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Analysis of wood transects in a manner that preserves the spatial distribution of the metabolites present is highly desirable to among other things: (1) facilitate ecophysiology studies that reveal the association between chemical make-up and environmental factors or climatic events over time; and (2) investigate the mechanisms of the synthesis and trafficking of small molecules within specialised tissues. While a variety of techniques could be applied to achieve these goals, most remain challenging and impractical. Laser ablation direct analysis in real time imaging-mass spectrometry (LADI-MS) was successfully used to survey the chemical profile of wood, while also preserving the small-molecule spatial distributions. The tree species Entandrophragma candollei Harms, Millettia laurentii DeWild., Pericopsis elata (Harms) Meeuwen, Dalbergia nigra (Vell.) Benth. and Dalbergia normandii BosserR.Rabev were analysed. Several compounds were associated with anatomical features. A greater diversity was detected in the vessels and parenchyma compared with the fibres. Analysis of single vessels revealed that the chemical fingerprint used for timber identification is mainly determined by vessel content. Laser ablation direct analysis in real time imaging-mass spectrometry offers unprecedented opportunities to investigate the distribution of metabolites within wood samples, while circumventing the issues associated with previous methods. This technique opens up new vistas for the discovery of small-molecule biomarkers that are linked to environmental events.

Pericopsis elata est une espèce ligneuse à grande valeur commerciale menacée d’extinction. Les plantations d’Assamela installées dans la Réserve Forestière de Deng-Deng en 1974 ont été abandonnées après leur mise en place. Dès lors, très peu de connaissances relatives au développement de ces peuplements sont disponibles. L’objectif de la présente étude est de contribuer à la compréhension des conditions de croissance de Pericopsis elata dans la réserve et induire un aménagement efficace. Trois inventaires exhaustifs ont été conduits, au cours desquels les données dendrométriques et structurales ont été collectées. Les indices de compétition de Hegyi, les semi-variogrammes et la distribution spatiale des tiges ont été analysés et interprétés. Les densités actuelles sont sans effet limitant pour la croissance des tiges. Les effets du milieu se révèlent comme étant le facteur qui a plus d’impact sur la croissance des tiges de Pericopsis elata. La plantation de recrû (33,21 cm), moins sensible à l’effet de la densité en termes de croissance comparée aux plantations des grands layons (26,91 cm et 26,89 cm), enregistre les meilleures performances de croissance en diamètre. Ainsi, des travaux d’entretien et des éclaircies portées vers une réduction considérable des compétitions interspécifique et intra spécifique sont nécessaires.Mots clés : Indice de Hegyi, méthodes sylvicoles, modes de compétition, plantations équiennes, semi-variogramme, Cameroun. English Title: Characterization of the competition and growth of Pericopsis elata (Harms) Van Meeuven in the plantations of the Deng-Deng Forest Reserve (East, Cameroon)Pericopsis elata is a valuable woody species threatened with extinction. The Assamela plantations established in the Deng-Deng Forest Reserve in 1974 were abandoned after their establishment. As a result, very little knowledge about the development of these stands is available. The objective of the present study is to contribute to the understanding of the growing conditions of Pericopsis elata in the Reserve and to induce proper management. Three exhaustive inventories were conducted, during which dendrometric data were collected. Hegyi’s competition indices, variograms and spatial distribution of stems were developed. Current densities have no limiting effect on stem growth. Environmental effects were found to be the factor that had the greatest impact on the growth of Pericopsis elata stems. The recruiting plantation (33.21 cm), which is less sensitive to the effect of density in terms of growth compared to the large layon method (26.91 cm and 16.89 cm), has the best growth in diameter performance. Thus, maintenance work and thinning leading to a considerable reduction in interspecific and intraspecific competition is necessary.Keywords: Regular plantations, Hegyi’s competition index, mode of competition, Silvicultural methods, semi-variogram, Cameroon.

