References of "Lejeune, Philippe"
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See detailVers une définition unique des zones périurbaines?: l'apport de l'écologie du paysage pour la segmentation du gradient urbain-rural
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

in Guinand, Sandra (Ed.) Journées APERAU 2012. Penser et Produire la Ville au XXIème Siècle. Modernisation écologique, qualité urbaine et justice spatiale. (2012, June 06)

L'avènement de l'agriculture, la sédentarisation de l'homme dans des villages, l'extension de ces derniers au point de devenir des villes de taille sans cesse croissante sont autant de phénomènes ... [more ▼]

L'avènement de l'agriculture, la sédentarisation de l'homme dans des villages, l'extension de ces derniers au point de devenir des villes de taille sans cesse croissante sont autant de phénomènes augmentant l'emprise de l'homme sur les ressources naturelles et participant à la dynamique paysagère (Mazoyer et Roudart, 1997). Le phénomène n'est pas négligeable: aujourd'hui, le nombre de personnes vivant dans ce qu'on désigne sous le terme de "ville" a dépassé celui des personnes vivant en dehors (United Nations, 2007). Il convient donc d'étudier en profondeur les conséquences de ce processus qu'est l'urbanisation et de les quantifier (Alberti, 2008). En particulier, la périurbanisation, caractérisée par une expansion diffuse de la ville dans un milieu mitoyen gardant son caractère rural, est au cœur des préoccupations de part sa position stratégique entre des espaces fortement et nettement moins anthropisés (Hervoët, 2001). Toute étude scientifique doit commencer par la délimitation du système étudié (Grimm et al., 2003). Paradoxalement, une synthèse bibliographique récente démontre qu'il n'existe pas de consensus sur le nombre de zones rencontrées dans ce gradient ni sur les définitions et caractéristiques de chacune de ces zones. L'article conclu qu'en vue d'une identification spatiale des zones à l'aide de la télédétection, il est préférable d'utiliser préférentiellement les caractéristiques morphologiques qu'il convient de traduire sous forme d'indices de structure spatiale permettant l'implémentation pratique des définitions données aux zones (André et al., en préparation). Suite à cette constatation, la présente contribution présente une méthode de segmentation du gradient urbain-rural qui s'appuie sur des éléments et indices paysagers décrivant la composition et la structure paysagères. Ces indices illustrent sous forme quantifiable les caractéristiques morphologiques les plus couramment citées pour décrire les différentes zones situées dans le gradient. [less ▲]

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See detailDeveloppement of an original aerial-based inventory method: first steps towards the use of mini Unmanned Areal Vehicle in elephant inventory
Lisein, Jonathan ULg; Vermeulen, Cédric ULg; Bouché, Philippe ULg et al

Scientific conference (2012, May 22)

This research aims at developping a new methodology for counting large mammals by means of an unmanned aerial vehicle. Test flights have been performed in the game ranch of Nazinga (Burkina Faso) during ... [more ▼]

This research aims at developping a new methodology for counting large mammals by means of an unmanned aerial vehicle. Test flights have been performed in the game ranch of Nazinga (Burkina Faso) during the month of february 2012. Aerial images shows that elephant detection is quite feasible. The systems still requires a lot of improvements in order to be able to cover bigger surfaces for a given pixels resolution. Nevertheless, this method seems very promissing and could advantageously replace traditionnal aerial-based inventory. [less ▲]

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See detailHarmonized Growth Models and Simulations of the Evolution of Pure Stands of Norway spruce, Larches and Douglas-fir for Southern Belgium (Wallonia).
Perin, Jérôme ULg; Ligot, Gauthier ULg; Cerisier, François ULg et al

Poster (2012, March 02)

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and ... [more ▼]

