Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    No effect of pyrolysis temperature and feedstock type on hydraulic properties of biochar and amended sandy soil
    Wiersma, Wietse ; Ploeg, Martine J. van der; Sauren, Ian J.M.H. ; Stoof, Cathelijne R. - \ 2020
    Geoderma 364 (2020). - ISSN 0016-7061
    Biochar - Hydrophobicity - Sandy soil - Saturated hydraulic conductivity - Soil amendment - Water retention

    Biochar has been lauded as a cure-all for improving water availability in soils. Yet the effect of pyrolysis temperature and feedstock type on biochar hydraulic properties and its subsequent effects on soils are not well known. We therefore systematically studied water retention, saturated hydraulic conductivity (Ksat) and hydrophobicity of 12 standard biochars (six feedstocks and two pyrolysis temperatures) developed by the UK Biochar Research Centre. The hydraulic properties were determined for pure crushed biochar, as well as for a sandy soil amended with 10 t ha−1 biochar (assessed three times over a period of 15 months). For pure biochar, the effect of feedstock-temperature treatments on the water retention curve was negligible. Rice husk at a pyrolysis temperature of 700 °C had a significantly lower saturated water content, plant available water content and Ksat than all other biochar treatments. This can be attributed to its severe hydrophobicity: while all other treatments were non-hydrophobic and rice husk at 550 °C and Miscanthus straw at 550 °C were both strongly hydrophobic, rice husk at 700 °C was severely hydrophobic. Incorporation of the biochar into a sandy soil did not significantly influence soil water retention, saturated hydraulic conductivity and hydrophobicity. There were also no significant differences between the biochar treatments. These results indicate that except for rice husk at 700 °C the different biochar feedstock types and pyrolysis temperatures yield surprisingly similar material in terms of hydraulic characteristics. Improved soil hydrology should not be a main reason to apply biochar on sandy soils, but if biochar is applied differences in hydrophobicity should be considered.

