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En Afrique, les plantations d'arbres sont amenées à se développer pour plusieurs raisons : restauration des capacités de production et des services rendus par les forêts naturelles, valorisation des terres agroforestières, récolte plus aisée du bois et des produits forestiers non ligneux, etc. Les espèces exotiques n'offrant que des services spécifiques, il importe de redynamiser la plantation d'espèces locales. C'est l'objet de ce guide, qui s'est focalisé sur les essences des forêts denses humides, en capitalisant des résultats d'essais passés ou récents de six pays africains, et en mobilisant des compétences et connaissances individuelles. L'ouvrage aborde de façon pratique les différentes étapes d'un programme sylvicole : récolte et gestion des semences, construction et gestion des pépinières, modalités d'installation et de conduite des plantations. Une estimation des coûts et de la rentabilité de telles plantations est également fournie. Enfin, le livre décrit en détail l'itinéraire sylvicole de 50 espèces d'arbres des forêts denses humides africaines. Ce guide est destiné à un large public : gestionnaires, aménagistes, techniciens et ingénieurs forestiers, étudiants et scientifiques intéressés par la sylviculture tropicale.

Entandrophragma genus includes exclusively African species (10 to 12), five of which are on the IUCN Red List. Characterized by a taxonomic evolution that has resulted in an important synonymy of species names (36-3 7) and insufficient ecological knowledge, it is the richest in valuable species exploited as timber in Africa. This important exploitation is likely to compromise their durability in the absence of sustainable management. Our study is mainly based on scientific data (e.g., publications), economic data (production and export statistics) and legal data (laws and regulations); on management plans and inventory reports. The heavy industrial exploitation as artisanal does not always proceed in the respect of a validated management plan, nor of the duration of the rotations which would make it possible to reach a rate of reconstitution likely to perpetuate the resource which these species represent. Their sustainable management requires the development and respect of management measures to make their exploitation sustainable in the long term. This exploitation must be based on an adequate management of natural stands and on reforestation as well as on conservation measures. The research to be developed must focus on their growth rate (eg, in the face of climate change), the analysis of stable rings and isotopes, the evaluation of their stocks (production, biomass, carbon), their spatial distribution and molecular phylogeny, the improvement of their natural regeneration, their reproduction, phenology and anatomy, as well as the reinforcement of other relevant lines of research to guarantee the durability of these forest species.

Xylem vessel features are the most investigated anatomical traits of Angiosperm wood. They are being analyzed in ecophysiological projects aiming at understanding sap flow and vulnerability to drought stress. Since long, size, grouping and density of vessels are also used as one of the first steps in timber identification, as they can easily be observed even with a hand lens. Vessels are also known to be related to tree height. The volumetric sap flow rate is inversely related to the length of the path, so that vessels need to widen at lower parts of the tree and taper towards the higher parts to assure optimal transport and a stable hydraulic resistance with progressing growth in height. Vessels are expected to narrow from roots to stem and further to the branches and the petioles. Accordingly it is also predictable that vessel features on pith-to-bark profiles are a proxy for height growth for individual trees. Since the functional groups of species of a tropical rainforest are based on height grow rate (related to light needs), it is expected that pith-to-bark profiles of vessels reveal information on temperament of the species. A methodology has been developed to establish pith-to-bark profiles of vessel features, based on long microtomic sections, image analysis and machine learning. Entandrophragma was used as a model genus. The differences between the four most common species of this genus have been explored. Wilcoxon signed rank test indicate that the difference in mean vessel size is significant between every species combination except between Entandrophragma candollei and Entandrophragma cylindricum. Interesting to note is the large vessel size range possible for Entandrophragma utile. Currently, pith-to-bark vessel trends are constructed that could help explaining difference in growth strategy. The approach offers appealing perspectives to find a formal way for sub setting tree species into functional groups and develop indexes for growing conditions of forest sites.

