References of "Claessens, Hugues"
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See detailAnalyse de l'adéquation actuelle et future des arbres à leur station en forêt de Soignes bruxelloise
Daise, Julien; Vanwijnsberghe, Stéphane; Claessens, Hugues ULg

in Forêt Wallonne (2011), 110

Qui ne connaît pas la forêt de Soignes de réputation ou pour l'avoir traversée ou s'y être promené? Cette cathédrale d'arbres, véritable patrimoine dont les Bruxellois ne sont pas peu fiers, est pourtant ... [more ▼]

Qui ne connaît pas la forêt de Soignes de réputation ou pour l'avoir traversée ou s'y être promené? Cette cathédrale d'arbres, véritable patrimoine dont les Bruxellois ne sont pas peu fiers, est pourtant en pleine crise. En cause, son grand âge, sa sylviculture, son son et... les changements climatiques en cours. Cet article tente d'évaluer l'impact des changements climatiques sur l'adéquation des essences forestières à leur milieu, avec une attention particulière au hêtre et aux chênes, qui constituent ensemble 90% de la forêt de Soignes. [less ▲]

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See detailMilieux ouverts forestiers, lisières forestières et biodiversité: de la théorie à la pratique.
Fichefet, Violaine; Branquart, Etienne; Claessens, Hugues ULg et al

Book published by Service public de Wallonie (2011)

L'aspect de la forêt naturelle, dans laquelle ont évolué les espèces forestières actuelles pendant des milliers d'années, était probablement beaucoup plus ouvert que ce que l'on peut imaginer aujourd'hui ... [more ▼]

L'aspect de la forêt naturelle, dans laquelle ont évolué les espèces forestières actuelles pendant des milliers d'années, était probablement beaucoup plus ouvert que ce que l'on peut imaginer aujourd'hui, sous l'effet de perturbations diverses et de l'action des grands herbivores. Si les ouvertures en forêt sont désormais le plus souvent liées à l'action humaine, le potentiel biologique de ces milieux n'en est pas moins élevé grâce au développement de cortèges d'organismes héliophiles caractéristiques des faciès de régénération des forêts naturelles. Par ailleurs, les lisières, qu'elles soient situées en bordure de ces ouvertures intra-forestières ou en périphérie des massifs forestiers, contribuent dans une large mesure à l'intérêt biologique des zones ouvertes, pour peu qu'elles soient progressives et dynamiques. La co-existence de lisières et de différents types de milieux ouverts variant entre eux à la fois dans l'espace (taille, forme,...) et dans le temps (événements ponctuels, récurrents ou permanents) au sein d'un massif géré est un atout incontestable pour la biodiversité. Leur intérêt biologique est intimement lié à la structure et à la composition de la végétation et, partant, à leur mode d'exploitation et de gestion. Ce guide propose donc, au-delà d'une révision théorique sur le sujet, de nombreux conseils pratiques d'aménagement et d'entretien des ouvertures forestières, afin d'en optimiser la capacité d'accueil tout en interférant le moins possible avec la production sylvicole. [less ▲]

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See detailMéthode pragmatique d’évaluation de la réserve en eau des stations forestières et cartographie à l’échelle régionale (Wallonie, Belgique)
Ridremont, François ULg; Lejeune, Philippe ULg; Claessens, Hugues ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(S2), 727-741

The assessment of the forest sites water availability constitutes a growing concern following the awareness of the potential impact of climate change on the soil moisture regime. At the present time, the ... [more ▼]

The assessment of the forest sites water availability constitutes a growing concern following the awareness of the potential impact of climate change on the soil moisture regime. At the present time, the forest managers lack tools for a quantitative estimation of the soil water reserve. This paper presents a simple estimation method that can be adopted on field by foresters. A map of this soil water reserve at the forest site scale has been established for the Southern Belgium. After the inventory of the possible techniques, the “textural method”, based on the pedotransfert classes of Jamagne et al. (1977), has been used. The soil profiles from the Aardewerk database have eased the translation of the Jamagne et al. (1977)’s results in the Belgian textural system. Moreover, the geodatabase of the Digital Soil Map of Wallonia (DSMW), through the typology of the major soil types, has been used as mapping support of the water reserve at the regional scale. Like a first attempt of validation, the result has been compared with the bioindicator character of forest understory vegetation. The regression results show a significant relationship between the soil water reserve and the vegetation estimate, but they also indicate that the water reserve does not explain alone the moisture level expressed by the flora. It emerges that the characterization of the Walloon parent materials will constitute an undeniable support for the development of the proposed method, the transposition of foreign results leading to some bias. The use prospects of this thematic map are multiple: integration as inputs for the autecological modelling, assessment of the moisture regime for the water availability of forest sites and building of sites catalogs; as many tools to guide forest managers in their planning measures. [less ▲]

