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See detailAnalyse des facteurs anthropiques de dégradation des bois de tapia (Uapaca bojeri) d'Arivonimamo
Rakotondrasoa, Olivia Lovanirina; Ayral, Astrid; Stein, Julien et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

The tapia woodland, an endemic ecosystem of Madagascar, plays an important role in the household economy of the local communities. The dependence of local people on the tapia woodland has led to the ... [more ▼]

The tapia woodland, an endemic ecosystem of Madagascar, plays an important role in the household economy of the local communities. The dependence of local people on the tapia woodland has led to the disturbance and degradation of this ecosystem. In this context, the current study aimed to identify and analyze the anthropogenic factors leading to the degradation of the tapia woodland in Arivonimamo. The working hypothesis was that fire constitutes today the main disturbance factor of the tapia woodland in Arivonimamo, leading to the deforestation and to a continuous degradation of this ecosystem. A typology of indicators of vegetation disturbance was established based upon literature; it was followed by an inventory of these indicators along four transects situated orthogonally around the six villages of the study site. This study showed that fire is no longer the main cause of deforestation and degradation of tapia woodlands in Arivonimamo. The continuing degradation of the woodland is mainly caused by illegal logging by the local population. These results provide key information to improve the management of the tapia woodlands in Arivonimamo. [less ▲]

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See detailActivité journalière et comportement d’alimentation de Borocera cajani Vinson 1863 (Lepidoptera: Lasiocampidae) sur deux de ses plantes hôtes : Uapaca bojeri Baillon 1874 et Aphloia theiformis (Vahl) Bennett 1840
Razafimanantsoa, Tsiresy; Raminosoa, Noromalala; Rakotondrasoa, Olivia et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Borocera cajani or landibe is a wild silk-moth, which silk is the most widely used in the textile industry in Madagascar. This endemic species is found throughout the island, but colonizes especially the ... [more ▼]

Borocera cajani or landibe is a wild silk-moth, which silk is the most widely used in the textile industry in Madagascar. This endemic species is found throughout the island, but colonizes especially the tapia forest in the central Highlands. The species has an important economic, culinary and cultural role in the Island. It is polyphagous and frequents several host plants. The daily activity of the larvae of B. cajani has been studied in their natural habitat on two native host plants of the tapia forest: Uapaca bojeri and Aphloia theiformis. Continuous observations during 24 hours on 54 individuals of the last instar of B. cajani have been conducted. Daily periods of activity were found to vary according to the host plant species. Larvae feeding on U. bojeri allocate 6.9% of their time to feed, while the larvae feeding on A. theiformis spend 3.3% of their time. Only 1.0% (15 minutes) and 0.7% (10 minutes) of the observed periods were allocated to movement, in the larvae feeding on U. bojeri et A. theiformis, respectively. Larvae observed on A. theiformis took an average of 3.1 ± 0.2 meals a day, which lasted 15,4 ± 1,3 min. Larvae observed on U. bojeri took an average of 1.9 ± 0.1 meals a day, which lasted 54.8 ± 5.2 min. [less ▲]

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See detailImportance de la méthode de coupe sur la régénération de Combretaceae du Bassin arachidier sénégalais
Faye, E; Diallo, H; Samba, SAN et al

in Tropicultura (2013), 31(1), 44-52

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See detailThe spatial footprint of the non-ferrous metal industry in Lubumbashi
Vranken, Isabelle ULg; Munyemba Kankumbi, François; Amisi Mwana, Yamba et al

in Tropicultura (2013), 31(1), 20-27

In the south-eastern part of the Katanga Province (Democratic Republic of the Congo), high concentrations of copper and cobalt are found in the soils of the well-known “Copper Belt”. Due to the dominant ... [more ▼]

In the south-eastern part of the Katanga Province (Democratic Republic of the Congo), high concentrations of copper and cobalt are found in the soils of the well-known “Copper Belt”. Due to the dominant south-eastern winds, the metallurgic industry in Lubumbashi has been the source of spatially concentrated atmospheric deposits of non-ferrous metal particles and associated substances in a cone-shaped zone, situated north-west of the metal processing site. The existence of this zone has been evidenced using two different techniques: firstly, by means of landscape metric comparisons of the vegetation and bare soil patterns in two study areas, one inside the pollution cone and one outside; secondly, by means of the theory on city perception developed by Kevin Lynch. Higher fragmentation and lower vegetation presence were observed inside the pollution cone, reflecting the negative impact of atmospheric deposits. Those differences were higher for sites closer to the emission source. Lynch’s approach outlined the negative impact of diverse industrial plants on the perception by the local population. Six pollution districts and several contaminated paths, limits, nodes and polluting landmarks were identified. Citizens even recognize them as part of the collective image of the city. [less ▲]

