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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An exposure-effect approach for evaluating ecosystem-wide risks from human activities
Knights, A.M. ; Piet, G.J. ; Jongbloed, R.H. ; Tamis, J.E. ; Robinson, L.A. - \ 2015
ICES Journal of Marine Science 72 (2015)3. - ISSN 1054-3139 - p. 1105 - 1115.
baltic sea - fisheries management - environmental-change - coastal ecosystems - marine ecosystems - human impact - new-zealand - food webs - support - climate
Ecosystem-based management (EBM) is promoted as the solution for sustainable use. An ecosystem-wide assessment methodology is therefore required. In this paper, we present an approach to assess the risk to ecosystem components from human activities common to marine and coastal ecosystems. We build on: (i) a linkage framework that describes how human activities can impact the ecosystem through pressures, and (ii) a qualitative expert judgement assessment of impact chains describing the exposure and sensitivity of ecological components to those activities. Using case study examples applied at European regional sea scale, we evaluate the risk of an adverse ecological impact from current human activities to a suite of ecological components and, once impacted, the time required for recovery to pre-impact conditions should those activities subside. Grouping impact chains by sectors, pressure type, or ecological components enabled impact risks and recovery times to be identified, supporting resource managers in their efforts to prioritize threats for management, identify most at-risk components, and generate time frames for ecosystem recovery.
Evaluation of ecosystem-based marine management strategies based on risk assessment
Piet, G.J. ; Jongbloed, R.H. ; Knights, A.M. ; Tamis, J.E. ; Paijmans, A.J. ; Sluis, M.T. van der; Vries, P. de; Robinson, L.A. - \ 2015
Biological Conservation 186 (2015). - ISSN 0006-3207 - p. 158 - 166.
fisheries management - new-zealand - vulnerability - support - areas - south - pressure - context - threats - number
This study presents a comprehensive and generic framework that provides a typology for the identification and selection of consistently defined ecosystem-based management measures and allows a coherent evaluation of these measures based on their performance to achieve policy objectives. The performance is expressed in terms of their reduction of risk of an adverse impact on the marine ecosystem. This typology consists of two interlinked aspects of a measure, i.e. the “Focus” and the “Type”. The “Focus” is determined by the part of the impact chain (Driver–Pressure–State) the measure is supposed to mitigate or counteract. The “Type” represents the physical measure itself in terms of how it affects the impact chain directly; we distinguish Spatio-temporal distribution controls, Input and Output controls, Remediation and Restoration measures. The performance of these measures in terms of their reduction in risk of adverse impacts was assessed based on an explicit consideration of three time horizons: past, present and future. Application of the framework in an integrated management strategy evaluation of a suite of measures, shows that depending on the time horizon, different measures perform best. “Past” points to measures targeting persistent pressures (e.g. marine litter) from past activities. “Present” favors measures targeting a driver (e.g. fisheries) that has a high likelihood of causing adverse impacts. “Future” involves impacts that both have a high likelihood of an adverse impact, as well as a long time to return to pre-impacted condition after the implementation of appropriate management, e.g. those caused by permanent infrastructure or persistent pressures such as marine litter or specific types of pollution.
Biogeography of Fusarium graminearum species complex and chemotypes: a review
Lee, T.A.J. van der; Zhang, H. ; Diepeningen, A. ; Waalwijk, C. - \ 2015
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 32 (2015)4. - ISSN 1944-0049 - p. 453 - 460.
head blight pathogen - nivalenol-producing chemotypes - small-grain cereals - trichothecene genotypes - new-zealand - genealogical concordance - mycotoxin chemotypes - population-structure - southern brazil - sensu-stricto
Differences in the geographic distribution of distinct trichothecene mycotoxins in wheat and barley were first recorded two decades ago. The different toxicological properties of deoxynivalenol (DON), nivalenol (NIV) and their acetylated derivatives require careful monitoring of the dynamics of these mycotoxins and their producers. The phylogenetic species concept has become a valuable tool to study the global occurrence of mycotoxin-producing Fusarium species. This has revolutionised our views on the terrestrial distribution of trichothecene-producing Fusaria in the context of agronomics, climatic conditions, and human interference by the global trade and exchange of agricultural commodities. This paper presents an overview of the dynamics of the different trichothecene-producing Fusarium species as well as their chemotypes and genotypes across different continents. Clearly not one global population exists, but separate ones can be distinguished, sometimes even sympatric in combination with different hosts. A population with more pathogenic strains and chemotypes can replace another. Several displacement events appear to find their origin in the inadvertent introduction of new genotypes into new regions: 3-acetyl-DON-producing F. graminearum in Canada; 3-acetyl-DON-producing F. asiaticum in Eastern China; 15-acetyl-DON F. graminearum in Uruguay; and NIV-producing F asiaticum in the southern United States
Relationships between soil fertility, herbage quality and manure composition on grassland-based dairy farms
Reijneveld, J.A. ; Abbink, G.W. ; Termorshuizen, A.J. ; Oenema, O. - \ 2014
European Journal of Agronomy 56 (2014). - ISSN 1161-0301 - p. 9 - 18.
