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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    Determinants of legacy effects in pine trees – implications from an irrigation-stop experiment
    Zweifel, Roman ; Etzold, Sophia ; Sterck, Frank ; Gessler, Arthur ; Anfodillo, Tommaso ; Mencuccini, Maurizio ; Arx, Georg von; Lazzarin, Martina ; Haeni, Matthias ; Feichtinger, Linda ; Meusburger, Katrin ; Knuesel, Simon ; Walthert, Lorenz ; Salmon, Yann ; Bose, Arun K. ; Schoenbeck, Leonie ; Hug, Christian ; Girardi, Nicolas De; Giuggiola, Arnaud ; Schaub, Marcus ; Rigling, Andreas - \ 2020
    New Phytologist 227 (2020)4. - ISSN 0028-646X - p. 1081 - 1096.
    cambial activity - drought stress - ecological memory - irrigation experiment - osmoregulation - point dendrometer - radial stem growth - TreeNet

    Tree responses to altered water availability range from immediate (e.g. stomatal regulation) to delayed (e.g. crown size adjustment). The interplay of the different response times and processes, and their effects on long-term whole-tree performance, however, is hardly understood. Here we investigated legacy effects on structures and functions of mature Scots pine in a dry inner-Alpine Swiss valley after stopping an 11-yr lasting irrigation treatment. Measured ecophysiological time series were analysed and interpreted with a system-analytic tree model. We found that the irrigation stop led to a cascade of downregulations of physiological and morphological processes with different response times. Biophysical processes responded within days, whereas needle and shoot lengths, crown transparency, and radial stem growth reached control levels after up to 4 yr only. Modelling suggested that organ and carbon reserve turnover rates play a key role for a tree’s responsiveness to environmental changes. Needle turnover rate was found to be most important to accurately model stem growth dynamics. We conclude that leaf area and its adjustment time to new conditions is the main determinant for radial stem growth of pine trees as the transpiring area needs to be supported by a proportional amount of sapwood, despite the growth-inhibiting environmental conditions.

    Begeleiding Startende Leraren : Praktijk en theorie
    Schellings, G. ; Helms-Lorenz, M. ; Runhaar, P.R. - \ 2019
    Antwerpen : Garant Uitgevers - ISBN 9789044136760 - 208 p.
    Een startende leraar moet vanaf dag één leren omgaan met belangen en wensen van vele actoren: leerlingen, collega’s, ouders en schoolleiders. Of volgens een starter: ‘Je komt met het idee dat je als leraar alleen leraar moet zijn, maar je bent ook pedagoog, opvoeder, je bent van alles’. Een goed ‘inductieprogramma’ voor startende leraren in de eerste jaren van hun loopbaan, is essentieel om een soepele transitie van opleiding naar beroep te realiseren, de praktijkschok te dempen en de professionele ontwikkeling te bevorderen.
    Dit boek beschrijft verschillende manieren waarop (onderdelen van) inductieprogramma’s kunnen worden vormgegeven en ingebed in de schoolorganisatie. De praktijkvoorbeelden komen uit een Nederlands project, dat geïnitieerd werd door het ministerie van Onderwijs Cultuur en Wetenschappen. Het nationale project bestond uit negen regionale projecten, waarin medewerkers van universitaire lerarenopleidingen en lerarenopleidingen uit instellingen voor hoger beroepsonderwijs in samenwerking met scholen uit hun regio intensief werkten aan de verbetering van inductieprogramma’s. De verschillende bijdragen bevatten concrete voorbeelden, aangevuld met theoretische en empirische inzichten, waarmee de auteurs de praktijk hopen te inspireren: Human Resource Management tools, professionaliseringstrajecten voor (vak)coaches en begeleiders, borging van inductiemaatregelen, interventies gericht op de startende leraren zelf, zoals professionele identiteitsworkshops, videoclubbegeleiding en vakdidactische Lesson Study. Dit boek illustreert zowel het inductieprogramma als het flankerend onderzoek en maakt het toegankelijk voor iedereen die betrokken is bij en/of geïnteresseerd is in het begeleiden van startende leraren. Elk hoofdstuk is geschreven door de onderzoekers die in de betreffende regio actief waren.
