L’ayous Triplochiton scleroxylon K. Schum., grande essence commerciale anthropophile de la forêt dense humide semi-décidue africaine, en déclin naturel ?

Poster (2009)

Enjeux méthodologiques autour des produits forestiers non ligneux dans le cadre de la certification en Afrique Centrale

in Bois et Forêts des Tropiques (2009), 300(2), 69-78

Reproduction et régénération naturelle de Milicia excelsa (Welw.) C. C. Berg au sud-est du Cameroun

Poster (2009)

Community hunting in logging concessions: towards a management model for Cameroon’s dense forests

in Biodiversity & Conservation (2009), 18(10), 2705-2718

In central Africa, commercial poaching and local village hunting are still two major issues that logging companies must address through the implementation of effective management plans in order to certify ... [more ▼]

In central Africa, commercial poaching and local village hunting are still two major issues that logging companies must address through the implementation of effective management plans in order to certify their concessions. However, current problems in developing suitable hunting management schemes for dense tropical forests arise from (1) the difficulty associated with setting quotas which take into account indiscriminate local hunting practices (e.g. snare trapping) and the ill-defined modes of resource appropriation by local populations, (2) the difficulty associated with evaluating the effect of illegal hunting, i.e. poaching, and (3) the relative complexity of the main available model. To overcome this, we propose to develop alternative management models where village hunting is planned along the same lines as existing logging operation models, through the implementation of a system of spatio-temporal rotation of hunting areas. In practice, the logging concession, initially divided into annual logging areas, is divided into similar annual hunting areas (AHAs), which are opened to hunting during the year preceding the logging operations. A depletion of the wildlife stock is expected within the annually opened hunting areas, but the model assumes a progressive re-colonization of the depleted AHA in subsequent years from neighbouring ones. In this paper, an empirical model of such a controlled hunting system employing spatio-temporal rotation of hunting areas is tested within a Forestry Management Unit (FMU) covering 47,585 ha in the Dja region, in south-east Cameroon. The model, based on large forest areas, seems particularly well adapted to Cameroon’s dense forests because it fits within the existing legal framework of Community-Managed Zones of Hunting Interest (CMZHI) and is aligned with current logging concession operations. Preliminary results suggest that sustainable hunting can be achieved in the FMU, provided a management scheme of AHAs is strictly enforced through effective stakeholder commitment. [less ▲]

Enrichment of logging gaps with moabi (Baillonella toxisperma Pierre) in a Central African rain forest

in Forest Ecology & Management (2009)

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we ... [more ▼]

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we present the results of an experimental enrichment planting with moabi (Baillonella toxisperma Pierre), a valuable and important timber species harvested in Central Africa. Although forest gaps are generally considered as favourable for the regeneration of this species, a survey conducted in a forest concession in southeastern Cameroon provided an estimate of only 12.7 seedlings ha 1, suggesting that the species was, in fact, poorly represented in logging gaps within the study area. To further investigate the dynamics of the moabi in logging gaps, 795 seeds were sown in 15 logging gaps and 410 nursery-raised seedlings were planted in 15 other gaps. A biannual monitoring program over a 30-month period showed a lower survival rate for seedlings from sowing (75.9%) compared to that of nursery-raised seedlings (95.3%). Planted seedlings reached on average 229.3 cm whereas seedlings from sowing were 167.5 cmtall, with the observed difference roughly corresponding to the average height of the nursery-raised seedlings at the time they were introduced to the logging gaps. After 30 months, the diameters of planted seedlings (16.8 mm) were also greater than those of the directly sown individuals (12.5 mm). Forest gap characteristics significantly influenced the growth of the plants. Factors accounting for the differences were total solar radiation, the soil content of coarse sand, the topographic position of the gap, the vegetation cover and the density of Macaranga spp. Whilst total solar radiation had a positive influence on growth, the remaining factors had impacted growth negatively. A streamlined technique was tested by planting 7 seedlings in 250 gaps. Without additional site maintenance, 29.3% of the moabi seedlings emerged naturally from the competing vegetation after 24 months. With biannual maintenance some 89.4% of seedlings became successfully established. Clearance operations had no significant influence on the height of plants whilst plant diameter was greater in cleared gaps. The total cost of the enrichment technique was 5.5 EUR per gap without maintenance and 7.5 EUR per gap with a single maintenance measure. Whilst long-term monitoring is needed, this study suggests a high survival rate of moabi introduced in logging gaps, and a growth rate 10 times higher than previously reported under canopy cover. These findings, combined with the low costs of the enrichment technique, support the use of silvicultural measures in logging gaps to restore the forest. [less ▲]