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See detailIdentification des indicateurs de dégradation de la forêt de tapia (Uapaca bojeri) par une analyse sylvicole
Rakotondrasoa, OL; Malaisse, François ULg; Rajoelison, G et al

in Tropicultura (2013), 31(1), 10-19

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See detailAnthropisation et dynamique des paysages en zone soudanienne au nord du Bénin
Mama, A; Sinsin, B; De Cannière, C et al

in Tropicultura (2013), 31(1), 78-88

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See detailDynamics in mangroves assessed by high-resolution and multi-temporal satellite data: a case study in Zhanjiang Mangrove National Nature Reserve (ZMNNR), P. R. China
Leempoel, K; Satyaranayana, B; Bourgeois, C et al

in Biogeosciences Discussions (2013), 10

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See detailSpecies persistence in landscapes with spatial variation in habitat quality: a pair approximation model
Liao, J; Li, ZQ; Hiebeler, DE et al

in Journal of Theoretical Biology (2013), 335

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See detailPertinence de la mise en oeuvre des initiatives de Réductions des Emissions dues à la Déforestation et à la Dégradation des forêts (REDD) pour les communautés locales. Cas des formations de tapia dans la région d'Itasy
Ratsimba, HR; Rabemananjara, ZH; Rabefarihy, AT et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches: Enjeux écologiques et socio-économiques (2013)

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See detailImpact de l'anthropisation sur les variables microclimatiques dans un écosystème forestier des environs de Kisangani (Réserve de Masako, R.D. Congo)
Iyongo Waya Mongo, L; Bulamuzi Bilha, J; Iyongo Bompetsa, C et al

in Annales des Instituts Supérieurs d’Etudes Agronomiques de Bengamisa (2013), 5

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See detailEffets de lisière sur la teneur en eau et la température du sol à l'échelle du jardin systématique de l'INERA/Yangambi en R.D. Congo
Alongo Longomba, S; Visser, M; Kombele Bishosha, F et al

in Annales des Instituts Supérieurs d’Etudes Agronomiques de Bengamisa (2013), 5

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See detailPropriétés et diagnostic de l'état agropédologique du sol de la série Yakonde après fragmentation de la forêt à Yangambi, R.D. Congo
Alongo Longomba, S; Visser, M; Kombele Bishosha, F et al

in Annales des Instituts Supérieurs d’Etudes Agronomiques de Bengamisa (2013), 5

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See detailStructure spatiale des trois espèces les plus abondantes dans la Réserve Forestière de la Yoko, Ubundu, République Démocratique du Congo
Kumba, S; Nshimba, H; Ndjele, L et al

in Tropicultura (2013), 31(1), 53-61

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See detailDiversité et distribution d'abondances des plantes d'un écosystème protégé dans un paysage anthropisé: cas de la Réserve Naturelle Forestière de Bururi, Burundi
Havyarimana, F; Bigendako, MJ; Masharabu, T et al

in Tropicultura (2013), 31(1), 28-35

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See detailEffets de lisière et sex-ratio de rongeurs forestiers dans un écosystème fragmenté en République Démocratique du Congo (Réserve de Masako, Kisangani)
Iyongo Waya Mongo, L; De Cannière, C; Ulyel, J et al

in Tropicultura (2013), 31(1), 3-9

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See detailEffets de la fragmentation des forêts par l'agriculture itinérante sur la dégradation de quelques propriétés physiques d'un ferralso échantillonné à Yangambi, R.D. Congo
Alongo, Sylvain; Visser, Marjolein; Drouet, Thomas et al

in Tropicultura (2013), 31(1), 36-43

The knowledge of changes occurring in the soil cover at the forest edge is needed to better understand the impact of forest fragmentation on soil parameters. The objective of this study is to evaluate the ... [more ▼]

The knowledge of changes occurring in the soil cover at the forest edge is needed to better understand the impact of forest fragmentation on soil parameters. The objective of this study is to evaluate the effects of forest fragmentation caused by shifting agriculture on texture, bulk density, total porosity and soil hydraulic conductivity in the layers at 0-10, 10-20 and 20-30 cm depth by the transect method in a perspective of sustainable land management in the region of Yangambi. The results obtained show that the edge between the fallow grassland and dense forest has a width of 70 m. Degradation of all the physical properties of soils relative to the dense forest is very significant (p<0.01) for the studied layers. Fragmentation of forests by shifting cultivation increases the phenomenon of selective loss of clays of the surface soil layers and consequently increases its bulk density and decreases the permeability and porosity with depth under the fallow grass and edge. The texture data associated with textural classes in the FAO textural triangle indicate a change in texture of the soil under different land uses for the tree layers studied. [less ▲]