    Digging deeper : Understanding the contribution of subsoil carbon for climate mitigation, a case study of Ireland
    Simo, I. ; Schulte, R. ; O'Sullivan, L. ; Creamer, R. - \ 2019
    Environmental Science & Policy 98 (2019). - ISSN 1462-9011 - p. 61 - 69.
    Agricultural soils - Soil carbon mapping - Soil organic carbon stocks

    In an attempt to counter the progress of climate change, the European Commission 2030 climate and energy framework developed a binding target to cut GHG emissions within the territory by at least 40% below 1990 levels, by 2030. In the past, this did not include the role of soils in providing a sink for carbon. As of 2014, the European Commission legislative proposed to integrate greenhouse gas emissions and removals from LULUCF in the 2030 climate and energy framework, allowing for the contribution of carbon sinks in national inventories. To calculate the potential of these sinks it is essential to firstly understand what stocks exist at a national scale and identify the so-called ‘carbon hotspots’ in the landscape to reduce the potential leaks in the system. This is further enhanced by identifying soils which provide the potential for further sequestration of carbon, due to their soil texture and aggregate composition. Moreover, deeper soil horizons may have a high capacity to sequester significant amounts of SOC as the turnover time and chemical recalcitrance of soil organic matter (SOM)increases with depth (Lorenz and Lal, 2005). This study highlights the need to dig deeper and assess soil carbon stocks below the standard 30 cm depth, applied in many calculations and models, in order to derive sufficiently accurate estimations of soil organic carbon (SOC)stocks and the total quantity of stable SOC at depth. Using Ireland as a case study, SOC stock maps are produced with the objective of identifying and securing existing information for SOC and to show the spatial distribution and geographical variation of SOC stock at different depths. Using empirical data from a national soil survey, SOC measurements from the surface 30 cm, 50 cm and 1 m were compared across all soil types. The results indicate a large variation between soils when comparing the SOC of the first 30 cm only, while the proportion of total SOC stock contained within 0–50 cm was more consistent within subgroups of soil types, and accounts for 90% of the carbon found to 1 m. Luvisols and Stagnosols have been previously identified as soils capable of sequestering larger stores of SOC in their subsoils. These soil types were spatially mapped and the stock converted to CO 2 emission equivalents. On average, up to 40 t ha −1 of stable SOC is contained at a depth below 30 cm. At national level, this adds up to 69 Mt of SOC. This research provides a spatially targeted approach that combines efforts to reduce CO 2 emissions from carbon hotspots while also augmenting the sequestration of stable carbon at depth in soils with clay illuviation and wetness (stagnic)diagnostic horizons.

    Reintroduction of freshwater macroinvertebrates : challenges and opportunities
    Jourdan, Jonas ; Plath, Martin ; Tonkin, Jonathan D. ; Ceylan, Maria ; Dumeier, Arlena C. ; Gellert, Georg ; Graf, Wolfram ; Hawkins, Charles P. ; Kiel, Ellen ; Lorenz, Armin W. ; Matthaei, Christoph D. ; Verdonschot, Piet F.M. ; Verdonschot, Ralf C.M. ; Haase, Peter - \ 2019
    Biological Reviews 94 (2019)2. - ISSN 1464-7931 - p. 368 - 387.
    conservation - invertebrate reintroduction - population restoration - restoring diversity - species management - translocation

    Species reintroductions – the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population – have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has been devoted to the reintroduction of invertebrates into restored freshwater habitats. Yet, reintroductions may improve restoration outcomes in regions where impoverished regional species pools limit the self-recolonisation of restored freshwaters. We review the available literature on macroinvertebrate reintroductions, focusing on identifying the intrinsic and extrinsic factors that determine their success or failure. Our study reveals that freshwater macroinvertebrate reintroductions remain rare, are often published in the grey literature and, of the attempts made, approximately one-third fail. We identify life-cycle complexity and remaining stressors as the two factors most likely to affect reintroduction success, illustrating the unique challenges of freshwater macroinvertebrate reintroductions. Consideration of these factors by managers during the planning process and proper documentation – even if a project fails – may increase the likelihood of successful outcomes in future reintroduction attempts of freshwater macroinvertebrates.

    Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer (ISOBAR)-the Hailuoto 2017 campaign
    Kral, Stephan T. ; Reuder, Joachim ; Vihma, Timo ; Suomi, Irene ; O'Connor, Ewan ; Kouznetsov, Rostislav ; Wrenger, Burkhard ; Rautenberg, Alexander ; Urbancic, Gabin ; Jonassen, Marius O. ; Båserud, Line ; Maronga, Björn ; Mayer, Stephanie ; Lorenz, Torge ; Holtslag, Albert A.M. ; Steeneveld, Gert J. ; Seidl, Andrew ; Müller, Martin ; Lindenberg, Christian ; Langohr, Carsten ; Voss, Hendrik ; Bange, Jens ; Hundhausen, Marie ; Hilsheimer, Philipp ; Schygulla, Markus - \ 2018
    Atmosphere 9 (2018)7. - ISSN 2073-4433
    Arctic - Boundary layer remote sensing - Ground-based in-situ observations - Polar - Remotely piloted aircraft systems (RPAS) - Sea ice - Stable atmospheric boundary layer - Turbulence - Unmanned aerial vehicles (UAV)

    The aim of the research project "Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer (ISOBAR)" is to substantially increase the understanding of the stable atmospheric boundary layer (SBL) through a combination of well-established and innovative observation methods as well as by models of different complexity. During three weeks in February 2017, a first field campaign was carried out over the sea ice of the Bothnian Bay in the vicinity of the Finnish island of Hailuoto. Observations were based on ground-based eddy-covariance (EC), automatic weather stations (AWS) and remote-sensing instrumentation as well as more than 150 flight missions by several different Unmanned Aerial Vehicles (UAVs) during mostly stable and very stable boundary layer conditions. The structure of the atmospheric boundary layer (ABL) and above could be resolved at a very high vertical resolution, especially close to the ground, by combining surface-based measurements with UAV observations, i.e., multicopter and fixed-wing profiles up to 200magl and 1800magl, respectively. Repeated multicopter profiles provided detailed information on the evolution of the SBL, in addition to the continuous SODAR and LIDAR wind measurements. The paper describes the campaign and the potential of the collected data set for future SBL research and focuses on both the UAV operations and the benefits of complementing established measurement methods by UAV measurements to enable SBL observations at an unprecedented spatial and temporal resolution.

    Overview of known organohalide-respiring bacteria-phylogenetic diversity and environmental distribution
    Atashgahi, Siavash ; Lu, Yue ; Smidt, Hauke - \ 2016
    In: Organohalide-Respiring Bacteria / Adrian, Lorenz, Löffler, Frank E., Springer Verlag - ISBN 9783662498750 - p. 63 - 105.

    To date, organohalide respiration (OHR) has been restricted to the bacterial domain of life. Known organohalide-respiring bacteria (OHRB) are spread among several phyla comprising both Gram-positive and Gram-negative bacteria. As a unique trait, OHRB benefit from reductive dehalogenase enzymes enabling them to use different organohalides as terminal electron acceptors and occupy a wide range of terrestrial and aquatic environments. This chapter comprises three sections: First, we give an overview of phylogeny of known OHRB and briefly discuss physiological and genetic characteristics of each group. Second, the environmental distribution of OHRB is presented. Owing to the application of molecular diagnostic approaches, OHRB are being increasingly detected not only from organohalide-contaminated groundwaters and sediments but also from pristine environments, including deep oceanic sediments and soils that are ample sources of naturally occurring organohalides. Finally, we highlight important factors that impact the ecology of OHRB and their interaction with other microbial guilds.

    Comparative genomics and transcriptomics of organohalide-respiring bacteria and regulation of rdh gene transcription
    Hansen, Thomas ; Smidt, Hauke ; Lechner, Ute - \ 2016
    In: Organohalide-Respiring Bacteria / Adrian, Lorenz, Löffler, Frank E., Springer Verlag - ISBN 9783662498736 - p. 345 - 376.

