Teis N. Mikkelsen

Technical University of Denmark, Lyngby, Capital Region, Denmark

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Publications (92)230.2 Total impact

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    ABSTRACT: Future barley cultivars will have to produce under the constraints of higher temperature in combination with increased concentrations of atmospheric carbon dioxide and ozone as a consequence of climate change. A diverse set of 167 spring barley genotypes was cultivated under elevated levels of temperature (+5 °C) and [CO2] (700 ppm) as single factors and in combination as well as under elevated [O3] (100-150 ppb) as single factor. The setting in general resembled changes projected by IPCC (AR5) to take place at the end of this century. A genome-wide association study (GWAS) was performed to identify markers for increased primary production under climate change conditions and reveal possible genes of interest. Phenotyped traits included grain yield, number of grains, number of ears per plant, aboveground vegetative biomass, harvest index and stability of the production parameters over the five applied treatments. The GWAS encompassed 7864 SNP markers (Illumina iselect), a compressed mixed linear model with the GAPIT package, and conservative validation of markers. A total of 60 marker-trait associations [−log10(P value) 2.97-5.58] were identified, e.g. grain yield under elevated temperature on barley chromosome 2H, static stability of grain yield on 7H, sites for exploitation of elevated [CO2] on 4H and 7H and associations under the two-factor treatment. Marker-trait associations identified from single-factor treatments were not retrieved, when elevated [CO2] and temperature were combined emphasizing the need for multifactor experiments. This GWA study identified markers and chromosome regions to be targeted in breeding for development of climate resilient cultivars.
    Molecular Breeding 03/2015; 35(3). DOI:10.1007/s11032-015-0283-8 · 2.28 Impact Factor
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    ABSTRACT: The response in production parameters to projected future levels of temperature, atmospheric carbon dioxide ([CO2]), and ozone ([O3]) was investigated in 138 spring barley accessions. The comprehensive set of landraces, cultivars, and breeder-lines, were during their entire life cycle exposed to a two-factor treatment of combined elevated temperature (+5 °C day/night) and [CO2] (700 ppm), as well as single-factor treatments of elevated temperature (+5 °C day/night), [CO2] (700 ppm), and [O3] (100–150 ppb). The control treatment was equivalent to present average South Scandinavian climate (temperature: 19/12 °C (day/night), [CO2]: 385 ppm). Overall grain yield was found to decrease 29% in the two-factor treatment with concurrent elevation of [CO2] and temperature, and this response could not be predicted from the results of treatments with elevated [CO2] and temperature as single factors, where grain yield increased 16% and decreased 56%, respectively. Elevated [O3] was found to decrease grain yield by 15%. Substantial variation in response to the applied climate treatments was found between the accessions. The results revealed landraces, cultivars, and breeder-lines with phenotypes applicable for breeding towards stable and high yield under future climate conditions. Further, we suggest identifying resources for breeding under multifactor climate conditions, as single-factor treatments did not accurately forecast the response, when factors were combined.
    European Journal of Agronomy 02/2015; 63. DOI:10.1016/j.eja.2014.12.003 · 2.92 Impact Factor
  • Dan Bruhn, Kristian R. Albert, Teis N. Mikkelsen, Per Ambus
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    ABSTRACT: Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone-depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20–50 nmol m−2 h−1, mostly due to the UV component. The emission response to UV-A is of the same magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N2O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.
    Atmospheric Environment 12/2014; 99:206–214. DOI:10.1016/j.atmosenv.2014.09.077 · 3.06 Impact Factor
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    ABSTRACT: The terrestrial vegetation is a source of UV radiation-induced aerobic methane (CH4 ) release to the atmosphere. Hitherto pectin, a plant structural component, has been considered as the most likely precursor for this CH4 release. However, most of the leaf pectin is situated below the surface wax layer, and UV transmittance of the cuticle differs among plant species. In some species, the cuticle effectively absorbs and/or reflects UV radiation. Thus, pectin may not necessarily contribute substantially to the UV radiation-induced CH4 emission measured at surface level in all species. Here, we investigated the potential of the leaf surface wax itself as a source of UV radiation-induced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two-step process initiated by a photolytic rearrangement reaction of the major component followed by an α-cleavage of the generated ketone.
    Plant Biology 01/2014; 16(2). DOI:10.1111/plb.12137 · 2.32 Impact Factor