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See detailOptimizing scale search in species distribution models
Serckx, Adeline ULg; Huynen, Marie-Claude ULg; Beudels-Jamar, Roseline et al

in Folia Primatologica : International Journal of Primatology = Internationale Zeitschrift für Primatologie = Journal international de Primatologie (2013), 84

The influence of spatial scale on ecological processes and pattern formation, such as species distribution is a major research topic since decades. It has become even more relevant in the context of ... [more ▼]

The influence of spatial scale on ecological processes and pattern formation, such as species distribution is a major research topic since decades. It has become even more relevant in the context of global change. In many studies the influence of a predictor on a response derived over multiple and discrete spatial scales is evaluated. Due to inherent issue of multiple testing, this approach can be problematic. In this study on bonobos distribution, we suggest a 3-steps procedure that overcomes this problem. It takes into account the decay of a predictor by using a weighting function of distance to the observation of interest. We use variables to account for human pressure, food availability, patchy structure of the forest and nesting sites re-use. In a first step, we run a model with a fixed scale for every predictor based on expert opinion. For significant variables, we derive then in a second step the distance weighted influence over a range of scales. This helps to narrow down the search for the final model parameter estimates. Findings indicate that bonobo distribution is driven on the intermediate scale by forest patches structure. Food availability explains their abundance only at smaller scales. Those results demonstrate the sadly well-known influence of habitat fragmentation on animals’ density and distribution but also highlight the importance to understand influences of scale, the animal perceptions of their environment, by using appropriate statistical procedures. Our method can be particularly useful to formulate specific management hypotheses for conservation. Furthermore, its principles can be of use to other types of studies, such as behavior. [less ▲]

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See detailLa soie naturelle des Hauts-Plateaux de Madagascar: les facteur socio-institutionnels entravant une filière dynamique et pérenne
Rabearisoa, Misha; Ramamonjisoa, Bruno; Poncelet, Marc ULg et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Despite the cultural, social and socio-economic importance for societies situated in the Highlands of Madagascar, the endemic silk moth Borocera cajani and its habitat Uapaca bojeri are endangered by many ... [more ▼]

Despite the cultural, social and socio-economic importance for societies situated in the Highlands of Madagascar, the endemic silk moth Borocera cajani and its habitat Uapaca bojeri are endangered by many factors. In order to sustainably manage these resources, the silk production chain has been studied combining economic and socio-anthropologic approaches. Silk chain production analysis situates the underlying rural realities in an economic context; socio-anthropological considerations link those economic factors to their social context. The current study focuses on decentralized natural resource management in Itasy and Amoron’i Mania. It appears that institutional, economic and social factors tend to determine silk moth production chain dynamics. Considering all of these parameters and their interactions is considered crucial for a sustainable management of these endangered resources. [less ▲]

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See detailInfluence des reboisements d'eucalyptus (Eucalyptus robusta) et de pin (Pinus kesiya) sur la régénération naturelle de tapia (Uapaca bojeri) en forêt d'Arivonimamo
Rakotondrasoa, Olivia Lovanirina; Stein, Julien; Ayral, Astrid et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Confronted with the ongoing degradation of the tapia woodlands (Uapaca bojeri), reforestation by Pinus sp. and Eucalyptus sp.was considered as an alternative in Arivonimamo to substitute tapia for the ... [more ▼]

Confronted with the ongoing degradation of the tapia woodlands (Uapaca bojeri), reforestation by Pinus sp. and Eucalyptus sp.was considered as an alternative in Arivonimamo to substitute tapia for the production of firewood. However, the invasion by these alien species is actually considered as one of the threats to the tapia woodland in Madagascar. In this context, this study aimed to analyze the regeneration of the tapia woodlands in Arivonimamo. Consequently, “contact zones” between stands of exotic species, Pinus kesiya or Eucalyptus robusta, and U. bojeri were identified, in order to study tree regeneration along transects in each cardinal direction starting inside the exotic forests and continuing into the native populations. This study showed that the density of tapia regeneration varied between sites. It also appeared that the capacity of P. kesiya to invade the tapia woodland is much higher than for E. robusta. Moreover, the regeneration of pine inside the pine’s plantations was rather low. In addition, it was observed that the canopy opening rate had no significant influence on the development of the regeneration of the three species involved. Differences in canopy opening are due to various human activities such as the collection of non-timber forest products (tapia), the forestry operation of cleaning (pine) and early cutting (eucalyptus). [less ▲]

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