Because of the quality of their wood and their many traditional uses, species of the Entandrophragma genus are being intensively logged, and this is likely to compromise their survival unless sustainable management is introduced. This study reviews the current status of the five main commercial Entandrophragma species: Entandrophragma angolense, E. congo-lense (often confused with E. angolense), E. candollei, E. cylindricum and E. utile. We suggest directions for research to improve sustainable management strategies for this genus. The study draws mainly on published scientific data, economic data (production and export sta-tistics) and on relevant laws and regulations, but also on existing management plans and inventory reports. Although these species are reported as vulnerable on the IUCN Red List, knowledge on their management is still patchy. Industrial and artisanal logging is intensive and does not always follow a validated management plan or abide by the minimum rotation period, both of which would help to ensure the renewal of these resources. Managing them to ensure that logging is sustainable in the long term requires management measures to be developed and complied with. Sustainable use has to be based on appropriate management of natural stands and on reforestation and conservation measures. Research studies to be developed should encompass the growth rates of the species in the light of the changing climate, assessments of stocks (timber, biomass and carbon), updates of their spatial distribution, improvements to natural regeneration, reproduction processes and the anatomical and technical properties of each species. All these research topics are necessary to ensure the permanence of these Entandrophragma species., SCOPUS: ar.j, info:eu-repo/semantics/published

Par la qualité de leur bois et leurs nombreux usages traditionnels, les espèces du genre Entandrophragma font l'objet d'une intense exploitation, susceptible de compromettre leur pérennité en l'absence de gestion durable. La présente étude dresse un état de la situation de cinq espèces commerciales principales de ce genre : Entandrophragma angolense, E. congoense (souvent assimilée par erreur à E. angolense), E. candollei, E. cylindricum et E. utile. Elle propose des pistes de recherche pour améliorer les stratégies de gestion durable au sein de ce genre. L'étude est principalement basée sur les données scientifiques (publications), économiques (statistiques de production et d'exportation) et juridiques (lois et réglementations), mais aussi sur les plans d'aménagement et les rapports d'inventaire. Les connaissances sur leur gestion sont encore fragmentaires alors qu'elles sont considérées comme vulnérables dans la liste rouge de l'UICN. La forte exploitation industrielle ou artisanale de ces espèces ne s'effectue pas toujours dans le respect d'un plan d'aménagement validé, ni de la durée minimum des rotations qui permettraient l'un et l'autre un taux de reconstitution pérennisant cette ressource. Leur gestion durable exige notamment le développement et le respect de mesures d'aménagement pour rendre leur exploitation renouvelable à long terme. Cette exploitation doit s'appuyer sur une gestion adéquate des peuplements naturels et sur le reboisement ainsi que sur des mesures de conservation. Les recherches à développer doivent intéresser leur vitesse de croissance face aux évolutions climatiques, l'évaluation de leurs stocks (production, biomasse, carbone), l'actualisation de leur distribution spatiale, l'amélioration de leur régénération naturelle, les processus de leur reproduction, leurs propriétés anatomiques et technologiques, autant de pistes pertinentes pour garantir la pérennité des espèces exploitables du genre Entandrophragma.