new-zealand - agricultural land - phosphorus status - central-europe - new-york - yield - management - magnesium - trends - fertilization
It is reasonable to expect that compliance with grassland fertilization recommendations in the long run results in optimal soil fertility, and subsequent herbage quality. Here, we evaluate the development of soil, herbage and manure characteristics and their relation over the last decades. We hypothesized that herbage and manure quality are related with soil fertility. We used a large database with results of soil tests, spring forage quality characteristics, and manure analyses, which were made on demand of dairy farmers. We considered the Netherlands as a whole and three selected regions with contrasting soil types (sandy soil, riverine clay, and peaty marine clay). Effects of soil fertility on herbage quality were evident when comparing farms. Farms higher in soil P and K generally have correspondingly higher contents in forage. On average, soil fertility and herbage characteristics were within or just above the agronomical optimal range during the last decades. Herbage crude protein content decreased in all regions during last two decades, which is likely an effect of legislative measures on decreasing the application of N. Selenium (Se) and sulphur (S) contents increased sharply on sandy soils, likely because of increased use of Se and S containing fertilizers. Manure composition did not differ between soil types. In conclusion, at farm level, the element composition of herbage reflected the soil fertility status. The contents of S, P, K, Na, Mg, and Ca in the herbage were all significantly influenced by soil fertility characteristics. Our results emphasize the importance of maintaining soil fertility for high quality roughage production. (C) 2014 Elsevier B.V. All rights reserved.
Evaluation of two commercial, rapid, ELISA kits testing or scrapie in retro-pharyngeal lymph nodes in sheep
Kittelberger, R. ; McIntuyre, L. ; Watts, S. ; MacDiarmid, S. ; Hannah, M.J. ; Jenner, J. ; Bueno, R. ; Swainsbury, R. ; Langeveld, J.P.M. ; Keulen, L.J.M. van; Zijderveld, F.G. van; Wemheuer, W.M. ; Richt, J.A. ; Sorenson, S.J. ; Pigott, C.J. ; O'Keefe, J.S. - \ 2014
New Zealand Veterinary Journal 62 (2014)6. - ISSN 0048-0169 - p. 343 - 350.
natural scrapie - prion protein - immunohistochemical detection - new-zealand - prp - accumulation - diagnosis - genotypes - tissues - brain
AIMS: To estimate the number of cases of scrapie that would occur in sheep of different prion protein (PrP) genotypes if scrapie was to become established in New Zealand, and to compare the performance of two commercially available, rapid ELISA kits using ovine retro-pharyngeal lymph nodes (RLN) from non-infected and infected sheep of different PrP genotypes. METHODS: Using published data on the distribution of PrP genotypes within the New Zealand sheep flock and the prevalence of cases of scrapie in these genotypes in the United Kingdom, the annual expected number of cases of scrapie per genotype was estimated, should scrapie become established in New Zealand, assuming a total population of 28 million sheep. A non-infected panel of RLN was collected from 737 sheep from New Zealand that had been culled, found in extremis or died. Brain stem samples were also collected from 131 of these sheep. A second panel of infected samples comprised 218 and 117 RLN from confirmed scrapie cases that had originated in Europe and the United States of America, respectively. All samples were screened using two commercial, rapid, transmissible spongiform encephalopathy ELISA kits: Bio-Rad TeSeE ELISA (ELISA-BR), and IDEXX HerdChek BSE-Scrapie AG Test (ELISA-ID). RESULTS: If scrapie became established in New Zealand, an estimated 596 cases would occur per year; of these 234 (39%) and 271 (46%) would be in sheep carrying ARQ/ARQ and ARQ/VRQ PrP genotypes, respectively. For the non-infected samples from New Zealand the diagnostic specificity of both ELISA kits was 100%. When considering all infected samples, the diagnostic sensitivity was 70.4 (95% CI=65.3-75.3)% for ELISA-BR and 91.6 (95% CI=88.2-94.4)% for ELISA-ID. For the ARQ/ARQ genotype (n=195), sensitivity was 66.2% for ELISA-BR and 90.8% for ELISA-ID, and for the ARQ/VRQ genotype (n=107), sensitivity was 81.3% for ELISA-BR and 98.1% for ELISA-ID. CONCLUSIONS: In this study, the ELISA-ID kit demonstrated a higher diagnostic sensitivity for detecting scrapie in samples of RLN from sheep carrying scrapie-susceptible PrP genotypes than the ELISA-BR kit at comparable diagnostic specificity.
