2 of 0.0258 and 0.0099 at two measurement stations, respectively). Since conventionally an R2 of ≥ 0,6 is required to indicate significant relationships in ecological/ecotoxicological field studies, no link between the increase of biomass and fluoride concentration for the accumulation indicator Lolium multiflorum Lam. is concluded. Therefore, it is recommended to revise the VDI guideline 3957 sheet 2 so that standardised grass culture samples of less than 2 g dry substance are also accounted for in the determination of the accumulation of air pollutants like fluoride in plants.
Cd and Zn concentrations in soil and silage maize following the addition of P fertilizer
(2021) Niño-Savala, Andrea Giovanna; Weishaar, Benedikt; Franzaring, Jürgen; Liu, Xuejun; Fangmeier, Andreas
Studies of soil Cd and Zn are often performed on sites that are contaminated or have deficient Zn conditions. Soil characteristics and crop management could impact the soil mobility and uptake of Cd and Zn, even when considering unpolluted Cd soils and adequate soil Zn levels. The concentrations of these two metals were assessed in soil and silage maize under five P fertilization treatments at two growth stages under low Cd and sufficient Zn conditions. Pearson correlation coefficients and stepwise linear regressions were calculated to investigate the soil characteristics influencing the bioavailable metal fraction in soil and the metal concentration in silage maize. P treatments did not impact Cd accumulation in maize; however, the Zn uptake was affected by P placement at the leaf development stage. From early development to maturity, the Cd level in maize decreased to 10% of the initial uptake, while the Zn level decreased to 50% of the initial uptake. This reduction in both metals may be attributed to a dilution effect derived from high biomass production. Silage maize could alleviate the initial Cd uptake while diminishing the depressant effect of P fertilizer on Zn concentration. Further research is required to understand the effect of P fertilizer on Cd uptake and its relation to Zn under field conditions at early and mature stages.
Effects of elevated atmospheric CO2 concentrations on insects and pathogens of spring wheat (Triticum aestivum L. cv. Triso) and oilseed rape(Brassica napus cv. Campino)
(2012) Oehme, Viktoriya; Fangmeier, Andreas
It is suggested that plants, herbivore insects and pathogens will be affected by rising atmospheric CO2. The working hypothesis of this study was that elevated CO2 will affect plant composition and will thus exert influence on plant-insect interactions by changing the nutritive value for insects feeding on phloem sap. To test this hypothesis, experiments were carried out on wheat and oilseed rape in two different systems: controlled environment chambers (climate chamber system) and an open field exposure system with natural climatic and soil conditions (Mini FACE system). The abundance of detrimental insects from different feeding guilds and plant damage by parasitic organisms were examined in a Mini FACE system, while the consequences of elevated CO2 on aphid performance and potential correlations to phloem sap composition of host plants were observed in controlled environment chambers. The concentrations of amino acids and carbohydrates in the phloem of host plants were analysed by high?performance liquid chromatography (HPLC), using a fluorescence detector for amino acids and the evaporative light scattering detector for carbohydrates. In a Mini-FACE system, phenological development of spring wheat and OSR was not significantly changed due to CO2 enrichment. However, elevated CO2 induced changes in plant chemistry (increased carbon:nitrogen ratio and defensive compounds), which resulted in changes in population densities of some pest species. In order to monitor alterations in insect population density, two different methods were applied: direct counts (method 1) and using of yellow sticky traps (method 2). These methods showed both increases and decreases of insect numbers due to elevated CO2, depending on species and on the period of observation. Concerning plant pathogens, leaves of spring wheat were only slightly and not significantly damaged by Erysiphe graminis, Puccinia striiformis, Puccinia recondita and Septoria tritici during the 2006/2008 years in all treatments. Also the OSR was not significantly damaged by Peronospora parasitica. The frequency and severity of disease infestation on spring wheat and OSR was not significantly impacted by elevated CO2. In controlled-environment chambers, the phenology, above ground biomass and RGR of OSR were not significantly impacted due to elevated CO2. And although the phenology of spring wheat was not influenced by raised CO2, significant increases were observed for plant above ground biomass and RGR. The aphid presence significantly reduced the aboveground biomass and RGR of spring wheat, while no effects due to aphids were observed in OSR. High-CO2 treatment differently impacted the performance of aphids. Slight and non-significant increases due to elevated atmospheric CO2 conditions were observed for the aphid relative developmental stages and intrinsic rates of increase, while the weight and RGR were significantly increased for Rhopalosiphum padi and decreased for Myzus persicae. In order to clear CO2-impacts on the insect performance, phloem sap from host plants was analysed for the composition and concentration of amino acids and carbohydrates. In summary, although the phenological development of spring wheat and OSR was not affected due to elevated CO2, significant changes were found for the concentration of carbohydrates in the phloem sap of spring wheat and individual amino acids in both host plants. These alterations in plant chemistry affected the performance and abundance of herbivore insects.