    Veluwse malenbossen en het Gortelsche Bos; verslag van een lezing en een excursie
    Laar, J.N. van; Sauren, P. - \ 2014
    Vakblad Natuur Bos Landschap 11 (2014)109. - ISSN 1572-7610 - p. 28 - 29.
    bossen - historisch grondgebruik - historische ecologie - veluwe - forests - land use history - historical ecology - veluwe
    Eerder dit jaar, op 24 april 2014, vond een door de Commissie Bosgeschiedenis georganiseerde excursie plaats in het Gortelsche Bos. Dit eeuwenoude bos is een onderdeel van het Kroondomein Het Loo. Zowel de respectabele ouderdom als de vroegere gemeenschappelijk bosbezitsvorm – het behoorde aan een maalschap - maakt het Gortelsche Bos bijzonder.
    Het Haagse bos : Fragmenten uit de geschiedenis van 's Graven Wildernisse (Gids)
    Sauren, P. ; Laar, J.N. van - \ 2013
    Wageningen : KNBV, Commissie Bosgeschiedenis - 18 p.
    Verslag Excursie Haagse Bos
    Laar, J.N. van; Sauren, P. - \ 2013
    Vakblad Natuur Bos Landschap 10 (2013)100. - ISSN 1572-7610 - p. 43 - 44.
    Origin matters! Difference in drought tolerance and productivity of coastal Douglas-fir (Pseudotsuga menziesii (Mirb.)) provenances
    Eilmann, B. ; Vries, S.M.G. de; Ouden, J. den; Mohren, G.M.J. ; Sauren, P. ; Sass, U.G.W. - \ 2013
    Forest Ecology and Management 302 (2013). - ISSN 0378-1127 - p. 133 - 143.
    climate-change - scots pine - tree-growth - variability - seedlings - forest - photosynthesis - populations - sylvestris - adaptation
    Forests of the future should be resistant to exacerbating climatic conditions, especially to increasing drought, but at the same time provide a sufficient amount and quality of timber. In this context coastal Douglas-fir (Pseudotsuga menziesii (Mirb.)) is a promising species since it remains productive even under chronic drought. By choosing suitable provenances within the range of Douglas-fir (P. menziesii (Mirb.)) for a given site we can further optimise tree fitness under dry conditions or even increase timber yield. Eighteen coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) var. menziesii) provenances were tested for seedling survival, yield, wood quality, and drought tolerance by taking advantage of a Dutch provenance trial, established in 1971 within the framework of the 1966/1967 IUFRO seed collection program. The site of the Dutch trial is representative for many sites in Central Europe and is characterised by a moderate precipitation and temperature regime. Measurements on height and diameter growth were combined with a dendrochronological study on growth response to drought years. We found a clear latitudinal trend indicating that Douglas-fir provenances from the northern part of the species-distribution range are generally more productive than provenances from the south. In contrast, drought tolerance increased towards the south. This suggests that it is impossible to identify provenances combining maximum productivity with lowest susceptibility towards drought. However, based on the results from the trial we can give recommendations on suitable provenances that are expected to perform best under future conditions in Central Europe. On sites where severe drought events are unlikely to occur in future, fast growing provenances from the north, like Nimkish, should be planted. These provenances respond plastically to drought years, but the strong reduction of tree growth in the drought year itself indicates that these provenances will be harmed by an increasing frequency of drought events. However, on sites where water availability is likely to decrease, provenances from the Olympic Peninsula like Forks and Matlock are very promising since they showed still relatively high yield in combination with a high potential to cope with drought. If summer drought increases in frequency and severity as expected, the latewood/earlywood ratio will be drastically reduced with negative consequences for wood quality and cavitation resistance. However, some provenances, like Marblemount or Matlock, might compensate for the negative effect of summer drought on latewood/earlywood ratio by the contribution of photosynthesis in winter to whole-year carbon stock.
    What are the main climate drivers for shrub growth in Northeastern Siberian tundra?
    Blok, D. ; Sass-Klaassen, U. ; Schaepman-Strub, G. ; Heijmans, M.M.P.D. ; Sauren, P. ; Berendse, F. - \ 2011
    Biogeosciences 8 (2011)5. - ISSN 1726-4170 - p. 1169 - 1179.
    plant functional types - alaskan arctic tundra - summer temperature - nitrogen mineralization - tree growth - manipulation experiment - environmental-change - cassiope-tetragona - vegetation types - northern alaska
    Deciduous shrubs are expected to rapidly expand in the Arctic during the coming decades due to climate warming. A transition towards more shrub-dominated tundra may have large implications for the regional surface energy balance, permafrost stability and carbon storage capacity, with consequences for the global climate system. However, little information is available on the natural long-term shrub growth response to climatic variability. Our aim was to determine the climate factor and time period that are most important to annual shrub growth in our research site in NE-Siberia. Therefore, we determined annual radial growth rates in Salix pulchra and Betula nana shrubs by measuring ring widths. We constructed shrub ring width chronologies and compared growth rates to regional climate and remotely sensed greenness data. Early summer temperature was the most important factor influencing ring width of S. pulchra (Pearson's r=0.73, p