Adverse Outcome Pathway and Risks of Anticoagulant Rodenticides to Predatory Wildlife
Rattner, B.A. ; Lazarus, R.S. ; Elliott, J.E. ; Shore, R.F. ; Brink, N.W. van den - \ 2014
Environmental Science and Technology 48 (2014). - ISSN 0013-936X - p. 8433 - 8445.
eastern screech-owls - polecats mustela-putorius - rats rattus-norvegicus - kites milvus-milvus - new-zealand - nontarget wildlife - pest-control - blood-coagulation - brodifacoum bait - megascops-asio
Despite a long history of successful use, routine application of some anticoagulant rodenticides (ARs) may be at a crossroad due to new regulatory guidelines intended to mitigate risk. An adverse outcome pathway for ARs was developed to identify information gaps and end points to assess the effectiveness of regulations. This framework describes chemical properties of ARs, established macromolecular interactions by inhibition of vitamin K epoxide reductase, cellular responses including altered clotting factor processing and coagulopathy, organ level effects such as hemorrhage, organism responses with linkages to reduced fitness and mortality, and potential consequences to predator populations. Risk assessments have led to restrictions affecting use of some second-generation ARs (SGARs) in North America. While the European regulatory community highlighted significant or unacceptable risk of ARs to nontarget wildlife, use of SGARs in most EU member states remains authorized due to public health concerns and the absence of safe alternatives. For purposes of conservation and restoration of island habitats, SGARs remain a mainstay for eradication of invasive species. There are significant data gaps related to exposure pathways, comparative species sensitivity, consequences of sublethal effects, potential hazards of greater AR residues in genetically resistant prey, effects of low-level exposure to multiple rodenticides, and quantitative data on the magnitude of nontarget wildlife mortality.
Bonamia parasites: a rapidly changing perspective on a genus of important mollusc pathogens
Engelsma, M.Y. ; Culloty, S.C. ; Lynch, S.A. ; Arzul, I. ; Carnegie, R.B. - \ 2014
Diseases of Aquatic Organisms 110 (2014)1-2. - ISSN 0177-5103 - p. 5 - 23.
oyster ostrea-edulis - european flat oyster - crassostrea-gigas mollusca - n. sp haplosporidia - new-zealand - tiostrea-chilensis - protozoan parasite - mikrocytos-roughleyi - pacific oyster - pcr assay
Organisms of the genus Bonamia are intracellular protistan parasites of oysters. To date, 4 species have been described (B. ostreae, B. exitiosa, B. perspora and B. roughleyi), although the status of B. roughleyi is controversial. Introduction especially of B. ostreae and B. exitiosa to naïve host populations has been shown to cause mass mortalities in the past and has had a dramatic impact on oyster production. Both B. ostreae and B. exitiosa are pathogens notifiable to the World Organisation for Animal Health (OIE) and the European Union. Effective management of the disease caused by these pathogens is complicated by the extensive nature of the oyster production process and limited options for disease control of the cultured stocks in open water. This review focuses on the recent advances in research on genetic relationships between Bonamia isolates, geographical distribution, susceptible host species, diagnostics, epizootiology, host-parasite interactions, and disease resistance and control of this globally important genus of oyster pathogens.