    Comparison of the genomes of organohalide-respiring bacteria has improved our understanding of the genetic background of the organohalide respiration process. In this chapter the remarkable differences between obligate and facultative organohalide-respiring bacteria in the number of reductive dehalogenaseencoding genes and the numbers and types of accessory genes are discussed in relation to different lifestyles and evolutionary aspects. Furthermore, the putative function of accessory genes is discussed and a unifying nomenclature is proposed. The genomes also reflect distinct mechanisms for the synthesis or acquisition of the corrinoid cofactors of reductive dehalogenases, which are well in accord with the observed growth requirements of the respective organohalide-respiring bacteria. The value of microarray-based comparative genomics, transcriptomics, and quantitative transcription analyses for understanding the physiology and environmental significance of organohalide respiration is discussed. The reductive dehalogenase genes are in general associated with genes encoding transcriptional regulators, which are likely involved in sensing the halogenated electron acceptors. The role of two types of regulators in transcriptional regulation of organohalide respiration has been investigated. A multiple antibiotic resistance regulator (MarR)-type regulator was shown to regulate negatively the transcription of reductive dehalogenase genes in Dehalococcoides mccartyi. In Desulfitobacterium hafniense, the cAMP receptor protein/fumarate and nitrate reduction (CRP/FNR) regulator, CprK, activates transcription of reductive dehalogenase genes. The molecular mechanism of how ortho- chlorophenols act as effectors has been elucidated and how, through the induction of structural changes, they lead to DNA binding of the regulator.

    Contrasting the roles of section length and instream habitat enhancement for river restoration success: a field study on 20 European restoration projects
    Hering, D. ; Aroviita, J. ; Baattrup-Pedersen, A. ; Brabec, K. ; Buijse, T. ; Ecke, F. ; Friberg, N. ; Gielczewski, Marek ; Januschke, K. ; Köhler, J. ; Kupilas, Benjamin ; Lorenz, A.W. ; Muhar, S. ; Paillex, Amael ; Poppe, Michaela ; Schmidt, T. ; Schmutz, S. ; Vermaat, J. ; Verdonschot, R.C.M. ; Verdonschot, P.F.M. ; Wolter, Christian ; Kail, J. - \ 2015
    Wageningen UR
    aquatic macrophytes - benthic invertebrates - fish - floodplain - flow patterns - food web - ground beetles - riparian vegetation - stable isotopes
    1. Restoration of river hydromorphology often has limited detected effects on river biota. One frequently discussed reason is that the restored river length is insufficient to allow populations to develop and give the room for geomorphologic processes to occur. 2. We investigated ten pairs of restored river sections of which one was a large project involving a long, intensively restored river section and one represented a smaller restoration effort. The restoration effect was quantified by comparing each restored river section to an upstream non-restored section. We sampled the following response variables: habitat composition in the river and its floodplain, three aquatic organism groups (aquatic macrophytes, benthic invertebrates and fish), two floodplain-inhabiting organism groups (floodplain vegetation, ground beetles), as well as food web composition and land–water interactions reflected by stable isotopes. 3. For each response variable, we compared the difference in dissimilarity of the restored and nearby non-restored section between the larger and the smaller restoration projects. In a second step, we regrouped the pairs and compared restored sections with large changes in substrate composition to those with small changes. 4. When comparing all restored to all non-restored sections, ground beetles were most strongly responding to restoration, followed by fish, floodplain vegetation, benthic invertebrates and aquatic macrophytes. Aquatic habitats and stable isotope signatures responded less strongly. 5. When grouping the restored sections by project size, there was no difference in the response to restoration between the projects targeting long and short river sections with regard to any of the measured response variables except nitrogen isotopic composition. In contrast, when grouping the restored sections by substrate composition, the responses of fish, benthic invertebrates, aquatic macrophytes, floodplain vegetation and nitrogen isotopic composition were greater in sections with larger changes in substrate composition as compared to those with smaller changes. 6. Synthesis and applications. The effects of hydromorphological restoration measures on aquatic and floodplain biota strongly depend on the creation of habitat for aquatic organisms, which were limited or not present prior to restoration. These positive effects on habitats are not necessarily related to the restored river length. Therefore, we recommend a focus on habitat enhancement in river restoration projects.