Influence de l’ecartement et du semencier sur la croissance des plants de Pericopsis elata durant les vingt premiers mois d’un essai de plantation Description du sujet. Pericopsis elata (Fabaceae) est un arbre heliophile des forets tropicales africaines qui produit du bois de grande valeur economique. Ses populations naturelles souffrent de surexploitation et presentent un deficit de regeneration naturelle. Les plantations pourraient augmenter sa production et limiter la pression sur les forets naturelles. Cependant, les connaissances sur l'influence de l'ecartement et du semencier sur la croissance des arbres font encore defaut pour les protocoles de plantation. Objectifs. Cette etude evalue l'influence de la densite de plantation et du semencier sur les croissances en diametre et en hauteur des plants de P. elata, 20 mois apres la plantation. Methode. Les graines ont ete collectees sur 19 semenciers dans un peuplement naturel de 400 ha pres de Kisangani (RDC). En octobre 2017, les plantules ont ete transplantees dans une plantation suivant le dispositif de Nelder en trois repetitions, pour comparer la croissance de 540 plants en plein decouvert suivant 10 densites differentes. Les accroissements en diametre et en hauteur ont ete analyses en fonction de la competition locale et du semencier, a l'aide des modeles additifs generalises. Resultats. Vingt mois apres la plantation, les croissances etaient maximales, en hauteur (165,6 ± 39,2 cm·an-1) a une densite intermediaire de 47 000 tiges·ha-1, en diametre (24,6 ± 8,3 mm·an-1) a une faible densite de 4 200 tiges·ha-1. L’origine genetique des plants a affecte leur croissance, les coefficients de variation entre semenciers ont atteint 7,6 % et 6,4 % pour les accroissements en diametre et en hauteur, respectivement. Le diametre initial a influence positivement la croissance diametrique mais la hauteur initiale n'a pas affecte la croissance en hauteur. Conclusions. Le dispositif de Nelder s'est avere utile pour confirmer la dependance de la croissance des plants vis-a-vis de l’ecartement et mettre en evidence l’influence de facteurs genetiques sur la croissance.

This study of the impact of heart rot of Pericopsis elata on logging yield was conducted in Libongo, in three logging concessions of the Societe d'Exploitation Forestiere et Agricole du Cameroun (SEFAC). An inventory of 92 P. elata stumps in four Annual Cutting Areas (AACs) divided among three Forest Management Units (FMUs) distinguished by Minimum Operating Diameter (MOD) revealed that 22 stumps were rotten. Decay was visible on stumps with a diameter of more than 100 cm with a frequency of occurrence of 23.91%, a percentage of abandonment of 55.20% and a yield of 44.79%. The most important economic loss was revealed on 9 abandoned whole logs that cumulated a volume of 145.547 m3. The correlation between the diameter of the stumps and that of the decay gives a coefficient or correlation rate r = 0.31. The MOD for P. elata could be 80 cm and covers the biological risk class. The results indicate that P. elata shows an increasing gradient of decay rate with increasing tree diameter, resulting in a loss of material for larger diameter trees, and consequently a decrease in material yield at processing.

The assamela (afrormosia) whose scientific name is “Pericopsis elata” (Harms), a large tree of great commercial value, is an exploited species. It is considered “endangered” by the IUCN.” Trees ready for harvesting are scarce because the logging diameter, which has been set at 100 cm, is very big. The studies recommended by the Cameroonian government as part of the ITTO/CITES project activities should be carried out to determine a new minimum logging diameter as the diameter increases with age. No credible solution is provided in the scientific literature to compensate for its scarcity of exploitation. Moreover, little or no information is available for describing the variation of its mechanical properties over time in order to determine the age at which its wood mechanical properties are good enough to be marketable. It is in this context that this work was undertaken. In this study, we adopted an experimental approach to evaluate the mechanical properties of this species exploited in southeast Cameroon. We then studied the variations in these properties as a function of tree age in order to propose leads for their exploitation. Thus, the compression and bending tests allowed us to estimate the relationship between the mechanical properties in three main directions of the log (MOE in compression and bending, failure stress in compression and bending, and creep in compression) and age (or diameter). We also used the 10-hour creep under low axial compressive loading data to implement the theoretical fractional Maxwell (MF) model, which was compared to the experimental data. For this purpose, after three months of natural drying in the laboratory, we evaluated the above mechanical properties according to age. This study shows that the mechanical properties change as the diameter increases and change very quickly from 70 cm diameter upwards. From the analysis of the experimental data, we deduced that the minimum diameter of exploitable trees should be equal to 80 cm corresponding to the age of about 200 years.

