References of "Lejeune, Philippe"
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See detailLe patron urbain, un facteur influençant l'impact de l'urbanisation sur les écosystèmes: les cas de Kisangani et de Lubumbashi (RDC)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in PACODEL (Ed.) Colloque international Territoires périurbains: développement, enjeux et perspectives dans les pays du sud (2013, December 19)

Les dynamiques et patrons paysagers de deux villes entre deux années (Kisangani entre 2002 et 2010 ; Lubumbashi entre 2002 et 2008, en République Démocratique du Congo) ont été étudiés afin d’évaluer leur ... [more ▼]

Les dynamiques et patrons paysagers de deux villes entre deux années (Kisangani entre 2002 et 2010 ; Lubumbashi entre 2002 et 2008, en République Démocratique du Congo) ont été étudiés afin d’évaluer leur influence sur l’impact de l’extension et/ou densification de ces villes, et plus particulièrement de leur zone périurbaine, sur leurs écosystèmes internes et périphériques. En effet, le patron paysager occupe une place fondamentale dans l’hypothèse centrale de l’écologie du paysage, appelée pattern-process paradigm puisqu’il influence les processus écologiques et inversement. Sa description et son analyse sont donc particulièrement importantes (Bogaert et al. 2004; Coulson et al. 1999). Les indices de composition, communément utilisés en écologie du paysage, décrivent entre autres le patron en quantifiant la présence et le nombre de taches issues des différentes classes du paysage (Alberti 2008). D’autre part, les villes ne cessant d'augmenter leur emprise sur les paysages dont elles font partie, l'étude des espaces qui les ceinturent, le phénomène de leur extension dans les régions rurales ainsi que les schémas conceptuels de leur morphologie et dynamique interne sont plus que jamais des sujets d'actualité (Bhatta et al., 2010; Borsdorf et al., 2002; De Blij, 1977; Gaston, 2010; Halleux, 2006). Paradoxalement, les scientifiques de différentes disciplines peinent à donner une définition, des caractéristiques et des limites acceptées par tous aux notions se rattachant aux différentes zones présentes dans le gradient urbain-rural. Cette étude se distingue des autres, généralement subjectives, par son approche quantifiée et objective. Pour chacune des deux villes, deux images SPOT 5 ont été classifiées sur base d’une approche orientée-objet (Definiens 2013). Ensuite, des indices de composition paysagère ont été évalués afin 1) d’identifier l’étendue de chaque zone (urbaine, périurbaine, rurale) au sein du gradient urbain-rural en utilisant les définitions de zones proposées par André et al. (sous presse), 2) de décrire ces différentes zones en quantifiant les caractéristiques morphologiques les plus couramment citées avant d’en borner les valeurs (André et al. 2012) et 3) de quantifier la dynamique des différentes zones au cours de la dernière décade. Ensuite, les similarités et différences entre ces villes ainsi que la pertinence et les faiblesses de la méthode ont été identifiées et discutées. Les résultats de cette étude ont pour ambition de contribuer à une meilleure compréhension et prise en compte du rôle du patron paysager dans la résistance potentielle des écosystèmes naturels à l’extension et/ou la densification d’une ville donnée. [less ▲]

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See detailUtilisation des drones comme outil de suivi de travaux de restauration : génération de séries temporelles d'orthomosaïques à très haute résolution et de modèles numériques de surface
Michez, Adrien ULg; Lisein, Jonathan ULg; Geerts, Cédric ULg et al

Poster (2013, October 15)

D'une invention initialement militaire, les drones - et les applications qui dérivent de leurs utilisation - tendent à se banaliser au sein du domaine civil. En terme d'applications géographiques, les ... [more ▼]