Ultrastructural comparison of Bonamia spp (Haplosporidia) infecting ostreid oysters
Hine, P.M. ; Carnegie, R.B. ; Kroeck, M.A. ; Villalba, A. ; Engelsma, M.Y. ; Burreson, E.M. - \ 2014
Diseases of Aquatic Organisms 110 (2014)1. - ISSN 0177-5103 - p. 55 - 63.
n. sp haplosporidia - flat oyster - tiostrea-chilensis - crassostrea-ariakensis - mikrocytos-roughleyi - new-zealand - edulis l - mytilus-galloprovincialis - north-carolina - parasite
The ultrastructure of Bonamia from Ostrea angasi from Australia, Crassostrea ariakensis from the USA, O. puelchana from Argentina and O. edulis from Spain was compared with described Bonamia spp. All appear conspecific with B. exitiosa. The Bonamia sp. from Chile had similarities to the type B. exitiosa from New Zealand (NZ), but less so than the other forms recognized as B. exitiosa. Two groups of ultrastructural features were identified; those associated with metabolism (mitochondrial profiles, lipid droplets and endoplasmic reticulum), and those associated with haplosporogenesis (Golgi, indentations in the nuclear surface, the putative trans-Golgi network, perinuclear granular material and haplosporosome-like bodies). Metabolic features were regarded as having little taxonomic value, and as the process of haplosporogenesis is not understood, only haplosporosome shape and size may be of taxonomic value. However, the uni-nucleate stages of spore-forming haplosporidians are poorly known and may be confused with Bonamia spp. uni-nucleate stages. The many forms of NZ B. exitiosa have not been observed in other hosts, which may indicate that it has a plastic life cycle. Although there are similarities between NZ B. exitiosa and Chilean Bonamia in the development of a larger uni-nucleate stage and the occurrence of cylindrical confronting cisternae, the clarification of the identity of Chilean Bonamia must await molecular studies.
Landscape Evolution Modelling of naturally dammed rivers
Gorp, W. van; Temme, A.J.A.M. ; Baartman, J.E.M. ; Schoorl, J.M. - \ 2014
Earth Surface Processes and Landforms 39 (2014)12. - ISSN 0197-9337 - p. 1587 - 1600.
western grand-canyon - landslide dams - new-zealand - soil redistribution - fluvial response - outburst flood - peak discharge - dem resolution - lava dams - pleistocene
Natural damming of upland river systems, such as landslide or lava damming, occurs worldwide. Many dams fail shortly after their creation, while other dams are long-lived and therefore have a long-term impact on fluvial and landscape evolution. This long-term impact is still poorly understood and landscape evolution modelling (LEM) can increase our understanding of different aspects of this response. Our objective was to simulate fluvial response to damming, by monitoring sediment redistribution and river profile evolution for a range of geomorphic settings.We used LEM LAPSUS, which calculates runoff erosion and deposition and can deal with non-spurious sinks, such as dam-impounded areas. Because fluvial dynamics under detachment-limited and transport-limited conditions are different, we mimicked these conditions using low and high erodibility settings, respectively. To compare the relative impact of different dam types, we evaluated five scenarios for each landscape condition: one scenario without a dam and four scenarios with dams of increasing erodibility. Results showed that dam-related sediment storage persisted at least until 15 000 years for all dam scenarios. Incision and knickpoint retreat occurred faster in the detachment-limited landscape than in the transport-limited landscape. Furthermore, in the transport-limited landscape, knickpoint persistence decreased with increasing dam erodibility. Stream capture occurred only in the transport-limited landscape due to a persisting floodplain behind the dam and headward erosion of adjacent channels. Changes in sediment yield variation due to stream captures did occur but cannot be distinguished from other changes in variation of sediment yield. Comparison of the model results with field examples indicates that the model reproduces several key phenomena of damming response in both transport-limited and detachment-limited landscapes. We conclude that a damming event which occurred 15 000 years ago can influence present-day sediment yield, profile evolution and stream patterns.
Marine neurotoxins: State of the art, bottlenecks, and perspectives for mode of action based methods of detection in seafood
Nicolas, J. ; Hendriksen, P.J.M. ; Gerssen, A. ; Bovee, T.F.H. ; Rietjens, I.M.C.M. - \ 2014
Molecular Nutrition & Food Research 58 (2014)1. - ISSN 1613-4125 - p. 87 - 100.