    Effects of different fungicides on the growth of aquatic macrphyte species
    Belgers, J.D.M. ; Sauren, S.S. ; Alderink, R.G.H. ; Brink, P.J. van den - \ 2005
    In: Abstract book; SETAC Europe 15th Annual Meeting. - Brussels (Belgium) : SETAC Europe - p. 11 - 11.
    Photothermal methods for sensitive and selective determination of gaseous pollutants in the air.
    Franko, M. ; Tran, C. ; Sauren, H. ; Bicanic, D. - \ 1994
    In: Abstract Conf. Air Quality in Slovenia. Bled (1994)
    New trends and perspectives in photoacoustic and photothermal spectroscopies in agricultural and environmental sciences.
    Bicanic, D. ; Chirtoc, M. ; Asselt, C. van; Gerkema, E. ; Jalink, H. ; Sauren, H. ; Groot, T. ; Torfs, P. ; Haupt, K. - \ 1993
    Acta Chimica Slovenica 40 (1993). - ISSN 1318-0207 - p. 175 - 202.
    Real time and in situ determination of ammonia concentration in the atmosphere by intermodulated Stark resonant CO2 laser spectroscopy.
    Sauren, H. ; Gerkema, E. ; Bicanic, D. ; Jalink, H. - \ 1993
    Atmospheric Environment 27 (1993)1. - ISSN 1352-2310 - p. 109 - 112.
    A concept of Intermodulated Photoacoustic Stark Spectroscopy (IMPASS) was used in an attempt to perform the interference-free field measurement of trace ammonia (3-40 ppbv) concentration levels in the air with a time resolution of 40 s.
    On the potentiality of intermodulated electric resonance, photoacoustic and photothermal spectroscopies for ground based in situ tracking of small polar molecules in air.
    Bicanic, D. ; Franko, M. ; Sauren, H. - \ 1993
    In: Optical methods in atmospheric chemistry, H. Schiff, U. Platt (eds.). Proc. Spie 1715, Bellingham, Wa., USA - p. 222 - 227.
    Interfacing photoacoustic and photothermal techniques for new hyphenated methodologies and instrumentation suitable for agricultural, environmental and medical applications.
    Bicanic, D. ; Jalink, H. ; Chirtoc, M. ; Sauren, H. ; Lubbers, M. ; Quist, J. ; Gerkema, E. ; Asselt, K. van; Miklos, A. ; Solyom, A. ; Angeli, Gy.Z. ; Helander, P. ; Vargas, H. - \ 1992
    In: Photoacoustic and photothermal phenomena 3 / Bicanic, D., Heidelberg/Berlin : Springer Verlag (Springer Series in Optical Sciences 69) - p. 20 - 27.
    Optimization of laserphotoacoustic spectrometer for environmental studies.
    Bicanic, D. ; Asselt, K. van; Sauren, H. ; Miklos, A. ; Angeli, G. ; Solyom, A. ; Gerkema, E. ; Lubbers, M. - \ 1992
    In: Eurotrac Annual Report 1991 Instrument Development - p. 40 - 43.
    Combined electric field resonance spectroscopy, intermodulation and laser photoacoustoc spectroscopy as a universal approach top selective trace detection of polar molecules: present state and further outlook in monitoring of environmental ammonia.
    Bicanic, D. ; Asselt, K. van; Gerkema, E. ; Sauren, H. ; Jalink, H. ; Franko, M. - \ 1992
    In: Abstract SPIE/Euroopto Int. Conf. Environmental sensing, Berlin - p. 32 - 32.
    Novel characterization techniques for agricultural and environmental appplications. II. Photoacoustic detection of ammonia in a simulated atmosphere of varying water content.
    Sauren, H. ; Bicanic, D. - \ 1992
    Analytical instrumentation 20 (1992). - ISSN 0743-5797 - p. 63 - 79.
    Laser photoacoustic and thermooptical sensing of the atmosphere: from the laboratory tool towards a field instrument.
    Bicanic, D. ; Miklos, A. ; Sauren, H. - \ 1992
    Eurotrac Letters 9 (1992). - p. 8 - 12.
    Quo vadis fotoakoestiek?
    Bicanic, D. ; Boccara, C. ; Sauren, H. ; Jalink, H. - \ 1992
    Nederlands Tijdschrift voor Natuurkunde 58 (1992). - ISSN 0926-4264 - p. 4 - 5.
    Optimization of laser photoacoustic spectrometer for environmental studies.
    Bicanic, D. ; Asselt, K. van; Sauren, H. ; Miklos, A. ; Angeli, Gy.Z. ; Solyom, A. ; Gerkema, E. ; Lubbers, M. - \ 1992
    In: Eurotrac Annual Report 1991, part 7 Instrument development - p. 40 - 43.
    Combined electric field resonance spectroscopy, intermodulation and laser photoacoustoc spectroscopy as a universal approach top selective trace detection of polar molecules: present state and further outlook in monitoring of environmental ammonia.
    Bicanic, D. ; Asselt, K. van; Gerkema, E. ; Sauren, H. ; Jalink, H. ; Franko, M. - \ 1992
    In: Proc. SPIE/Euroopto Int. Conf. Environmental sensing. SPIE 1517, Bellingham, Washington, USA - p. 939 - 948.
    Ammonia monitor based on intermodulated CO2 laser photoacoustic Stark spectroscopy
    Sauren, J.J.A.M. - \ 1992
    Agricultural University. Promotor(en): J. Reuss; D.D. Bicanic. - S.l. : Sauren - 108
    meting - luchtverontreiniging - meteorologische instrumenten - milieu - verontreiniging - monitoring - ammoniak - spectroscopie - spectraalanalyse - analytische methoden - analyse - spectrofotometrie - lasers - optica - measurement - air pollution - meteorological instruments - environment - pollution - monitoring - ammonia - spectroscopy - spectral analysis - analytical methods - analysis - spectrophotometry - lasers - optics

