Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Records 1 - 20 / 42

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: q=Wirth
Check title to add to marked list
Management of Malnutrition in Older Patients—Current Approaches, Evidence and Open Questions
Volkert, Dorothee ; Beck, Anne Marie ; Cederholm, Tommy ; Cereda, Emanuele ; Cruz-Jentoft, Alfonso ; Goisser, Sabine ; Groot, Lisette de; Großhauser, Franz ; Kiesswetter, Eva ; Norman, Kristina ; Pourhassan, Maryam ; Reinders, Ilse ; Roberts, Helen C. ; Rolland, Yves ; Schneider, Stéphane M. ; Sieber, Cornel C. ; Thiem, Ulrich ; Visser, Marjolein ; Wijnhoven, Hanneke A.H. ; Wirth, Rainer - \ 2019
Journal of Clinical Medicine 8 (2019)7. - ISSN 2077-0383 - 16 p.
Malnutrition is widespread in older people and represents a major geriatric syndrome with multifactorial etiology and severe consequences for health outcomes and quality of life. The aim of the present paper is to describe current approaches and evidence regarding malnutrition treatment and to highlight relevant knowledge gaps that need to be addressed. Recently published guidelines of the European Society for Clinical Nutrition and Metabolism (ESPEN) provide a summary of the available evidence and highlight the wide range of different measures that can be taken—from the identification and elimination of potential causes to enteral and parenteral nutrition—depending on the patient’s abilities and needs. However, more than half of the recommendations therein are based on expert consensus because of a lack of evidence, and only three are concern patient-centred outcomes. Future research should further clarify the etiology of malnutrition and identify the most relevant causes in order to prevent malnutrition. Based on limited and partly conflicting evidence and the limitations of existing studies, it remains unclear which interventions are most effective in which patient groups, and if specific situations, diseases or etiologies of malnutrition require specific approaches. Patient-relevant outcomes such as functionality and quality of life need more attention, and research methodology should be harmonised to allow for the comparability of studies.
The Future of Complementarity : Disentangling Causes from Consequences
Barry, Kathryn E. ; Mommer, Liesje ; Ruijven, Jasper van; Wirth, Christian ; Wright, Alexandra J. ; Bai, Yongfei ; Connolly, John ; Deyn, Gerlinde B. De; Kroon, Hans de; Isbell, Forest ; Milcu, Alexandru ; Roscher, Christiane ; Scherer-Lorenzen, Michael ; Schmid, Bernhard ; Weigelt, Alexandra - \ 2019
Trends in Ecology and Evolution 34 (2019)2. - ISSN 0169-5347 - p. 167 - 180.
Abiotic facilitation - Biodiversity - Biotic feedbacks - Complementarity - Complementarity effect - Ecosystem functioning - Plant-soil feedback - Resource partitioning - Resource tracers - Stress amelioration

Evidence suggests that biodiversity supports ecosystem functioning. Yet, the mechanisms driving this relationship remain unclear. Complementarity is one common explanation for these positive biodiversity–ecosystem functioning relationships. Yet, complementarity is often indirectly quantified as overperformance in mixture relative to monoculture (e.g., ‘complementarity effect’). This overperformance is then attributed to the intuitive idea of complementarity or, more specifically, to species resource partitioning. Locally, however, several unassociated causes may drive this overperformance. Here, we differentiate complementarity into three types of species differences that may cause enhanced ecosystem functioning in more diverse ecosystems: (i) resource partitioning, (ii) abiotic facilitation, and (iii) biotic feedbacks. We argue that disentangling these three causes is crucial for predicting the response of ecosystems to future biodiversity loss.

Circumpolar Arctic Vegetation Classification
Walker, Donald A. ; Daniëls, Fred J.A. ; Matveyeva, Nadezhda V. ; Šibík, Jozef ; Walker, Marilyn D. ; Breen, Amy L. ; Druckenmiller, Lisa A. ; Raynolds, Martha K. ; Bültmann, Helga ; Hennekens, Stephan ; Buchhorn, Marcel ; Epstein, Howard E. ; Ermokhina, Ksenia ; Fosaa, Anna M. ; Heidmarsson, Starri ; Heim, Birgit ; Jónsdóttir, Ingibjörg S. ; Koroleva, Natalia ; Lévesque, Esther ; MacKenzie, William H. ; Henry, Greg H.R. ; Nilsen, Lennart ; Peet, Robert ; Razzhivin, Volodya ; Talbot, Stephen S. ; Telyatnikov, Mikhail ; Thannheiser, Dietbert ; Webber, Patrick J. ; Wirth, Lisa M. - \ 2018
Phytocoenologia 48 (2018)2. - ISSN 0340-269X - p. 181 - 201.
