Northern Belgium Research Articles

Selective woodland exploitation for charcoal production. A detailed analysis of charcoal kiln remains (ca. 1300–1900 AD) from Zoersel (northern Belgium)

A detailed study of charcoal burning activities has been made for the Zoersel forest (Northern Belgium) based on an inventory of charcoal kiln remains, the analyses of wood charcoal and other charred botanical macroremains and radiocarbon dating of 10 of these kilns. Age determination of the youngest kilns was refined by dendrochronological analysis of trees growing on top of these kiln sites. The results show that, although many kilns were found, charcoal was produced in Zoersel only at certain moments during late and post-medieval times suggesting that charcoal burning was not a part of the regular management practice of these forests. The wood used for the production of charcoal mainly consists of taxa of alluvial (alder) forests while the kilns are situated on sites that currently are rather dry, with an oak dominated vegetation. For the older kilns, this contrast could be explained by an important change in local soil conditions. The younger kilns may be related to the conversion of alder woodland to grassland in the lower parts of the domain, with the kilns being constructed in the nearby dryer woodland areas.

Social inequalities in mental health: results from the EU contribution to the World Mental Health Surveys Initiative

The objective of the present study was to provide updated data from nine European countries about the impact of social inequalities in the prevalence of common mental disorders. Cross-sectional household survey of a representative sample of the adult general population of Belgium, Bulgaria, Germany, Italy, The Netherlands, Northern Ireland, Portugal, Romania and Spain. In total, 34,395 individuals were included. Social inequalities in 12-month mood, anxiety and alcohol-related disorders were evaluated. In Europe, income seems not to be related to the prevalence of mental disorders. Unemployment and disablement are associated with mental disorders. Lower educational level augments the risk for mood disorders. Living in small (rural) areas decreases the risk for mood disorders and living in urban settings increases it. Northern Ireland, Portugal and Belgium are the countries with the highest risks for mental disorders. Despite some contradictions with previous literature, in Europe there are social inequalities in the prevalence of mental disorders. However, income showed not to be associated with inequalities in mental health. Being younger, unemployed or disabled, with no education or incomplete primary studies, living in urban settings, and in Northern Ireland, Portugal or Belgium were associated to an augmented prevalence of mental disorders. Policy makers could focus on mental health promotion and mental disorders prevention programmes for risk groups such as unemployed/disabled individuals. Support to vulnerable groups (unemployed or those with less education) and mental health literacy can improve European citizens' mental health.

Estimation of Hydraulic Conductivity and Its Uncertainty from Grain-Size Data Using GLUE and Artificial Neural Networks

Various approaches exist to relate saturated hydraulic conductivity (K s) to grain-size data. Most methods use a single grain-size parameter and hence omit the information encompassed by the entire grain-size distribution. This study compares two data-driven modelling methods—multiple linear regression and artificial neural networks—that use the entire grain-size distribution data as input for K s prediction. Besides the predictive capacity of the methods, the uncertainty associated with the model predictions is also evaluated, since such information is important for stochastic groundwater flow and contaminant transport modelling. Artificial neural networks (ANNs) are combined with a generalised likelihood uncertainty estimation (GLUE) approach to predict K s from grain-size data. The resulting GLUE-ANN hydraulic conductivity predictions and associated uncertainty estimates are compared with those obtained from the multiple linear regression models by a leave-one-out cross-validation. The GLUE-ANN ensemble prediction proved to be slightly better than multiple linear regression. The prediction uncertainty, however, was reduced by half an order of magnitude on average, and decreased at most by an order of magnitude. This demonstrates that the proposed method outperforms classical data-driven modelling techniques. Moreover, a comparison with methods from the literature demonstrates the importance of site-specific calibration. The data set used for this purpose originates mainly from unconsolidated sandy sediments of the Neogene aquifer, northern Belgium. The proposed predictive models are developed for 173 grain-size K s-pairs. Finally, an application with the optimised models is presented for a borehole lacking K s data.