Quelques données chiffrées concernant la place de la Belgique dans le commerce du bois de Pericopsis elata

in Rapport général de l’Atelier OIBT/CITES sur l’Afrormosia (Kribi, Cameroun, 02.04.-04.04.08.) (2008)

The origin of the forests in the North of the Congo Republic: an anthraco-pedological contribution.

in Damblon, F.; Court-Picon, M. (Eds.) Geological survey of Belgium professional papers N. 303-2008/1 (2008)

The vegetation of the Sangha region in the North of the Congo Republic is composed of a mosaic of forest formations including semi-deciduous humid dense forests characterized by Ulmaceae and Sterculiaceae ... [more ▼]

The vegetation of the Sangha region in the North of the Congo Republic is composed of a mosaic of forest formations including semi-deciduous humid dense forests characterized by Ulmaceae and Sterculiaceae, evergreen forests with Gilbertiodendron dewevrei and woodland with Marantaceae. Palynological analyses proved that this region witnessed an arid phase 2500 years ago. This was associated with an important reduction of the forest cover and an equal extension of savannahs that could have facilitated the migrations of the Bantou people and the propagation of the shifting cultivation agriculture in the whole region which is, still at the moment, sparsely populated. In order to verify climatic and anthropological influences on the present composition of the forest vegetation, a pedological investigation has been set up in the region of Pokola (1.5° N; 16.5 °E) comprising 43 drillings and 12 pits along a gradient covering the different forest types. Charcoal has been found in 84% of the cores in all the forest formations especially between 30 cm and 60 cm depth. Charred oil palm seeds (Elaeis guineensis), often a culture accompanying species, have been found in 60% of the pits. C14 analysis revealed dates between 600 and 2200 years BP. Pedological analyses showed the association between semi-deciduous humid dense forest and red ferralsols, between Marantaceae woodlands and ochre ferralsols (poorer than the former) and between Gilbertiodendron dewevrei stands and pseudogleys and gleysols. The identification of the botanical taxon of charcoal fragments from tropical regions deals with important limitations due to scarce reference collections that are far from being complete. Therefore it is crucial to combine a thorough knowledge of the different vegetation types and their character species with a wood anatomical study. Given the hypothesised strong influence of man induced perturbations and past climatic changes, these results emphasize the importance of edaphic factors in differentiating the forest stands in the North of the Congo Republic. They also permit a better understanding of a potential evolution of the forests in this region driven by the actual climatic changes. [less ▲]

Consommation de bois dans les zones humides du complexe ouest du Bénin: besoins et gestion locale des formations ligneuses

in Bois et Forêts des Tropiques (2008), (298), 13-24

L’étude propose une estimation de la consommation de bois dans les villages du complexe ouest des zones humides du Sud-Bénin. Les enquêtes ont été réalisées dans dix villages. Les résultats montrent ... [more ▼]