Alaska - Bioclimate gradient - Braun-Blanquet approach - Habitat type - Plant growth form - Plot database - Syntaxon - Tundra - Vegetation mapping

Aims: An Arctic Vegetation Classification (AVC) is needed to address issues related to rapid Arctic-wide changes to climate, land-use, and biodiversity. Location: The 7.1 million km2 Arctic tundra biome. Approach and conclusions: The purpose, scope and conceptual framework for an Arctic Vegetation Archive (AVA) and Classification (AVC) were developed during numerous workshops starting in 1992. The AVA and AVC are modeled after the European vegetation archive (EVA) and classification (EVC). The AVA will use Turboveg for data management. The AVC will use a Braun-Blanquet (Br.-Bl.) classification approach. There are approximately 31,000 Arctic plots that could be included in the AVA. An Alaska AVA (AVA-AK, 24 datasets, 3026 plots) is a prototype for archives in other parts of the Arctic. The plan is to eventually merge data from other regions of the Arctic into a single Turboveg v3 database. We present the pros and cons of using the Br.-Bl. classification approach compared to the EcoVeg (US) and Biogeoclimatic Ecological Classification (Canada) approaches. The main advantages are that the Br.-Bl. approach already has been widely used in all regions of the Arctic, and many described, well-accepted vegetation classes have a pan-Arctic distribution. A crosswalk comparison of Dryas octopetala communities described according to the EcoVeg and the Braun-Blanquet approaches indicates that the non-parallel hierarchies of the two approaches make crosswalks difficult above the plantcommunity level. A preliminary Arctic prodromus contains a list of typical Arctic habitat types with associated described syntaxa from Europe, Greenland, western North America, and Alaska. Numerical clustering methods are used to provide an overview of the variability of habitat types across the range of datasets and to determine their relationship to previously described Braun-Blanquet syntaxa. We emphasize the need for continued maintenance of the Pan-Arctic Species List, and additional plot data to fully sample the variability across bioclimatic subzones, phytogeographic regions, and habitats in the Arctic. This will require standardized methods of plot-data collection, inclusion of physiogonomic information in the numeric analysis approaches to create formal definitions for vegetation units, and new methods of data sharing between the AVA and national vegetation- plot databases.

Territorial cohesion through cross-border landscape policy? The European case of the Three Countries park (BE-NL-DE)
Brüll, A. ; Wirth, T.M. ; Lohrberg, F. ; Kempenaar, Annet ; Brinkhuijsen, M. ; Godart, M.F. ; Coppens, A. ; Nielsen, M. - \ 2017
Change and Adaptation in Socio-Ecological Systems 3 (2017)1. - ISSN 2300-3669 - p. 68 - 92.
Landscapes can be understood as socialecological systems under constant change. In Europe various territorial dynamics pose persistent challenges to maintaining diverse landscapes both as European heritage and in their capacity to provide vital functions and services. Concurrently, under the competence of cohesion policy, the EU is attempting to improve policy making by better policy coordination and respecting regional specifics. This paper explores the question how a policy dedicated to landscape can help to handle territorial change and support territorial cohesion. It presents results and performances of the ESPON applied research study LP3LP: (1) a common landscape policy for the Three Countries Park, across the Dutch, German and Belgium borders, including a spatial landscape vision, a governance proposal of adaptive landscape management, and thematic strategies dealing with green infrastructure, cultural heritage, complementary biomass and quality production; (2) recommendations at the EU level. In discussing the significance of a landscape approach for EU policy,three dimensions of landscape are linked withimportant aspects of territorial cohesion: ‘landscape as asset’ addressing natural-cultural territorial capital as an indigenous base forsmart, sustainable, and inclusivedevelopment;‘landscape as place’ stressing the relevance of landscape for place-based policies; and ‘landscape as common ground’ highlighting its potential for horizontal, vertical, and territorial integration.
Mapping local and global variability in plant trait distributions
Butler, Ethan E. ; Datta, Abhirup ; Flores-Moreno, Habacuc ; Chen, Ming ; Wythers, Kirk R. ; Fazayeli, Farideh ; Banerjee, Arindam ; Atkin, Owen K. ; Kattge, Jens ; Amiaud, Bernard ; Blonder, Benjamin ; Boenisch, Gerhard ; Bond-Lamberty, Ben ; Brown, Kerry A. ; Byun, Chaeho ; Campetella, Giandiego ; Cerabolini, Bruno E.L. ; Cornelissen, Johannes H.C. ; Craine, Joseph M. ; Craven, Dylan ; Vries, Franciska T. De; Díaz, Sandra ; Domingues, Tomas F. ; Forey, Estelle ; González-Melo, Andrés ; Gross, Nicolas ; Han, Wenxuan ; Hattingh, Wesley N. ; Hickler, Thomas ; Jansen, Steven ; Kramer, Koen ; Kraft, Nathan J.B. ; Kurokawa, Hiroko ; Laughlin, Daniel C. ; Meir, Patrick ; Minden, Vanessa ; Niinemets, Ülo ; Onoda, Yusuke ; Peñuelas, Josep ; Read, Quentin ; Sack, Lawren ; Schamp, Brandon ; Soudzilovskaia, Nadejda A. ; Spasojevic, Marko J. ; Sosinski, Enio ; Thornton, Peter E. ; Valladares, Fernando ; Bodegom, Peter M. Van; Williams, Mathew ; Wirth, Christian ; Reich, Peter B. ; Schlesinger, William H. - \ 2017
Proceedings of the National Academy of Sciences of the United States of America 114 (2017)51. - ISSN 0027-8424 - p. E10937 - E10946.