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See detailFINE-SCALE HABITAT SELECTION BY TWO SPECIALIST WOODPECKERS OCCURRING IN BEECH AND OAK-DOMINATED FORESTS IN SOUTHERN BELGIUM
Delahaye, Laurence; Monticelli, David; Lehaire, François ULg et al

in Ardeola (2010), 57(2), 339-362

We studied the identification of key habitat parameters for two specialist woodpecker species (middle spotted woodpecker Dendrocopos medius and lesser spotted woodpecker D. minor) associated with mature ... [more ▼]

We studied the identification of key habitat parameters for two specialist woodpecker species (middle spotted woodpecker Dendrocopos medius and lesser spotted woodpecker D. minor) associated with mature broadleaved forests ecosystems in Europe, and the modelling of their specific requirements with a view to assist forest managers. The study was conducted in four beech and oak-dominated forests (Haut-Fays, Halma, Gembes and Croix-Scaille) located in the Ardennes Region of Southern Belgium. The study sites covered a total area of ca. 20 km². A census of woodpecker occurrence (presenceabsence) was implemented from 2000 to 2003 within 255 1-ha plots. Habitat variables describing stand age, tree density, snag density, stand composition and vertical vegetation structure were also sampled at the same plots to develop both logistic and autologistic regression models describing habitat use.Middle spotted woodpecker (MSW) uses the oak-rich locations (mean basal area of 15.6 m²/ha), with selection of areas with the largest, oldest oak trees (mean circumference > 150 cm), and with a high diversity of tree species in the overstory. Similarly, the lesser spotted woodpecker (LSW) was detected in areas presenting the highest percentage cover of oak trees but with a selection of younger stands, with a high density of snags and dead wood (mean of 9 m³/ha). The integration of an autocorrelation term improved model performance for the LSW but not for MSW. Our results highlight the importance of a high disponibility of oak trees for these two sympatric species. The climax forest in northwest Europe is beech so that public and private owners must develop appropriate forest management plans to prevent the conversion of oak to beech forests. In particular, forest managers can promote an active oakregeneration management to obtain a balanced representation of age classes. They must also aim to maintain/increase the volume of dead wood resources by reserving all trees produced by storms or any other cause of natural mortality. [less ▲]

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See detailLe chêne en forêt ardennaise, un atout à préserver
Alderweireld, Matthieu ULg; Ligot, Gauthier ULg; Latte, Nicolas ULg et al

in Forêt Wallonne (2010), 109(6), 10-24

Dans la forêt ardennaise, les chênes sont en nette diminution. Plusieurs facteurs sont responsables de cette diminution, voici quelques exemples : régénération plus difficile que le hêtre, abroutissement ... [more ▼]

Dans la forêt ardennaise, les chênes sont en nette diminution. Plusieurs facteurs sont responsables de cette diminution, voici quelques exemples : régénération plus difficile que le hêtre, abroutissement par le gibier, mauvaise réputation de la qualité du chêne ardennais dû aux anciens traitements, conditions de marché du bois défavorable aux essences à grandes révolution. Pourtant, ces dernières années, on prend conscience de leur importance. Les apports du chêne dans la hêtraie ardennaise sont nombreux, notamment dans le contexte du changement climatique : le chêne favorise le développement d’un cortège d’organismes diversifiés, favorise la décomposition de la litière et la fertilité des sols, permet l’exploitation des stations impropres au hêtre, favorise la stabilité des peuplements et permet la production de bois de qualité. Favoriser la régénération du chêne requiert une sylviculture interventionniste, les éléments principaux sont l’apport de lumière et la protection contre le gibier. Même s’il est possible de donner des pistes pour favoriser le chêne, de nombreuses questions se posent encore. Dans le contexte de l’Accord-cadre de recherche et vulgarisation forestières, l’ULg (GxABT) et l’UCL ont mis en place des dispositifs qui devraient bientôt permettre de mettre au point des scénarios sylvicoles. [less ▲]