    Contrasting the roles of section length and instream habitat enhancement for river restoration success : A field study of 20 European restoration projects
    Hering, Daniel ; Aroviita, Jukka ; Baattrup-Pedersen, Annette ; Brabec, Karel ; Buijse, Tom ; Ecke, Frauke ; Friberg, Nikolai ; Gielczewski, Marek ; Januschke, Kathrin ; Köhler, Jan ; Kupilas, Benjamin ; Lorenz, Armin W. ; Muhar, Susanne ; Paillex, Amael ; Poppe, Michaela ; Schmidt, Torsten ; Schmutz, Stefan ; Vermaat, Jan ; Verdonschot, Piet F.M. ; Verdonschot, Ralf C.M. ; Wolter, Christian ; Kail, Jochem - \ 2015
    Journal of Applied Ecology 52 (2015)6. - ISSN 0021-8901 - p. 1518 - 1527.
    Aquatic macrophytes - Benthic invertebrates - Fish - Floodplain - Flow patterns - Food web - Ground beetles - Riparian vegetation - Stable isotopes

    Restoration of river hydromorphology often has limited detected effects on river biota. One frequently discussed reason is that the restored river length is insufficient to allow populations to develop and give the room for geomorphological processes to occur. We investigated ten pairs of restored river sections of which one was a large project involving a long, intensively restored river section and one represented a smaller restoration effort. The restoration effect was quantified by comparing each restored river section to an upstream non-restored section. We sampled the following response variables: habitat composition in the river and its floodplain, three aquatic organism groups (aquatic macrophytes, benthic invertebrates and fish), two floodplain-inhabiting organism groups (floodplain vegetation, ground beetles), as well as food web composition and land-water interactions reflected by stable isotopes. For each response variable, we compared the difference in dissimilarity of the restored and nearby non-restored section between the larger and the smaller restoration projects. In a second step, we regrouped the pairs and compared restored sections with large changes in substrate composition to those with small changes. When comparing all restored to all non-restored sections, ground beetles were most strongly responding to restoration, followed by fish, floodplain vegetation, benthic invertebrates and aquatic macrophytes. Aquatic habitats and stable isotope signatures responded less strongly. When grouping the restored sections by project size, there was no difference in the response to restoration between the projects targeting long and short river sections with regard to any of the measured response variables except nitrogen isotopic composition. In contrast, when grouping the restored sections by substrate composition, the responses of fish, benthic invertebrates, aquatic macrophytes, floodplain vegetation and nitrogen isotopic composition were greater in sections with larger changes in substrate composition as compared to those with smaller changes. Synthesis and applications. The effects of hydromorphological restoration measures on aquatic and floodplain biota strongly depend on the creation of habitat for aquatic organisms, which were limited or not present prior to restoration. These positive effects on habitats are not necessarily related to the restored river length. Therefore, we recommend a focus on habitat enhancement in river restoration projects. The effects of hydromorphological restoration measures on aquatic and floodplain biota strongly depend on the creation of habitat for aquatic organisms, which were limited or not present prior to restoration. These positive effects on habitats are not necessarily related to the restored river length. Therefore, we recommend a focus on habitat enhancement in river restoration projects.

    Assessing the potential of in-field rainwater harvesting as an adaptation strategy to climate change for African agriculture
    Lebel, S. ; Fleskens, L. ; Forster, P.M. ; Jackson, L.S. ; Lorenz, S. - \ 2015
    Water Resources Management 29 (2015)13. - ISSN 0920-4741 - p. 4803 - 4816.
    Stabilizing smallholder crop yields under changing climatic conditions in sub-Saharan Africa will require adaptation strategies focused on soil and water management. Impact studies of climate change on crop yields often ignore the potential of adaptation strategies such as rainwater harvesting (RWH). While RWH is bringing benefits to agricultural systems today, it is still unclear which regions could increasingly benefit from RWH under changing climatic conditions. Here we employ a continental scale modelling strategy using the latest CMIP5 data and explicitly take into account design factors of RWH to show that it is a valuable adaptation strategy to climate change in Africa for maize (Zea mays L.). We find that RWH can bridge up to 40 % of the yield gaps attributable to water deficits under current conditions and 31 % under future (2050s) climatic conditions during the main growing season for maize, hence providing an alternative to irrigation from scarce or inaccessible groundwater resources. RWH could increase maize yields by 14–50 % on average for the 2050s across Africa, by bridging water deficits. While in situ RWH strategies show great biophysical potential as an adaptation strategy to climate change, there remain locally specific barriers to their adoption, which will need to be addressed to ensure their successful implementation at a larger scale.
