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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    'Wat triggert de kopers van jouw product?' : actualiteitenavond Bovenkarspel
    Gude, Henk - \ 2015
    horticulture - ornamental bulbs - tulips - knowledge transfer - coating - scalding - marketing - turnover
    De actualiteitenavond die op 9 september, op initiatief van KAVB en CNB, plaatsvond in bij CNB in Bovenkarspel stond bol van de waardevolle informatie voor het vak. Zo was er een update over het onderzoek naar de effecten van bolcoating, en ging Flora- Holland in op het nieuwe broeiseizoen en de marketing van tulp. De grote vraag blijft immers: voor wie produceer je nou eigenlijk? En wat verwacht de consument van jouw product?
    Auswirkungen der Erhöhung des Mehrwertsteuersatzes für Zierpflanzenerzeugnisse : Situation im Jahr 2015
    Bunte, F. ; Galen, M.A. van - \ 2015
    LEI Wageningen UR (Rapport / LEI Wageningen UR 2015-103) - ISBN 9789086157167 - 25
    ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
    This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
    Effects of increased VAT rates for ornamentals : situation 2015
    Bunte, F. ; Galen, M.A. van - \ 2015
    LEI Wageningen UR (Report / LEI Wageningen UR 2015-103) - ISBN 9789086157174 - 23
    ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
    This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
    Effets de l'augmentation du taux de TVA pour les produits d'horticulture ornementale : situation 2015
    Bunte, F.H.J. ; Galen, M.A. van - \ 2015
    Wageningen : LEI Wageningen UR (Rapport / LEI Wageningen UR 2015-103) - ISBN 9789086157167 - 25
    ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands - sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland
    This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
    Effecten van verhoging btw-tarief voor sierteeltproducten : situatie 2015
    Bunte, F.H.J. ; Galen, M.A. van - \ 2015
    Wageningen : LEI Wageningen UR (LEI rapport 2015-103) - ISBN 9789086157167 - 25
    sierteelt - belasting toegevoegde waarde - verandering - effecten - omzet - economische evaluatie - werkgelegenheid - europese unie - nederland - ornamental horticulture - value added tax - change - effects - turnover - economic evaluation - employment - european union - netherlands
    This report evaluates the effects of a possible application of the general VAT rate to ornamentals on turnover and employment in the Dutch and European ornamental supply chain. The effects are calculated for the scenario in which the Netherlands decide to apply the general VAT rate and the scenario in which all member states of the European Union (EU) decide to apply the general VAT rate. In 2015, the lower VAT rate is applied to ornamentals in 13 EU member states. The effects are measured using the Hortus model of LEI Wageningen UR, which models demand and supply in European horticulture.
    Achtergronddocument Driemeting : Verantwoording van de berekeningen en gemaakte keuzes voor het komen tot de omzet van de multifunctionele landbouw 2013
    Veen, E.J. ; Schoutsen, M.A. ; Meulen, H.A.B. van der; Voskuilen, M.J. ; Vijn, M.P. - \ 2015
    Lelystad : PPO AGV (PPO 654) - 52
    multifunctionele landbouw - neveninkomsten - inkomen van landbouwers - zorgboerderijen - agrarisch natuurbeheer - boerderijwinkels - agrarische bedrijfsvoering - bedrijfsvoering - omzet - vakanties op de boerderij - multifunctional agriculture - supplementary income - farmers' income - social care farms - agri-environment schemes - on-farm sales - farm management - management - turnover - farm holidays
    Neveninkomsten op de boerderij door: Agrarisch natuurbeheer, boerderijeducatie, agrarische kinderopvang, zorglandbouw, recreatie of boerderijverkoop
    De Nederlandse visverwerkende industrie en visgroothandel : economische analyse van de sector, ontwikkelingen en trends
    Beukers, R. - \ 2015
    Den Haag : LEI Wageningen UR (Report LEI 2014-026) - ISBN 9789086157099 - 87
    visverwerkende industrie - handel - vis - economische analyse - tendensen - werkgelegenheid - omzet - import - export - fish industry - trade - fish - economic analysis - trends - employment - turnover - imports - exports
    Dit onderzoek geeft inzicht in de economische situatie van de visverwerkende industrie en visgroothandel in Nederland door een analyse van de economische structuur van de sector en de belangrijkste ontwikkelingen. De bedrijven in de visverwerkende industrie en visgroothandel hadden in 2013 een gezamenlijke omzet van 3.6 miljard euro; een groei van 7% ten opzichte van de omzet in 2009. 70% van de totale omzet van Nederlandse visverwerkende bedrijven en visgroothandels werd behaald uit export; 30% werd gerealiseerd op de binnenlandse markt.