cerebellar granule neurons - paralytic shellfish toxins - receptor-binding assay - mouse taste cells - voltage-gated na+ - domoic acid - sodium-channels - new-zealand - sandwich elisa - kainic acid
Marine biotoxins can accumulate in fish and shellfish, representing a possible threat for consumers. Many marine biotoxins affect neuronal function essentially through their interaction with ion channels or receptors, leading to different symptoms including paralysis and even death. The detection of marine biotoxins in seafood products is therefore a priority. Official methods for control are often still using in vivo assays, such as the mouse bioassay. This test is considered unethical and the development of alternative assays is urgently required. Chemical analyses as well as in vitro assays have been developed to detect marine biotoxins in seafood. However, most of the current in vitro alternatives to animal testing present disadvantages: low throughput and lack of sensitivity resulting in a high number of false-negative results. Thus, there is an urgent need for the development of new in vitro tests that would allow the detection of marine biotoxins in seafood products at a low cost, with high throughput combined with high sensitivity, reproducibility, and predictivity. Mode of action based in vitro bioassays may provide tools that fulfil these requirements. This review covers the current state of the art of such mode of action based alternative assays to detect neurotoxic marine biotoxins in seafood.
Inferring product healthfulness from nutrition labelling. The influence of reference points
Herpen, E. van; Hieke, S. ; Trijp, J.C.M. van - \ 2014
Appetite 72 (2014)1. - ISSN 0195-6663 - p. 138 - 149.
front-of-pack - reference information - food-products - new-zealand - consumers - choices - attention - formats - impact - labels
Despite considerable research on nutrition labelling, it has proven difficult to find a front-of-pack label which is informative about product healthfulness across various situations. This study examines the ability of different types of nutrition labelling schemes (multiple traffic light label, nutrition table, GDA, logo) to communicate product healthfulness (a) across different product categories, (b) between options from the same product category, and (c) when viewed in isolation and in comparison with another product. Results of two experiments in Germany and The Netherlands show that a labelling scheme with reference point information at the nutrient level (e.g., the traffic light label) can achieve all three objectives. Although other types of labelling schemes are also capable of communicating healthfulness, labelling schemes lacking reference point information (e.g., nutrition tables) are less effective when no comparison product is available, and labelling schemes based on overall product healthfulness within the category (e.g., logos) can diminish consumers’ ability to differentiate between categories, leading to a potential misinterpretation of product healthfulness. None of the labels affected food preferences.
Preventing Campylobacter at the Source: Why Is It So Difficult?
Wagenaar, J.A. ; French, N.P. ; Havelaar, A.H. - \ 2013
Clinical infectious diseases 57 (2013)11. - ISSN 1058-4838 - p. 1600 - 1606.
united-states - new-zealand - disease burden - broiler meat - vertical transmission - foodborne pathogens - source attribution - risk-assessment - poultry - spp.
Campylobacteriosis in humans, caused by Campylobacter jejuni and Campylobacter coli, is the most common recognized bacterial zoonosis in the European Union and the United States. The acute phase is characterized by gastrointestinal symptoms. The long-term sequelae (Guillain-Barre syndrome, reactive arthritis, and postinfectious irritable bowel syndrome) contribute considerably to the disease burden. Attribution studies identified poultry as the reservoir responsible for up to 80% of the human Campylobacter infections. In the European Union, an estimated 30% of the human infections are associated with consumption and preparation of poultry meat. Until now, interventions in the poultry meat production chain have not been effectively introduced except for targeted interventions in Iceland and New Zealand. Intervention measures (eg, biosecurity) have limited effect or are hampered by economic aspects or consumer acceptance. In the future, a multilevel approach should be followed, aiming at reducing the level of contamination of consumer products rather than complete absence of Campylobacter.
An innovative team-based stop smoking competition among Maori and Pacific Island smokers: rationale and method for the study and its evaluation
Glover, M. ; Bosman, A. ; Wagemakers, A. ; Kira, A. ; Paton, C. ; Cowie, N. - \ 2013
BMC Public Health 13 (2013). - ISSN 1471-2458 - 15 p.
international quit - social support - win contest - new-zealand - cessation - intervention - community - campaign - population - efficacy
Maori and Pacific Island people have significantly higher smoking rates compared to the rest of the New Zealand population. The main aim of this paper is to describe how knowledge of Indigenous people’s practices and principles can be combined with proven effective smoking cessation support into a cessation intervention appropriate for Indigenous people.