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and silvicultural operations. As a first approach we limited the scope of our work to even-aged and pure coniferous stands of the three most important coniferous species in Wallonia (southern part of Belgium): Norway spruce (Picea abies), douglas-fir (Pseudotsuga menziensii) and larches (Larix sp.). This presentation introduces carried out simulations and compare their outcomes. First we gathered data sets from the permanent regional inventory, from observation networks and experimental plots throughout Wallonia. Then we adjusted, for these species, harmonized and distance-independent models of dominant-height growth, tree diameter growth, mortality, and the distribution of tree diameter frequency before the first thinning. Next we implemented those models in the Capsis platform, and we simulated, for the three species, the evolution of virtual stands using different scenarios. On one hand the evolution was performed without thinning, and on the other hand we applied silvicultural scenarios that are commonly used in Wallonia. As a result these models highlight, for example, the great juvenile growth and sensibility to stands density of larches whereas Norway spruce behaves the opposite. Further work is however needed to predict and simulate wood quality and value. Once this will be achieved we will attempt to optimize silvicultural scenarios for the three species. [less ▲]

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See detailCould current Pericopsis elata (Fabaceae) patches in southeastern Cameroon be reasonably linked to past anthropogenic activities ?
Bourland, Nils ULg; Cerisier, François ULg; Livingstone Smith, Alexandre et al

Poster (2012, March 01)

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at ... [more ▼]

Pericopsis elata is one of the most valuable African timber species. This IUCN Red Listed tree suffers from a lack of regeneration, thus its current presence provokes questioning. Our work aimed at understanding its origins so as to help securing its future. This study, lead away from engineering works, was conducted in four different sites located within the natural distribution area of the species and took into account the different growing conditions were the species occurs. Our observations were based on an analysis of charcoal elements and pottery fragments discovered in subsurface layers of soils as well as on current botanical and pedological surveys. Discovered evidence of past human activities led to the assumption that this part of the Congo Basin was much more inhabited than previously thought. Some of the results obtained for P. elata could apply for other long lived light demanding species growing in the same environment. [less ▲]

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See detailToward a single definition of periurban areas? A review of terms, definitions and characteristics relating to the "urban" terminology.
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Poster (2012, February 10)

Remote sensing image interpretation and classification require a clear definition of what is considered as a rural, a periurban, a suburban or an urban area. Such a definition is also essential in order ... [more ▼]

Remote sensing image interpretation and classification require a clear definition of what is considered as a rural, a periurban, a suburban or an urban area. Such a definition is also essential in order to compare results of studies in periurban zones. Different terms, definitions and characteristics relating to these four concepts have been reviewed in the literature and compared according to different criteria like their type, citation frequency, strenghts and weaknesses, in the scope of a landscape evolution analysis. [less ▲]

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See detailLes outils cartographiques open source au service de la gestion des forêts et des milieux naturels
Fourneau, François ULg; Bonnet, Stéphanie ULg; Toromanoff, François ULg et al

in Forêt Wallonne (2012), (118), 14-22

Les Systèmes d'Information Géographiques (SIG) occupent une place de plus en plus importante dans la boîte à outils des gestionnaires de forêts et de milieux naturels. Malheureusement, le pas vers l ... [more ▼]

Les Systèmes d'Information Géographiques (SIG) occupent une place de plus en plus importante dans la boîte à outils des gestionnaires de forêts et de milieux naturels. Malheureusement, le pas vers l'utilisation de cet outil n'est pas toujours évident à franchir et le choix d'un logiciel adapté à ses besoins et à ses moyens financiers peut s'avérer complexe. Cet article présente un logiciel cartographique libre d'accès (open source) performant et pouvant constituer un choix intéressant pour de nombreux profils d'utilisateurs impliqués dans la gestion des ressources naturelles. [less ▲]

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See detailStructure spatiale des arbres des savanes boisées et forêts claires soudaniennes : implication pour les enrichissements forestiers
Fonton, Noël Houédougbé; Atindogbe, Gilbert; Fandohan, Belarmain et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(4), 429-440