Risk factors for Psoroptes ovis mange on Belgian Blue farms in Northern Belgium

The parasitic mite Psoroptes ovis causes important economic losses in Belgian Blue cattle. Because mange problems vary significantly between farms, a cross-sectional questionnaire survey and subsequent farm visits were performed to identify potential risk factors for P. ovis infections on Belgian Blue farms in Flanders, Belgium.The questionnaire was sent to 1800 beef farms to evaluate the presence and severity of psoroptic mange in the herd and to assess farm management practices, including antiparasitic treatments. Subsequently, about 10% of the farms with a completed questionnaire were visited to validate the questionnaire and to retrieve supplementary information on additional management parameters, such as barn infrastructure and climate. Associations between parasitism and putative risk factors were assessed by logistic regression.Out of 1800 contacted farms, 680 (38%) completed questionnaires were received. Data were collected from 238 barns during 66 farm visits. The questionnaire results demonstrated a high farm prevalence of mange (74%; 95% CI (70.7–77.3)) and half of the farmers declared that the problem was difficult to control. Nevertheless, in only 14% of the barns a high scratching index was recorded and in most of the sampled animals (80%) the affected body surface was less than 10%. This indicates that despite the high prevalence and the difficulty to control the infection, clinical signs were often quite moderate.Logistic regression analyses of the questionnaire and the farm visit data suggested that heavily infested farms treat more intensively against mange. On most farms mange occurred the whole year round and more problems with mange were found on farms where a higher number of animals were purchased per year. In addition, the disease was more prevalent when the animals had a lower hygiene score. This score was strongly correlated with environmental hygiene, indicating that transmission of mites from the environment to the animals should not be underestimated. Conflicting results were obtained on the effect of supplementing minerals on the occurrence of mange. In this study, temperature, light intensity and relative humidity in the barns, ventilation systems, barn infrastructure, animal stocking rate and blood mineral levels were not indicated as risk factors for mange. In conclusion, maintaining a good animal hygiene and if possible, avoiding introduction of cattle may help to control psoroptic mange in Belgian Blue cattle.

RADIOCARBON DATING OF MESOLITHIC OPEN‐AIR SITES IN THE COVERSAND AREA OF THE NORTH‐WEST EUROPEAN PLAIN: PROBLEMS AND PROSPECTS

This paper discusses the problems with sampling materials and sampled contexts in the framework of radiocarbon dating of Mesolithic sites situated in generally dry, acid and bioturbated coversand deposits within north‐western Europe. The case studies presented all relate to the coversand regions of northern Belgium and the Netherlands, two areas for which very large sets of radiocarbon dates performed on different organic components are currently available. The study points out that charred hazelnut shells from surface hearths and charcoal from hearth pits guarantee the most secure dating results, while the dating of calcined bones and food crusts from Final Mesolithic pottery so far remains problematic.

Perceptions of fatigue – and perceived consequences – among Flemish obstetricians-gynaecologists: A survey

Objectives The effects of fatigue on the performance of medical trainees have been extensively studied. Much less is known about the effects of fatigue among doctors who have completed their training. The aim of this study was to inquire about the perception of fatigue and its consequences among certified obstetricians-gynaecologists (OGs).Methods A questionnaire was mailed to all certified OGs working in Flanders (Northern Belgium). Descriptive statistics as well as uni- and multivariate analyses for potential determinants of fatigue are presented.Results Of the 450 questionnaires mailed, 260 (58%) were returned. Half (52%) of the doctors worked more than 60 h/week. During an average working day, four out of ten respondents indicated they experienced a certain degree of fatigue, and one in ten felt really tired. Fatigue was associated with long working hours and led in a sizeable proportion of respondents to dissatisfaction (29%) and to medical/surgical errors (19%). None of the perceived errors resulted in loss of life. Academic OGs worked more hours/week but fewer during the night than their colleagues in private practice. The former reported having made significantly more medical errors (26%) than the latter (11%).Conclusions Tired OGs have less job satisfaction, and perceive they make more errors. None of the perceived errors resulted in loss of life. Certified OGs working more than 60 h/week are more frequently tired.