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See detailLa sectorisation des cours d'eau wallons
Burton, Christophe ULg; Henrotay, Frédéric ULg; Borensztein, Aurélie ULg et al

Poster (2010, October 20)

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See detailHydrologic modelling and dendrochronology as tool of site-species adequation assessment in a changing climate context
Sohier, Catherine ULg; Debruxelles, Jérôme ULg; Brusten, Thomas ULg et al

Poster (2010, September 21)

A hydrologic model is related to dendrochronological measurements performed in a 52 years old Spruce stand. The site is situated on a hillside with shallow and acid brown soil in the ecoregion of Ardenne ... [more ▼]

A hydrologic model is related to dendrochronological measurements performed in a 52 years old Spruce stand. The site is situated on a hillside with shallow and acid brown soil in the ecoregion of Ardenne (Wallonia, Southern Belgium). Hydrologic modelling The hydrologic simulation runs from 1971 to 2005 at daily time step. The model is based on an EPIC code, adapted to the site concerning soil reservoirs depth, characteristic water contents, root profile and water uptake. Weather data come from the Royal Meteorological Institute. Outputs from the model are real evapotranspiration, surface runoff; interflows, deep percolation and soil moisture at daily time step. Dendrochronological study Tree ring thickness is measured on 24 core samples extracted from 12 dominant trees of the stand. Annual increments are standardised by the ARIMA function in order to produce the annual deviation of ring thickness. Means of annual deviation for the 12 trees are then related to annual soil drought intensities. Results Years 1976 and 1996 are emphasised by both the modelling outputs and the dendrochronological measurements as very dry. Model shows a severe drought and tree ring shows a very low growth. Years like 1990, 1992, 1994 and 2004 shows a less severe drought event but a drought that occurs in June-July, which seems to penalize spruce’s growth. On the other hand, years 1981 and 1998 show an important growth and a high value of mean soil moisture during June and July. The poster will show how the time evolution of the ARIMA index is related to some meaningful hydrologic indexes. These considerations will allow us to progress towards forecasting forest trees reaction to climate events and change. With this in mind, we will use a climate scenario build up in the frame of the AMICE interreg project. [less ▲]

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See detailGuide d'entretien des ripisylves
Mouchet, Frédéric; Laudelout, Arnaud; Debruxelles, Natacha et al

Book published by F. Lambot SPW, DGARNE (2010)

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See detailTypologie des chênaies de la Région wallonne
Perin, Jérôme ULg; Brostaux, Yves ULg; Claessens, Hugues ULg

Poster (2010, May 12)

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See detailAvifaune forestière - Etude d'habitat du Pic mar
Lehaire, François ULg; Paquet, Jean-Yves; Delahaye, Laurence et al

Poster (2010, May 12)

En tant que bio-indicateurs, les espèces spécialistes des grands massifs forestiers feuillus ont un intérêt pour l'étude et le suivi de la diversité de ces milieux.

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See detailA Silvicultural Decision Support System to Compare Forest Management Scenarios for Larch Stands on a Multicriteria Basis
Rondeux, Jacques ULg; Hebert, Jacques ULg; Claessens, Hugues ULg et al

in Delvin, Ger (Ed.) Decision Support Systems, Advances in (2010)

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See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium).
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

in Hallet, Vincent; Vanclooster, Marnik (Eds.) ENVITAM and UNITER : PhD Student Day 2010 Proceedings (2010, January 12)

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See detailModelling of Forest Trees Autecology. An applied research at the Walloon Region scale (Belgium)
Ridremont, François ULg; Claessens, Hugues ULg; Lejeune, Philippe ULg et al

Poster (2010, January 12)

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests ... [more ▼]