During the last decade, management of woodlands in the Sudanian region of Benin has been based on enrichment with valuable tree-species. Yet, no previous research has been undertaken to support enrichment ... [more ▼]

During the last decade, management of woodlands in the Sudanian region of Benin has been based on enrichment with valuable tree-species. Yet, no previous research has been undertaken to support enrichment design with respect to plant eye view, tree growth magnitude or survival capacity under local forest environments. To fill in this gap, Ripley's K function was used to assess the spatial pattern of trees, diameter classes and dominant valuable species in the Sudanian zone. Data were collected in four sites of variable size (150 X 100 m, 150 X 100 m, 100 X 50 m and 150 X 150 m). Mostly, the spatial patterns of the target species revealed small-clumps. Within these small-clumps, intraspecific repulsions were observed on average at a 3 m scale, while interspecific repulsions were noticed at a 4.5 m scale. Only a weak repulsion between diameter size was also remarked, suggesting that proximity to adult trees would not affect the survival of young plants. With regard to observed repulsion scales, we would suggest using a minimum of a 3 m space between trees of the same species and a 4.5 m space between trees of different species, for enrichment plantings in Sudanian woodlands, if based on the target species. However, this suggested spacing may not be optimal with regard to plant growth. Further investigation is needed to address this aspect. [less ▲]

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See detailCaractérisation des plantations privées de teck (Tectona grandis L.f.) du département de l'Atlantique au Sud-Bénin
Atindogbé, Gilbert; Fonton, Noël Houédougbé; Fandohan, Belarmain et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(4), 441-451

Teak plantations are an undeniable asset, representing socio-economic and environmental importance in South Benin. Plantation owners see teak as an asset, enabling them to supplement their income through ... [more ▼]

Teak plantations are an undeniable asset, representing socio-economic and environmental importance in South Benin. Plantation owners see teak as an asset, enabling them to supplement their income through timber production and sales. Sustainable management of teak plantations requires a high level of knowledge and understanding of the resource by plantation owners. The snowball sampling method was used in order to reach private teak plantations owners. This is a chain sampling method, which uses information from the first informant (plantation owner) to trace the others in the sample. Data were collected on the socio-economic status of plantation owners, and on both the geographical location and the size of the plantations. Dendrometrical parameters were measured through strip sampling. Factor analysis followed by hierarchical classification and stepwise discriminant analysis were performed in order to build a profile of the owners. We have identified 2,431 owners and 2,624 plantations. Young plantations (up to 5 years old) represent 16.4% of the total plantation area, high forests 12.7% and coppices 70.9%. Overall, these plantations were small in size (average = 0.44 ha). The number of trees per ha was found to be high, regardless of the forest system (respectively 3,371 trees/ha for young plantations, 3006 trees/ha for high forests and 6305 trees/ha for coppice). These high numbers reflect the fact that the trees represent farm-grown timber. Four groups of owners were distinguished: smallholder farmers seeking income (group 1), small city dweller planters and those motivated by securing their properties (group 2), city dweller planters with medium size plantations (group 3); and owners with large-scale plantations (group 4). All groups were willing to secure their land or be involved in the timber trade. The specific characteristics of each group need to be taken into account in considering the sustainable management of private teak plantations in South Benin. [less ▲]

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See detailEcology and management of Pericopsis elata (Harms) Meeuwen (Fabaceae) populations: a review
Bourland, Nils ULg; Kouadio, Yao Lambert; Fétéké, Fousséni et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(4), 486-498

Pericopsis elata (Fabaceae) is a valuable timber species occurring in moist semi-deciduous African forests. While it is at present substantially reduced, the tree’s natural distribution previously covered ... [more ▼]