D'une invention initialement militaire, les drones - et les applications qui dérivent de leurs utilisation - tendent à se banaliser au sein du domaine civil. En terme d'applications géographiques, les micro-drones (< 2 kg) occupent un segment nouveau dans les techniques d’acquisition d'informations, à mi-chemin entre deux segments plus classiques, représentés par les techniques d'acquisitions « terrain » (LiDAR terrestre, lever topographique, cartographie GPS, ..) et l'imagerie aérienne (caméra métrique, LiDAR aérien, imagerie satellitale). A l'aide d'un micro-drone X100 (Gatewing-Trimble), l'Unité GRFMN a effectué différents survols du projet de restauration du ruisseau du Morby, entrepris dans le cadre du projet Life+ Walphy. Les survols ont permis la réalisation d'orthomosaïques et de MNS (à l'aide d'Agisoft Photoscan) aux différentes étapes du chantier. Une évaluation de la qualité des MNS photogrammétriques générés est réalisée sur base de données LiDAR aérien disponible sur la zone. Une comparaison des coûts sera également réalisée entre les différentes techniques d'acquisition de données topographiques déployées sur le site lors du projet : MNS photogrammétriques UAV et caméra large format, LiDAR aérien. [less ▲]

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See detailANALYSE SPATIO-TEMPORELLE DES DÉGÂTS D’ÉCORCEMENT DANS LES PLANTATIONS RÉSINEUSES EN RÉGION WALLONNE
Ligot, Gauthier ULg; Lehaire, François ULg; Gheysen, Thibaut et al

in Forêt Wallonne (2013), 126

Les dégâts d’écorcement inquiètent de très nombreux gestionnaires forestiers. Depuis plus de 10 ans, des inventaires sont réalisés annuellement et des outils de diagnostic ont été développés afin d’en ... [more ▼]

Les dégâts d’écorcement inquiètent de très nombreux gestionnaires forestiers. Depuis plus de 10 ans, des inventaires sont réalisés annuellement et des outils de diagnostic ont été développés afin d’en quantifier l’ampleur en Région wallonne. L’examen de ces données met en évidence le rôle prépondérant des densités de cerfs ainsi que de la structure du paysage, de la rigueur des hivers et de la capacité d’accueil du milieu. [less ▲]

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See detailModeling the Distribution of Marketable Timber Products of Private Teak (Tectona grandis L.f.) Plantations
Fonton, Noël Houédougbé; Atindogbé, Gilbert; Akossou, Arcadius Y. et al

in Open Journal of Forestry (2013), 3(4), 115-121

Management of marketable products of private plantations will not be sustainable without class girth be-ing identifiable readily. Modeling marketable products is a key to obtain good fitness between ... [more ▼]

Management of marketable products of private plantations will not be sustainable without class girth be-ing identifiable readily. Modeling marketable products is a key to obtain good fitness between observed and theoretical girth distribution. We determine the best parameter recovery method with the Weibull function for two sylvicultural regimes (coppice and high forest). Data on stand variables were collected from 1101 sample plots. The three Weibull function parameters were estimated with three parameters re-covery methods: the maximum likelihood method, the method of moments and the method of percentiles. Stepwise regression and the simultaneously re-estimated parameter using the Seemingly Unrelated Re-gression Estimation were applied to model each parameter. The results indicated that the three methods successfully predicted girth size distributions within the sample stands. The method of moments was the best one with lowest values of Reynolds error index and Kolmogorov-Smirnov statistic however the syl-vicultural regimes. The Weibull parameter distribution model developed for each of the two sylvicultural regimes was quite reliable. [less ▲]

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See detailAerial surveys using an Unmanned Aerial System (UAS): comparison of different methods for estimating the surface area of sampling strips
Lisein, Jonathan ULg; Linchant, Julie ULg; Lejeune, Philippe ULg et al

in Tropical Conservation Science (2013), 6(4), 506-520

Conservation of natural ecosystems requires regular monitoring of biodiversity, including the estimation of wildlife density. Recently, unmanned aerial systems (UAS) have become more available for ... [more ▼]