    Important Bird Areas in Antarctica 2015
    Harris, C. ; Lorenz, K. ; Franeker, J.A. van - \ 2015
    Cambridge : BirdLife Int. and Env. Research & Assessment - 313 p.
    Methods
    Muhar, S. ; Aroviita, J. ; Baattrup-Pedersen, A. ; Brabec, K. ; Ecke, F. ; Verdonschot, P.F.M. - \ 2014
    In: Results of the hydromorphological and ecological survey. Effects of large- and small-scale river restoration on hydromorphology and ecology / Kail, J., Lorenz, A., Hering, D., EU (REFORM WP4 4.3) - p. 19 - 41.
    Ground Beetles
    Januschke, K. ; Verdonschot, R.C.M. - \ 2014
    In: REstoring rivers FOR effective catchment Management : Effects of large- and small-scale river restoration on hydromorphology and ecology / Kail, J., Lorenz, A., Hering, D., EU (REFORM WP4 4.3) - p. 113 - 130.
    Macroinvertebrates
    Verdonschot, R.C.M. ; Kail, J. ; Verdonschot, P.F.M. - \ 2014
    In: Results of the hydromorphological and ecological survey. Effects of large- and small-scale river restoration on hydromorphology and ecology / Kail, J., Lorenz, A., Hering, D., EU (REFORM WP4 4.3) - p. 80 - 93.
    Overview analysis
    Hering, D. ; Aroviita, J. ; Baattrup-Pedersen, A. ; Brabec, K. ; Buijse, T. ; Verdonschot, P.F.M. ; Verdonschot, R.C.M. - \ 2014
    In: REstoring rivers FOR effective catchment Management : Effects of large- and small-scale river restoration on hydromorphology and ecology / Kail, J., Lorenz, A., Hering, D., EU (REFORM WP4 4.3) - p. 41 - 54.
    The presence of a below-ground neighbour alters within-plant seed size distribution in Phaseolus vulgaris
    Chen, B. ; During, H.J. ; Vermeulen, P.J. ; Anten, N.P.R. - \ 2014
    Annals of Botany 114 (2014). - ISSN 0305-7364 - p. 937 - 943.
    root competition - variable environments - optimal balance - number - recognition - germination - growth - consequences - adaptation - plasticity
    * Background and Aims Considerable variation in seed size commonly exists within plants, and is believed to be favoured under natural selection. This study aims to examine the extent to which seed size distribution depends on the presence of competing neighbour plants. * Methods Phaseolus vulgaris plants rooting with or without a conspecific neighbourwere grown in soil with high or low nutrient availability. Seeds were harvested at the end of the growth cycle, the total nitrogen and phosphorus invested in seed production were measured and within-plant seed size distribution was quantified using a set of statistical descriptors. * Key Results Exposure to neighbours’ roots induced significant changes in seed size distribution. Plants produced proportionally more large seeds and fewer small ones, as reflected by significant increases in minimal seed size, mean seed size, skewness and Lorenz asymmetry coefficient. These effects were different from, and in several cases opposite to, the responses when the soil nutrient level was reduced, and were significant after correction for the amount of resources invested in seed production. * Conclusions Below-ground neighbour presence affects within-plant seed size distribution in P. vulgaris. This effect appears to be non-resource-mediated, i.e. to be independent of neighbour-induced effects on resource availability. It implies that, based on current environmental cues, plants can make an anticipatory adjustment of their investment strategy in offspring as an adaptation to the local environment in the future. Key words: Anticipatory maternal effect, bet-hedging, game theory, neighbour detection, Phaseolus vulgaris, kidney bean, root competition, seed-setting, seed size variation, size inequality, skewness. INTRODUCTION A considerable degree of variation in seed size within plants is commonly observed (Michaels et al., 1988; Silvertown, 1989; Ruiz