Landscape evolution and changes in soil hydraulic properties at the decadal, centennial and millennial scale: A case study from the Campine area, northern Belgium

Soil hydraulic properties evolve over time as a result of soil formation processes. We investigated the rate and circumstances of change in soil hydraulic properties as a result of soil and landscape evolution that took place over a period of a few decades to several thousands of years. To this end, a sediment-soil sequence in which different sandy landscapes and associated soils are preserved was studied with respect to its geomorphological and pedohydrological characteristics. Three stages of soil development corresponding to specific landscapes were observed within a 2-m deep profile: 1) a stabilisation surface within an active drift sand landscape, 2) an A-horizon that developed on a stabilised drift sand landscape and 3) a pronounced podzol that developed in a stabilised landscape from the last glacial. Measurement of soil physical properties was conducted including grain size analysis, organic carbon content, soil water retention characteristic and hydraulic conductivity using constant head and air permeability analyses. Age control of soil horizons and vegetation history were obtained from optically stimulated luminescence (OSL) dating, radiocarbon ( 14 C) dating, pollen analysis and historical archives. The results suggest a strong relationship between landscape evolution, soil development and hydraulic properties. Small changes in hydraulic properties may already be observed on a decadal and centennial scale, while long-term podzolisation processes may decrease the hydraulic conductivity of parent material up to three orders of magnitude in several thousands of years. It is concluded that combination of geomorphological and pedohydrological analyses of sediment-soil archives may provide a unique means to gain insight into the rate and extent of past changes in soil hydraulic properties and the consequences of future hydrological changes as a result of these evolving properties. ► The influence of evolving sandy landscapes on soil hydraulic properties is investigated. ► Landscape reconstruction techniques and pedohydrological methods are used. ► Below and above order of magnitude K sat changes can be observed on various timescales.

Strategic selection of an optimal sorbent mixture for in-situ remediation of heavy metal contaminated sediments: Framework and case study

Aquatic sediments contaminated with heavy metals originating from mining and metallurgical activities pose significant risk to the environment and human health. These sediments not only act as a sink for heavy metals, but can also constitute a secondary source of heavy metal contamination. A variety of sorbent materials has demonstrated the potential to immobilize heavy metals. However, the complexity of multi-element contamination makes choosing the appropriate sorbent mixture and application dosage highly challenging. In this paper, a strategic framework is designed to systematically address the development of an in-situ sediment remediation solution through Assessment, Feasibility and Performance studies. The decision making tools and the experimental procedures needed to identify optimum sorbent mixtures are detailed. Particular emphasis is given to the utilization and combination of commercially available and waste-derived sorbents to enhance the sustainability of the solution. A specific case study for a contaminated sediment site in Northern Belgium with high levels of As, Cd, Pb and Zn originating from historical non-ferrous smelting is presented. The proposed framework is utilized to achieve the required remediation targets and to meet the imposed regulations on material application in natural environments.

The abundance ofIxodes ricinusticks depends on tree species composition and shrub cover

The mainstream forestry policy in many European countries is to convert coniferous plantations into (semi-natural) deciduous woodlands. However, woodlands are the main habitat for Ixodes ricinus ticks. Therefore, assessing to what extent tick abundance and infection with Borrelia spirochetes are affected by forest composition and structure is a prerequisite for effective prevention of Lyme borreliosis. We selected a total of 25 pine and oak stands, both with and without an abundant shrub layer, in northern Belgium and estimated tick abundance between April and October 2008-2010. Additionally, the presence of deer beds was used as an indicator of relative deer habitat use. Borrelia infections in questing nymphs were determined by polymerase chain reactions. The abundance of larvae, nymphs, and adults was higher in oak stands compared to pine stands and increased with increasing shrub cover, most likely due to differences in habitat use by the ticks' main hosts. Whereas tick abundance was markedly higher in structure-rich oak stands compared to homogeneous pine stands, the Borrelia infection rates in nymphs did not differ significantly. Our results indicate that conversion towards structure-rich deciduous forests might create more suitable tick habitats, but we were unable to detect an effect on the infection rate.