Bayesian modeling - Climate - Global - Plant traits - Spatial statistics
Our ability to understand and predict the response of ecosystems to a changing environment depends on quantifying vegetation functional diversity. However, representing this diversity at the global scale is challenging. Typically, in Earth system models, characterization of plant diversity has been limited to grouping related species into plant functional types (PFTs), with all trait variation in a PFT collapsed into a single mean value that is applied globally. Using the largest global plant trait database and state of the art Bayesian modeling, we created fine-grained global maps of plant trait distributions that can be applied to Earth system models. Focusing on a set of plant traits closely coupled to photosynthesis and foliar respiration - specific leaf area (SLA) and dry mass-based concentrations of leaf nitrogen (Nm) and phosphorus (Pm), we characterize how traits vary within and among over 50,000 ∼50×50-km cells across the entire vegetated land surface. We do this in several ways - without defining the PFT of each grid cell and using 4 or 14 PFTs; each model's predictions are evaluated against out-of-sample data. This endeavor advances prior trait mapping by generating global maps that preserve variability across scales by using modern Bayesian spatial statistical modeling in combination with a database over three times larger than that in previous analyses. Our maps reveal that the most diverse grid cells possess trait variability close to the range of global PFT means.
Root chemistry and soil fauna, but not soil abiotic conditions explain the effects of plant diversity on root decomposition
Chen, Hongmei ; Oram, Natalie J. ; Barry, Kathryn E. ; Mommer, Liesje ; Ruijven, Jasper van; Kroon, Hans de; Ebeling, Anne ; Eisenhauer, Nico ; Fischer, Christine ; Gleixner, Gerd ; Gessler, Arthur ; González Macé, Odette ; Hacker, Nina ; Hildebrandt, Anke ; Lange, Markus ; Scherer-lorenzen, Michael ; Scheu, Stefan ; Oelmann, Yvonne ; Wagg, Cameron ; Wilcke, Wolfgang ; Wirth, Christian ; Weigelt, Alexandra - \ 2017
Oecologia 185 (2017)3. - ISSN 0029-8549 - p. 499 - 511.
Functional groups - Jena Experiment - Root litter - SEM - Species richness
Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we simultaneously assessed the effects of three pathways—root litter quality, soil biota, and soil abiotic conditions—on the relationships between plant diversity (in terms of species richness and the presence/absence of grasses and legumes) and root decomposition using structural equation modeling. Our final structural equation model explained 70% of the variation in root mass loss. However, different measures of plant diversity included in our model operated via different pathways to alter root mass loss. Plant species richness had a negative effect on root mass loss. This was partially due to increased Oribatida abundance, but was weakened by enhanced root potassium (K) concentration in more diverse mixtures. Equally, grass presence negatively affected root mass loss. This effect of grasses was mostly mediated via increased root lignin concentration and supported via increased Oribatida abundance and decreased root K concentration. In contrast, legume presence showed a net positive effect on root mass loss via decreased root lignin concentration and increased root magnesium concentration, both of which led to enhanced root mass loss. Overall, the different measures of plant diversity had contrasting effects on root decomposition. Furthermore, we found that root chemistry and soil biota but not root morphology or soil abiotic conditions mediated these effects of plant diversity on root decomposition.
Biodiversity effects on ecosystem functioning in a 15-year grassland experiment : Patterns, mechanisms, and open questions
Weisser, Wolfgang ; Roscher, Christiane ; Meyer, Sebastian T. ; Ebeling, Anne ; Luo, Guangjuan ; Allan, Eric ; Beßler, Holger ; Barnard, Romain L. ; Buchmann, Nina ; Buscot, François ; Engels, Christof ; Fischer, Christine ; Fischer, Markus ; Gessler, Arthur ; Gleixner, Gerd ; Halle, Stefan ; Hildebrandt, Anke ; Hillebrand, Helmut ; Kroon, Hans de; Lange, Markus ; Leimer, Sophia ; Roux, Xavier Le; Milcu, Alexandru ; Mommer, Liesje ; Niklaus, Pascal A. ; Oelmann, Yvonne ; Proulx, Raphael ; Roy, Jacques ; Scherber, Christoph ; Scherer-lorenzen, Michael ; Scheu, Stefan ; Tscharntke, Teja ; Wachendorf, Michael ; Wagg, Cameron ; Weigelt, Alexandra ; Wilcke, Wolfgang ; Wirth, Christian ; Schulze, Ernst Detlef ; Schmid, Bernhard ; Eisenhauer, Nico - \ 2017
Basic and Applied Ecology 23 (2017). - ISSN 1439-1791 - p. 1 - 73.