Three reasons have urged the Walloon Forest Administration (Walloon Public Service) on to solicit the help of forest researchers to bring practical responses to the adaptation of its current forests management: (i) the progression of research in applied autecology, (ii) the development of software for the management and the analysis of georeferenced data (GIS technologies) and, (iii) the awareness of the potential negative impacts of climate change on forests. To answer to this request, this research aims to model the autecology of the main forest tree species at the Walloon Region scale (Beech, Oak, Norway Spruce, Douglas-fir and valuable broadleaves species). The results will be used to update current practical tools to assess the adequacy of forest tree species on sites, especially in the climate change context. The research is built into three main steps: • update the autecology knowledge for the targeted forest tree species through a state of the art; • compile and create different ecological parameters that can explain the major part of trees growth such as climatic, topographic, geologic, edaphic and phytosociological data gathered from forest plots or geodatabases. In the context of climate change, a particular attention will be brought on bioclimatic and soil moisture conditions because of their narrow link with the potential risk of trees ecophysiological stress; • model tree species reaction to environmental conditions with tree growth indicators. Three types of indicators with different spatio-temporal scales are foreseen: stand site index (30-50 years), periodic diameter growth (5-10 years) and tree-ring growth (1-3 years). The use of these three scales is justified by the interest presented by their cross-validations which are necessary for an accurate extrapolation of results to the entire region. Results should indicate the tree species behaviour, especially towards stress conditions. The integration of climatic data, provided by global climate models based on IPCC's climate scenarios, in autecological models could be used to assess the behaviour of forest stands in future climate conditions. From those results, we expect to identify and assess accurately the risky “sites-species pairs” to avoid in the context of a sustainable silviculture. Finally, results will be used to provide autecological synthesis and practical tools to help forest managers and foresters to identify the best “site-species pairs” (tree-site adequacy maps, sites catalogue and computer platform). [less ▲]

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See detailEtude des habitats utilisés par le Pic mar en Région wallonne à partir des données de l'inventaire forestier
Lehaire, François ULg; Paquet, Jean-Yves; Monticelli, David et al

in Forêt Wallonne (2010), (104), 50-61

Le Pic mar est une espèce-clé de nos forêts feuillues. Il apparaît généralement comme étant un indicateur des forêts de grande valeur biologique. Autrefois cantonné dans les grands massifs feuillus ... [more ▼]

Le Pic mar est une espèce-clé de nos forêts feuillues. Il apparaît généralement comme étant un indicateur des forêts de grande valeur biologique. Autrefois cantonné dans les grands massifs feuillus d’Ardenne et de Gaume, il a remarquablement étendu son aire à toute la Wallonie lors des deux dernières décennies. L’étude de cette aire d’extension récente devrait nous permettre de mieux apprécier ses exigences écologiques dans un habitat encore peu ou mal connu et pourrait ouvrir des portes vers des recommandations de gestion forestière plus précises quant aux pics et leur biodiversité associée. [less ▲]

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See detailA review of the characteristics of black alder (Alnus glutinosa (L.) Gaertn.) and their implications for silvicultural practices
Claessens, Hugues ULg; Oosterbaan, Anne; Savill, Peter et al

in Forestry (2010), 83(2), 163-175

Black alder is a scattered, widespread and short-lived species that thrives in low-lying damp and riparian places. It has a use in flood control, stabilization of riverbanks and in functioning of the ... [more ▼]

Black alder is a scattered, widespread and short-lived species that thrives in low-lying damp and riparian places. It has a use in flood control, stabilization of riverbanks and in functioning of the river ecosystems. To thrive, precipitation must exceed 1500 mm if access to groundwater is not possible. Alders are unusual among European trees in that they fix nitrogen. To regenerate naturally, alder requires high levels of both light and moisture, usually achievable only on disturbed sites. Growth rates up to ages 7–10 are very fast but then slow rapidly. Sixty to seventy years is the maximum rotation for growing timber if heart rot is to be avoided. Maximum mean annual increments range from 4 to 14 m3 ha21 year21. Alder wood is used for energy, as fibre for paper and particle board and, most profitably, in joinery as solid wood or veneer. Logs must be at least 3 m long and ideally 50–60 cm diameter. Aspects of plantation silviculture are discussed with emphasis on thinning, which needs to be started early and to be heavy and frequent around selected final crop trees to achieve marketable timber before heart rot sets in. [less ▲]

