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See detailEvolution régressive récente de la végétation des tourbières hautes à sphaignes en Haute Ardenne (Hautes-Fagnes, Belgique)
Hindryckx, Marie-Noëlle ULg

Doctoral thesis (1999)

In temperate Europe, intact raised bogs from Northern Germany to the French Massif Central are part of rare postglacial ecosystems that one can consider as natural or very close to the natural state ... [more ▼]

In temperate Europe, intact raised bogs from Northern Germany to the French Massif Central are part of rare postglacial ecosystems that one can consider as natural or very close to the natural state. Unfortunately, many of them have been degraded or highly disturbed by intense human activities. Some of them, however, kept a subintact central part. This is the case for the three big raised bogs situated in the Hautes-Fagnes plateau in Belgium: the fagne Wallonne, the fagne de Clefaye and the Misten raised bogs. Their vegetation belongs to the Vaccinio oxycocci-Sphagnetea magellanici Br.-Bl. & Tx. 43 and Eriophoro vaginati-Sphagnetalia papillosi Tx. 70. But the legal conservation measures are not sufficient to guarantee their protection : in the course of the last 30 years, 10 to 25% of the area covered with intact raised bogs of the Hautes-Fagnes plateau have been degraded, mainly invaded by Molinia caerulea. Although it is important to bring forward such alarming observations, it is more essential to understand exactly the origin of the factors causing the degradation, if suitable measures to thwart the factors that condition them, and try to attenuate if not suppress their harmful effects, and thereby restore the conditions that will enable the natural vegetation from these environments to recover the lost areas. Here are the main objectives of this work: • To highlight the current and recent ecological and phytodynamic consequences of the degradation of the raised bogs; • To identify and date the causes of the degradation that struck the intact parts of the raised bogs present on the Hautes-Fagnes plateau; • To examine the practical management measures in the short-, medium-, and long-term taken in Belgium and abroad in order to restore the natural evolution of the peatlands. Studies of the vegetation The vegetation maps, on a scale of 1/250, indicate that, despite some differences, the degradation phenomenon seems to begin in the same way in the three bogs. We can notice: • an invasion by Molinia caerulea of the intact peat areas (in sometimes very high tussocks) but also its presence, in a more diffuse form, within the -narrowzones of transition and even among typical bog species; • a soil draining, resulting in the proliferation of Ericaceae, especially around relatively intact zones; • the existence of Deschampsia flexuosa, which seems to be linked to rather steep slopes at the edge of zones exclusively colonised by Molinia caerulea,; • the poor representation, both in terms of quality as quantity, of bryophytes; fewer than 10 species of peatmosses occur in these peatlands, where they are often little or ill-developed; • the occupation of peat bogs by relatively exclusive species (Empetrum nigrum, Molinia caerulea and other very thick Ericaceae bushes) which prevent other peat forming communities from developing. The analysis of the vegetation releves taken along three transects shows that the Misten bog appears as the most intact one (or the best preserved one) based on the cover, distribution and vitality of peatmosses, although as indicated by the vegetation map, Molinia caerulea surrounds this raised bog. The fagne de Clefaye peat bog seems much drier and the percentage of peatmosses cover is lower compared to the Misten bog. Some Empetrum nigrum clumps no longer contain any mosses. On the other hand, this bog holds more Sphagnum species than either of the other two bogs investigated. The raised bog of the fagne Wallonne is the most degraded one (at least the north-west part of it). The complexity of the problem composed already the focus of several studies as part of a graduate work. In order to have some idea of the evolution of the vegetation, all the releves which have been carried out along the transects of the three bogs have been the subject of an observation follow-up. Even if six or seven years between the vegetation releves is too short a time to show some significant evolution in a peat bog, the results nonetheless enable to bring to the fore some trends in the evolution of the vegetation present in the main bogs of the haut-plateau, Along the itemised transect, the vegetation of the peat bog seems to be stable and optimal for a peat forming activity typical of an ombrotrophic raised bog, to develop. The northern part of the fagne Wallonne bog shows much more worrying signs of evolution (heaths developing quickly) or signs of degradation of its vegetation (reduction of the number of peatmosses, increasing density of Molinia caerulea, and invasion by Betula alba subsp. glutinosa). The vegetation of the fagne de Cléfaye bog clearly evolves towards a drier phase (high intensification of heaths development) without leading to the rarefaction of peatmosses. We wanted to put these evolutional studies in a broader context and take advantage of previous studies carried out on the haut-plateau in similar conditions. Despite the interpretation difficulties that were met, the different studies allow to assert that there has been a quick change in the vegetation of the raised bogs in the last forty years. Are we in the presence of a Natural evolution or a degradation process? The ground cover in the northern part of the fagne Wallonne bog shows obvious signs of degradation. The southern part of it as well as the fagne de Cléfaye bog show instead an evolution of the vegetation towards a stage heavily composed of heaths, with, however, a strong reduction of peatmosses. The Misten bog seems to experience the slowest evolution: is this a former evolution stage of the vegetation or is the balance achieved? Hydrological studies In natural conditions, the fluctuations of the water table of an ombrotrophic bog on a one-year scale remain