Biomass - Carbon storage - Complementarity - Multi-trophic interactions - Nutrient cycling - Selection effect
In the past two decades, a large number of studies have investigated the relationship between biodiversity and ecosystem functioning, most of which focussed on a limited set of ecosystem variables. The Jena Experiment was set up in 2002 to investigate the effects of plant diversity on element cycling and trophic interactions, using a multi-disciplinary approach. Here, we review the results of 15 years of research in the Jena Experiment, focussing on the effects of manipulating plant species richness and plant functional richness. With more than 85,000 measures taken from the plant diversity plots, the Jena Experiment has allowed answering fundamental questions important for functional biodiversity research.First, the question was how general the effect of plant species richness is, regarding the many different processes that take place in an ecosystem. About 45% of different types of ecosystem processes measured in the 'main experiment', where plant species richness ranged from 1 to 60 species, were significantly affected by plant species richness, providing strong support for the view that biodiversity is a significant driver of ecosystem functioning. Many measures were not saturating at the 60-species level, but increased linearly with the logarithm of species richness. There was, however, great variability in the strength of response among different processes. One striking pattern was that many processes, in particular belowground processes, took several years to respond to the manipulation of plant species richness, showing that biodiversity experiments have to be long-term, to distinguish trends from transitory patterns. In addition, the results from the Jena Experiment provide further evidence that diversity begets stability, for example stability against invasion of plant species, but unexpectedly some results also suggested the opposite, e.g. when plant communities experience severe perturbations or elevated resource availability. This highlights the need to revisit diversity-stability theory.Second, we explored whether individual plant species or individual plant functional groups, or biodiversity itself is more important for ecosystem functioning, in particular biomass production. We found strong effects of individual species and plant functional groups on biomass production, yet these effects mostly occurred in addition to, but not instead of, effects of plant species richness.Third, the Jena Experiment assessed the effect of diversity on multitrophic interactions. The diversity of most organisms responded positively to increases in plant species richness, and the effect was stronger for above- than for belowground organisms, and stronger for herbivores than for carnivores or detritivores. Thus, diversity begets diversity. In addition, the effect on organismic diversity was stronger than the effect on species abundances.Fourth, the Jena Experiment aimed to assess the effect of diversity on N, P and C cycling and the water balance of the plots, separating between element input into the ecosystem, element turnover, element stocks, and output from the ecosystem. While inputs were generally less affected by plant species richness, measures of element stocks, turnover and output were often positively affected by plant diversity, e.g. carbon storage strongly increased with increasing plant species richness. Variables of the N cycle responded less strongly to plant species richness than variables of the C cycle.Fifth, plant traits are often used to unravel mechanisms underlying the biodiversity-ecosystem functioning relationship. In the Jena Experiment, most investigated plant traits, both above- and belowground, were plastic and trait expression depended on plant diversity in a complex way, suggesting limitation to using database traits for linking plant traits to particular functions.Sixth, plant diversity effects on ecosystem processes are often caused by plant diversity effects on species interactions. Analyses in the Jena Experiment including structural equation modelling suggest complex interactions that changed with diversity, e.g. soil carbon storage and greenhouse gas emission were affected by changes in the composition and activity of the belowground microbial community. Manipulation experiments, in which particular organisms, e.g. belowground invertebrates, were excluded from plots in split-plot experiments, supported the important role of the biotic component for element and water fluxes.Seventh, the Jena Experiment aimed to put the results into the context of agricultural practices in managed grasslands. The effect of increasing plant species richness from 1 to 16 species on plant biomass was, in absolute terms, as strong as the effect of a more intensive grassland management, using fertiliser and increasing mowing frequency. Potential bioenergy production from high-diversity plots was similar to that of conventionally used energy crops. These results suggest that diverse 'High Nature Value Grasslands' are multifunctional and can deliver a range of ecosystem services including production-related services.A final task was to assess the importance of potential artefacts in biodiversity-ecosystem functioning relationships, caused by the weeding of the plant community to maintain plant species composition. While the effort (in hours) needed to weed a plot was often negatively related to plant species richness, species richness still affected the majority of ecosystem variables. Weeding also did not negatively affect monoculture performance; rather, monocultures deteriorated over time for a number of biological reasons, as shown in plant-soil feedback experiments.To summarize, the Jena Experiment has allowed for a comprehensive analysis of the functional role of biodiversity in an ecosystem. A main challenge for future biodiversity research is to increase our mechanistic understanding of why the magnitude of biodiversity effects differs among processes and contexts. It is likely that there will be no simple answer. For example, among the multitude of mechanisms suggested to underlie the positive plant species richness effect on biomass, some have received limited support in the Jena Experiment, such as vertical root niche partitioning. However, others could not be rejected in targeted analyses. Thus, from the current results in the Jena Experiment, it seems likely that the positive biodiversity effect results from several mechanisms acting simultaneously in more diverse communities, such as reduced pathogen attack, the presence of more plant growth promoting organisms, less seed limitation, and increased trait differences leading to complementarity in resource uptake. Distinguishing between different mechanisms requires careful testing of competing hypotheses. Biodiversity research has matured such that predictive approaches testing particular mechanisms are now possible.