Conservation of natural ecosystems requires regular monitoring of biodiversity, including the estimation of wildlife density. Recently, unmanned aerial systems (UAS) have become more available for numerous civilian applications. The use of small drones for wildlife surveys as a surrogate for manned aerial surveys is becoming increasingly attractive and has already been implemented with some success. This raises the question of how to process UAS imagery in order to determine the surface area of sampling strips within an acceptable confidence level. For the purpose of wildlife surveys, the estimation of sampling strip surface area needs to be both accurate and quick, and easy to implement. As GPS and an inertial measurement units are commonly integrated within unmanned aircraft platforms, two methods of direct georeferencing were compared here. On the one hand, we used the image footprint projection (IFP) method, which utilizes collinearity equations on each image individually. On the other hand, the Structure from Motion (SfM) technique was used for block orientation and georeferencing. These two methods were compared on eight sampling strips. An absolute orientation of the strip was determined by indirect georeferencing using ground control points. This absolute orientation was considered as the reference and was used for validating the other two methods. The IFP method was demonstrated to be the most accurate and the easiest to implement. It was also found to be less demanding in terms of image quality and overlap. However, even though a flat landscape is the type most widely encountered in wildlife surveys in Africa, we recommend estimating IFP sensitivity at an accentuation of the relief. [less ▲]

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See detailHeight competition between Quercus petraea and Fagus sylvatica natural regeneration in mixed and uneven-aged stands
Ligot, Gauthier ULg; Balandier, Philippe; Fayolle, Adeline ULg et al

in Forest Ecology & Management (2013), 304

We monitored in situ natural regeneration in 23 uneven-aged stands. We modelled height growth in the regeneration of Quercus petraea and Fagus sylvatica. Beech saplings grew faster than oak saplings at ... [more ▼]

We monitored in situ natural regeneration in 23 uneven-aged stands. We modelled height growth in the regeneration of Quercus petraea and Fagus sylvatica. Beech saplings grew faster than oak saplings at all light levels. Oak gained greater benefit from direct radiation than did beech. Canopy opening is insufficient to promote oak over beech regeneration. [less ▲]

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See detailClassification of riparian forest species (individual tree level) using UAV-based Canopy Height Model and multi-temporal orthophotos (Vielsalm, Eastern Belgium)
Michez, Adrien ULg; Lisein, Jonathan ULg; Toromanoff, François ULg et al

Poster (2013, September 09)

Introduction : Despite their relatively low area coverage, riparian forests are central landscape features providing several ecosystem services. Nevertheless, they are critically endangered in European ... [more ▼]

Introduction : Despite their relatively low area coverage, riparian forests are central landscape features providing several ecosystem services. Nevertheless, they are critically endangered in European countries by human pressures (livestock grazing, land use conflicts, canalizations, waste water, ...) andalso by natural hazards such as the recent black alder (Alnus glutinosa) extensive decline caused by Phytophthora alni. In this study UAV is used to improve the characterization of riparian areas. Riparian forest species are identified at the individual tree level. The health condition of black alder is assessed. For this purpose a computer based approach has been developped, with low needs of specific operator ability or training. Methods : We used the Gatewing X100 to acquire 16 aerial photographs datasets (7 in classic RGB and 9 in RG NIR) during 5 days (form Augustus to October 2012). We processed a CHM in ArcGIS by combining a national Digital Terrain Model with a photogrammetric DSM generated from a single flight photographs dataset with the "MicMac" opensource platform. The 16 orthophotos were computed with Agisoft Photoscan. Based on the CHM and some basic vegetation index (mean NDVI), a classification/segmentation process was developped in eCognition allowing tree crown extraction. An amount of 113 metrics were computed in eCognition for every tree crown object. The metrics were both derived from the CHM raster and spectral information. Metrics were computed by band (object spectral mean and CHM mean, Harralick entropy, Skewness) but also with band combination (Green NDVI and NDVI). A reference dataset was also acquired through a field survey of 624 individual tree positions accurately localized. The health condition of the black alder was recorded during the field survey. A supervised classification algorithm was developed in R (Random Forest package). Results : Several classification trees were assessed trough global accuracy using the Out Of Bag (OOB) error. The best global accuracy (82%) was obtained when distinguishing the black alder (with no regards for health condition during field survey) from the rest of riparian forest objects. The global accuracy tended to decline when other species were added. When separating healthy black alders from those with symptoms, the global accuracy is 77%. Conclusions : Our study highlights the potential of UAV-based multitemporal orthophotos to identify riparian forest species and health conditions at the tree level. Future studies will focus on quick radiometrics corrections. This could improve global accuracy by reducing the variability caused by illumination conditions [less ▲]