modest: about 10 centimetres from one season to the other. It is thus interesting to check if the variations of the water table level are of the same nature in different spots of the three studied bogs or if the alteration phenomena, that are visible at the vegetation level and are present on the three bogs also appear in the behaviour of water tables at the surface of these bogs. Based on the follow-up of the 148 dip wells scattered on the three peat bogs, it appears that the Misten bog water table level is the most stable one. This means that the peat forming species, present on the fagne de Clefaye and especially in the studied part of the fagne Wallonne, are constantly subjected to fluctuations (which are sometimes significant) of the water table level. Now, if the peatmosses usually spread according to a humidity gradient, some of them tolerating a greater distance of the water table level than others, it does not mean however that a same species can survive such variations. The dip wells maps and the 3-dimensional representations of the water table enable to better understand the spreading of the vegetation at the surface of the bog. But these measures also reveal the presence of pedological phenomena, natural or not, such as drainage ditches, outlet, exploitation scar, fissures in the peat mass and others, that very much influence the variation of the water table level and thereby the surface vegetation in the short-, medium-, and long-term Paleo-ecological studies In order to better understand the evolution of raised bogs and especially try to find signs of their degradation, it is essential to investigate the peat lying right under the present vegetation. All the steps that have been set about within this context tried to answer the following questions: Is there a link between the vegetation present at the surface and the recent peat composition lying right under? Is there a link between the recently formed peat composition and the water table level observed on the peat bog? Are the microfossils, that are contained in the peat, affected by variations of the water table? Can we draw differences in the composition of the peat according to how far the boring has been carried out from the current active central zone of the peat bog? It clearly appears that the composition of the peat varies according to the type of present vegetation under which the sample was taken and the range of fluctuations of the water table level recorded on this spot. On the Misten peat bog, the palynological study of peat borings 10 m away from one another allowed to show that peat layers representing the same paleobotanical event(s) do not have the same thickness in each boring and can even be absent. In the same way, at a constant rate of pollen, the accumulation speed of the peat is higher in the bog centre compared to its margins. If one considers a same paleo-botanical event, and thus a same period of time, one can see that the pollen concentration is inversely proportional to the thickness of the peat. Two distinct parts are visible on the borings of the Misten peat bog surface: the upper part, the most recent one, characterised by the influence of the topographic position of the boring on the peat forming speed; the lower part, the oldest one, in which the influence is less pronounced. Thanks to different dating techniques (l4C, pollen concentrations and reference borings), this boundary between the two parts can approximately be dated back to the middle of the 14th century. This phenomenon should be related to an anthropogenic phenomenon rather than to a climatic one, given the short distance separating the borings. It would rather be the result of the manual exploitation of the peat than the harmful effects of the Eupen ditch which was dug much later (1774). A lot of microfossils, identifiable or not, present in the borings (rhizopodes, conidia ...) can doubtless be used as degradation indicators. Of course, these studies need to be deepened and systematised before going any further. What emerges especially from these studies is that when one undertakes regeneration attempts on a peat bog, one should not only take the present vegetation and hydrological parameters into account, but also the peat structure and composition, in at least the upper part of the deposits. Research and management Although acting on the current evolution of the Belgian bogs appears essential in order to prevent them from disappearing, it is clear that restoration measures that were appropriate elsewhere, cannot be applied to other areas without some thorough knowledge of the ecological parameters that govern them. The obvious result of this work is that the scientific follow-up of the management measures that have been taken is not only imperative, but that prior study measures of the sites and their characteristics are indispensable. This type of study is heavy because it requires an important investment from the researcher and often causes a lot of damage to the studied flora and fauna. However, these studies are necessary to understand the peatland systems and should even be complemented by further studies (lysimetric, structural or chemical...) . The standardisation of the data gathering system, the improvement of the information techniques and the management of the results organised in a way that allows all the researchers to consult them should contribute towards some lightening of the work. The computer science and the miniaturised electronic technology could improve the efficiency of the measures implemented, thereby benefiting the researcher and the reserve. Given the implied advanced technologies, these modern studies and data gathering processes would be expensive but it is cheap in comparison to the costs of the heavy works that are to be undertaken in the hope of preserving the raised bogs. Moreover, such a preparation of management measures can only improve their efficiency. If, despite all the efforts, the preservation of the jewels of the state nature reserve of the Haute-Fagnes is jeopardised, these studies will at least allow to go further in the understanding of the raised bogs systems. [less ▲]