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    ABSTRACT: The projected future climate will affect the global agricultural production negatively, however, to keep abreast of the expected increase in global population, the agricultural production must increase. Therefore, to safeguard the future crop yield and quality, the adaptive potential of crops to environmental change needs to be explored in order to select the most productive genotypes. Presently, it is unknown whether cereal crops like spring barley can adapt to climate stressors over relatively few generations. To evaluate if strong selection pressures could change the performance of barley to environmental stress, we conducted a selection experiment over five plant generations (G0–G4) in three scenarios, where atmospheric [CO2] and temperature were increased as single factors and in combination. The treatments represented the expected environmental characteristics in Northern Europe around year 2075 [700 ppm CO2, 22/17 °C (day/night)] as well as a control mimicking present day conditions (390 ppm CO2, 19/12 °C). Two different barley accessions, a modern cultivar and an old landrace, were evaluated in terms of yield and biomass production. In all treatments representing future environmental scenarios, the G4-generation of selected plants did not improve its reproductive output compared to the G0-generation, as G4 produced less seeds and had a lower yield than unselected plants. These results indicate that barley might not respond positively to rapid and strong selection by elevated [CO2] and temperature, contrary to previous results from oilseed rape. The two barley accessions analyzed presented almost the same response pattern in a given treatment, though the modern cultivar had the highest yield in the climate scenarios, while the landrace was superior in yield under present day climate conditions.
    Genetic Resources and Crop Evolution 01/2014; 61(1). DOI:10.1007/s10722-013-0021-1 · 1.48 Impact Factor
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    Open Journal of Forestry 01/2014; DOI:10.4236/ojf.2014.43026
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    ABSTRACT: Plant responses to warming, elevated CO2, and changes in summer precipitation patterns involve complex interactions. In this study we aim to reveal the single factor responses and their interactive effects on photosystem II (PSII) performance during an autumn-to-winter period. The study was carried out in the CLIMAITE multifactor experiment, which includes the combined impact of elevated CO2 (free air carbon enrichment; CO2), warming (passive nighttime warming; T) and summer drought (rain-excluding curtains; D) in a temperate heath ecosystem. PSII performance was probed by the effective quantum yield in light, Fv′/Fm′, using the pulse amplitude methodology, and the total performance index, PItotal, which integrate changes of the chlorophyll-a fluorescence transient including the maximal quantum yield in darkness, Fv/Fm. Decreasing temperature during autumn linearly reduced PItotal, both in the wavy hair-grass, Deschampsia flexuosa, and in the evergreen dwarf shrub common heather, Calluna vulgaris, and following freezing events the PItotal and Fv′/Fm′ were reduced even more. Contrary to expected, indirect effects of the previous summer drought reduced PSII performance before freezing events, particularly in Calluna. In combinations with elevated CO2 interactive effects with drought, D × CO2 and warming, T × D × CO2, were negatively skewed and caused the reduction of PSII performance in both species after occurrence of freezing events. Neither passive nighttime warming nor elevated CO2 as single factors reduced PSII performance via incomplete cold hardening as hypothesized. Instead, the passive nighttime warming strongly increased PSII performance, especially after freezing events, and when combined with elevated CO2 a strongly skewed positive T × CO2 interactive effect was seen. This indicates that these plants take advantage of the longer growing season induced by the warming in elevated CO2 until a winter frost period becomes permanent. However, if previously exposed to summer drought this positive effect reverses via interactive D × CO2 and T × D × CO2 effects immediately after freezing events, causing the full combination of TDCO2 not to differ from the control. In a future warmer climate with high CO2 and summer drought, the occurrence of freezing events thus seem highly decisive for reducing PSII performance in the autumn-to-winter period. Such a reduced robustness of PSII performance may be highly decisive for the magnitude of the late season photosynthetic carbon uptake and reduce the growing season length in these temperate heath plants.
    Environmental and Experimental Botany 09/2013; 93:1-12. DOI:10.1016/j.envexpbot.2013.03.008 · 3.00 Impact Factor