L’étude propose une estimation de la consommation de bois dans les villages du complexe ouest des zones humides du Sud-Bénin. Les enquêtes ont été réalisées dans dix villages. Les résultats montrent l’existence de deux zones distinctes du point de vue de l’intensité de la consommation de bois et des espèces utilisées. Dans la zone 1 composée des villages bordant la mangrove, Cocos nucifera, quoique peu appréciée, est l’espèce la plus consommée des dix-huit ligneux utilisés comme combustible. Soixante-douze espèces de bois d’énergie sont recensées dans la zone 2 regroupant les villages de terre ferme. Azadirachta indica y est l’espèce la plus consommée et appréciée. Les indices de consommation moyens de ces deux zones sont respectivement de 0,88 kg/j/p et de 1,26 kg/j/p. En matière de construction, les espèces précédemment citées sont une nouvelle fois majoritairement utilisées : C. nucifera et Rhizophora racemosa dans la zone de mangrove, A. indica en milieu de terre ferme. En moyenne, une personne dispose d’une surface bâtie de 8,84 m2 nécessitant environ 117 dm3 de bois. Pour le bois d’œuvre, le complexe dépend presque entièrement de l’extérieur. Tenant compte de la population du complexe et de ses besoins, de l’état et de la productivité de ses formations boisées, l’étude prévoit une situation de dégradation sérieuse de la végétation en zone 2. Des mesures de sensibilisation et de reboisement urgentes sont préconisées pour réduire la dépendance de cette région vis-à-vis des autres contrées du pays. [less ▲]

Changer le tissu agroforestier : une approche plurisectorielle

in Vermeulen, Cédric; Doucet, Jean-Louis (Eds.) Les premières forêts communautaires du Gabon : Récits d'une expérience pilote (2008)

Trop techniques ou trop éloignées des attentes des villageois, les innovations agroforestières se sont souvent soldées par de cuisants échecs… L’approche adoptée dans le cadre du projet DACEFI a été ... [more ▼]

Trop techniques ou trop éloignées des attentes des villageois, les innovations agroforestières se sont souvent soldées par de cuisants échecs… L’approche adoptée dans le cadre du projet DACEFI a été développée en totale concertation avec les villageois. Plurisectorielle, elle a porté notamment sur les modalités de production et d’introduction des plants ligneux (fruitiers et bois d’œuvre) dans le fi nage. Elle a intégré tant les essences commerciales que des produits forestiers non ligneux et aussi bien des espèces classiques que des espèces moins connues. En termes d’appropriation et de viabilité, une grande attention a été portée à deux niveaux. D’une part, à l’identifi cation de l’existant et des attentes villageoises ; d’autre part, à l’apprentissage par la sensibilisation, l’information, l’éducation et la formation. Simultanément, une dynamisation du milieu associatif a été lancée. Cette approche de foresterie sociale se veut complémentaire de la foresterie communautaire telle qu’elle est formulée par la loi. [less ▲]

Influence of woodland cover on habitat selection and reproductive parameters of tropical roseate terns: implications for colony management

in Endangered Species Research (2008), 4

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a ... [more ▼]

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a Pisonia grandis dominated woodland on Aride Island, Seychelles, western Indian Ocean. Long-term observations (1995 to 2006) revealed that areas with high vegetation density and canopy cover (>50%) were abandoned, in favour of nearby more open forest areas, such as clearings. The attractiveness of a forest clearing (0 to 25% canopy cover) to breeding birds was also largely supported by experimental manipulation of vegetation density in 2004. Most birds moved from areas under canopy cover to experimentally cleared plots, where they nested at higher densities and had a higher probability of successfully fledging a chick. However, some individuals remained in their original areas, despite their greater canopy cover, and had a lower fledging success. This site tenacity is presumably explained by an imprinting process leading some birds to breed in successive years in the same, familiar locations, despite their nest-sites having become sub-optimal for fledging success. Roseate terns choosing a nest site in woodland on Aride must trade off the need for some cover, offering protection from the sun, against the need for easy access through gaps in the canopy to fly to and from their nests. A suitable nest-site should also minimize chick/parent infestation by ticks and mortality caused by contamination of feathers with the sticky fruits of Pisonia grandis. We suggest that, when they are not formed naturally, small artificial forest clearings within the usual breeding area are likely to be attractive for roseate terns and may result in enhanced colony productivity. These findings may be applicable to other seabird colonies (e.g. sooty terns) found under forest cover on oceanic islands throughout the Indo-Pacific region. [less ▲]