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See detailCity pattern as a factor influencing the impact of urbanization on ecosystems - A diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Conference (2013, September 06)

The patterns and dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate ... [more ▼]

The patterns and dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how they influence the impact of extension and/or of densification on urban internal and peripheral ecosystems. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then composition landscape metrics (built area proportion index, anthropized surface proportion index, equitability index of area proportion of classes, dominant class index, dominant class proportion index) have been evaluated in order to 1) identify the extend of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the most commonly cited morphological characteristics to describe these different areas and 3) quantify the dynamic of the different areas during this decade. Landscape ecology assumes that the landscape pattern description is important because, according to the central hypothesis called “pattern-process paradigm”, the ecological processes influence landscape structure and vice versa. Composition metrics, which are commonly used in landscape ecology, describe the pattern among other things in quantifying the presence and the number of patches from the various classes within the landscape. This study singularizes itself from the subjective ones by its quantified and objective approach. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. The results of this study are aimed to be used by urban planners for the evaluation of the potential resistance of internal and peripheral natural ecosystems to the extension and/or the densification of a given city, taking into account its pattern and dynamic. It might help them in their choice between different planning alternatives. [less ▲]

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See detailCity pattern as a factor influencing the impact of urbanization on ecosystems - A diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo)
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in Nunes Silva, Carlos (Ed.) Colonial and postcolonial urban planning in Africa (2013, September 06)

The patterns and dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate ... [more ▼]

The patterns and dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how they influence the impact of extension and/or of densification on urban internal and peripheral ecosystems. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then composition landscape metrics (built area proportion index, anthropized surface proportion index, equitability index of area proportion of classes, dominant class index, dominant class proportion index) have been evaluated in order to 1) identify the extend of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the most commonly cited morphological characteristics to describe these different areas and 3) quantify the dynamic of the different areas during this decade. Landscape ecology assumes that the landscape pattern description is important because, according to the central hypothesis called “pattern-process paradigm”, the ecological processes influence landscape structure and vice versa. Composition metrics, which are commonly used in landscape ecology, describe the pattern among other things in quantifying the presence and the number of patches from the various classes within the landscape. This study singularizes itself from the subjective ones by its quantified and objective approach. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. The results of this study are aimed to be used by urban planners for the evaluation of the potential resistance of internal and peripheral natural ecosystems to the extension and/or the densification of a given city, taking into account its pattern and dynamic. It might help them in their choice between different planning alternatives. [less ▲]

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See detailUsing drones to count the elephants: a new approach of wildlife inventories
Linchant, Julie ULg; Vermeulen, Cédric ULg; Lisein, Jonathan ULg et al

Conference (2013, August 29)

The use of UASs (Unmanned Aerial Systems) in wildlife survey is still recent but the fast development of this technology shows great possibilities and it could soon become an inevitable tool in wildlife ... [more ▼]

The use of UASs (Unmanned Aerial Systems) in wildlife survey is still recent but the fast development of this technology shows great possibilities and it could soon become an inevitable tool in wildlife management. The purpose of this study was to test the feasibility of inventories by UAS to survey large mammals in the Nazinga Game Ranch in the south of Burkina Faso. The Gatewing X100TM equipped with a Ricoh GR III camera was used to test the animal reaction as it passed, and their visibility on the images. A set of more than 7000 images was collected and observations revealed that only elephants (Loxodonta africana) were easily visible while medium and small sized mammals were not. At a height of 100 m the easy observation of elephant allows experts to enumerate them on images and no reaction was recorded as the UAS passed. We therefore implemented an aerial strip sample count along transects used for the annual wildlife foot count. A total of 34 elephants has been recorded on 4 transects, each overflown twice. The elephant density was estimated at 2.47 elephants/km2 with a coefficient of variation (CV%) of 36.10 %. UAS inventory of elephants is promising but improvements need to be done. The main drawback of our UAS was its autonomy. If we wish to replace manned aircraft survey of large areas (about 1000 km of transect per day vs 40 km for our UAS), increased endurance of small UAS is a requirement and the monitoring strategy should be adapted according to the sampling plan. Also, the UAS is as expensive as a second-hand light aircraft. However the logistic and flight implementation are easier, the running costs are lower and its use is safer. With technological evolution making civil UASs more efficient, they will be able to compete with light aircrafts for aerial wildlife surveys. [less ▲]