    Kijk op multifunctionele landbouw. Omzet en impact 2007-2013
    Dijkshoorn-Dekker, M.W.C. ; Jager, J.H. ; Meulen, H.A.B. van der; Schoorlemmer, H.B. ; Schoutsen, M.A. ; Veen, E.J. ; Venema, G.S. ; Vijn, M.P. ; Voskuilen, M.J. ; Weegh, J.B.M. op de - \ 2014
    LEI, WUR / PPO, WUR
    agrarische bedrijfsvoering - akkerbouw- en tuinbouwbedrijven - landbouwbedrijven - multifunctionele landbouw - zorgboerderijen - kinderverzorging - boerderijwinkels - boerderijeducatie - recreatie - nevenactiviteiten - omzet - farm management - crop enterprises - farms - multifunctional agriculture - social care farms - child care - on-farm sales - farm education - recreation - ancillary enterprises - turnover
    Op veel land- en tuinbouwbedrijven worden niet alleen dieren gehouden en/of gewassen geteeld. Ongeveer 20% van de agrariërs pakt ook andere activiteiten op zoals zorglandbouw, kinderopvang, boerderijeducatie, streekproducten, natuurbeheer en/of recreatie. Hierdoor krijgt het bedrijf een multifunctioneel karakter. Deze brochure geeft een beknopt overzicht van de omzet en impact van de sectoren van multifunctionele landbouw over de periode 2007-2013.
    A model-based approach to studying changes in compositional heterogeneity
    Baeten, L. ; Warton, D. ; Calster, H. van; Frenne, P. De; Verstraeten, G. ; Bonte, D. ; Bernhardt-Romermann, M. ; Cornelis, R. ; Decocq, G. ; Eriksson, O. ; Hommel, P.W.F.M. - \ 2014
    Methods in Ecology and Evolution 5 (2014)2. - ISSN 2041-210X - p. 156 - 164.
    with-standards forest - biotic homogenization - beta-diversity - plant-communities - deciduous forest - vegetation - turnover - dissimilarity - nestedness - dispersion
    1. Non-random species loss and gain in local communities change the compositional heterogeneity between communities over time, which is traditionally quantified with dissimilarity-based approaches. Yet, dissimilarities summarize the multivariate species data into a univariate index and obscure the species-level patterns of change, which are central to understand the causes and consequences of the community changes. 2. Here, we propose a model-based approach that looks for species-level effects of time period and construct a multiple-site metric as a sum across species to test the consistency of the individual species responses. Species fall into different response types, showing how they influence the changes in community heterogeneity. 3. In a comparison with other multiple-sitemetrics, we illustrate the properties of our method and the differences and similarities with other approaches. For instance, ourmetric estimates the total variation in a community data set based on species-level contributions, not the compositional dissimilarities between particular sites. Similar to some other approaches, we can distinguish between heterogeneity derived from turnover or richness differences. 4. Our approach was applied to a set of 23 forest understorey resurvey studies spread across Europe. We show the species gains and lossesmay as well decrease or increase levels of community heterogeneity. Although species occurrences and communities have not changed in a consistent way along continental-scale environmental gradients such as climatic conditions, several species shifted in a similar way across the different data sets. 5. Testing the significance of shifts in species prevalence over time to infer corresponding changes in the compositional heterogeneity among sites provides a very intuitive tool for community resurvey studies. The main strengths of our framework are the explicit consideration of the relative roles of species gains and losses and the straightforward generalization to different sets of hypotheses related to community changes. Key-words: biodiversity, community composition, biotic homogenization, binomial deviance, dissimilarity, beta diversity,multivariate analysis,meta-analysis, forest understorey
    The association between plasma homocysteine levels and bone quality and bone mineral density parameters in older persons
    Enneman, A.W. ; Swart, K.M.A. ; Zillikens, M.C. ; Dijk, S.C. van; Wijngaarden, J.P. van; Brouwer-Brolsma, E.M. ; Dhonukshe-Rutten, R.A.M. ; Hofman, A. ; Rivadeneira, F. ; Cammen, T.J.M. van der; Lips, P. ; Groot, C.P.G.M. de; Uitterlinden, A.G. ; Meurs, J.B.J. van; Schoor, N.M. van; Velde, N. van der - \ 2014