    One of the causes of the acidification of the environment are high ammonia (NH 3 ) emission rates. In environmental research it is an impetus to measure the ammonia concentration sufficiently accurate and fast. This thesis describes the development, construction and testing of a 12C 16O 2 laser photoacoustic monitor for trace detection of ambient ammonia. It is for the first time that hyphenated photoacoustics has been applied to the direct detection of ambient ammonia.

    The difficulties met in the practice with NH 3 monitors based on chemical or physicalchemical detection has stimulated the research towards the development of a monitor based on physical detection principles.

    Gas-phase photoacoustic spectroscopy has proven a sensitive and feasible technique for detection of pollutants. Owing to the availability of powerful, collimated, monochromatic and tunable light sources (such as the CO 2 (waveguide) laser) the detection of trace gases at ppbv and even at pptv levels appears within reach.

    Although a sensitive technique, classical photoacoustic spectroscopy is limited by the complex interpretation and additive character of signal resulting from spectral interferences (when dealing with mixtures), occurring in the wavelength region of the emitting light source. Especially in the infrared (2-20 μm), molecular fingerprints of important trace gas molecules frequently overlap or are masked by water vapor and carbon dioxide absorption. Spectral interference from the previously mentioned and largely abundant ambient species impedes the unique determination of ambient ammonia in the 12C 16O 2 laser emission frequency region.

    Using the Stark effect induced in ammonia and subsequent detection of the generated photoacoustic signal at the sum and difference sidebands of the modulated laser and Stark electric fields, detection of ammonia at trace levels employing the 10R(8) and 10R(6) CO 2 laser lines has been successfully achieved. The sensitivity of the method was tested in a simulated atmosphere (present limit 2 ppbv NH 3 ). Although materials exhibiting a low NH 3 adsorption affinity have been used to construct the photoacoustic Stark cell, signal response time of the system is at present limited to 40 sec.

    In addition to a brief historical review Chapter 1 contains an outline of the methods used in detecting ammonia. Intrinsic difficulties associated with the different chemical and photoacoustic methods are described, as well as an experimental and theoretical description of the method employed in this thesis (InterModulated PhotoAcoustic Stark Spectroscopy or IMPASS). The theory of infrared rotational-vibrational transitions as well as the Stark effect applied to the case of symmetric rotators exhibiting inversion doubling are presented in Chapter 2. Details of the photoacoustic Stark cell, the three frequency phase-locked loop, progress and improvements made on the 12C I6O 2 waveguide laser as well as a new method for calibrating photoacoustic cells are given in Chapter 3. Experiments performed on detection of ammonia in a closely simulated atmosphere and in realistic air samples are discussed in Chapter 4.

    Finally, Chapter 5 presents closing remarks concerning suggestions for improving the performance of the present instrument.

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