Modeling the cadmium balance in Australian agricultural systems in view of possible impacts on food quality
Vries, W. de; McLaughlin, M.J. - \ 2013
Science of the Total Environment 461-462 (2013). - ISSN 0048-9697 - p. 240 - 257.
heavy-metal balances - new-zealand - potato-tubers - phosphate fertilizers - soil concentrations - trace-elements - grazed-pasture - united-states - wheat-grain - lead
The historical build up and future cadmium (Cd) concentrations in top soils and in crops of four Australian agricultural systems are predicted with a mass balance model, focusing on the period 1900–2100. The systems include a rotation of dryland cereals, a rotation of sugarcane and peanuts/soybean, intensive dairy production and intensive horticulture. The input of Cd to soil is calculated from fertilizer application and atmospheric deposition and also examines options including biosolid and animal manure application in the sugarcane rotation and dryland cereal production systems. Cadmium output from the soil is calculated from leaching to deeper horizons and removal with the harvested crop or with livestock products. Parameter values for all Cd fluxes were based on a number of measurements on Australian soil–plant systems. In the period 1900–2000, soil Cd concentrations were predicted to increase on average between 0.21 mg kg-1 in dryland cereals, 0.42 mg kg-1 in intensive agriculture and 0.68 mg kg-1 in dairy production, which are within the range of measured increases in soils in these systems. Predicted soil concentrations exceed critical soil Cd concentrations, based on food quality criteria for Cd in crops during the simulation period in clay-rich soils under dairy production and intensive horticulture. Predicted dissolved Cd concentrations in soil pore water exceed a ground water quality criterion of 2 µg l-1 in light textured soils, except for the sugarcane rotation due to large water leaching fluxes. Results suggest that the present fertilizer Cd inputs in Australia are in excess of the long-term critical loads in heavy-textured soils for dryland cereals and that all other systems are at low risk. Calculated critical Cd/P ratios in P fertilizers vary from b50 to >1000 mg Cd kg P-1 for the different soil, crop and environmental conditions applied.
Psychological and behavioural approaches to understanding and governing sustainable mobility
Higham, J. ; Cohen, S. ; Peeters, P.M. ; Gössling, S. - \ 2013
Journal of Sustainable Tourism 21 (2013)7. - ISSN 0966-9582 - p. 949 - 967.
travel mode choice - climate-change - new-zealand - tourism - emissions - transport - biofuels - mitigation - reduction - footprint
This paper introduces and explores the psychological and social factors that both contribute to and inhibit behaviour change vis-à-vis sustainable (tourist) mobility. It is based on papers presented at the Freiburg 2012 workshop. Specifically, it reviews climate change attitudes and perceptions, the psychological benefits of tourism mobilities, addictive elements of mobility and social norming effects, the attitude–behaviour gap (i.e. cognitive dissonance between understandings of, and responses to, climate change), the psychology of modal shifts, the psychology of travel speed/time and psychological explanations for the perceived importance of long distance travel. It notes that anthropogenic climate change is an inescapable reality and that tourism's share of greenhouse gas emissions appears set to rise substantially. There is little prospect of technical solutions adequately addressing this problem. The paper concludes that, while a comprehensive understanding of tourist psychology is necessary to inform policy-makers, it alone will be insufficient to achieve emission reductions, and bring tourism to a climatically sustainable pathway, if treated in isolation. Radical change in the structures of provision is also necessary. That change may take the form of infrastructure planning, including financial and economic infrastructure (e.g. taxation regimes and emission trading schemes) for sustainable mobility.
Disturbance History of a Seasonal Tropical Forest in Western Thailand: A Spatial Dendroecological Analysis
Middendorp, R.S. ; Vlam, M. ; Rebei, K.T. ; Baker, P.J. ; Bunyavejchewin, S. ; Zuidema, P.A. - \ 2013
Biotropica 45 (2013)5. - ISSN 0006-3606 - p. 578 - 586.
central amazon forest - tree-ring analysis - stand dynamics - age structure - rain-forests - new-zealand - large-scale - growth - patterns - ecology
Disturbances play an important role in forest dynamics across the globe. Researchers have mainly focused on the temporal context of disturbances, but have largely ignored the spatial patterns of tree recruitment they create. Geostatistical tools enable the analysis of spatial patterns and variability in tropical forest disturbance histories. Here, we examine the potential of combining dendroecological analysis and spatial statistics to reconstruct the disturbance history of a seasonal dry evergreen tropical forest plot at the Huai Kha Khaeng Wildlife Sanctuary (HKK), western Thailand. We used tree-ring-derived age estimates for 70 individuals of the shade-intolerant pioneer species Melia azederach (Meliaceae) and tree locations across a 316-ha study plot to identify the timing and spatial extent of past disturbances. Although the age distribution for Melia suggested that regeneration had been continuous over the past 60 yr, spatial analyses (mark correlation function and kriging) demonstrated the presence of three spatially discrete age cohorts. Two of these cohorts suggested a severe disturbance ~20 yr before present. A third cohort appears to have established ~50 years ago. Using historical records, we conclude that fire disturbance is the most likely disturbance factor affecting HKK. Nevertheless, we do not rule out other disturbance factors. The combined application of tree-ring analysis and spatial statistics as applied in this study could be readily applied to reconstruct disturbance histories in other tropical regions where tree species with annual growth rings are present.