    Bone 63 (2014). - ISSN 8756-3282 - p. 141 - 146.
    band ultrasound attenuation - quantitative ultrasound - postmenopausal women - fracture risk - osteoporotic fracture - elderly-people - vitamin-b-12 - homocystinuria - mortality - turnover
    Introduction High plasma homocysteine levels have been associated with incident osteoporotic fractures, but the mechanisms underlying this association are still unknown. It has been hypothesized that homocysteine might interfere with collagen cross-linking in bone, thereby weakening bone structure. Therefore, we wanted to investigate whether plasma homocysteine levels are associated with bone quality parameters, rather than with bone mineral density. Methods Cross-sectional data of the B-PROOF study (n = 1227) and of two cohorts of the Rotterdam Study (RS-I (n = 2850) and RS-II (n = 2023)) were used. Data on bone mineral density of the femoral neck and lumbar spine were obtained in these participants using dual-energy X-ray assessment (DXA). In addition, participants of B-PROOF and RS-I underwent quantitative ultrasound measurement of the calcaneus, as a marker for bone quality. Multiple linear regression analysis was used to investigate the associations between natural-log transformed plasma levels of homocysteine and bone mineral density or ultrasound parameters. Results Natural-log transformed homocysteine levels were inversely associated with femoral neck bone mineral density in the two cohorts of the Rotterdam Study (B = - 0.025, p = 0.004 and B = - 0.024, p = 0.024). In B-PROOF, no association was found. Pooled data analysis showed significant associations between homocysteine and bone mineral density at both femoral neck (B = - 0.032, p = 0.010) and lumbar spine (B = - 0.098, p = 0.021). Higher natural-log transformed homocysteine levels associated significantly with lower bone ultrasound attenuation in B-PROOF (B = - 3.7, p = 0.009) and speed of sound in both B-PROOF (B = - 8.9, p = 0.001) and RS-I (B = - 14.5, p = 0.003), indicating lower bone quality. Pooled analysis confirmed the association between homocysteine and SOS (B = - 13.1, p = 0.016). Results from ANCOVA-analysis indicate that differences in SOS and BUA between participants having a plasma homocysteine level above or below median correspond to 0.14 and 0.09 SD, respectively. Discussion In this study, plasma levels of homocysteine were significantly inversely associated with both bone ultrasound parameters and with bone mineral density. However, the size of the associations seems to be of limited clinical relevance and may therefore not explain the previously observed association between plasma homocysteine and osteoporotic fracture incidence.
    Modeling the vertical soil organic matter profile using Bayesian parameter estimation
    Braakhekke, M.C. ; Wutzler, T. ; Beer, C. ; Kattge, J. ; Schrumpf, M. ; Ahrens, B. ; Schoning, I. ; Hoosbeek, M.R. ; Kruijt, B. ; Kabat, P. ; Reichstein, M. - \ 2013
    Biogeosciences 10 (2013)1. - ISSN 1726-4170 - p. 399 - 420.
    terrestrial ecosystem model - scots pine forest - carbon dynamics - radioactive isotopes - temperate soils - lead - pb-210 - stabilization - transport - turnover
    The vertical distribution of soil organic matter (SOM) in the profile may constitute an important factor for soil carbon cycling. However, the formation of the SOM profile is currently poorly understood due to equifinality, caused by the entanglement of several processes: input from roots, mixing due to bioturbation, and organic matter leaching. In this study we quantified the contribution of these three processes using Bayesian parameter estimation for the mechanistic SOM profile model SOMPROF. Based on organic carbon measurements, 13 parameters related to decomposition and transport of organic matter were estimated for two temperate forest soils: an Arenosol with a mor humus form (Loobos, the Netherlands), and a Cambisol with mull-type humus (Hainich, Germany). Furthermore, the use of the radioisotope Pb-210(ex) as tracer for vertical SOM transport was studied. For Loobos, the calibration results demonstrate the importance of organic matter transport with the liquid phase for shaping the vertical SOM profile, while the effects of bioturbation are generally negligible. These results are in good agreement with expectations given in situ conditions. For Hainich, the calibration offered three distinct explanations for the observations (three modes in the posterior distribution). With the addition of Pb-210(ex) data and prior knowledge, as