Affairs happen-To whom? A study on extrapair paternity in common nightingales
Landgraf, Conny ; Wilhelm, Kerstin ; Wirth, Jutta ; Weiss, Michael ; Kipper, Silke - \ 2017
Current Zoology 63 (2017)4. - ISSN 1674-5507 - p. 421 - 431.
Common nightingale - Direct fitness - Extrapair paternity - Luscinia megarhynchos - Repertoire size - Territorial settlement
Most birds engage in extrapair copulations despite great differences across and within species. Besides cost and benefit considerations of the two sex environmental factors have been found to alter mating strategies within or between populations and/or over time. For socially monogamous species, the main advantage that females might gain from mating with multiple males is probably increasing their offspring's genetic fitness. Since male (genetic) quality is mostly not directly measurable for female birds, (extrapair) mate choice is based on male secondary traits. In passerines male song is such a sexual ornament indicating male phenotypic and/or genetic quality and song repertoires seem to affect female mate choice in a number of species. Yet their role in extrapair mating behavior is not well understood. In this study, we investigated the proportion of extrapair paternity (EPP) in a population of common nightingales Luscinia megarhynchos. We found that EPP rate was rather high (21.5% of all offspring tested) for a species without sexual dimorphism and high levels of paternal care. Furthermore, the occurrence of EPP was strongly related to the spatial distribution of male territories with males settling in densely occupied areas having higher proportions of extrapair young within their own brood. Also, song repertoire size affected EPP: here larger repertoires of social mates were negatively related to the probability of being cuckolded. When directly comparing repertoires sizes of social and extrapair mates, extrapair mates tended to have larger repertoires. We finally discuss our results as a hint for a flexible mating strategy in nightingales where several factors-including ecological as well as male song features- need to be considered when studying reproductive behavior in monogamous species with complex song.
Plant species richness negatively affects root decomposition in grasslands
Chen, Hongmei ; Mommer, Liesje ; Ruijven, Jasper Van; Kroon, Hans De; Fischer, Christine ; Gessler, Arthur ; Hildebrandt, Anke ; Scherer-lorenzen, Michael ; Wirth, Christian ; Weigelt, Alexandra ; Wurzburger, Nina - \ 2017
Journal of Ecology 105 (2017)1. - ISSN 0022-0477 - p. 209 - 218.
1. Plant diversity enhances many ecosystem functions, including root biomass production, which drives soil carbon input. Although root decomposition accounts for a large proportion of carbon input for soil, little is known about plant diversity effect on this process. Plant diversity may affect root decomposition in two non-exclusive ways: by providing roots of different substrate quality (e.g. root chemistry) and/or by altering the soil environment (e.g. microclimate).
2. To disentangle these two pathways, we conducted three decomposition experiments using a litter-bag approach in a grassland biodiversity experiment. We hypothesized that: (i) plant species richness negatively affects substrate quality (indicated by increased C:N ratios), which we tested by decomposing roots collected from each experimental plot in one common plot; (ii) plant species richness positively affects soil environment (indicated by increased soil water content), which we tested by decomposing standardized roots in all experimental plots; (iii) the overall effect of plant species richness on root decomposition, due to the contrast between quality and environmental effects, is neutral, which we tested by decomposing community roots in their ‘home’ plots.
3. Plant species richness negatively affected root decomposition in all three experiments. The negative effect of plant species richness on substrate quality was largely explained by increased root C:N ratios along the diversity gradient. Functional group presence explained more variance in substrate quality than species richness. Here, the presence of grasses negatively affected substrate quality and root C:N ratios, while the presence of legumes and small herbs had positive effects. Plant species richness had a negative effect on soil environment despite its positive effect on soil water content which is known to stimulate decomposition. We argue that – instead of soil water content – a combined effect of soil temperature and seasonality might drive environmental effect of plant diversity on decomposition in our plant communities, but this remains to be tested.
4. Synthesis. Our results demonstrate that both substrate quality and soil environment contribute to the net negative effect of plant diversity on root decomposition. This study promotes our mechanistic understanding of increased soil carbon accumulation in more diverse grassland plant communities.