Fallstudien zu Stickstoffdioxid und Feinstaub - Untersuchung und Vergleich verschiedener Pflanzenarten und Dachflächen im urbanen Raum
(2022) Neher, Philipp; Fangmeier, Andreas
More and more people are living in cities. Therefore, one of the main tasks of municipalities is to ensure a good quality of life for people living in cities. Among many other factors, air quality plays a decisive role, because we all need air to live and consume many litres of it every day. This study therefore deals with the question of whether urban vegetation, especially green roofs, can contribute to an improvement in air quality. In order to answer this question, parameters reflecting air quality were recorded on several roof surfaces. The parameters investigated were primarily particles in the range of 2.5 to 80 micrometres and nitrogen dioxide (NO2). Airborne particles were recorded using Sigma-2-samplers and NO2 using Palmes tubes. On the other hand, morphological leaf characteristics of different plant species were examined microscopically and a statement was made about the "filtering capacities" of the species. In support of this, heavy metal contents in the substrate and wash-out were investigated. Investigations on roof surfaces showed that, due to the height difference, significantly lower pollutant levels were recorded on roof surfaces than at street level. For NO2, about 50 % lower values were recorded. The comparison between greened and ungreened roof surfaces showed slightly significantly lower values for both particulate matter and NO2 on greened roofs. Investigations on the different plant species showed that plants with a structurally rich leaf surface, dense and tall growth, "filter" more particles from the ambient air than low-growing species or species with a smooth leaf surface. In summary, it can be stated that green roofs can lead to a slight improvement in air quality with regard to particulate matter and NO2. The decisive factors here are the choice of plants used in greening systems and ultimately also the distance to the emitters.
Heavy metals from phosphate fertilizers in maize-based food-feed energy systems
(2023) Niño Savala, Andrea Giovanna; Fangmeier, Andreas
The problem of polluted agricultural lands with heavy metals due to anthropogenic activities, including applying phosphorous (P) fertilizers polluted with cadmium (Cd) and other metal such as uranium, has been extensively studied. Several reviews, including the one in the present dissertation, have elaborated this issue with often the same results: the application of P fertilizers with high Cd levels is strongly correlated to Cd accumulation in arable soil, which could imply environmental risks as well as health risks for humans and animals through the food chain. Therefore, these reviews have often the same conclusion: the application of low Cd-P fertilizers, either mineral, organic or recycled, is diminishing the risks of Cd pollution at the soil, crop and consumption level. However, globalization, trade politics, economy, dependency on Morocco mineral P fertilizers, and the finite stock in the raw material have challenged this possibility, especially in the European Union. Meanwhile, in China, polluted arable soils are related to other anthropogenic activities and type of fertilizers rather than Cd-polluted phosphate rock and mineral P fertilizers. At the farm level, other options to diminish Cd pollution in soil and crops, besides low Cd-P fertilizers, could consist of different fertilizer and crop management. These options were studied in this dissertation. A different P management, including different rate applications and placements, did not influence the total Cd concentration in silage maize grown in Germany, regardless of the developmental stage of the crop and the Cd levels in P fertilizer. Silage maize might take up Cd derived from P fertilizers under unpolluted soils, without high risks due to its high biomass production. However, significant changes in the labile Cd fraction were already visible after applying Cd-polluted P fertilizers at 150% of the required amount to the soil after only two growing seasons. Further research should be done to understand the correlations between the bioavailable metal fraction and the actual Cd uptake by silage maize, especially in unpolluted soils. This recommendation also follows the meta- analysis results presented in the second publication, which indicated a possible bias as most of the studies are performed under polluted conditions. Considering the results of the third and fourth publication, the Cd uptake by silage maize was strongly correlated to labile Zn in the soil and the Zn uptake at the early development stage after two field seasons. Placed P fertilizer had a significant and negative effect on the Zn uptake by young silage maize. Further research is needed to understand the behavior of Cd and Zn in the uptake process by maize under P fertilization in unpolluted soils. According to three of the four publications presented in this dissertation, the soil pH was the main soil characteristic influencing the bioavailability and the plant uptake of Cd under unpolluted conditions, regardless of the P treatment, the development