Enjeux fonciers, exploitation des ressources naturelles et Forêts des Communautés Locales en périphérie de Kinshasa, RDC

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(4), 535-544

Peri-urban forests are under strong anthropic pressure. Any activity needs a previous identification of stakeholders, landscape perception, socio-economic trends in local communities and their ... [more ▼]

Peri-urban forests are under strong anthropic pressure. Any activity needs a previous identification of stakeholders, landscape perception, socio-economic trends in local communities and their relationships with land and natural resources. Kinshasa (capital of Democratic Republic of Congo, DRC) is a 10 millions inhabitants city with rapid growth and increasing impacts on surrounding villages linked with forest natural resources. This paper describes the relationship amongst local communities stakeholders and their relations with land areas and wood resources. Two areas surrounding Kinshasa (Bas-Congo and Bateke Plateaux) are considered as major fuel-wood and charcoal supply zones for the city. Those two areas are different in terms of land pressure (very high in Bas-Congo and focused on riparian forests on Bateke Plateaux), but show the same pattern of overuse of the forest and woody natural resources. In both areas, local management of forest resources by the traditional authorities (heads of village or lineage) has failed. Local population willingness for reforestation and forest restoration activities is much more important in Bas-Congo than on Bateke Plateaux. In both areas, shifting cultivation due to slash and burn practices for agricultural and charcoal practices are more and more quick. This has strong negative impact on the potential of regeneration process with local forest species. Sustainability of forest natural resources management by communities is discussed in regard to the on going negotiations on community based forest management regulations. [less ▲]

Predicting alpha diversity of African rain forests: models based on climate and satellite-derived data do not perform better than a purely spatial model

in Journal of Biogeography (2011), 38(6), 1164-1176

Aim Our aim was to evaluate the extent to which we can predict and map tree alpha diversity across broad spatial scales either by using climate and remote sensing data or by exploiting spatial ... [more ▼]

Aim Our aim was to evaluate the extent to which we can predict and map tree alpha diversity across broad spatial scales either by using climate and remote sensing data or by exploiting spatial autocorrelation patterns. Location Tropical rain forest, West Africa and Atlantic Central Africa. Methods Alpha diversity estimates were compiled for trees with diameter at breast height ‡ 10 cm in 573 inventory plots. Linear regression (ordinary least squares, OLS) and random forest (RF) statistical techniques were used to project alpha diversity estimates at unsampled locations using climate data and remote sensing data [Moderate Resolution Imaging Spectroradiometer (MODIS), normalized difference vegetation index (NDVI), Quick Scatterometer (QSCAT), tree cover, elevation]. The prediction reliabilities of OLS and RF models were evaluated using a novel approach and compared to that of a kriging model based on geographic location alone. Results The predictive power of the kriging model was comparable to that of OLS and RF models based on climatic and remote sensing data. The three models provided congruent predictions of alpha diversity in well-sampled areas but not in poorly inventoried locations. The reliability of the predictions of all three models declined markedly with distance from points with inventory data, becoming very low at distances > 50 km. According to inventory data, Atlantic Central African forests display a higher mean alpha diversity than do West African forests. Main conclusions The lower tree alpha diversity in West Africa than in Atlantic Central Africa may reflect a richer regional species pool in the latter. Our results emphasize and illustrate the need to test model predictions in a spatially explicit manner. Good OLS or RF model predictions from inventory data at short distance largely result from the strong spatial autocorrelation displayed by both the alpha diversity and the predictive variables rather than necessarily from causal relationships. Our results suggest that alpha diversity is driven by history rather than by the contemporary environment. Given the low predictive power of models, we call for a major effort to broaden the geographical extent and intensity of forest assessments to expand our knowledge of African rain forest diversity. [less ▲]

The first community forests of Gabon : towards sustainable local forest management ?

in Nature et Faune (2011), 25(2), 40-45

Forest resources abound in Gabon. Species diversity and quality of trees in the Gabonese forests make it a very lucrative production niche. Even though international forest operators are well established ... [more ▼]

Forest resources abound in Gabon. Species diversity and quality of trees in the Gabonese forests make it a very lucrative production niche. Even though international forest operators are well established there and are making profit, the Gabonese rural communities have not yet developed their own operations. In view of their remoteness from decision-making centers, villagers often unlawfully lose, without being aware of it, a great deal of the riches in their villages. Today, the rural socio-economic component is not sufficiently integrated in the management factors of the resource, even though populations that depend on them daily are supposedly the best placed individuals to make wise use of them. In this sense, community forestry helps to promote sustainable use of forest resources at a scale that is at par with the needs of the community, and seeks to guarantee that profits are shared at village level. In Gabon, the process of legalization of community forests is ongoing since 2001. Pilot projects such as DACEFI (Development of Community Alternatives to Illegal Logging) strive to assist communities in securing their community forest. However their legalization is slow in coming, while logging activities in the rural forest estate are increasing, and the quality of the species is deteriorating continually. [less ▲]