well as additional information about in situ conditions, we were able to identify the most likely explanation, which indicated that root litter input is a dominant process for the SOM profile. For both sites the organic matter appears to comprise mainly adsorbed but potentially leachable material, pointing to the importance of organo-mineral interactions. Furthermore, organic matter in the mineral soil appears to be mainly derived from root litter, supporting previous studies that highlighted the importance of root input for soil carbon sequestration. The Pb-210(ex) measurements added only slight additional constraint on the estimated parameters. However, with sufficient replicate measurements and possibly in combination with other tracers, this isotope may still hold value as tracer for SOM transport.
    Soil organic matter dynamics in Mediterranean A-horizons-The use of analytical pyrolysis to ascertain land-use history
    Schellekens, J. ; Barbera, G.G. ; Buurman, P. ; Perez-Jorda, G. ; Martinez-Cortizas, A. - \ 2013
    Journal of Analytical and Applied Pyrolysis 104 (2013). - ISSN 0165-2370 - p. 287 - 298.
    chromatography-mass-spectrometry - black carbon - fractionation methods - calcareous soils - nw spain - gc/ms - turnover - biomass - lignin - forest
    In archaeology and nature conservation studies, knowledge about (pre)historical land-use is important. The molecular composition of soil organic matter (SOM) supplies information about its history, as its composition is controlled by input material and decay processes. In this study, the molecular composition of SOM of calcareous A-horizons from SE Spain was studied with pyrolysis gas chromatography/mass spectrometry (pyrolysis-GC/MS). The effect of vegetation type (Pinus halepensis forest and Stipa tenacissima grassland), land-use (cultivation with cereals and olive trees) and wildfire were examined. In addition, former grassland and agricultural soils that had been reforested with P. halepensis (35 yr) were selected. Three locations were sampled for each vegetation type, except for the olive tree (two) and cereal (six) fields, resulting in a total of 26 samples. Each sample was a composite of ten sub-samples taken from a plot of I ha. After removal of weakly or non-decomposed particulate OM, two OM fractions were obtained; (i) sodium hydroxide (NaOH) extractable OM and (ii) the OM that remained after extraction, which was isolated after dissolution of minerals by repeated hydrofluoric acid (HF) treatment. The NaOH-extractable fraction is generally used in soil chemistry (i.e. humic acid), but surprisingly little is known about the SOM that remains in the residue (i.e. humin plus minerals). Comparison of the two SOM fractions (by factor analyses applied to 82 quantified pyrolysis products) provided insight into soil OM dynamics. Polyaromatic pyrolysis products were more prominent in the extractable OM, while a relative enrichment of aliphatic compounds was found in the non-extractable OM. Although some pyrolysis products were associated with one vegetation type in both SOM fractions (C-3-naphthalene, dimethylphenanthrene and 2,3,5-trimethylphenanthrene, retene, and monoterpenes for both burnt and unburnt P. halepensis forest: benzene, naphthalene and C-1-naphthalene for burnt and unburnt S. tenacissima grassland), lignin content and composition highly differed between agricultural soils and soils under native vegetation in both SOM fractions. These differences were mainly decay characteristics, reinforced by cultivation. In reforested soils it was still possible to identify their former land-use, decades after the vegetation change. The probability of the sites to be correctly attributed to its present land-use was P > 0.7 for grassland and pine forest, while most of the cultivated sites had a P > 0.5 to be assigned correctly. The results obtained suggest that the molecular composition of SOM has a large potential for reconstructing land-use history, at least at the scale of decades/centuries. (C) 2013 Elsevier B.V. All rights reserved.
    Bivalve nutrient cycling : nutrient turnover by suspended mussel communities in oligotrophic fjords
    Jansen, H.M. - \ 2012
    Wageningen University. Promotor(en): Aad Smaal, co-promotor(en): Ø. Strand; Marc Verdegem. - S.l. : s.n. - ISBN 9789461732439 - 152
    voedingsstoffen - mossels - aquacultuur - omzet - bivalvia - diervoedering - aquatische gemeenschappen - diervoeding - nutrients - mussels - aquaculture - turnover - bivalvia - animal feeding - aquatic communities - animal nutrition