Landslide model performance in a high resolution small-scale landscape
Sy, V. De; Schoorl, J.M. ; Keesstra, S.D. ; Jones, K.E. ; Claessens, L.F.G. - \ 2013
Geomorphology 190 (2013). - ISSN 0169-555X - p. 73 - 81.
physically-based model - soil redistribution - new-zealand - shallow landslides - sediment yield - dem resolution - stability - hazard - prediction
The frequency and severity of shallow landslides in New Zealand threatens life and property, both on- and off-site. The physically-based shallow landslide model LAPSUS-LS is tested for its performance in simulating shallow landslide locations induced by a high intensity rain event in a small-scale landscape. Furthermore, the effect of high resolution digital elevation models on the performance was tested. The performance of the model was optimised by calibrating different parameter values. A satisfactory result was achieved with a high resolution (1 m) DEM. Landslides, however, were generally predicted lower on the slope than mapped erosion scars. This discrepancy could be due to i) inaccuracies in the DEM or in other model input data such as soil strength properties; ii) relevant processes for this environmental context that are not included in the model; or iii) the limited validity of the infinite length assumption in the infinite slope stability model embedded in the LAPSUS-LS. The trade-off between a correct prediction of landslides versus stable cells becomes increasingly worse with coarser resolutions; and model performance decreases mainly due to altering slope characteristics. The optimal parameter combinations differ per resolution. In this environmental context the 1 m resolution topography resembles actual topography most closely and landslide locations are better distinguished from stable areas than for coarser resolutions. More gain in model performance could be achieved by adding landslide process complexities and parameter heterogeneity of the catchment.
Multiplex detection and identification of bacterial pathogens causing potato blackleg and soft rot in Europe, using padlock probes
Slawiak, M. ; Doorn, R. van; Szemes, M. ; Speksnijder, A.G.C.L. ; Waleron, M. ; Wolf, J.M. van der; Lojkowska, E. ; Schoen, C.D. - \ 2013
Annals of Applied Biology 163 (2013)3. - ISSN 0003-4746 - p. 378 - 393.
fragment-length-polymorphism - carotovora ssp-atroseptica - erwinia-carotovora - pectobacterium-carotovorum - sp-nov. - oligonucleotide-microarray - dickeya-chrysanthemi - genetic diversity - pectin lyase - new-zealand
The objective of this study was to develop a multiplex detection and identification protocol for bacterial soft rot coliforms, namely Pectobacterium wasabiae (Pw), Pectobacterium atrosepticum (Pba) and Dickeya spp., responsible for potato blackleg and tuber soft rot. The procedures were derived from the phylogenetic relationships of these and other Enterobacteriaceae based on recA sequences. The group of Pw strains was highly homogeneous and could be distinguished from the other species. A ligation-based method for detection of Pw was developed. Five padlock probes (PLPs) were designed, targeting recA sequences to identify the Pw, Pba or Dickeya spp., whereas a sixth probe recognised recA sequences of all soft rot coliforms including Pectobacterium carotovorum subsp. carotovorum (Pcc). Two PLP-based applications were developed: one using real-time PCR and one using universal microarrays. Assay sensitivity and specificity were demonstrated using 71 strains of Pw, Pcc, Pba and Dickeya spp. Both multiplex methods can be potentially used for seed testing and in ecological studies, but further validation is required
Fluvial response to Holocene volcanic damming and breaching in the Gediz and Geren rivers, western Turkey
Gorp, W. van; Veldkamp, A. ; Temme, A.J.A.M. ; Maddy, D. ; Demir, T. ; Schriek, T. van der; Reimann, T. ; Wallinga, J. ; Wijbrans, J. ; Schoorl, J.M. - \ 2013
Geomorphology 201 (2013). - ISSN 0169-555X - p. 430 - 448.