Data from: Plant species richness negatively affects root decomposition in grasslands
Chen, H. ; Mommer, L. ; Ruijven, J. van; Kroon, H. de; Fischer, C. ; Gessler, A. ; Hildebrandt, A. ; Scherer-Lorenzen, M. ; Wirth, C. ; Weigelt, A. - \ 2016
Biodiversity-ecosystem functioning - C:N ratio - litter bags - microenvironment - plant diversity - plant functional group - plant-soil (below-ground) interactions - root substrate quality - soil water content - the jena experiment
This data set contains mass loss of community roots decomposing in the common plot in the Jena experiment in 2014. The Metadata contains the Dataset ID in the Jena Experiment database and detailed information of column: 'plotcode' is plot ID in the Jena Experiment; 'bag_ID' is the ID for litter bags within each decomposition experiment; 'root_type' is the type of roots in the litter bags where plot coded for community roots, lolium coded for standardized roots; 'site' is the location of where decomposition happened; 'sector' is the subplots in common plot; 'mass_initial' is root mass in the litter bags before buried in the field and handling loss is seduced already; 'mass_remain' is root mass in the litter bags at each retrieval; 'date_in' is the exact dates when the litter bags were buried. In the form of DD-MM-YY; 'date_out' is the exact dates when the litter bags were retrieved. In the form of DD-MM-YY; 'actual_decomptime' is the exact days litter bags were in the field; 'massloss' is actual mass loss =100 - mass_remain/mass_initial*100; 'std_decomptime' is standardized days litter bags were in the field; 'std_massloss' is stadardized mass loss = massloss/actual_decomp.time*std_decomp.time.
The Alaska Arctic Vegetation Archive (AVA-AK)
Walker, Donald A. ; Breen, Amy L. ; Druckenmiller, Lisa A. ; Wirth, Lisa W. ; Fisher, Will ; Raynolds, Martha K. ; Šibík, Jozef ; Walker, Marilyn D. ; Hennekens, Stephan ; Boggs, Keith ; Boucher, Tina ; Buchhorn, Marcel ; Bültmann, Helga ; Cooper, David J. ; Daniëls, Fred J.A. ; Davidson, Scott J. ; Ebersole, James J. ; Elmendorf, Sara C. ; Epstein, Howard E. ; Gould, William A. ; Hollister, Robert D. ; Iversen, Colleen M. ; Jorgenson, M.T. ; Kade, Anja ; Lee, Michael T. ; MacKenzie, William H. ; Peet, Robert K. ; Peirce, Jana L. ; Schickhoff, Udo ; Sloan, Victoria L. ; Talbot, Stephen S. ; Tweedie, Craig E. ; Villarreal, Sandra ; Webber, Patrick J. ; Zona, Donatella - \ 2016
Phytocoenologia 46 (2016)2. - ISSN 0340-269X - p. 221 - 229.
Circumpolar - Cluster analysis - Database - Tundra - Turboveg - Vegetation classification

The Alaska Arctic Vegetation Archive (AVA-AK, GIVD-ID: NA-US-014) is a free, publically available database archive of vegetation-plot data from the Arctic tundra region of northern Alaska. The archive currently contains 24 datasets with 3,026 non-overlapping plots. Of these, 74% have geolocation data with 25-m or better precision. Species cover data and header data are stored in a Turboveg database. A standardized Pan Arctic Species List provides a consistent nomenclature for vascular plants, bryophytes, and lichens in the archive. A web-based online Alaska Arctic Geoecological Atlas (AGA-AK) allows viewing and downloading the species data in a variety of formats, and provides access to a wide variety of ancillary data. We conducted a preliminary cluster analysis of the first 16 datasets (1,613 plots) to examine how the spectrum of derived clusters is related to the suite of datasets, habitat types, and environmental gradients. We present the contents of the archive, assess its strengths and weaknesses, and provide three supplementary files that include the data dictionary, a list of habitat types, an overview of the datasets, and details of the cluster analysis.

Potential and limitations of inferring ecosystem photosynthetic capacity from leaf functional traits
Musavi, Talie ; Migliavacca, Mirco ; Weg, Martine Janet van de; Kattge, Jens ; Wohlfahrt, Georg ; Bodegom, Peter M. van; Reichstein, Markus ; Bahn, Michael ; Carrara, Arnaud ; Domingues, Tomas F. ; Gavazzi, Michael ; Gianelle, Damiano ; Gimeno, Cristina ; Granier, André ; Gruening, Carsten ; Havránková, Kateřina ; Herbst, Mathias ; Hrynkiw, Charmaine ; Kalhori, Aram ; Kaminski, Thomas ; Klumpp, Katja ; Kolari, Pasi ; Longdoz, Bernard ; Minerbi, Stefano ; Montagnani, Leonardo ; Moors, Eddy ; Oechel, Walter C. ; Reich, Peter B. ; Rohatyn, Shani ; Rossi, Alessandra ; Rotenberg, Eyal ; Varlagin, Andrej ; Wilkinson, Matthew ; Wirth, Christian ; Mahecha, Miguel D. - \ 2016
Ecology and Evolution 6 (2016)20. - ISSN 2045-7758 - p. 7352 - 7366.