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    ABSTRACT: Background and aims Accurate predictions of nutrient acquisition by plant roots and mycorrhizas are critical in modelling plant responses to climate change. Methods We conducted a field experiment with the aim to investigate root nutrient uptake in a future climate and studied root production by ingrowth cores, mycorrhizal colonization, and fine root N and P uptake by root assay of Deschampsia flexuosa and Calluna vulgaris. Results Net root growth increased under elevated CO2, warming and drought, with additive effects among the factors. Arbuscular mycorrhizal colonization increased in response to elevated CO2, while ericoid mycorrhizal colonization was unchanged. The uptake of N and P was not increased proportionally with root growth after 5 years of treatment. Conclusions While aboveground biomass was unchanged, the root growth was increased under elevated CO2. The results suggest that plant production may be limited by N (but not P) when exposed to elevated CO2. The species-specific response to the treatments suggests different sensitivity to global change factors, which could result in changed plant competitive interactions and belowground nutrient pool sizes in response to future climate change.
    Plant and Soil 08/2013; 369(1-2). DOI:10.1007/s11104-013-1601-8 · 3.24 Impact Factor
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    ABSTRACT: The impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO2, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split-plot with 6 blocks 9 2 levels of CO2 9 2 levels of warming 9 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea suturalis THOMSON), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO2 (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under the drought treatment, and there was a three-way interaction between time, CO2, and drought. Survival was lowest when drought, warming, and elevated CO2 were combined. Effects of climate change drivers depended on other co-acting factors and were mediated by changes in plant secondary compounds, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers.
    Ecology and Evolution 06/2013; 3(6):1149-1160. DOI:10.1002/ece3.564 · 1.66 Impact Factor
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    ABSTRACT: Infrared reflective (IR) curtains have been widely used to obtain passive nighttime warming in field ecosystem experiments in order to simulate and study climate warming effects on ecosystems. For any field installation with IR-reflective curtains in an ecosystem the achieved heating effect depends on the heat gain determined by the stored energy during daytime (incoming radiation can be used as a proxy) the heat conservation determined by the IR-reflective effect of the curtains (cloudiness can be used as a proxy) and the heat loss determined by convectional heat loss (wind speed can be used as a proxy). In this study, we demonstrate some feasible avenues for improving the achieved temperature increase (�T) when using IR-reflective curtains at field scale by attacking the three main factors determining the efficiency of the curtains: (i) improving the long wave IR reflection by the curtains, (ii) insulating the curtains and (iii) reducing the lateral wind speed. We provide experimentally based replies to the major concerns raised in the literature about the passive nighttime warming method. We show (a) that using IR-reflective curtains during night does in fact not result in nighttime warming only as there is a small carryover (<0.5 ◦C) into the following daytime, and (b) although the employment of IR-reflective curtains at nighttime may alter the RH, it is a small change and not always in the same direction.
    Agricultural and Forest Meteorology 05/2013; 173:53-62. DOI:10.1016/j.agrformet.2013.01.004 · 3.89 Impact Factor
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    ABSTRACT: Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi-generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full-factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co-occur.
    Ecology and Evolution 05/2013; 3(5):1163-72. DOI:10.1002/ece3.523 · 1.66 Impact Factor
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    ABSTRACT: High air concentrations of ammonium were detected at low and high altitude sites in Sweden, Finland and Norway during the spring 2006, coinciding with polluted air from biomass burning in eastern Europe passing over central and northern Fennoscandia. Unusually high values for throughfall deposition of ammonium were detected at one low altitude site and several high altitude sites in north Sweden. The occurrence of the high ammonium in throughfall differed between the summer months 2006, most likely related to the timing of precipitation events. The ammonia dry deposition may have contributed to unusual visible injuries on the tree vegetation in northern Fennoscandia that occurred during 2006, in combination with high ozone concentrations. It is concluded that long-range transport of ammonium from large-scale biomass burning may contribute substantially to the nitrogen load at northern latitudes.
    Environmental Pollution 02/2013; 176C:71-79. DOI:10.1016/j.envpol.2012.12.006 · 3.73 Impact Factor