stage, and the maizes intended use. However, the total Cd concentration in the soil was the dominant variable for the Cd concentration in maize grain when the soil was polluted with high Cd levels, which was the case in several experiments analyzed in the second publication. P fertilizers with average Cd contamination might enhance labile Cd accumulation in arable land and crops when applied to low biomass crops, such as wheat and legume crops. In this regard, crop management such as crop rotation in the central field experiment indicated that the wheat rotation induced a lower Cd accumulation in maize-soil systems, owing to wheat likely accumulating Cd at higher levels than other crops. The results presented in the second publication also indicated high Cd accumulation by the wheat crop: the wheat grain accumulated more Cd than the maize grain. Thus, potential hazards related to Cd accumulation in wheat grain should also be considered in wheat-maize systems. In conclusion, suitable crop rotations considering the crop-specific potential of Cd accumulation, efficient P management including soil P levels and nutrient use efficiency, and low Cd-P fertilizers remain the most viable options and the main challenge to avoid Cd accumulation in arable soils.
Pathways of C and N turnover in soil under elevated atmospheric CO2
(2008) Dorodnikov, Maxim; Fangmeier, Andreas
In the present thesis the C and N transformations in soil as influenced by indirect effect of elevated atmospheric CO2, soil physical structure and land use change were studied in four laboratory experiments using stable-C and N isotopes, as well as soil microbiological techniques. To test the interrelations between chemical and biological characteristics of soil organic matter (SOM) as affected by land use change and elevated atmospheric CO2 an approach for SOM partitioning based on its thermal stability was chosen. In the first experiment C isotopic composition of soils subjected to C3-C4 vegetation change (grassland to Miscanthus x gigantheus, respectively) was used for the estimation of C turnover in SOM pools. In the 2nd (Free Air CO2 Enrichment ? FACE ? Hohenheim) and 3rd (FACE Braunschweig) experiments CO2 applied for FACE was strongly depleted in 13C and thus provided an opportunity to study C turnover in SOM based on its δ13C value. Simultaneous use of 15N labeled fertilizers allowed N turnover to be studied (in the 2nd experiment). We hypothesized that the biological availability of SOM pools expressed as the mean residence time (MRT) of C or N is inversely proportional to their thermal stability. Soil samples were analysed by thermogravimetry coupled with differential scanning calorimetry (TG-DSC). According to differential weight losses between 20 and 1000 °C (dTG) and energy release or consumption (DSC), SOM pools (4 to 5 depending on experiment) with increasing thermal stability were distinguished. Soil samples were heated up to the respective temperature and the remaining soil was analyzed for δ13C and δ15N by IRMS. For all three experiments the separation of SOM based on its thermal stability was not sufficient to reveal pools with contrasting turnover rates of C and N. A possible explanation for the inability of thermal oxidation for isolating SOM pools of contrasting turnover times is that the fractionation of SOM pools according to their thermal stability is close to chemical separation. In turn, it was found that chemical separations of SOM failed to isolate the SOM pools of different turnover time because different biochemical plant components (cellulose, lignin) are decomposed in a wide temperature range. Individual components of plant residues may be directly incorporated into, or even mixed with the thermal stable SOM pools and will so mask low turnover rates of these pools. To evaluate the interactions between availability of SOM for decomposition by soil microbial biomass (biological characteristic) under elevated atmospheric CO2 and protection of SOM due to the occlusion within aggregates of different sizes (physical property, responsible for SOM sequestration) we measured the activity of microbial biomass (indicated by enzyme activities) and growth strategies of soil microorganisms (fast- vs. slow growing organisms) in isolated macro- and microaggregates. The contribution of fast (r-strategists) and slowly growing microorganisms (K-strategists) in microbial communities was estimated by the kinetics of the CO2 emission from bulk soil and aggregates amended with glucose and nutrients (Substrate Induced Growth Respiration method). Although Corg and total Cmic were unaffected by elevated CO2, maximal specific growth rates were significantly higher under elevated than ambient CO2 for bulk soil, small macroaggregates, and microaggregates. Thus, we conclude that elevated atmospheric CO2 stimulated the r-selected microorganisms. Such an increase in r-selected microorganisms could increase C turnover in terrestrial ecosystems in a future elevated atmospheric CO2 environment. The activities of β-glucosidase, phosphatase and sulphatase were unaffected in bulk soil and in aggregate-size classes by elevated CO2, however, significant changes were observed in potential enzyme production