de Clavijo, 2002; Vo¨ller et al., 2012). Such variation is often interpreted as an adaptive bet-hedging strategy (Harper et al., 1970; McGinley et al., 1987; McGinley and Charnov, 1988; Venable and Brown, 1988; Geritz, 1995). Many studies also reveal that plants modify the pattern of variation (i.e. distribution) to cope with their abiotic environmental conditions (e.g. temperature, Wulff, 1986; light, Galloway, 2001; nutrients, Galloway, 2001;water, Parciak, 2002). Herewe demonstrate that seed size distribution may also be modified in response to the presence of a below-ground neighbour. Within a species, seed size (following common practice, seed size refers to seedweight in this paper) often correlates positively with the competitiveness of the offspring (e.g. Houssard and Escarre´, 1991; Eriksson, 1999; Lehtila¨ and Ehrle´n, 2005; Dubois and Cheptou, 2012). Based on the trade-off, induced by resource limitation in plants, between competition (favours large seeds) and colonization (favours a large number of small seeds), Geritz (1995) extended an optimal offspring size model (Smith and Fretwell, 1974) by considering seedling competition and using
    Effect of supplementing coconut or krabok oil, rich in medium-chain fatty acids on ruminal fermentation, protozoa and archaeal population of bulls
    Panyakaew, P. ; Boon, N. ; Goel, G. ; Yuangklang, C. ; Schonewille, J.T. ; Hendriks, W.H. ; Fievez, V. - \ 2013
    Animal 7 (2013)12. - ISSN 1751-7311 - p. 1950 - 1958.
    different hypervariable regions - gradient gel-electrophoresis - myristic acid - in-vitro - methane suppression - ciliate protozoa - energy-balance - lauric acid - dairy-cows - rumen
    Medium-chain fatty acids (MCFA), for example, capric acid (C10:0), myristic (C14:0) and lauric (C12:0) acid, have been suggested to decrease rumen archaeal abundance and protozoal numbers. This study aimed to compare the effect of MCFA, either supplied through krabok (KO) or coconut (CO) oil, on rumen fermentation, protozoal counts and archaeal abundance, as well as their diversity and functional organization. KO contains similar amounts of C12:0 as CO (420 and 458 g/kg FA, respectively), but has a higher proportion of C14:0 (464 v. 205 g/kg FA, respectively). Treatments contained 35 g supplemental fat per kg DM: a control diet with tallow (T); a diet with supplemental CO; and a diet with supplemental KO. A 4th treatment consisted of a diet with similar amounts of MCFA (i.e. C10:0+C12:0+C14:0) from CO and KO. To ensure isolipidic diets, extra tallow was supplied in the latter treatment (KO+T). Eight fistulated bulls (two bulls per treatment), fed a total mixed ration predominantly based on cassava chips, rice straw, tomato pomace, rice bran and soybean meal (1.5% of BW), were used. Both KO and CO increased the rumen volatile fatty acids, in particular propionate and decreased acetate proportions. Protozoal numbers were reduced through the supplementation of an MCFA source (CO, KO and KO+T), with the strongest reduction by KO. Quantitative real-time polymerase chain reaction assays based on archaeal primers showed a decrease in abundance of Archaea when supplementing with KO and KO+T compared with T and CO. The denaturing gradient gel electrophoresis profiles of the rumen archaeal population did not result in a grouping of treatments. Richness indices were calculated from the number of DGGE bands, whereas community organization was assessed from the Pareto–Lorenz eveness curves on the basis of DGGE band intensities. KO supplementation (KO and KO+T treatments) increased richness and evenness within the archaeal community. Further research including methane measurements and productive animals should elucidate whether KO could be used as a dietary methane mitigation strategy.