Pericopsis elata (Fabaceae) is a valuable timber species occurring in moist semi-deciduous African forests. While it is at present substantially reduced, the tree’s natural distribution previously covered several distinct areas from Côte d’Ivoire to the Democratic Republic of Congo. This species has been logged since the second half of the 20th century. Because it suffers from a lack of regeneration, P. elata is now included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. As with other long-lived light-demanding species, the survival of P. elata may have been favored by important disturbances that occurred in the Congo Basin during the last millennia. While both international trade and industrial uses of the wood of P. elata are well documented, information about its ecology are very sparse or contradictory, and even absent in some cases (e.g., regarding its effective flowering diameter). Furthermore, data describing the management of P. elata are scarce, including potential solutions to compensate for the deficit of natural regeneration. Along the same lines, genetic studies still remain at an early stage and only vague hypotheses have been offered to explain the origins of the tree’s populations. We emphasize the need for new research on those topics. Further studies would be useful in deciding whether P. elata populations can continue to be logged without the species being threatened with extinction. Finally, such research needs to target effective and inexpensive management procedures that could secure the future of the species in a logging context. [less ▲]

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See detailGame over! Wildlife collapse in northern Central African Republic
Bouché, Philippe ULg; Nzapa Mbeti Mange, Roland; Tankalet, Floride et al

in Environmental Monitoring & Assessment (2012), 184(11), 7001-7011

The wildlife populations of northern Central African Republic (CAR) have long suffered intense uncontrolled hunting. Socio-political turmoil in northern CAR that started in 2002 resulted in a rebellion in ... [more ▼]

The wildlife populations of northern Central African Republic (CAR) have long suffered intense uncontrolled hunting. Socio-political turmoil in northern CAR that started in 2002 resulted in a rebellion in 2006. An aerial sample count was carried out in northern CAR after the cease-fire to assess the impact of this troubled period on wildlife. The survey was flown at the end of the dry season in February-March 2010. It covered a landscape complex of 95 000 km² comprising national parks, hunting reserves and community hunting areas. Comparison with earlier surveys reveal a dramatic decline of wildlife: the numbers of large mammals fell by 94% in 30 years, probably due to poaching, loss of habitat and diseases brought by illegal movements of cattle. Elephant (Loxodonta africana), reduncini and topi (Damaliscus lunatus) populations showed the greatest decline (each over 90%). Other species declined by 70 to 80% during the same period. The future of the rest of the wildlife in this area is dark without a strong commitment to provide adequate funding and quickly implement determined field management. Reinforced cooperation with neighbouring Chad and Sudan is required since they are facing similar problems. [less ▲]

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See detailThe Status of the Medium-Sized Ungulate Populations in 2010, Nazinga Game Ranch, Burkina Faso (Western Africa)
Marchal, Antoine; Lejeune, Philippe ULg; Ouedraogo, Moumouni et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(3),

The present study consists of analyzing the raw data collected from the annual line-transect foot count of medium-sized ungulates, carried out at the Nazinga Game Ranch (NGR), Burkina Faso (Western Africa ... [more ▼]

The present study consists of analyzing the raw data collected from the annual line-transect foot count of medium-sized ungulates, carried out at the Nazinga Game Ranch (NGR), Burkina Faso (Western Africa), in both 2001 and 2010. The annual census focused on the seven main medium-sized ungulates, namely (in alphabetical order), the Bushbuck (Tragelaphus scriptus), the Common Warthog (Phacochoerus africanus), the Defassa Waterbuck (Kobus ellipsiprymnus), the Grimm’s Duiker (Sylvicapra grimmia), the Oribi (Ourebia ourebi), the Roan Antelope (Hippotragus equinus) and the Western Hartebeest (Alcelaphus buselaphus). The census also focused on illegal anthropogenic activities. The wildlife populations were quantitatively analyzed through an estimation of their absolute density via the distance sampling method and through their evolution over the last decade using two relative density indexes, namely the Kilometric Abundance Index (KAI) and a spatial distribution index. These indexes were also used to measure the evolution of illegal activities over the same period. Both the wildlife observations and the anthropogenic observations were mapped using the Kernel method. Following an increasing trend in their population between 2001 and 2010, both the Roan Antelope and the Western Hartebeest reached an estimated density of 4.7 individuals per km², while the Defassa Waterbuck reached 2.4 individuals per km². Following an inverse trend over the same period, the Bushbuck, the Grimm’s Duiker and the Oribi reached an estimated density of 0.4 individuals per km². As for the Common Warthog, its estimated density of 2.5 individuals per km² seemed to remain unchanged during that decade. A comparison between wildlife observations and anthropogenic observations reveals a high decrease in animal densities in the north, east and west peripheral borders of the NGR and a flagrant extension of the proportion of the ranch being subjected to illegal activities (poaching, cattle herding, etc.). [less ▲]