FLUXNET - Ecosystem functional property - Eddy covariance - Interannual variability - Photosynthetic capacity - Plant traits - Spatiotemporal variability - TRY database

The aim of this study was to systematically analyze the potential and limitations of using plant functional trait observations from global databases versus in situ data to improve our understanding of vegetation impacts on ecosystem functional properties (EFPs). Using ecosystem photosynthetic capacity as an example, we first provide an objective approach to derive robust EFP estimates from gross primary productivity (GPP) obtained from eddy covariance flux measurements. Second, we investigate the impact of synchronizing EFPs and plant functional traits in time and space to evaluate their relationships, and the extent to which we can benefit from global plant trait databases to explain the variability of ecosystem photosynthetic capacity. Finally, we identify a set of plant functional traits controlling ecosystem photosynthetic capacity at selected sites. Suitable estimates of the ecosystem photosynthetic capacity can be derived from light response curve of GPP responding to radiation (photosynthetically active radiation or absorbed photosynthetically active radiation). Although the effect of climate is minimized in these calculations, the estimates indicate substantial interannual variation of the photosynthetic capacity, even after removing site-years with confounding factors like disturbance such as fire events. The relationships between foliar nitrogen concentration and ecosystem photosynthetic capacity are tighter when both of the measurements are synchronized in space and time. When using multiple plant traits simultaneously as predictors for ecosystem photosynthetic capacity variation, the combination of leaf carbon to nitrogen ratio with leaf phosphorus content explains the variance of ecosystem photosynthetic capacity best (adjusted R2 = 0.55). Overall, this study provides an objective approach to identify links between leaf level traits and canopy level processes and highlights the relevance of the dynamic nature of ecosystems. Synchronizing measurements of eddy covariance fluxes and plant traits in time and space is shown to be highly relevant to better understand the importance of intra- and interspecific trait variation on ecosystem functioning.

From pots to plots: Hierarchical trait-based prediction of plant performance in a mesic grassland
Schroeder, T.C. ; Wirth, C. ; Nadrowski, K. ; Meyer, S. ; Mommer, L. ; Weigelt, A. - \ 2016
Journal of Ecology 104 (2016)1. - ISSN 0022-0477 - p. 206 - 218.
Traits are powerful predictors of ecosystem functions pointing to underlying physiological and ecological processes. Plant individual performance results from the coordinated operation of many processes, ranging from nutrient uptake over organ turnover to photosynthesis, thus requiring a large set of traits for its prediction. For plant performance on higher hierarchical levels, e.g. populations, additional traits important for plant-plant and trophic interactions may be required which should even enlarge the spectrum of relevant predictor traits.(2)The goal of this study was to assess the importance of plant functional traits to predict individual and population performance of grassland species with particular focus on the significance of root traits. We tested this for 59 grassland species using 35 traits divided into three trait clusters: leaf traits (16), stature traits (8) and root traits (11), using individual biomass of mesocosm plants as a measure of individual performance and population biomass of monocultures as a measure of population performance. We applied structural equation models to disentangle direct effects of single traits on population biomass and indirect effects via individual plant biomass or shoot density.We tested multivariate trait effects on individual and population biomass to analyze whether the importance of different trait clusters shifts with increasing hierarchical integration from individuals to populations.(3)Traits of all three clusters significantly correlated with individual and population biomass. However, in spite of a number of significant correlations, above-below-ground linkages were generally week, with few exceptions like N content.(4)Stature traits exclusively affected population biomass indirectly via their effect on individual biomass, whereas root and leaf traits showed also direct effects and partly indirect effects via density.(5)The inclusion of root traits in multiple regression models improved the prediction of individual biomass compared to models with only above-ground information only slightly (95% vs. 93% of variance prediction with and without root traits, respectively) but was crucial for the prediction of population biomass (77% and 49%, respectively). Root traits were more important for plant performance than leaf traits and were even the most important predictors at the population level(6)Synthesis: Upscaling from the individual to the population level reflects an increasing number of processes requiring traits from different trait clusters for their prediction. Our results emphasize the importance of root traits for trait-based studies especially at higher organizational levels. Our approach provides a comprehensive framework acknowledging the hierarchical nature of trait influences. This is one step towards a more process-oriented assessment of trait-based approaches
Landschapsbeleid voor het Drielandenpark: een praktische samenvatting : Landscape Policy for the Three Countries Park: a practical summary
Brinkhuijsen, M. ; Houwen, J. ; Blokland, A. ; Wirth, T.M. - \ 2015
Der Hund als Spürnase in der Medizin
Wirth, J. - \ 2015
MTA Dialog
Hunde sind schlau und die ältesten Vertrauten des Menschen [1]. Durch Training werden sie zu Wachhunden oder Helferhunden, die auch in Notfallgebieten als Rettungshunde einsetzbar sind.