    Patterns of covariance between airborne laser scanning metrics and Lorenz curve descriptors of tree size inequality
    Valbuena, R. ; Maltamo, M. ; Martín-Fernández, S. ; Packalén, P. ; Pascual, C. ; Nabuurs, G.J. - \ 2013
    Canadian Journal of Remote Sensing 39 (2013)Suppl. 1. - ISSN 1712-7971 - p. S18 - S31.
    nearest-neighbor imputation - partial least-squares - forest structure - lidar data - stand - regression - inventory - northwest - selection - canopies
    The Lorenz curve, as a descriptor of tree size inequality within a stand, has been suggested as a reliable means for characterizing forest structure and distinguishing even from uneven-sized areas. The aim of this study was to achieve a thorough understanding on the relations between airborne laser scanning (ALS) metrics and indicators based on Lorenz curve ordering: Gini coefficient (GC) and Lorenz asymmetry (S). Exploratory multivariate analysis was carried out using correlation tests, partial least squares (PLS), and an information-theoretic approach for multimodel inference (MMI). Best subset linear model was selected for GC and S prediction, as variable transformations yielded no improvement in the relation of ALS with the given response. Relative variable importance based on the MMI model showed that GC is best predicted by ALS metrics expressing canopy coverage, return dispersion, and low high percentile combinations. Although ALS metrics showed no correlation with S, they did so against its constituting components: the proportions of basal area (Mg) and stem density (xg) stocked above the mean quadratic diameter. The study of PLS loading vectors illustrated how ALS metrics explain variance in opposing directions for each of these components, so that their effects cancel each other out in the overall S. Cross-validation showed that only marginal differences are nevertheless found between predicting S directly or as the sum Mg and xg estimations. The differing relation of diverse ALS metrics was therefore observed for Mg and xg. The conclusions obtained by this research may assist in selecting relevant Lorenz curve descriptors for forest structure characterization, as well as in variable reduction strategies for their wall-to-wall prediction by means of ALS metrics.
    Ecosystem carbon and soil biodiversity
    Deyn, G.B. de - \ 2013
    In: Ecosystem services and carbon sequestration in the biosphere / Lal, R., Lorenz, K., Hüttl, R.F., Schneider, B.U., Braun, J., Potsdam : Springer - ISBN 9789400764552 - p. 131 - 153.
    Substratum associations of benthic invertebrates in lowland and mountain streams
    Schröder, M. ; Kiesel, J. ; Schattmann, A. ; Jähnig, S.C. ; Lorenz, A.W. ; Kramm, S. ; Keizer-Vlek, H.E. ; Rolauffs, P. ; Graf, W. ; Leitner, P. ; Hering, D. - \ 2013
    Ecological Indicators 30 (2013). - ISSN 1470-160X - p. 178 - 189.
    macroinvertebrate assemblages - community structure - species assemblages - habitat type - bioassessment - rivers - reach - microdistribution - quality - sites
    The preferences of aquatic invertebrate species for specific substrata at the river bottom have been subject of many studies. Several authors classified the substratum preferences of species or higher taxonomic units. Most of these compilations, however, are based on literature analyses and expert knowledge as opposed to the analysis of original data. To enhance our knowledge of invertebrate substratum preferences, we applied a ‘Multi-level pattern’ analysis based on almost 1000 substrate-specific invertebrate samples. The samples were taken in 18 streams in Germany, the Netherlands and Austria, comprising a total of 40 sampling sites and equally covering lowland and mountain streams. The main objectives of our analysis were (I) to derive substratum preferences of taxa in lowland and mountain streams, (II) to compare the preferences with existing data and (III) to compare species substratum associations between lowland and mountain streams. Of the 290 taxa analyzed, 188 were associated significantly to specific substrata. Twenty-five taxa in lowland streams and 51 taxa in mountain streams prefer one or two substratum types (of nine substratum types considered in total). In contrast, 112 species (mountain streams n = 84, lowland streams n = 28) are associated significantly with a broader range of substrata. We compared the classifications derived from our data analysis with those provided in the freshwaterecology.info database (www.freshwaterecology.info). Our results support the existing classifications of substratum preferences in most cases (70%). For 25 species, substratum preferences for both lowland and mountain streams were derived, many of them indicating different substratum associations in the two stream groups. As substratum preferences differed between closely related species, preferences should always be given at the species level as opposed to coarser taxonomic units
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