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See detailFine-scale analysis of ungulate-vehicle collisions in Southern Belgium
maron, Julie; Lehaire, François ULg; Morelle, Kevin ULg et al

Poster (2013, August)

Ungulate-vehicle collisions (UVC) are an increasing phenomenon in many European countries. These road accidents are a threat to wildlife populations but also to human safety and generate high economic ... [more ▼]

Ungulate-vehicle collisions (UVC) are an increasing phenomenon in many European countries. These road accidents are a threat to wildlife populations but also to human safety and generate high economic costs. Wallonia, the Southern part of Belgium, is also affected by the UVC problem and offers an interesting study area because of its very dense road network and increasing big game populations. The aim of our study was to determine where and when UVC hotspots occurred along highways in Wallonia, in order to provide recommendations regarding the location and design of mitigation measures. The study site is located in Wallonia (Southern Belgium) in the provinces of Liege and Namur (5,875 km²). Ungulates species present in this area are wild boar, roe deer and red deer. The UVC data were collected by the police and covered the period between 2008 and 2011 (n= 2,704). We analyzed the landscape and road-related variables of sections with high UVC risk in contrast with section of low risk. The landscape and road-related variables related to the location of UVC were highlighted using a generalized linear model (GLM) with simulated pseudo-absences. Concerning traffic accidents, the most involved game species are wild boar (37% of all casualties). That’s why the amount of data on wild boar was higher than for the other species. The results of the spatial and temporal analysis of wild boar-vehicle collisions (WVC) are therefore more accurate than for the other species. Consequently we decided to focused on the wild boar in the present poster. Temporal analysis showed strong variations in the WVC frequency over time, on the daily and seasonal scale. These critical periods correspond to the activity periods of the species (more UVC at night and during autumn and winter). The study also points out a negative correlation between the occurrence of UVC and the traffic volume (R² = 9.79%). This result doesn’t match with the literature but can be explained if we assume that when traffic increase, the road represents a more impassable barrier for animal species. As expected we also noticed a positive correlation between game density and UVC risk. These results indicate clear spatial and temporal clustering of WVC. Identification of hotspots enables us to identify the priority areas where mitigation measures must be considered. For further research, the accuracy of the police data should be improved in order to predict more exactly the risk of UVC. This would also make the mitigation measures more cost-effective. [less ▲]

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See detailWild boar movement ecology: what do we (don’t) know ?
Morelle, Kevin ULg; Prévot, Céline; Lehaire, François ULg et al

Poster (2013, August)

Although subject of many researches since decades, movement studies have been recently enhanced by the emergence of the movement ecology paradigm (Nathan 2008). Under this paradigm, Nathan et al. (2008 ... [more ▼]

Although subject of many researches since decades, movement studies have been recently enhanced by the emergence of the movement ecology paradigm (Nathan 2008). Under this paradigm, Nathan et al. (2008) proposed to break down movement of animal into four basic mechanistic components: i) internal states (motivation, physiology, why to move ?), ii) motion capacities (how to move ?), iii) navigation capacities and (when and where to move ?) and iv) external factors (physical environment and living organisms – conspecifics or not). Considering these four components of an individual’s movement, we reviewed literature dealing with wild boar (Sus scrofa L.), a species of important ecological and socio-economic concern, and tried to identify the key processes influencing this species’ movement. We conclude this review of the literature by highlighting the gaps in movement ecology of wild boar and suggesting further research directions under the light of the most recent used techniques. [less ▲]