Organic matter of subsoil horizons under broadleaved forest: Highly processed or labile and plant-derived?

Between 30 and 63% of the soil organic matter (SOM) is stored below 30 cm, making subsoil-SOM an important source and sink in the global carbon cycle. Nevertheless, detailed information on the composition of subsoil-SOM remains scarce. This study aims to evaluate the chemical composition of SOM in topsoil and subsoil horizons in broadleaved forests on acid loamy soils. Six sites were chosen in Northern Belgium under beech, oak and hybrid poplar, on Gleysols, Umbrisols, Cambisols and Albeluvisols on loamy Quaternary deposits. Analytical pyrolysis–gas chromatography/mass spectrometry (pyrolysis–GC/MS) was performed on the dialyzed alkaline extract, which represents between 41 and 90% of the total organic carbon for the selected sites. All extracts show a significant shift in chemical composition between the topsoil and the subsoil. While topsoil-SOM mainly differs according to input and nutrient status, subsoil-SOM shows high relative amounts of alkanes and alkenes or polysaccharides for coarse and fine textured soils respectively. Lignins, lignin-derived phenols or aromatics were not major contributors to subsoil-SOM, regardless of soil type. Furthermore, results show that very labile plant-derived molecules are present in the subsoil, i.e. long-chain aliphatics and (cellulose-derived) anhydrosugars. The organic matter signature of the subsoil samples was evaluated for typical indications of fresh material, decay, podzolisation and anaerobic processes, and indicates root input and stabilization of certain labile plant-derived compounds against microbial decay to be important in the subsoil.

Carbon and nitrogen stable isotope ratio analysis of freshwater, brackish and marine fish from Belgian archaeological sites (1st and 2nd millennium AD)

Carbon and nitrogen stable isotope ratios were measured in 157 fish bone collagen samples from 15 different archaeological sites in Belgium which ranged in ages from the 3rd to the 18th c. AD. Due to diagenetic contamination of the burial environment, only 63 specimens produced results with suitable C : N ratios (2.9–3.6). The selected bones encompass a wide spectrum of freshwater, brackish, and marine taxa (N = 18), and this is reflected in the δ13C results (−28.2‰ to −12.9%). The freshwater fish have δ13C values that range from −28.2‰ to −20.2‰, while the marine fish cluster between −15.4‰ and −13.0‰. Eel, a catadromous species (mostly living in freshwater but migrating into the sea to spawn), plots between −24.1‰ and −17.7‰, and the anadromous fish (living in marine environments but migrating into freshwater to spawn) show a mix of freshwater and marine isotopic signatures. The δ15N results also have a large range (7.2‰ to 16.7‰) indicating that these fish were feeding at many different trophic levels in these diverse aquatic environments. The aim of this research is the isotopic characterization of archaeological fish species (ecology, trophic level, migration patterns) and to determine intra-species variation within and between fish populations differing in time and location. Due to the previous lack of archaeological fish isotope data from Northern Europe and Belgium in particular, these results serve as an important ecological backdrop for the future isotopic reconstruction of the diet of human populations dating from the historical period (1st and 2nd millennium AD), where there is zooarchaeological and historical evidence for an increased consumption of marine fish.

Pleistocene Rhine–Thames landscapes: geological background for hominin occupation of the southern North Sea region

AbstractThis paper links research questions in Quaternary geology with those in Palaeolithic archaeology. A detailed geological reconstruction of The Netherlands' south‐west offshore area provides a stratigraphical context for archaeological and palaeontological finds. Progressive environmental developments have left a strong imprint on the area's Palaeolithic record. We highlight aspects of landscape evolution and related taphonomical changes, visualized in maps for critical periods of the Pleistocene in the wider southern North Sea region. The Middle Pleistocene record is divided into two palaeogeographical stages: the pre‐Anglian/Elsterian stage, during which a wide land bridge existed between England and Belgium even during marine highstands; and the Anglian/Elsterian to Saalian interglacial, with a narrower land bridge, lowered by proglacial erosion but not yet fully eroded. The Late Pleistocene landscape was very different, with the land bridge fully dissected by an axial Rhine–Thames valley, eroded deep enough to fully connect the English Channel and the North Sea during periods of highstand. This tripartite staging implies great differences in (i) possible migration routes of herds of herbivores as well as hominins preying upon them, (ii) the erosion base of axial and tributary rivers causing an increase in the availability of flint raw materials and (iii) conditions for loess accumulation in northern France and Belgium and the resulting preservation of Middle Palaeolithic sites. Copyright © 2011 John Wiley & Sons, Ltd.