pleistocene lava-dam - grand-canyon - luminescence signals - terrace staircase - natural dams - k-feldspars - new-zealand - evolution - arizona - uplift
This study discusses the complex late Holocene evolution of the Gediz River north of Kula, western Turkey, when a basaltic lava flow dammed and filled this river valley. Age control was obtained using established and novel feldspar luminescence techniques on fluvial sands below and on top of the flow. This dating constrained the age of the lava flow to 3.0–2.6 ka. Two damming locations caused by the lava flow have been investigated. The upstream dam caused lake formation and siltation of the upstream Gediz. The downstream dam blocked both the Gediz and a tributary river, the Geren. The associated lake was not silted up because the upstream dam already trapped all the Gediz sediments. Backfillings of the downstream lake are found 1.5 km upstream into the Geren valley. The downstream dam breached first, after which the upstream dam breached creating an outburst flood that imbricated boulders of 10 m3 size and created an epigenetic gorge. The Gediz has lowered its floodplain level at least 15 m since the time of damming, triggering landslides, some of which are active until present. The lower reach of the Geren has experienced fast base level lowering and changed regime from meandering to a straight channel. Complex response to base level change is still ongoing in the Geren and Gediz catchments. These findings are summarized in a diagram conceptualizing lava damming and breaching events. This study demonstrates that one lava flow filling a valley floor can block a river at several locations, leading to different but interrelated fluvial responses of the same river system to the same lava flow.
Evaluation of a feeding strategy to reduce greenhouse gas emissions from dairy farming: The level of analysis matters
Middelaar, C.E. van; Berentsen, P.B.M. ; Dijkstra, J. ; Boer, I.J.M. de - \ 2013
Agricultural Systems 121 (2013). - ISSN 0308-521X - p. 9 - 22.
life-cycle assessment - enteric methane emissions - milk-production - carbon footprint - grazing behavior - eco-efficiency - new-zealand - land-use - model - rumen
The dairy sector contributes to climate change through emission of greenhouse gases (GHGs), via mainly carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Replacing grass silage with maize silage is a feeding strategy to reduce enteric CH4 emission. The effect of this strategy on GHG emissions can be analyzed at three different levels: animal, farm, and chain level. The level of analysis might affect results and conclusions, because the strategy affects not only enteric CH4 emissions at animal level, but also other GHG emissions at farm and chain levels. The objective of this study was to determine if the level of analysis influences conclusions about the GHG reduction potential of increasing maize silage at the expense of grass and grass silage in a dairy cow’s diet. First, we used a linear programming (LP, maximizing labor income) dairy farm model to define a typical Dutch dairy farm on sandy soils without a predefined feeding strategy (i.e. reference situation). Second, we combined mechanistic modeling of enteric fermentation and life cycle assessment to quantify GHG emissions at all three levels. Third, continuing from the diet derived in the reference situation, maize silage was increased by 1 kg DM per cow per day at the expense of grass (summer), or grass silage (winter). Next, the dairy farm model was used again to determine a new optimal farm plan including the feeding strategy, and GHGs were quantified again at the three levels. Finally, we compared GHG emissions at the different levels between the reference situation and the situation including the feeding strategy. We performed this analysis for a farm with an average intensity (13,430 kg milk/ha) and for a more intensive farm (14,788 kg milk/ha). Results show that the level of analysis strongly influences results and conclusions. At animal level, the strategy reduced annual emissions by 12.8 kg CO2e per ton of fat-and-protein-corrected-milk (FPCM). Analysis at farm and chain level revealed first of all that the strategy is not feasible on the farm with an average intensity because this farm cannot reduce its grassland area because of compliance with the EU derogation regulation (a minimum of 70% grassland). This is reality for many Dutch dairy farms with an intensity up to the average. For the more intensive farm, that can reduce its area of grassland, annual emissions reduced by 17.8 kg CO2e per ton FPCM at farm level, and 20.9 kg CO2e per ton FPCM at chain level. Ploughing grassland into maize land, however, resulted in non-recurrent emissions of 913 kg CO2e per ton FPCM. At farm and chain levels, therefore, the strategy does not immediately reduce GHG emissions as opposed to what results at animal level may suggest; at chain level it takes 44 years before annual emission reduction has paid off emissions from land use change.
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