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See detailSpatial analysis of bark-stripping damage by red deer in irregular hardwood forest
Lehaire, François ULg; Mercier, Grégoire; Lejeune, Philippe ULg

Poster (2013, August)

Over the past years, the population size of red deer (Cervus elaphus L.) is following an upward trend in Wallonia. This has led to an increased pressure on vegetation as well as to forest damages of ... [more ▼]

Over the past years, the population size of red deer (Cervus elaphus L.) is following an upward trend in Wallonia. This has led to an increased pressure on vegetation as well as to forest damages of greater frequency and intensity. Among these damages, bark-stripping can be especially harmful to the timber quality due to the development of rot. The impact of these populations may thus lead to a reduction in forest productivity and to economic losses. Nevertheless, these damages doesn’t depend only on the density of red deer but also on the environmental characteristics of their habitats. The main objective of this study is to perform a spatial analysis of the occurrence of bark stripping in order to identify the environmental factor that affect the occurrence of the damages in hardwood forests. The bark-stripping damages in coniferous stands are well-known due to the fact that they are relatively frequent. Such information is however unavailable for hardwood stands. The study site (6500 hectares) is located in the Ardennes in Southern Belgium (Wallonia) and is mainly composed of beech stands. We used data of inventory campaigns that were carried out for management purposes. In each sampling unit (total of 321 units), we measured different stand characteristics and, during a second phase, the bark-stripping damages. These latter measurements concerned the presence or absence of bark-stripping on each recorded stem and damage age (presence or not of a healing roll). Only trees with dbh greater than 5 cm were taken into account. All the data were collected in hardwood stands. To perform the spatial analysis, a set of environmental variables, including landscape (distances to the natural or artificial feeding points, to watering-place, to the different types of road and to the forest paths, to refuge areas for deer and to forest edges, etc.) and tree dimension variables, have been collected. The estimated red deer density was also took into account. All these variables have been included in a fixed linear model using stepwise regression. An angular transformation was applied in order to guarantee appropriate conditions of application of the linear regressions. Over one hundred variables were tested but only six of them have a significant impact on the bark-stripping rate. This model explains only 10,2% of the bark-stripping rate. Tree dimension variables explain most of the bark-stripping rate. Thus, forest structure has an important impact on the bark-stripping probability. The roads and the human activities in general can have an impact on the bark-stripping rate. These activities can disturb the red deer feeding periods during the day and lead to important bark-stripping damages. We expected to observe other variables contributing to the model such as red deer density and altitude. The absence of effect of altitude can be explained by the fact that bark-stripping of beech trees occurs mainly in summer. The scale of the study can explain the absence of red deer density. [less ▲]

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See detailBioindicators for measurement of red deer pressure on understory vegetation in temperate deciduous forests
Lehaire, François ULg; Morelle, Kevin ULg; Ligot, Gauthier ULg et al

Poster (2013, August)

During the last decades, populations of large herbivores have largely increased. Consequently, their pressure on forest vegetation has been exacerbated, reaching in some cases levels that reduced the ... [more ▼]

During the last decades, populations of large herbivores have largely increased. Consequently, their pressure on forest vegetation has been exacerbated, reaching in some cases levels that reduced the diversity of forest ecosystem services. Assessing the balance between timber production and hunting activities remains a crucial question for forest managers who hence need reliable tools such as ecological indicators. Our aim was to review ecological indicators that characterize the pressure of red deer (Cervus elaphus L.) on understory vegetation in temperate deciduous forest ecosystem. The choice of plants on which the variables are measured is crucial to accurately characterize the deer pressure. This choice must take into account the feeding behavior of red deer, silvicultural objectives, ease of the measurement and the occurrence of these plants within the studied habitat. Generally, it is more appropriate to use common species with a wide ecological amplitude. The choice of indicator plants must take into account plant abundance and palatability, as they both affects considerably the performance of the ecological indicator. The variability of indicators generally increases with the scarcity of the chosen indicator plant. Therefore, choosing abundant plant species appear often the best solution as the resulting have a lower variability and hence enable better to detect changes of deer pressure. At low herbivore pressure, palatable species to offer quick response to the pressure variations. Palatable species are therefore reliable plant indicator especially if these is a good balance between game population and forestry. At excessive herbivore pressure, non-palatable species are preferred. In this case, the variability of ecological indicator is smaller with non palatable plant than with palatable plant. Ecological indicators of deer pressure help to understand the relationships between biodiversity, carrying capacity and deer populations. They are intended to forest managers that would like to monitor red deer pressure in regards to forest management goals and forest sustainability. [less ▲]