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See detailMathematical formulation and exact solution for landing location problem in tropical forest selective logging, a case study in Southeast Cameroon
Philippart, Julien ULg; Minghe, Sun; Doucet, Jean-Louis ULg et al

in Journal of Forest Economics (2012), 18

In Central Africa, creating forest roads and skid trails is one of the most costly and environmentally damaging operations for the forest's ecosystem. An optimized road network is essential for reducing ... [more ▼]

In Central Africa, creating forest roads and skid trails is one of the most costly and environmentally damaging operations for the forest's ecosystem. An optimized road network is essential for reducing construction costs and improving the sustainable management of timber resources. The location of landings is vital in the development of a future forest road network. In this study, a binary integer programming model similar to the uncapacitated facility location problem is formulated to optimize the locations of the landings. The model is applied to selective logging in Central Africa and tested on an annual logging zone in Southeast Cameroon. The results are compared to that of manual road planning, the currently used method. [less ▲]

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See detailHow to count elephants in West African savannahs? Synthesis and comparison of main gamecount methods
Bouché, Philippe ULg; Lejeune, Philippe ULg; Vermeulen, Cédric ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 77-91

The comparison of some elephants count methods – aerial sampling count, aerial total count and direct foot count – has been presented through surveys’ study cases implemented in Benin, Burkina Faso and ... [more ▼]

The comparison of some elephants count methods – aerial sampling count, aerial total count and direct foot count – has been presented through surveys’ study cases implemented in Benin, Burkina Faso and Niger. We compare them in terms of effort and cost to survey an area (sampling efficiency), efficiency in data collection (detection efficiency) as well as accuracy and precision. Aerial sampling count returns low sampling and detection efficiency and very low precision and accuracy figures when counting elephants populations below 0.5 elephant.km-2. Precision can partly be improved by stratification. Direct foot count returns the best sampling and detection efficiency but insufficient data number to produce reliable estimates. Therefore some authors often produced no results for elephants. Aerial total count is a costly method in absolute value. It requires important logistic and no measure of error is possible. However it provides relatively good sampling and detection efficiency as well as relatively accurate figures appreciated by wildlife managers if technical requirements are respected. Aerial total count could be recommended to survey small population of West African elephants each 3 to 5 years to minimize yearly count costs. [less ▲]

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See detailWild boar and roe deer monitoring with road-based surveys and thermal imaging
Morelle, Kevin ULg; Lejeune, Philippe ULg

Conference (2011, September 08)

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See detailWill Elephants Soon Disappear from West African Savannahs?
Bouché, Philippe ULg; Douglas-Hamilton, Iain; Wittemyer, George et al

in PLoS ONE (2011), 6(6), 1-11

Precipitous declines in Africa’s native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6 ... [more ▼]