after substrate amendment. After adding glucose, enzyme activities under elevated CO2 were 1.2-1.9-fold higher than under ambient CO2. This indicates an increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Significantly higher chitinase activity in bulk soil and in large macroaggregates under elevated CO2 revealed an increased contribution of fungi to turnover processes. At the same time, less chitinase activity in microaggregates underlined microaggregate stability and the difficulties for fungi hyphae penetrating them. We conclude that quantitative and qualitative changes of C input by plants into the soil at elevated CO2 affect microbial community functioning, but not its total content. Future studies should therefore focus more on the changes of functions and activities, but less on the pools. In conclusion, elevated CO2 concentrations in the atmosphere along with soil physical structure have a pronounced effect on qualitative but not quantitative changes in C and N transformations in soil under agricultural ecosystem. The physical parameters of soil such as aggregation correlate more with biological availability of SOM than the chemical properties of soil organic materials. The increase of soil microbial activity under elevated CO2 detected especially in soil microaggregates, which are supposed to be responsible for SOM preservation, prejudice sequestration of C in agroecosystems affected by elevated atmospheric CO2.
Reaktionen einer Weizen-Wildkraut Gemeinschaft auf erhöhtes CO2 im FACE Experiment: Proteomik, Physiologie und Bestandesentwicklung
(2006) Weber, Simone; Fangmeier, Andreas
The enhancement of the atmospheric carbon dioxide concentration in the last 150 years due to human activities is one of the main components of global change. For the future, different scenarios predict a steadily increase of carbon dioxide in our atmosphere. As carbon dioxide is the most important carbon source for plants, higher CO2 concentrations have the potential to cause direct effects on plant metabolism and vegetation development. Until now almost all of the studies concerning the effects of elevated CO2 on plants were carried out under controlled conditions, whereas the effects under natural conditions are in-vestigated at only 33 sites worldwide. The aims of this study were to investigate the effects of elevated carbon dioxide on a plant community under natural conditions with regard of (i) the plant proteome, (ii) the plant physiology, (iii) the vegetation development and (iv) the potential interactions between these criteria. Therefore a Mini-FACE system was used to expose a plant community composed of wheat and weeds to two different treatments: (a) Ambient (ambient CO2 concentration, circa 380 ppm) and (b) FACE (Ambient + 150 ppm CO2). The study mainly focussed on the bio-chemical and physiological reactions of spring wheat (Triticum aestivum cv. Triso) as a crop species and wild mustard (Sinapis arvensis L.) as a weed species on carbon dioxide enrich-ment. The SELDI-TOF-MS technology was applied for the first time in the topic of carbon dioxide impacts on plants. The technology provides the opportunity to quantitatively and qualitatively investigate low molecular weight proteins with low abundances, which has been difficult to realise with the standardized methodology in proteomics until now. In addition to the biochemical and physiological analysis, the vegetation development was investigated continuously during the vegetation period using non-destructive methods. This included the assessment of species phenology and species dominance. The results of the performed study show that the carbon dioxide enrichment affects the protein profiles of both species wheat and wild mustard. Interestingly, many alterations in the protein concentrations were found, but no protein could be detected to be exclusively ex-pressed under CO2 treatment. The degree of modification in both species was influenced by their developmental stage. Particularly the protein profile of wheat leaves was strongly in-fluenced during generative plant development, therefore the plants seems to be highly sensitive to environmental changes during this developmental stage. Altogether three proteins were identified which were affected by CO2 treatment. The first protein, the saccharose-H+-symporter protein, was detected in the grain of spring wheat and is associated with the plant?s primary metabolism. This protein plays an important role in controlling the import of saccharose in developing grain. Consequently, elevated CO2 seems to regulate the allocation of assimilates in an active way by influencing the saccharose-H+-symporter concentration in the grain of spring wheat. Furthermore, the remaining two proteins, the PR4 protein localized in the grains and the LRR-kinase protein accumulated in the leaves of spring wheat, are associated with the secondary plant metabolism and they also responded to the elevated CO2 concentrations. These proteins are linked with defense reactions of the plants against patho-gens. The elevated CO2 concentrations caused a decrease in defense recognition in the vege-tative tissue. If the plant is infected by pathogens this down-regulation could result in