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See detailPeatlands of Wallony (S-Belgium)
Frankard, Philippe; Ghiette, Pascal; Hindryckx, Marie-Noëlle ULg et al

in Suoseura - Finnish Peatland Society (1998), 49(2), 33-47

Various types of peatlands are present in Wallony: raised bogs, oligotrophic and rich fens, wet heaths, marshy woodlands. Many areas have been degraded by past and recent human activities. Much attention ... [more ▼]

Various types of peatlands are present in Wallony: raised bogs, oligotrophic and rich fens, wet heaths, marshy woodlands. Many areas have been degraded by past and recent human activities. Much attention is now devoted to their protection, scientific study and ecological management. Besides their exceptional biological and ecological interest, they are among the last natural spaces in a very urbanised country like Belgium. [less ▲]

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See detailEvolution de la végétation du secteur sud de la tourbière haute active de la fagne Wallonne, au cours de ces 60 dernières années (Plateau des Hautes-Fagnes, Belgique)
Frankard, Philippe; Hindryckx, Marie-Noëlle ULg

in Belgian Journal of Botany (1998), 131(1), 28-40

Evolution of the vegetation in the southern part of the fagne Wallonne raised bog, during the last 60 years (Hautes- Fagnes, Belgium). – Less than 500 years ago, raised bogs covered over 1000 ha on the ... [more ▼]

Evolution of the vegetation in the southern part of the fagne Wallonne raised bog, during the last 60 years (Hautes- Fagnes, Belgium). – Less than 500 years ago, raised bogs covered over 1000 ha on the Hautes-Fagnes plateau. Today, only + 125 ha of ombrotrophic little disturbed raised bogs remain. Recent studies have proved that these remnants show evidences of typical peat-forming communities regression. The aim of this study is to follow the vegetation dynamic of the southern part of the fagne Wallonne raised bog, by comparison of old and recent vegetation transects made in 1938, 1957 and 1995 and to detect in it some possible signs of evolution or regression. The vegetation has been mapped at 1 :10 scale and qualitatively surveyed on 4 m2 plots each 20 m along the transect. The cover degree of each species has been estimated. The results show a large reduction of the cover degree of Sphagnum species, an almost disappearance of the "Schlenken" and an increase of heathland species. These results are compared with the observations for the northern and the central zones (HINDRYCKX 1989). The damage to the typical raised bog vegetation is very clear and important in the northern part of the bog: disappearance of typical species overgrown by Molinia caerulea. In the central and the southern parts, the increasing cover degree of ericaceous plants indicates clearly that the peat forming activity is strongly slowed down. [less ▲]

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See detailEt si on travaillait ensemble?
Guillaume, Marie-Elisabeth; Hindryckx, Marie-Noëlle ULg

Learning material (1997)

Detailed reference viewed: 8 (1 ULg)
See detailY'a du projet dans l'air
Antoine, Nathalie; Guillaume, Marie-Elisabeth; Hindryckx, Marie-Noëlle ULg

Report (1997)

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See detailElementverteilung in einem moorprofil (Präboreal bis subatlantikum) im Tal der Helle/Hill (Hohes Venn, Belgien)
Gaida, R.; Olbrechts, S.; Hindryckx, Marie-Noëlle ULg et al

in Geoökodynamik (1997), XVIII(2/3), 79-90

This investigation was on the distribution of some elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Zn) in a groundwater bog in the Helle/Hill valley in the Hohes Venn, Belgium. The thickness of the ... [more ▼]

This investigation was on the distribution of some elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Zn) in a groundwater bog in the Helle/Hill valley in the Hohes Venn, Belgium. The thickness of the deposit is 155 cm. This bog has developed since the Pre Boreal period. The distribution in the lower part of the bog profile is very strongly influenced by water from the adjacent slope which is characterised by a high content of different metals. This resulted in a significant amount of Fe, Ni and Zn and to a lesser degree of Cu and Cd. The metals stem from ore which originated from the nearby Hill valley tonalite. The weathering of the sulphidic ore created sulphuric acid which is responsible for the low pH values of the peat samples. Not only the influence of the local geology and mineralogy is discussed, but also the behaviour of different plants with respect to element uptake and accumulation. Atmospheric input also has an influence, especially on the distribution of the elements in the upper part of the profile. [less ▲]