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See detailAssessment and monitoring of forest-game balance: an exclosure experiment
Lehaire, François ULg; Licoppe, Alain ULg; Lejeune, Philippe ULg

Poster (2013, August)

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become ... [more ▼]

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become unavoidable for sustainable forest management. Such monitoring requires a rigorous approach in order to evaluate objectively the balance between game population and forestry. The use of exclosure experiment offers an interesting solution to observe the effects of game populations on forest ecosystem. When objectives expected from forest management are clearly defined, exclosure experiments can effectively be used as a monitoring tool, to allow detecting unbalanced situations, for example, herbivore pressure threatening forest regeneration. The monitoring tool combines on one side an exclosure, defined as "the real environment", fully accessible to herbivores and, on the other side an enclosure, which is the "control treatment", fenced and therefore unavailable to any large ungulates. Our main aim was to compute a set of indicators characterizing the ecological changes due to large herbivores pressure on forest ecosystems. We identified 2 categories of ecological indicators: the short-term and the medium-term indicators. Short-term indicators require only two-year of monitoring to correctly quantify herbivore pressure whereas medium-term indicators require at least 4 years of monitoring. The study site is located in Southern Belgium (Wallonia), in mixed beech and oak forests. The predominant vegetation type is the "Luzulo-Fagetum", typically found in acidophileous beech forests. The ungulate species of interest are red deer, roe deer, wild boar and mouflon. In 2006, enclosures and exclosures (4 x 4 m) were installed in 17 sites scattered in two zones with contrasted deer densities to assess indicators efficiency. Between 2006 and 2012, we performed floristic surveys and we recorded the height, density and cover of the understory vegetation of every plot. [less ▲]

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See detailSynthesis and new definition of the areas included in the urban-rural gradient
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Conference (2013, July 26)

Every scientific studies should begin with the delimitation of the studied system. Ours aims at evaluating and quantifying the resistence of landscape classes and ecosystems to the urbanization process ... [more ▼]

Every scientific studies should begin with the delimitation of the studied system. Ours aims at evaluating and quantifying the resistence of landscape classes and ecosystems to the urbanization process. This is done by studying a dozen cities in sub-Saharan Africa, conducting a diachronic (2000 - 2010) landscape evolution analysis from SPOT satellite imagery. Paradoxaly, when tackling this subject, one must recognize that no consensus exists about the definition and localization of the areas included in the urban-rural gradient. This prevents from comparing the results of different cities. A bibliography analysis has been conducted in order to 1) identify the different areas in the urban-rural gradient, the characteristics and types of characteristics used to define the most cited ones (i.e. urban, suburbs, sprawl, exurban, rurban, periurban and rural) ; 2) Through citation frequency indexes, evaluate the relative importance of characteristics and types of characteristics for every area and then for the whole gradient; 3) Evaluate the principal characteristics according to a series of criteria (the best characteristic is supposed to be quantitative, integrative, marking a consensus, discriminative and easy to apply on the field); 4) On the basis of retained characteristics, propose single and simple definitions to the most cited areas. These new definitions aim at enable areas identification on the field and on satellite images. These new definitions have been applied to the field study of the city of Lubumbashi (D.R.C) and seem to be convenient. Retained characteristics have then been translated into landscape composition indexes for the future study of the following cities on basis of satellite imagery, without field research. Indeed, such indexes are commonly used in landscape ecology because they allow the description of the urban landscape pattern or structure which, according to the central hypothesis of landscape ecology, i.e. “pattern-process paradigm”, influence landscape ecological processes. [less ▲]

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