Precipitous declines in Africa’s native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6,213,000 km2 Sudano-Sahelian range of West and Central Africa assessed through the analysis of aerial and ground surveys conducted over the past 4 decades. These surveys are focused on the best protected areas in the region, and therefore represent the best case scenario for the northern savanna elephants. A minimum of 7,745 elephants currently inhabit the entire region, representing a minimum decline of 50% from estimates four decades ago for these protected areas. Most of the historic range is now devoid of elephants and, therefore, was not surveyed. Of the 23 surveyed elephant populations, half are estimated to number less than 200 individuals. Historically, most populations numbering less than 200 individuals in the region were extirpated within a few decades. Declines differed by region, with Central African populations experiencing much higher declines (276%) than those in West Africa (233%). As a result, elephants in West Africa now account for 86% of the total surveyed. Range wide, two refuge zones retain elephants, one in West and the other in Central Africa. These zones are separated by a large distance (,900 km) of high density human land use, suggesting connectivity between the regions is permanently cut. Within each zone, however, sporadic contacts between populations remain. Retaining such connectivity should be a high priority for conservation of elephants in this region. Specific corridors designed to reduce the isolation of the surveyed populations are proposed. The strong commitment of governments, effective law enforcement to control the illegal ivory trade and the involvement of local communities and private partners are all critical to securing the future of elephants inhabiting Africa’s northern savannas. [less ▲]

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See detailPotentialities of using ASTER & SRTM DEM for road planning in Central African sustainable forest logging context. A case study in East Gabon
Philippart, Julien ULg; Handerek, Daphné ULg; Lejeune, Philippe ULg et al

Poster (2011, June 02)

Slope is the main constraint for sustainable forest road planning in Central Africa. Remote sensing now provides free and downloadable Data Elevation Model (DEM) covering most of appeared lands. In this ... [more ▼]

Slope is the main constraint for sustainable forest road planning in Central Africa. Remote sensing now provides free and downloadable Data Elevation Model (DEM) covering most of appeared lands. In this study, we evaluate potentialities and limitations of Shuttle Radar Topography Mission (SRTM) DEMs, derived from radar interferometry and Advanced Spaceborn Thermal Emission and Reflection Radiometer (ASTER) DEMs, themselves derived from digital photogrammetry for slope evaluation. Assessment is presented for hilly (Milole) and flat (Okondja) areas. Three elevation maps were derived from initial ASTER 30-m and SRTM 90-m DEMs : a SRTM 30-m resampled from SRTM 90-m and two ASTER 30-m where absurd values (artifacts) were corrected with SRTM 90-m and resampled SRTM 30-m respectively. We qualitatively and quantitatively assess the accuracy of all elevation maps compared to 992 (698) slope measures on field along transects of 10.5 (7.5) km in Milolé (Okondja). We estimated root mean square error (RMSE) for slope estimation at 7.8 (10.7), 8.1 (10.1), 11.7 (11.2), 10.1 (11.2) and, 9.3° (11.0°) for SRTM 90-m, SRTM 30-m, ASTER 30-m, ASTER 30-m CORR 90 and ASTER 30-m CORR 30 respectively in Milolé (Okondja). We also use a classification error matrix to assess Global Accuracy (GA) and User’s Accuracy (UA) of elevation maps by classifying ground slopes in two categories: lower or equal and higher than maximum slope limitation of 12% (30%) for primary (secondary) roads. All DEMs show a greater GA in hilly area (Milolé) than in flat area (Okondja) and SRTM derived DEMs show a higher UA for secondary roads constraint. UA for the lower or equal category varies between 55.5 and 75.2% (63.9 and 91.7%) for primary (secondary) roads. The use of corrected aster DEMs increases initial ASTER UA from 0.1 to 18.8% depending on category and slope limitation. Despite a relatively high RMSE for slope grade, all of the DEMs tested were found to be consistent for consideration of maximum slope constraint aiming at sustainable road planning for forest logging in Central Africa. [less ▲]

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See detailA Regional Inventory and Monitoring Setup to Evaluate Bark Peeling Damage by Red Deer (Cervus Elaphus) in Coniferous Plantations in Southern Belgium
Gheysen, Thibaut; Brostaux, Yves ULg; Hebert, Jacques ULg et al

in Environmental Monitoring & Assessment (2011), 181(1-4), 335-45

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to ... [more ▼]