Soil seed bank characteristics in Cameroonian rainforests and implications for post-logging recovery

in Ecological Engineering (2011)

The soil seed bank is considered as an important component for resilience of climacic vegetation. No investigation has ever been conducted in Central African rainforests regarding this topic. We studied ... [more ▼]

The soil seed bank is considered as an important component for resilience of climacic vegetation. No investigation has ever been conducted in Central African rainforests regarding this topic. We studied the soil seed bank characteristics in relation to the standing vegetation in three Cameroonian forest zones with different disturbance regimes. There was no significant difference between sites in terms of density of the seed bank. But dissimilarities of the floristic compositions between sites were high. Overall, seeds came from 43 species including three commercial tree species. Whereas the seedlings emerging from soil samples mostly came from weedy and short-lived pioneer species, climax species predominated in the extant vegetation, leading to a very weak similarity between soil seed flora and the surrounding vegetation. Canopy openness could significantly affect the species richness of soil seed stocks but not the seed density. These results show that the soil seed bank contribution to the resilience of mature tropical forests is low. In particular, very few timber tree species could benefit from soil seed stocks for their regeneration. Therefore, the development of enrichment techniques including use of the soil seed bank as a source of tree regeneration in such a context would be irrelevant. [less ▲]

Population history and gene dispersal inferred from spatial genetic structure of a Central African timber tree, Distemonanthus benthamianus (Caesalpinioideae)

in Heredity (2011), 106

African rainforests have undergone major distribution range shifts during the Quaternary, but few studies have investigated their impact on the genetic diversity of plant species and we lack knowledge on ... [more ▼]

African rainforests have undergone major distribution range shifts during the Quaternary, but few studies have investigated their impact on the genetic diversity of plant species and we lack knowledge on the extent of gene flow to predict how plant species can cope with such environmental changes. Analysis of the spatial genetic structure (SGS) of a species is an effective method to determine major directions of the demographic history of its populations and to estimate the extent of gene dispersal. This study characterises the SGS of an African tropical timber tree species, Distemonanthus benthamianus, at various spatial scales in Cameroon and Gabon. Displaying a large continuous distribution in the Lower Guinea domain, this is a model species to detect signs of past population fragmentation and recolonization, and to estimate the extent of gene dispersal. Ten microsatellite loci were used to genotype 295 adult trees sampled from eight populations. Three clearly differentiated gene pools were resolved at this regional scale and could be linked to the biogeographical history of the region, rather than to physical barriers to gene flow. A comparison with the distribution of gene pools observed for two other tree species living in the same region invalidates the basic assumption that all species share the same Quaternary refuges and recolonization pathways. In four populations, significant and similar patterns of SGS were detected. Indirect estimates of gene dispersal distances (sigma) obtained for three populations ranged from 400 to 1200m, whereas neighbourhood size estimates ranged from 50 to 110. [less ▲]

Etude écologique d'une espèce alimentaire d'Afrique centrale et de l'ouest: le noisetier d'Afrique (Coula edulis Baill.)

Poster (2010, September)

Pericopsis elata (Harms) van Meeuwen in southeastern Cameroon : ecological and pedological approaches to improve the management of an endangered commercial timber species

Poster (2010, August)

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

Poster (2010, March)

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

Poster (2010, March)

CpDNA-based species identification and phylogeography: application to African tropical tree species

in Molecular Ecology (2010), 19(24), 5469-5483

Despite the importance of the African tropical rainforests as a hotspot of biodiversity, their history and the processes that have structured their biodiversity are understood poorly. With respect to past ... [more ▼]

Despite the importance of the African tropical rainforests as a hotspot of biodiversity, their history and the processes that have structured their biodiversity are understood poorly. With respect to past demographic processes, new insights can be gained through characterizing the distribution of genetic diversity. However, few studies of this type have been conducted in Central Africa, where the identification of species in the field can be difficult. We examine here the distribution of chloroplast DNA (cpDNA) diversity in Lower Guinea in two tree species that are difficult to distinguish, Erythrophleum ivorense and Erythrophleum suaveolens (Fabaceae). By using a blind-sampling approach and comparing molecular and morphological markers, we first identified retrospectively all sampled individuals and determined the limits of the distribution of each species. We then performed a phylogeographic study using the same genetic data set. The two species displayed essentially parapatric distributions that were correlated well with the rainfall gradient, which indicated different ecological requirements. In addition, a phylogeographic structure was found for E. suaveolens and, for both species, substantially higher levels of diversity and allelic endemism were observed in the south (Gabon) than in the north (Cameroon) of the Lower Guinea region. This finding indicated different histories of population demographics for the two species, which might reflect different responses to Quaternary climate changes. We suggest that a recent period of forest perturbation, which might have been caused by humans, favoured the spread of these two species and that their poor recruitment at present results from natural succession in their forest formations. [less ▲]