    This study examined a range of eco-physiological processes (i.e filtration, growth, excretion,

    faeces production) and feedback mechanisms with the aim to investigate the contribution of

    suspended mussel Mytilus edulis communities to nutrient cycling in oligotrophic fjords. Previous

    work has shown that bivalves have the potential to play an important role in coastal nutrient

    cycling. Understanding bivalve nutrient dynamics is particularly essential in oligotrophic

    environments, where bivalve communities potentially have a higher influence as a consequence

    of low background nutrient levels.

    The eco-physiological response of individual mussels to oligotrophic conditions indicated that

    clearance and biodeposition rates were related to food/nutrient availability and were therefore

    respectively higher and lower compared to rates determined for eutrophic conditions. No

    specific responses to oligotrophic conditions were observed for excretion of inorganic

    metabolites or nutrient storage in tissue. However, in situ methods that determined nutrient

    dynamics along suspended communities (ropes) demonstrated that rates under field conditions

    may differ from what can be expected from extrapolation of rates measured in the laboratory for

    individual mussels. Clearance rates were lower for communities while nutrient regeneration was

    higher, specifically during periods with high fouling activity of ascidians. This study thereby

    highlights the need to consider community specific processes while evaluating bivalve-ecosystem

    interactions.

    Biodeposition is an important pathway in bivalve nutrient cycling and represented up to

    47% of ingested nutrients under oligotrophic conditions. Nutrient releases from decomposing

    biodeposits were high for all nutrients (C-N-P-Si), and approximately 24% of carbon and 17% of

    nitrogen in the biodeposits were mineralized with enhanced temperatures resulting in faster

    decomposition (Q10=2-3).

    Combining mussel physiology with physical conditions of the systems showed that the

    fraction of ingested nutrients allocated to either nutrient regeneration (source) or nutrient

    removal (sink) was similar between oligotrophic fjords and eutrophic bays. Nutrient regeneration

    was imbalanced for each of the elements and differed from ratios observed in the ambient water.

    Mussel cultures thereby have the potential to influence phytoplankton community composition.

    However, positive and negative feedback estimates indicated that present mussel aquaculture in

    Norwegian fjord systems has low influence on nutrient cycling due to the low bivalve densities

    and physical characteristics of the fjords.