Trends in atmospheric nitrogen and sulphur deposition in northern Belgium

Abstract Temporal trends (2002–2009) in air concentrations and wet and dry atmospheric deposition of inorganic nitrogen (N) and sulphur (S) were determined for nine stations in northern Belgium (Flanders). Wet deposition of NH 4 + , NO 3 − and SO 4 2− was measured with wet-only precipitation collectors and air concentrations of NH 3 , NO 2 and SO 2 with passive samplers. Dry deposition was calculated from the air concentrations and literature-based deposition velocities. Generalized additive models were used to assess seasonal and long-term trends of biweekly measurements. Kendall tests on annual data were also applied but found to be less powerful. There was no trend in wet N deposition, while wet deposition of SO 4 2− and air concentrations of NH 3 and SO 2 decreased significantly ( P 2 , no significant long-term trend was detected, but opposite to the other compounds, the NO 2 concentration tended to increase at all stations. Overall, inorganic N deposition and potentially acidifying deposition (N + S) to grassland decreased significantly at seven stations. The N and N + S deposition to grassland in 2009 was generally below deposition targets for 2010, but the difference was not significant when accounting for data uncertainty using a bootstrap resampling procedure. For most stations, atmospheric deposition to heathland and deciduous forest insignificantly exceeded the targets, while deposition to coniferous forest was significantly too high. Consequently, additional policy measures are needed to reach deposition targets in order to prevent further eutrophication and acidification of (semi)natural ecosystems and to protect groundwater layers in Flanders.

Local habitat and landscape affect Ixodes ricinus tick abundances in forests on poor, sandy soils

A large fraction of the forests in northern Belgium consists of homogeneous pine stands on nutrient-poor and acid sandy soils. However, in common with many other parts of Europe, the current forest management aims at increasing the share of deciduous and mixed forests. This might create favourable habitats for the tick Ixodes ricinus, which is Europe’s main vector of Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis in humans. Considering the threat to human health, it is important to know which factors regulate tick abundance. The influence of local habitat and landscape variables on the abundance of I. ricinus ticks were studied by collecting questing larvae, nymphs, and adults at 176 locations in forests in the Campine region (northern Belgium). Both I. ricinus ticks and B. burgdorferi spirochetes occurred throughout the study area, which means that the entire region represents an area of risk for contracting Lyme borreliosis. At the forest stand level, the main tree species and the shrub cover significantly affected the abundance of all life stages of I. ricinus. The abundance was higher in oak stands compared to pine stands, and increased with increasing shrub cover. Additionally, at the landscape level, a positive effect was found for forest edge length but not for forest cover. These patterns may be explained by the habitat preferences of the tick’s main hosts. Our results indicate that forest conversion might indeed create suitable habitats for ticks, which highlights the need for intensive information campaigns and effective tick control measures.

Connecting the Chalk Group of the Campine Basin to the dinoflagellate cyst biostratigraphy of the Campanian to Danian in borehole Meer (northern Belgium)