a ne-gative impact. The concentration of soluble proteins and of total nitrogen decreased in the leaves of spring wheat whereas the C/N ratio increased. Despite this the relative concentration of Chlorophyll a was not affected and therefore an accelerated growth of the plants due to the carbon dioxide enrichment can be excluded. Thus the detected pattern of responses suggests an enhanced nitrogen use efficiency under increased CO2 concentrations. The biomass of single spring wheat plants was unaltered during the vegetation period whereas other investi-gations in parallel showed an enhanced growth and a greater yield of spring wheat at the end of the vegetation period. Species dominance of wheat and weeds was neither influenced in the first nor the second year of investigation with regard to CO2 enrichment. The results indicate that annual crop systems under natural conditions indeed exhibit strong reactions concerning proteomics and physiology, but not concerning the plant development probably due to a relative short time of exposition. Based on long term considerations the detected reactions of the plant proteome may play an important role in the breeding of optimal adapted plants.
Rye (Secale cereale L.) : agronomic performance under drought and methods of crop physiology to determine the drought tolerance of winter rye
(2015) Kottmann, Lorenz; Fangmeier, Andreas
Winter rye (Secale cereale L.) is predominantly cultivated on light and sandy soils with a low water holding capacity and will therefore be especially affected by drought induced yield losses in Central and Eastern Europe in the future. Drought adaption through breeding is therefore an important task in order to adapt this crop to future climate conditions. In this context, the crop physiology methods canopy temperature depression (CTD = Tair - Tcanopy) and carbon isotope discrimination (delta) were examined for their suitability as selection criterion under drought on a small number of genotypes. Two sets of each 16 genotypes were therefore grown under different drought conditions in rain-out shelters and under well-watered conditions in the years 2011, 2012, and 2013. The CTD was determined several times during the growth period using two infrared (IR) thermometers and an IR camera. delta-analyses were performed on mature flag leaves (delta_leaf) and grains (delta_grains). Furthermore, ash content in mature flag leaves and grains, as well as mineral concentrations in mature flag leaves (Ca, K, Mg, and Si) were examined for their use as surrogates for the expensive and time-consuming delta-analyses. In addition to the evaluation of possible selection criterions, the agronomic performance of rye in the different drought regimes was assessed: Grain-, straw-, and total aboveground biomass yields, the grain yield components spikes m-2, kernels spike-1, and thousand kernel weight (TKW), leaf area index (LAI), and phenological characteristics were examined. Drought induced grain yield reductions ranged from 14 to 57%, whereas straw yield was generally lesser affected. The growth period was shortened by up to 12 days under drought conditions compared to optimal water supply. Grain yield was positively associated to straw yield, LAI, spikes m-2, and kernels spike-1 under water deficit. High number of grains per area land seemed to be especially important for high grain yields under drought. Furthermore, the results suggest a strong importance of pre-anthesis reserves for the reallocation of assimilates for grain filling under drought in rye. Regarding the suitability of possible selection criterions, CTD was significantly positively related to grain yield under drought. Significant correlations between CTD and grain yield were, however, only observed when the measurements were carried out on days with optimal weather conditions. Optimal conditions turned out to be days with a clear sky, a solar irradiation >700 W m-2, an air temperature of at least 20°C, as well as wind speeds <3 m s-1. Furthermore, the results showed that also rather inexpensive IR instruments are suitable to assess the CTD. Regarding the carbon isotope discrimination, delta_leaf was significantly positively related to grain yield under water deficit, but the correlation was weaker than between CTD and grain yield. Delta_grains was not related to grain yield at all. Ash content and mineral concentrations were significantly related to grain yield under drought, but the correlations were quite inconsistent between the two experimental years. Because of the weak or missing relationship with grain yield, carbon isotope discrimination and its potential surrogates ash content and mineral concentration cannot be recommended for their use as selection criterions under German climate conditions at present. A general limitation of the preset work was, however, the low genetic variability of the genotypes, which may have reduced the significance of the results. The results should therefore be validated with a more diverse set of genotypes. However, especially the CTD seemed to be a promising selection criterion which may help to develop drought tolerant rye genotypes, if this method can be successfully integrated into the breeding process.