Introduction. Les espèces d’arbres du genre Entandrophragma font l’objet d’une attention toute particulière de la part des exploitants forestiers et des scientifiques depuis plusieurs décennies. Établir un bilan exhaustif actualisé des connaissances acquises sur leur taxonomie et leur écologie afin d’en dégager des pistes de nouvelles recherches est le but de cette synthèse bibliographique. Littérature. Le genre Entandrophragma compte des espèces (10 à 12) exclusivement africaines et qui sont exploitées pour la qualité de leur bois. Ces espèces sont répandues dans la région guinéo-congolaise (6 espèces) et dans les régions zambézienne et afromontagnarde (5 espèces). Le genre est caractérisé par une évolution taxonomique qui s’est traduite par une importante synonymie des noms d’espèces (36 à 37). Des études écologiques un peu larges ont été réalisées sur quelques principales espèces commerciales (Entandrophragma angolense, Entandrophragma congoense, Entandrophragma candollei, Entandrophragma cylindricum, Entandrophragma palustre et Entandrophragma utile) dans leurs zones phytogéographiques comprises principalement dans la région guinéo-congolaise.Conclusions. Les informations sur la taxonomie et l’écologie des espèces d’arbres d’Entandrophragma des forêts claires et des savanes sont insuffisantes comparativement à celles des forêts denses humides. Des travaux de recherches devraient être développés pour l’amélioration des connaissances taxonomiques, génétiques et la maitrise de leur écologie en vue de formuler des recommandations adéquates en matière de préservation et de gestion durable de ces espèces., Entandrophragma: taxonomy and ecology of a genus of African tree species with economic importance. A review Introduction. Entandrophragma tree species have been the subject of special attention by foresters and scientists for several decades. The purpose of this bibliographic review is to examine the current knowledge acquired on the taxonomy and ecology of this genus in order to identify new research priorities.Literature. The genus Entandrophragma has exclusively African species (10 to 12) that are exploited for the quality of their wood. These species are widespread in the Guineo-Congolese region (6 species) and in the Zambezian and Afromontane regions (5 species). The genus is characterized by a taxonomic evolution that has resulted in an important synonymy of species names (36 to 37). Ecological studies have been carried out on some major commercial species (Entandrophragma angolense, Entandrophragma congoense, Entandrophragma candollei, Entandrophragma cylindricum, Entandrophragma palustre and Entandrophragma utile) in their phytogeographic zones, mainly in the Guineo-Congolese region.Conclusions. Taxonomy and ecology of Entandrophragma tree species typically occurring in woodlands and savannas have been insufficiently studied in comparison with Entandrophragma species occurring in rainforests. Research needs to be developed for the improvement of taxonomic, genetic and ecological knowledge, with a view to formulating appropriate recommendations for the conservation and sustainable management of these species.

Polymorphic (1) and monomorphic (0) SNP loci (P0040, P0095, etc.) in the six genetic clusters of Milicia (K1 to K6). Table S2. Geographic coordinates of Central African individuals of Milicia that may represent a new species according to SNP and based on the whole Milicia sample of the ITTO Project PD 620/11 Rev.1 (M): “Development and implementation of species identification and timber tracking in Africa with DNA fingerprints and stable isotopes” (1833 individuals). Individuals in bold are those selected for the SNP-SSR comparison (435 individuals in total) and which all turned out to be representatives of a new species as the nuclear gene At103 confirmed. Figure S1. Determination of the number of genetic clusters in Milicia populations based on SNPs genotypes. Figure S2. Determination of the number of clusters in Milicia populations based on SSRs genotypes. Figure S3. (A) Lower surface of leaf for a tree morphologically identified as M. regia in Central Africa and confirmed by molecular markers, compared to a neighbour tree with typical leaves of M. excelsa (B). Figure S4. Graphical membership coefficient of Central African individuals of Milicia (genetic clusters K3 to K6) based on nuclear SSR loci. The six colours (blue, black, yellow, pink, green and red) stand for the six genetic clusters. The West African genetic clusters, K1 and K2, were not illustrated but were represented in some individual genome (blue and dark colors). Figure S5. Haplotype network and geographical distribution of trnH-psbA haplotypes in Milicia populations. Figure S6. Haplotype network and geographical distribution of trnC-ycf6 haplotypes in Milicia populations. Figure S7. Ecological niches of the six genetic clusters of Milicia derived from nuclear SSR loci, in the environmental space produced by the principal component analysis method (PCA). The figure above indicates projection of the climatic variables in the plan formed by the two first axes (71.9% of the total variance). Similarly, the grey-to-black shading in the six small figures (1 = cluster K1; 2 = cluster K2; etc.) represents the grid cell density (black being the highest density) of the concerned genetic cluster in the PCA plan. The first dashed curve represents the 50% of the available environment space whereas the solid line stands for the entirety of the species environment. Figure S8. Potential distribution range of Milicia genetic clusters during the Last Glacial Maximum (LGM) according to niche modelling through Maxent approach. Black areas represent predicted regions with a probability higher than 50%. (DOCX 1353 kb)