Sensitive Noses in the Hospital
Wirth, J. - \ 2015
Lab Times
Detecting dangerous infections and even cancer in its early stages is important but not easy. Luckily, clinical science can increasingly rely on man’s best friends, dogs.
Chemische & Pharmazeutische Industrie: Alternative Prüfmethoden. Neue Trends: Die tierversuchsfreie Route
Wirth, J. - \ 2015
GIT Laborportal
In der chemischen und in der pharmazeutischen Industrie ist der Trend zu tierfreien Testmethoden sichtbar. Kosten, ethische Gründe und die Robustheit der neuen Ersatzmethoden sind sicherlich die wichtigsten Gründe. Einen Einstieg in die Arbeitsweisen und Optimierungen zellbasierter in vitro Methoden als Alternativmethode zum Tierversuch bekommen Sie durch fachgerechte Weiterbildung. Über 30000 Chemikalien, die in der EU produziert oder eingeführt werden, werden seit 2006 unter die Lupe genommen. Die erlassene EU Chemikalienverordnung REACH [1] hat die Zulassung, Bewertung und Registrierung von Chemikalien neu angeordnet um die Gesundheit des Menschen und der Umwelt sicherzustellen. Solche Chemikalien, die in einem Volumen von einer Tonne und mehr pro Jahr im Handel sind, werden auf ihre gesundheitsschädliche Wirkung hin getestet.
Happy medical products
Wirth, J. - \ 2015
Germany : MTA
Prevalence of genetic disorders in dog breeds: a literature review
Wirth, J. - \ 2015
Wageningen : Wetenschapswinkel van Wageningen UR (318 ) - ISBN 9789461738899 - 18 p.
Genetic disorders are common in dogs and in the media it is reported that genetic disorders are more frequent in pedigree dogs than in look-a-likes or in mixed-breed dogs. Here, we consider pedigree dogs as purebred dogs (i.e. matching a breed-specific morphology) with a registered and certified pedigree, whereas look-a-likes dogs are dogs without a certification. Thus, look-a-likes may be non-pure bred or purebred but lacking the supporting evidence. Dutch experts have indicated that more than 40 percent of purebred dogs in the Netherlands suffer from genetic disorders. Uncertainty about the validity of such indications, and if pedigree dogs are at increased risk of genetic disorders, together with societal concerns about the well-being of (pedigree) dogs, incited a Wageningen UR Science Shop project commissioned by the Dutch animal protection foundation Dier&Recht. Genetic disorders are heterogeneous in aetiology and manifestations across dog breeds, which complicates studying them. One feasible approach is to study specific disorders in pre-selected breeds only, as a model for the complex reality. This report, as part of this project’s products, provides a scientific literature overview on prevalence data for two genetic disorders (hip dysplasia and elbow dysplasia) in the German Shepherd and the Rottweiler in various countries including the Netherlands. The prevalence data assembled and compared in this study are based on results of screening programs published from national and international Kennel Clubs and Veterinarian Associations. In both breeds, the disease prevalence for hip dysplasia (HD), ranging from 10-46% in European and non -European countries, was remarkably variable, with a substantial proportion of the population at risk in, for example, Finland (33-46%). In the Netherlands, the prevalence for HD reported for both breeds (10-18%) was intermediate compared to that in other European countries (8-46%). Different methodology and scoring systems for HD are used in screening programs, whereas interpretations of radiographs to determine the HD grade, and the quality of databases, are critical factors. Methodological differences between studies make a valid comparison between studies difficult. The results for elbow dysplasia (ED) are similar regarding the high variation in prevalence among different countries (7-65%). However, the ED condition is estimated to be at least twice as prevalent in Rottweilers (40-60%) than in German Shepherds (20%). Yet, in the Netherlands, the estimated ED prevalence in both breeds is low (7-14%). This literature search found no data that allowed to test if the subcategory of look-a-likes are less affected by the specific genetic disorders HD and ED than pedigree dogs. Earlier studies have indicated that purebred dogs are more at risk of genetic disorders than mixed breed dogs, but this need not be the case for every disorder-dog breed combination. The detection of subtle differences in the prevalence of genetic disorders, for example between pedigree dogs and look-a-likes, require data that are presently unavailable as look-a-likes and mixed breeds are not nationally monitored for ED and HD.
Fit for job
Wirth, J. - \ 2014
Germany : MTA Dialog
Die Entwicklungen in der Gesundheitsmedizin sind nicht mehr zu bremsen. Neue Medikamente werden getestet, und wirksame Impfstoffe werden für die gefährliche Wintergrippe hergestellt.
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.