AbstractA palynological study of the Chalk Group (Campanian-Danian) in the Meer borehole (northern Belgium), which penetrated the thickest succession known in the Campine Basin, has revealed diverse, well-preserved organic-walled dinoflagellate cyst assemblages. The succession contains numerous chronostratigraphically significant dinocyst events, which are based mainly on the highest consistent occurrences of index species. At least 35 bio-events have enabled a subdivision into nine intervals, at stage or substage level, within the Campanian to Danian interval, as based on comparison with coeval assemblages elsewhere in northwest Europe, inclusive of stratotypes of stages and stage boundaries. Bio-events allow correlation of the section studied with the CampanianExochosphaeridium? masureae, Areoligera coronataandSamlandia mayizones, the MaastrichtianPervosphaeridium tubuloaculeatum, Deflandrea galeataandHystrichostrogylon coninckiizones, and the DanianDamassadinium californicumZone. In addition, a correlation with other zonal schemes for the southern North Sea Basin and with conventional northwest European belemnite zones is presented. Comparisons with Boreal and Tethyan realms confirm that most bio-events may also be useful for interregional and global correlation. The Campanian-Danian dinocyst biostratigraphy of the Meer borehole is put alongside geophysical well logs and an ecozonation, in order to check the validity of lithostratigraphical correlations across the Campine Basin. This first, detailed correlation attempt shows that sensitivities to facies change associated with differences in accommodation space and sediment supply appear to be at the base of slight, yet consistent, shifts between the local lithological succession and the standard lithostratigraphical scheme of the Maastricht type area.

Biased morph ratios and skewed mating success contribute to loss of genetic diversity in the distylous Pulmonaria officinalis.

In heterostylous plant species, skewed morph ratios are not uncommon and may arise from a range of factors. Despite the recognized importance of skewed morph ratios on overall reproductive success within populations, little is known about the impact of skewed morph ratios on population genetic diversity and differentiation in heterostylous species. This study specifically aimed to clarify the effect of population size and morph bias on population genetic diversity and differentiation in the temperate forest herb Pulmonaria officinalis. This species is characterized by a distylous breeding system and shows morph-specific differences in reproductive success. Genetic diversity was determined for 27 P. officinalis populations in northern Belgium by using eight recently developed microsatellite markers. Multiple regressions were used to assess the relationship between genetic diversity, morph bias and population size, and F(ST)-values were calculated for short- and long-styled morphs separately to study genetic differentiation as a function of morph type. For all genetic measures used, morph bias was more important in explaining patterns of genetic diversity than population size, and in all cases patterns of population genetic diversity followed a quadratic function, which showed a symmetrical decrease in genetic diversity with increasing morph bias. However, probably due to the reproductive advantage of L-morphs relative to S-morphs, maximum genetic diversity was found in populations showing an excess of L-morphs (60·7 % L-morph). On the other hand, no significant difference in pairwise genetic distances between populations was observed between L- (0·107) and S-morphs (0·106). Our results indicate that significant deviations from equal morph ratios not only affect plant reproductive success but also population genetic diversity of heterostylous plant species. Hence, when defining conservation measures for populations of heterostylous plant species, morph ratios should be considered as an important trait affecting their long-term population viability.

Distinguishing between management-induced and climatic trends in phreatic groundwater levels

Summary A method is proposed for distinguishing between climatic and anthropogenic or management-induced contributions to observed trends in phreatic groundwater levels. The method is tested on 245 phreatic screens distributed over 168 wells in Northern Belgium that were monitored monthly during 1999–2009. The SWAP (Soil Water Atmosphere Plant), an existing physically-based model, is used to simulate the observed time series of groundwater levels at each of the screens. SWAP simulates 1-D water transport by applying the Richards’ equation for the unsaturated–saturated zone, while accounting for interception and water extraction by vegetation. The model thus incorporates climatic effects on the groundwater level but ignores management-induced impacts such as groundwater abstraction. The management-induced contribution to observed trends in groundwater levels can therefore be derived by analysing the model residuals, i.e. observed minus predicted groundwater levels. Five and 10 year management-induced trends in groundwater levels (cm/year) were estimated for each screen by a simple linear regression of the residuals of a SWAP model that was calibrated to optimise the agreement between observed and predicted groundwater levels at that screen. This management-induced trend was compared with the trend in observed groundwater levels. It is concluded that a correct interpretation of monitoring data in the context of the evaluation of the effectiveness of water management strategies, requires that observed trends are adjusted for climatic variation. In shallow water table environments, this climatic correction can be associated with precipitation surplus. However, when the water table is more than 3 m below the soil surface, the relation with precipitation surplus is less straightforward and varies from place to place, because of differences in vadoze zone travel time.