The prediction of the mechanical properties of wood and the evolution of its damage has been essential for its application in many fields such as bridges and houses construction, racks of trucks and so on. In more valorization of biomaterials following the example material wood arouses for a few years a private interest on behalf of the populations. The experimental characterization makes it possible to consider the mechanical properties local of Pericopsis elata (Assamela) according to various parameters (the wood turpentine, the orientation of wood fibers, water the content, the type of test …). From the results, we evaluate the mechanical characteristics of Pericopsis elata (Assamela) according to the three directions of Orthotropy. Then from the tests of load-discharge we measured the evolution of the damage using the variation of the Young modulus, which enabled us to note the reduction in the modulus of elasticity because of the damage following the three directions. Finally we noted a progressive and irreversible degradation of mechanical properties induced by the development of the microscopic cracks within material.

Reliable tree height-diameter (H-D) allometric equations are a key tool for the estimation of forest productivity and Above Ground Biomass (AGB). Most existing H-D allometric equations developed for the tropical region are based on large-scale multi-species datasets, and their use to derive information on productivity and AGB at the species level is prone to uncertainties. The single-species H-D allometric equations available are mainly focused on monocultures or stands with simple tree species mixtures and did not account for the site effects. Here we measured the height and diameter of 2,288 trees of the emergent tree species Pericopsis elata (Harms) Meeuwen in the Democratic Republic of the Congo (DRC) and in Cameroon. We first examined how accurate multispecies H-D allometric equations are in predicting the total height of P. elata. We then tested whether single-species H-D allometric equations vary between sites. We developed the first H-D allometric equation of P. elata and tested whether and how stand-level and environmental variables induce changes in H-D allometric relationship of P. elata at the regional level. We additionally evaluated whether tree-level variables are important at the local level where climate and stand development stage are expected to be less variable. We found that pantropical, regional and local H-D allometric equations significantly underestimate the total height of P. elata. The local multi-species H-D allometric equation developed for Yangambi showed the highest underestimation in all the studied sites. This result supports the need for an H-D allometric equation specific for P. elata. The species-level H-D allometric equation developed showed significant underestimations for trees from the disturbed and undisturbed forests in DRC, while overestimations were observed for similar sites in Cameroon. Using a mixed-effect H-D allometric equation, we showed that even within a single species, a substantial variation exists between sites. This variation showed to be driven by the differences in the maximum asymptotic height (Hmax) between sites. We found that P. elata trees are taller and attain higher Hmax in DRC than in Cameroon. The basal area showed to be a significant covariate accounting for the site effects at the regional-scale where climate variables showed minor effects. However, at the local-scale, none of climate or stand variables showed to be significant. Local-scale variation showed to be associated with differences in light availability, highlighting the potential of management options that shape the local environment in driving species productivity.

One of the problems limiting high survival rates of Pericopsis elata (afrormosia, assamela), a high value timber species, is lack of data on its pedological requirements. A study was conducted in the East Region of Cameroon to identify possible soil properties favoring its spatial distribution. Two test areas, in and out of a Pericopsis elata natural forest stand were identified and in each sampling units of 50 × 50 m delineated. Thirty eight and sixteen quadrats in and out of the stands were respectively sampled for soil physico-chemical properties, number of stems and diameter at breast height. Soil samples in each quadrat were analyzed following standard laboratory procedures. Soil properties were tested for normality and compared for the two sites using Student’s t-test. Principal component analysis and correlation analysis were performed on tree and soil data to identify soil factors responsible for spatial distribution. From our findings, key soil indicators favouring Pericopsis elata distribution appear to be acidity (soil pH and exchangeable acidity), base status (base saturation and exchangeable bases) and texture (clay content). More specifically, optimal soil conditions for growth and survival of Pericopsis elata are: pH (4.1 - 5.0), exchangeable acidity (&#183kg-1), base saturation (6.2% - 17.8%), and clay content (24.0% - 49.0%), which should be considered in site selection for reforestation with Pericopsis elata.