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    ABSTRACT: There is an ongoing debate on how to correct leaf gas-exchange measurements for the unavoidable diffusion leakage that occurs when measurements are done in non-ambient CO(2) -concentrations. In this study we present a theory on how the CO(2) diffusion gradient over the gasket is affected by leaf mediated pores (LMP) and how LMP reduce diffusive exchange across the gaskets. Recent discussions have so far neglected the processes in the quasi-laminar boundary layer around the gasket. Counter intuitively, LMP reduce the leakage through gaskets, which can be explained by assuming that the boundary layer at the exterior of the cuvette is enriched with air from the inside of the cuvette. The effect can thus be reduced by reducing the boundary layer thickness. The theory clarifies conflicting results from earlier studies. We developed leaf adaptor frames that eliminate LMP during measurements on delicate plant material such as grass leaves with circular cross section, and the effectiveness is shown with respiration measurements on a harp of Deschampsia flexuosa leaves. We conclude that the best solution for measurements with portable photosynthesis systems is to avoid LMP rather than trying to correct for the effects.
    Plant Cell and Environment 01/2013; DOI:10.1111/pce.12064 · 5.91 Impact Factor
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    Climate Change, Air Pollution and Global Challenges: Knowledge, Understanding and Perspectives from Forest Research, Edited by R Matyssek, N Clarke, P Cudlin, TN Mikkelsen, J Tuovinen, G Wieser, E Paoletti, 01/2013: chapter 13: pages 497-520; Elsevier Physical Sciences Series “Developments in Environmental Science” (S. Krupa Ed.).
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    Agricultural and Forest Meteorology 01/2013; 173:53– 62. · 3.89 Impact Factor
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    ABSTRACT: The evidence that is currently available demonstrates that future changes in precipitation patterns will affect plant carbon uptake. However, the outcome in terms of success, productivity and fecundity depends upon individual species and different responses of various growth forms. Examination of these differences in response in dry versus rewetting conditions can be used to highlight the limitations coherent in different strategies adopted by, for example, evergreen shrubs and grasses. We investigated the leaf-level photosynthetic performance, leaf C, N and δ13C along with vegetation cover and biomass in the evergreen dwarf shrub Calluna vulgaris and the grass species Deschampsia flexuosa in a temperate heath during seasonal changes in soil moisture.Higher photosynthetic capacity compensated for lower stomatal conductance and sustained higher rates of photosynthesis in the grass compared to the dwarf shrub. In combination with dieback of aboveground biomass and reduction of stomatal conductance reduction during dry conditions, the grass continued to have high carbon uptake in the remaining leaves. The dwarf shrub endured the dry conditions by preserving shoot biomass and reducing stomatal conductance. Soil rewetting increased leaf nitrogen and photosynthesis in the grass much more than for the dwarf shrub.These different strategies may have a considerable impact on carbon uptake and on the ability of a species to compete, as future climatic changes are likely to extend the summer drought period together with the more frequent and extensive precipitation events outside the summer season.
    Acta Oecologica 11/2012; 45:79-87. DOI:10.1016/j.actao.2012.09.003 · 1.84 Impact Factor
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    D. Bruhn, K. R. Albert, T. N. Mikkelsen, P. Ambus
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    ABSTRACT: The global burden of carbon monoxide, CO, is rather uncertain. In this paper we address the potential of UV-induced CO emission by terrestrial surfaces. Real-time measurements of [CO] were made with a cavity enhanced laser connected in closed loop to either an ecosystem chamber or a leaf scale chamber. Sand and leaves of all examined plant species exhibited emission of CO in response to artificial UV-radiation and the UV-component of natural solar radiation. The UV-induced rate of CO emission exhibited a rather low dependence on temperature, indicating an abiotic process. The emission of CO in response to the UV-component of natural solar radiation was also evident at the ecosystem scale. When scaled to the global level, the UV-induced emission of CO by the major types of terrestrial surfaces, living leaves and soil (here represented by sand), amounts up to 28 Tg yr-1. This source has till now not been accounted for by IPCC, but is equivalent to 14-56% of the 50-200 Tg yr-1 from sources currently accounted for (IPCC 2001). In addition to this are other known sources that ought to be considered. The hitherto unaccounted for terrestrial sources of CO amounts up to 207 Tg yr-1, almost two-thirds of the latest estimated global CO burden of 360 Tg yr-1 (IPCC, 2001).
    Biogeosciences Discussions 07/2012; 9(7):8449-8473. DOI:10.5194/bgd-9-8449-2012

Publication Stats

1k Citations
230.20 Total Impact Points

Institutions

  • 2007–2015
    • Technical University of Denmark
      • • Department of Chemical and Biochemical Engineering
      • • National Laboratory for Sustainable Energy
      Lyngby, Capital Region, Denmark
  • 1994–2006
    • IT University of Copenhagen
      København, Capital Region, Denmark