New dinoflagellate cyst species of the Microdinium and Phanerodinium Complexes (Evitt) from the Upper Cretaceous–Lower Paleogene Chalk Group in the Meer borehole, northern Belgium

A high-resolution palynological study of the Campanian to Danian Chalk Group from the Meer borehole in northern Belgium has revealed the presence of four new smaller organic-walled dinoflagellate cyst species previously left in open nomenclature, within rich, diverse and well-preserved assemblages. A formal description of the new species, an emendation of Phanerodinium fourmarieri Lejeune-Carpentier based on a comparison of well preserved specimens with the type material, and as a result a re-assessment of the stratigraphic occurrences of each of these species are provided. Druggidium discretum sp. nov. is characterized by a finely spongeous wall surface and a discreet indication of tabulation, while Druggidium meerensis sp. nov. is suturocavate with a granulate, vermiculate to rarely pseudoreticulate ornamentation. Gillinia denticulata sp. nov. is distinguishable by its high and denticulate crests. Phanerodinium belgicum sp. nov. has a microgranulate to vermiculate surface wall and membranous crests. We retain Phanerodinium fourmarieri in the genus Phanerodinium, and reject the transfer of the species to the genus Druggidium by Lejeune-Carpentier and Sarjeant, as we demonstrate that the ventral surface of the species is untabulated and that the anterior intercalary plates are lacking. Both features are characteristic of every Phanerodinium species.

Tick-Borne Encephalitis Virus Seropositive Dog Detected in Belgium: Screening of the Canine Population as Sentinels for Public Health

Tick-borne encephalitis virus (TBEV) is an important emerging tick-borne viral infection of humans and dogs in Europe. Currently, TBEV surveillance is virtually nonexistent in Belgium, which is considered nonendemic. A commercial enzyme-linked immunosorbent assay (ELISA) was adapted for the detection of TBEV-specific IgG-antibodies in canine sera. Serum samples of Belgian dogs were obtained from three diagnostic laboratories from Northern (n=688) and Southern Belgium (n=192). ELISA-positive and borderline samples were subjected to a TBEV rapid fluorescent focus inhibition confirmation test. One dog was confirmed TBEV seropositive. Several ELISA-positive and borderline sera underwent seroneutralization and hemagglutinin inhibition tests to rule out West Nile and Louping Ill viruses, but tested negative. The clinical history of the seropositive dog could not explain beyond doubt where and when TBEV infection was acquired. Further surveillance is necessary to determine whether this dog remains a single travel-related case or whether it represents an early warning of a possible future emergence of TBEV.

Forest structure and soil fertility determine internal stem morphology of Pedunculate oak: a modelling approach using boosted regression trees

This study aims at the explanation of internal stem morphology of vital (co)dominant Pedunculate oak (Quercus robur L.) trees in homogeneous even-aged high-forests by the factors tree age, forest structure and site quality, using boosted regression trees as a powerful modelling technique. The study area covers the region of Flanders (Northern Belgium), which is characterised by the absence of strong topographic and climatic gradients. For 76 adult sample trees covering the entire productivity range of Pedunculate oak, morphological characteristics were derived from measurements of ring width or heartwood area on wood cores. Forest structure, soil physicochemical properties, humus quality, vegetation indices and litter nutrient contents were quantified at each sample location. Model predictive performance and generality are good. Tree age effects correspond to expected trends in age-related radial growth and heartwood portion. Even if management of oak trees in even-aged high-forests is rather similar over Flanders, forest structure is the most important factor determining ring width, followed by soil fertility. Heartwood portion is determined by soil fertility and crown structure. Effects of topsoil and humus physicochemical characteristics, litter nutrient contents and water supply mainly confirm autecological knowledge on oak. However, variables related to soil water availability are only occasionally relevant, and always of lower importance than soil fertility. The low importance of water availability in the models contradicts results from other studies, and the potential effect of confounding is discussed. The observed growth reduction at low litter N/P ratios might be indirectly linked to early litterfall.