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to fungus attacks that result in considerably depreciated timber. This article presents a monitoring setup for recent bark peeling damage in spruce plantings in Wallonia (southern part of Belgium). This setup implies to collect data annually from a survey involving cluster sampling. It has been employed since 2004 in coniferous stands amounting to 165,000 ha of land, where Norway spruce is the predominant species. The study area was divided into blocks delineated along features preventing deer migrations. A set of indicators was computed either at the whole study area level or at block level. The resulting set of indicators enabled forest managers to follow up debarking intensity in productive forests. Additional analyses were carried out in order to assess the relationship between the social position of trees in the stand and the debarking probability on the one hand, and the relationship between the variation in damage magnitude and seasonality, namely summer versus winter, on the other hand. [less ▲]

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See detailPrincipes de base de la télédétection et ses potentialités comme outil de caractérisation de la ressource forestière. I. Images aériennes et satellitaires
Bonnet, Stéphanie ULg; Toromanoff, François ULg; Fourneau, François ULg et al

in Forêt Wallonne (2011), (114), 45-56

Face aux enjeux pesant sur la forêt, la caractérisation de cette ressource multifonctionnelle est primordiale pour une gestion efficace et raisonnée. Cependant, la réalisation d'inventaires forestiers ... [more ▼]

Face aux enjeux pesant sur la forêt, la caractérisation de cette ressource multifonctionnelle est primordiale pour une gestion efficace et raisonnée. Cependant, la réalisation d'inventaires forestiers représente un travail substantiel en termes de temps et de budget. Dans ce contexte, les images aériennes et satellitaires deviennent, après l'avènement des Systèmes d'Information Géographique (SIG), des outils indispensables pour analyser la composition et l'évolution de nos forêts. Cet article présente synthétiquement les grands principes de télédétection et les services qu'elle peut rendre au forestier. [less ▲]

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See detailTaille des placeaux de caractérisation des teckeraies à sylviculture paysanne au Sud-Bénin
Atindogbe, Gilbert; Aoudji, Augustin Kossi; Fonton, Noël Houédougbé et al

in Bois et Forêts des Tropiques (2011), 310(4), 69-78

Success of teak, Tectona grandis, plantations in State forests has encouraged involvement of private landowners in this sector, with inadequate planting method and a management system livelihood ... [more ▼]

Success of teak, Tectona grandis, plantations in State forests has encouraged involvement of private landowners in this sector, with inadequate planting method and a management system livelihood-improvement oriented. Any assessment and characterisation of this resource therefore demands a study on the representativeness of the sampling units. Three sampling types and twelve sampling units were compared: plots defined by area (100 m2, 200 m2, 400 m2 and 600 m2); plots with a fixed number of trees (7, 9, 11, 13 and 15 trees) and strip sampling (5, 10 and 15 trees). The units were established randomly and a full inventory conducted, with one to four reiterations in each of the eighteen plantations of different ages managed as high stands and coppices. The dendrometric parameters calculated for each observation unit and for the full inventory are as follows: density (Na/ha), basal area (G), arithmetical average diameter of stems (dg), average basal area of stems. The criterion for comparison is the root mean square error relative (RRMSE) to the reference value: from the full inventory. The analysis of results shows that RRMSE can be as high as 36 %, and even more in high stand plantations. Plots with a fixed surface area produce the best estimations for characterising plantations, with approximately equivalent efficiency for 400 and 600 m2 plots, with a RRMSE of 10 % (Na/ha), 13 % for (G) and 7 % for (dg). Strip sampling produced better results than plots with a fixed number of trees, with a better (dg) estimation of 10 % to 12 %. Given the cost of the inventory, 400 m2 sampling plots may be recommended to improve the charaterisation of teak plantations under farm silviculture. [less ▲]

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