    This thesis provided insights in the pathways in which mussels interact with nutrient cycling,

    with special reference to oligotrophic conditions. The empirical data collected in this study can

    be applied to optimize models that simulate bivalve-ecosystem interactions, and thereby help to

    understand and predict the exploitation and management of coastal zones.

    Rhizosphere anode model explains high oxygen levels during operation of a Glyceria maxima PMFC
    Timmers, R.A. ; Strik, D.P.B.T.B. ; Arampatzoglou, C. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Bioresource Technology 108 (2012). - ISSN 0960-8524 - p. 60 - 67.
    microbial fuel-cells - triticum-aestivum l - rice plants - electricity production - root exudation - organic-acids - carbon - solubilization - rhizodeposits - turnover
    In this paper, the effect of root oxygen loss on energy recovery of the plant microbial fuel cell (PMFC) is described. In this manner, advanced understanding of competing processes within the rhizosphere-anode interface was provided. A microscopic model was developed on the basis of exudation, oxygen loss, biological oxidation, and biological current generation. The model was successfully validated by comparison to oxygen concentration profiles, volatile fatty acid profiles, and chemical oxygen demand profiles measured in the anode compartment. The model predicted oxic zones around roots in the anode of the plant microbial fuel cell. Results show no direct link between current generation and photosynthesis. This was consistent with the model which predicted that current was generated via hydrolysis of root-derived organic compounds. This result means that to optimize energy recovery of a PMFC, the plant selection should focus on high root biomass production combined with low oxygen loss.
    A step towards underpinning the molecular signalling events regulating muscle protein loss in critically ill patients
    Kouw, I.W. ; Tieland, C.A.B. ; Gorissen, S.H. - \ 2011
    Journal of Physiology 589 (2011)24. - ISSN 0022-3751 - p. 5925 - 5926.
    skeletal-muscle - turnover
    Adaptation of photosystem II to high and low light in wild-type and triazine-resistant Canola plants: analysis by a fluorescence induction algorithm
    Rensen, J.J.S. van; Vredenberg, W.J. - \ 2011
    Photosynthesis Research 108 (2011)2-3. - ISSN 0166-8595 - p. 191 - 200.
    brassica-napus l - chenopodium-album - chloroplasts - photoinhibition - kinetics - photosynthesis - turnover - oxygen - photoinactivation - cyanobacteria
    Plants of wild-type and triazine-resistant Canola (Brassica napus L.) were exposed to very high light intensities and after 1 day placed on a laboratory table at low light to recover, to study the kinetics of variable fluorescence after light, and after dark-adaptation. This cycle was repeated several times. The fast OJIP fluorescence rise curve was measured immediately after light exposure and after recovery during 1 day in laboratory room light. A fluorescence induction algorithm has been used for resolution and analysis of these curves. This algorithm includes photochemical and photo-electrochemical quenching release components and a photo-electrical dependent IP-component. The analysis revealed a substantial suppression of the photo-electrochemical component (even complete in the resistant biotype), a partial suppression of the photochemical component and a decrease in the fluorescence parameter Fo after high light. These effects were recovered after 1 day in the indoor light.
    SOMPROF: A vertically explicit soil organic matter model
    Braakhekke, M.C. ; Beer, M. ; Hoosbeek, M.R. ; Kruijt, B. ; Kabat, P. - \ 2011
    Ecological Modelling 222 (2011)10. - ISSN 0304-3800 - p. 1712 - 1730.
    temperature sensitivity - carbon dynamics - atmospheric co2 - climate-change - forest soils - elevated co2 - turnover - respiration - transport - decomposition
    Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to interactions with the soil temperature and moisture profile, as well as on long (years to centuries) time scale because of depth-specific stabilization mechanisms of organic matter. It is likely that a representation of the SOM profile and surface organic layers in SOM models can improve predictions of the response of land surface fluxes to climate and environmental variability. Although models capable of simulating the vertical SOM profile exist, these were generally not developed for large scale predictive simulations and do not adequately represent surface organic horizons. We present SOMPROF, a vertically explicit SOM model, designed for implementation into large scale ecosystem and land surface models. The model dynamically simulates the vertical SOM profile and organic layer stocks based on mechanistic representations of bioturbation, liquid phase transport of organic matter, and vertical distribution of root litter input. We tested the model based on data from an old growth deciduous forest (Hainich) in Germany, and performed a sensitivity analysis of the transport parameters, and the effects of the vertical SOM distribution on temporal variation of heterotrophic respiration. Model results compare well with measured organic carbon profiles and stocks. SOMPROF is able to simulate a wide range of SOM profiles, using parameter values that are realistic compared to those found in previous studies. Results of the sensitivity analysis show that the vertical SOM distribution strongly affects temporal variation of heterotrophic respiration due to interactions with the soil temperature and moisture profile.
    Het verlaagde btw-tarief voor sierteeltproducten : situatie 2010
    Bunte, F.H.J. ; Poel, N. van der - \ 2010
    Den Haag : LEI (LEI-rapport : Markt & ketens ) - ISBN 9789086154562 - 22
    sierteelt - belasting toegevoegde waarde - effecten - economische evaluatie - verandering - omzet - werkgelegenheid - arbeidseconomie - europese unie - ornamental horticulture - value added tax - effects - economic evaluation - change - turnover - employment - labour economics - european union
    Dit rapport evalueert het effect van een mogelijke verhoging van het btw-tarief op sierteeltproducten op de omzet en wergelegenheid in de sierteeltketen. Het lage btw-tarief wordt in 13 EU-lidstaten op bloemen en planten toegepast. Het effect wordt gemeten met behulp van een partieel evenwichtsmodel dat beschikbaar is op het LEI. Het model modelleert vraag en aanbod in de Europese tuinbouw.
    Effect btw-verlaging hoveniersdiensten
    Meer, R.W. van der; Bunte, F.H.J. - \ 2010
    Den Haag : LEI Wageningen UR (LEI-nota : Onderzoeksveld Sector & ondernemerschap ) - 16
    tuinbouwbedrijven - beroepen - dienstensector - belasting toegevoegde waarde - heffingen - bedrijfsvoering - omzet - werkgelegenheid - hoveniers - bedrijfseconomie - groenbeheer - boomverzorging - market gardens - occupations - services - value added tax - levies - management - turnover - employment - landscape gardeners - business economics - management of urban green areas - tree care
    Onderzoek van LEI, naar de omzet werkgelegeheid in de hoveniersbranche als het btw-tarief van 19% naar 6% wordt verlaagd. De Vereniging van Hoveniers en Groenvoorzieners (VHG) heeft het LEI deze vraag voorgelegd, omdat andere arbeidsintensieve diensten het lage tarief gebruiken. Conclusie is dat ruim 3000 extra fte werkgelegenheid beschikbaar komt en de omzet met maximaal 16% toeneemt.
    Derde kwartaal 2010 sierteelt: omzet groeit
    Jukema, G.D. - \ 2010
    Agri-monitor 2010 (2010)okt. - ISSN 1383-6455
    bloementeelt - sierplanten - potplanten - bedrijfsresultaten in de landbouw - export - prijzen - omzet - floriculture - ornamental plants - pot plants - farm results - exports - prices - turnover
    In het derde kwartaal van 2010 is de omzet op de bloemenveilingen en de exportwaarde opnieuw toegenomen. De omzetstijging op de bloemenveilingen bedroeg een kleine 12% voor de in Nederland geproduceerde producten. Dit is inmiddels het derde achtereenvolgende kwartaal met een hogere omzet dan in dezelfde periode vorig jaar. Ook de exportwaarde groeide in het derde kwartaal, met 8% tot 1,1 miljard euro. Hogere inkoopprijzen, een voorzichtig herstel van het consumentenvertrouwen en gunstigere valutaverhoudingen speelden een rol bij het bereiken van deze hogere exportwaarde.
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