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See detailUne chênaie n'est pas l'autre : analyse des contextes sylvicoles du chêne en forêt wallonne
Claessens, Hugues ULg; Perin, Jérôme ULg; Latte, Nicolas ULg et al

in Forêt Wallonne (2010), 108(sept-oct), 3-18

Le chêne n’est pas une essence facile à conduire vers la production de bois de qualité. Pour beaucoup d’entre eux, leur forme a été conditionnée il y a plus d’un siècle au sein de peuplements bien ... [more ▼]

Le chêne n’est pas une essence facile à conduire vers la production de bois de qualité. Pour beaucoup d’entre eux, leur forme a été conditionnée il y a plus d’un siècle au sein de peuplements bien différents de ce qu’ils sont devenus car originellement adaptés aux conditions socio-économiques qui prévalaient aux XIXe et au début du XXe siècle. Mais dans bien des cas, la sylviculture que l’on mène maintenant est encore sous la contrainte de ce passé. Cet article envisage les contextes « historico-sylvicoles » des chênaies de Wallonie à la lumière de leur état actuel. [less ▲]

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See detailLa "maladie du Hêtre" en Ardenne belge
Claessens, Hugues ULg

in Gauquelin, Xavier (Ed.) Guide de gestion des Forêts en crise sanitaire (2010)

Les crises sanitaires font partie des aléas auxquels les forêts gérées sont parfois confrontées. Elles sont susceptibles de se multiplier au cours des décennies à venir, notamment du fait des conséquences ... [more ▼]

Les crises sanitaires font partie des aléas auxquels les forêts gérées sont parfois confrontées. Elles sont susceptibles de se multiplier au cours des décennies à venir, notamment du fait des conséquences attendues des changements globaux. Les acteurs forestiers ont alors à faire face à des évènements qui désorganisent la gestion forestière courante, pouvant conduire à des épisodes de crise qui se déroulent sur plusieurs années (3 à 10 ans). Ce document met à disposition des acteurs forestiers les bonnes pratiques à mettre en œuvre pour affronter les différents évènements liés à une crise sanitaire, sur les plans organisationnels (partenariat, surveillance sanitaire, cellule de crise, communication) et techniques (mobilisation des bois, aménagement et sylviculture, suivi des phénomènes observés). [less ▲]

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See detailGrowing scattered broadleaved tree species in Europe in a changing climate: a review of risks and opportunities
Hemery, G. E.; Clark, J. R.; Aldinger, E. et al

in Forestry (2009)

Scattered broadleaved tree species such as ashes ( Fraxinus excelsior L. and Fraxinus angustifolia Vahl.), black alder ( Alnus glutinosa (L.) Gaertn.), birches ( Betula pendula Roth. and Betula pubescens ... [more ▼]

Scattered broadleaved tree species such as ashes ( Fraxinus excelsior L. and Fraxinus angustifolia Vahl.), black alder ( Alnus glutinosa (L.) Gaertn.), birches ( Betula pendula Roth. and Betula pubescens Ehrh.), elms ( Ulmus glabra Huds., Ulmus laevis Pall. and Ulmus minor Mill.), limes ( Tilia cordata Mill. and Tilia platyphyllos Scop.), maples ( Acer campestre L., Acer platanoides L. and Acer pseudoplatanus L.), wild service tree ( Sorbus domestica L. and Sorbus torminalis L. Crantz), walnuts ( Juglans regia L., Juglans nigra L. and hybrids) and wild cherry ( Prunus avium L.) are important components of European forests. Many species have high economic, environmental and social values. Their scattered distributions, exacerbated in many cases by human activity, may make them more vulnerable to climate change. They are likely to have less ability to reproduce or adapt to shifting climate space than more widespread species. The general impacts of climate change on these scattered species are reviewed. Some specific risks and opportunities are highlighted for each species, although there is considerable uncertainty and therefore, difficulty in quantifying many specific risks and/or impacts on scattered broadleaved tree species. [less ▲]

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