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See detailL'accompagnement d'équipes éducatives dans la mise en place de la réforme du premier degré: parcours scolaires et pratiques de différenciation
Guillaume, Marie-Elisabeth; Hindryckx, Marie-Noëlle ULg

in Informations pédagogiques (1996), 29

Synthèse d'une année de recherche-action basée sur l'accompagnement d'équipes éducatives dans la mise en place de la réforme du premier degré du secondaire : chronique d'une collaboration. Le travail ... [more ▼]

Synthèse d'une année de recherche-action basée sur l'accompagnement d'équipes éducatives dans la mise en place de la réforme du premier degré du secondaire : chronique d'une collaboration. Le travail collaboratif s'est effectué avec des équipes de professeurs de français de l'Athénée de Visé. Les axes de travail choisis furent les suivants :définir les compétences minimales qui devront être maîtrisées par les élèves au terme du premier degré de l'enseignement secondaire - concevoir et mettre au point de nouvelles pratiques pédagogiques et de nouveaux outils visant la construction des compétences choisies pour la première année du cycle - Intégrer des démarches d'évaluation diagnostique (quels savoirs, quelles compétences sont acquises), d'évaluation formative (repérage et analyse des difficultés d'apprentissage rencontrées par les élèves) et de pratiques de différenciation - Expérimenter les actions éducatives conçues - Evaluer celles-ci, analyser les paramètres qui ont présider à leur élaboration. [less ▲]

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See detailL'avenir des tourbières hautes à sphaignes en Europe tempérée, à l'exemple des Hautes-Fagnes belges
Schumacker, René ULg; Wastiaux, Cécile; Hindryckx, Marie-Noëlle ULg

in Colloques Phytosociologiques (1996), XXIV

The main factors involved in the regression of peat-bogs in temperate W-Europe are examined at hand of the situation in the Belgian Hautes-Fagnes. The consequences of the greenhouse effect on their future ... [more ▼]

The main factors involved in the regression of peat-bogs in temperate W-Europe are examined at hand of the situation in the Belgian Hautes-Fagnes. The consequences of the greenhouse effect on their future are evaluated at the light of simulations done in N-America and in Belgium. [less ▲]

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See detailNécessité des études paléoécologiques pour une gestion raisonnée des tourbières hautes
Hindryckx, Marie-Noëlle ULg; Damblon, Freddy; Schumacker, René ULg

in Région wallonne, conservation de la nature (Ed.) colloque "Gérer la nature?" travaux n° 15 (1990)

A l'exemple des Hautes Fagnes, nous proposons de se baser sur une série d'études paléoécologiques pour entreprendre une gestion raisonnée des tourbières : cartographie et études comparatives de la ... [more ▼]

A l'exemple des Hautes Fagnes, nous proposons de se baser sur une série d'études paléoécologiques pour entreprendre une gestion raisonnée des tourbières : cartographie et études comparatives de la végétation et de son évolution; études hydrologiques de nappes et études paléoécologiques (pollens, macrorestes végétaux, charbons, taux d'humification et datations). Quelques pistes de solutions à la dégradation des tourbières hautes sont proposées. [less ▲]

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See detailDans quelques années, pourra-t-on encore parler des tourbières hautes actives du plateau des Hautes-Fagnes?
Hindryckx, Marie-Noëlle ULg

in Documents de la Station scientifique des Hautes-Fagnes (1990), 15(3), 69-77

Evolution récente de la dégradation de la végétation de la partie centrale de la tourbière de la fagne Wallonne (Hautes-Fagnes). Résumé des travaux réalisés dans le cadre d'un mémoire de licence : cartes ... [more ▼]

Evolution récente de la dégradation de la végétation de la partie centrale de la tourbière de la fagne Wallonne (Hautes-Fagnes). Résumé des travaux réalisés dans le cadre d'un mémoire de licence : cartes de végétation, transects des espèces, analyses de la constitution de la tourbe, analyses palynologiques, analyses hydrologiques et propositions de quelques pistes de gestion de la tourbière pour enrayer les phénomènes de dégradation de la tourbière active. [less ▲]

Detailed reference viewed: 37 (8 ULg)