Testing vegetation flammability : examining seasonal and local differences in six mediterranean tree species
(2016) Kauf, Zorica; Fangmeier, Andreas
Fire is an important factor controlling vegetation structure, with 40% of terrestrial ecosystems owing their distribution and ecological properties to the accompanying fire regime. In recent decades climate and land use change led to shifts in fire regimes rendering ecosystems more vulnerable to fire. The greatest effects of these changes are expected in the Mediterranean regions. Vegetation is the only factor affecting fire regime which can be directly managed. Promotion of less flammable species is considered to be a valid management option for reducing negative consequences of wildland fires, but reliable information on vegetation flammability and its fluctuations is still lacking. This study strived to bring new insight on the relationship between environmental conditions, fluctuations of morphological characteristics, physiological activity and measured flammability related parameters of Mediterranean tree species. Only a small part of the field study data is included in the final thesis. The field study was conducted from May to October 2010 in the Mediterranean biogeographic region of Croatia, where three sampling locations were positioned along a climate gradient. Selected species included: Aleppo pine (Pinus halepensis Mill.), Holm oak (Quercus ilex L.), olive (Olea europaea L.), carob (Ceratonia siliqua L.), pomegranate (Punica granatum L.), and strawberry tree (Arbutus unedo L.). If possible, all the species were sampled on all the locations during each sampling event. Presented results include: results of the leaf litter flammability method pretesting, regular measurements on leaf litter samples, and monthly measurements on fresh leaf samples. P. granatum samples were not included in the method pretesting, instead laurel (Laurus nobilis L.), mastic (Pistacia lentiscus L.) and Japanese mock orange (Pittosporum tobira Thunb.) were sampled in order to increase the diversity of the materials included. All measured traits of leaf litter) are reported and the relationships between them examined. For fresh leaves only ignition related traits and moisture content results are presented, the relationship between them is examined, and potential effects of the Keetch-Byram drought index on these parameters are explored. Initially, the application of already established epiradiator based methods was intended. Nevertheless, method pretesting identified several flaws of established methods. It revealed that an epiradiator is not a stabile heat source as previously thought, recognising a need for monitoring and stabilizing epiradiator temperature to ensure similar heat exposure at the beginning of each tests. Furthermore, pretesting results demonstrated that materials that rarely flame under certain testing conditions can readily flame if testing conditions are slightly altered, thus challenging the presumption that low ignition frequency always corresponds to low fire danger (flammability) – a basic presumption of the vegetation flammability tests. Results of leaf litter flammability testing showed that properties of the leaf litter particles significantly change within the fire season, and indicated that species specific weathering and decomposition could play an important role in these changes. They demonstrated that a change in a single leaf trait can have opposite effects on different flammability parameters, and that these relationships are dependent on the incoming heat flux. Results of fresh leaves testing identified phenological changes as important factor governing fluctuation of moisture content and ignition related parameters, and showed that the relationship between drought indices and moisture content is not limited to shallow rooting species. They challenged the presumption that increasing leaf thickness is related to “fire retardance” – a relationship found if samples are tested outside their natural moisture content range. Instead, this study, in which fresh leaves were tested within their natural moisture content range, implies that higher sclerophylly is related to higher ignition frequency, indicating an opposite trend and confirming the importance of moisture content as one of the most important factors governing fire behaviour of the materials. All the gathered data indicated that, O. europaea, Q. ilex and P. halepensis exhibit higher tendency to ignite than C. siliqua and P. granatum; A. unedo showed high variation in ignition related parameters. Nevertheless, ignition related parameters reveal only a part of the information on fire behaviour of the material. Overall results demonstrated that the experimental setup can have tremendous impacts on the results of flammability tests, thus data interpretation should be done with caution. Furthermore, instead of attributing single flammability scores based on all measured parameters, interpretation of test results in relation to their influence on fire behaviour is advocated.