Background and Objectives: The origin of traded timber is one of the main questions in the enforcement of regulations to combat the illegal timber trade. Substantial efforts are still needed to develop techniques that can determine the exact geographical provenance of timber and this is vital to counteract the destructive effects of illegal logging, ranging from economical loss to habitat destruction. The potential of chemical fingerprints from pith-to-bark growth rings for individual comparison and geographical provenance determination is explored. Materials and Methods: A wood sliver was sampled per growth ring from four stem disks from four individuals of Pericopsis elata (Democratic Republic of the Congo) and from 14 stem disks from 14 individuals of Terminalia superba (C&ocirc, te d&rsquo, Ivoire and Democratic Republic of the Congo). Chemical fingerprints were obtained by analyzing these wood slivers with Direct Analysis in Real Time Time-Of-Flight Mass Spectrometry (DART TOFMS). Results: Individual distinction for both species was achieved but the accuracy was dependent on the dataset size and number of individuals included. As this is still experimental, we can only speak of individual comparison and not individual distinction at this point. The prediction accuracy for the country of origin increases with increasing sample number and a random sample can be placed in the correct country. When a complete disk is removed from the training dataset, its rings (samples) are correctly attributed to the country with an accuracy ranging from 43% to 100%. Relative abundances of ions appear to contribute more to differentiation compared to frequency differences. Conclusions: DART TOFMS shows potential for geographical provenancing but is still experimental for individual distinction, more research is needed to make this an established method. Sampling campaigns should focus on sampling tree cores from pith-to-bark, paving the way towards a chemical fingerprint database for species provenance.

Plant functional traits have shown to be relevant predictors of forest functional responses to climate change. However, the trait-based approach to study plant performances and ecological strategies has mostly been focused on trait comparisons at the interspecific and intraspecific levels. In this study, we analyzed traits variation and association at the individual level. We measured wood and leaf traits at different height locations within the crown of five individuals of Pericopsis elata (Harms) Meeuwen (Fabaceae) from the northern tropical forest of the Democratic Republic of the Congo. All traits varied between and within individuals. The between-individual variation was more important for leaf traits (23%&ndash, 48%) than for wood traits (~10%) where the within-individual variation showed to be more important (33%&ndash, 39%). The sample location height within the crown was found to be the driving factor of this within-individual variation. In a gradient from the base to the top of the crown, theoretical specific hydraulic conductivity and specific leaf area decreased while the stomatal density increased. We found significant relationships among traits and between wood and leaf traits. However, these relationships varied with the position within the crown. The relationship between vessel size and vessel density was negative at the bottom part of the crown but positive upward. Also, the negative relationship between stomatal density and stomatal size became stronger with increasing height within the crown. Finally, the positive relationship between specific leaf area and theoretical specific hydraulic conductivity became stronger in higher parts of the crown, suggesting that P. elata constantly adapts its water use with respect to its water supply, more strongly at the top of the crown where the environment is more extreme and less buffered against environmental fluctuations.

Résumé De par sa capacité à fournir les variations de croissance diamétrique sur toute la durée de la vie de l’arbre, la dendrochronologie est reconnue comme un outil important et efficace pour évaluer le lien possible entre la croissance et le climat. Dans cette étude, la croissance de deux espèces d’arbres tropicaux, Milicia excelsa (Welw.) C.C. Berg et Pericopsis elata (Harms) Meeuwen, a été analysée en réponse aux variations mensuelles de précipitations. La préparation des échantillons de bois ainsi que les mesures de cernes ont été effectuées suivant une approche particulière basée sur l’utilisation des outils SIG (Système d’Information Géographique). Pour chacune des espèces ciblées, une chronologie de croissance a été construite pour le site sur base de la datation de séries individuelles d’arbres récoltés. La comparaison de séries temporelles de croissance avec les précipitations a révélé que les croissances annuelles des arbres sont positivement liées aux variations des précipitations, mais à de périodes différentes au cours de l’année : première période de pluies (avril à mai) corrélée à la croissance de M. excelsa et la seconde période de pluies (septembre à octobre) à celle de P. elata. Dans le contexte actuel d’aménagement durable des forêts, il serait très indiqué de réaliser les études de ce genre sur d’autres espèces pour mieux comprendre la réponse des écosystèmes forestiers aux possibles modifications climatiques. Abstract Due to its ability to provide rapid growth variations over the life of the tree, Dendrochronology is recognized as an important and effective tool to assess the link between growth and climate. In this study, response of two tropical species from tropical forest, Milicia excelsa (Welw.) C.C. Berg and Pericopsis elata (Harms) Meeuwen, to rainfall variations was analyzed. Wood sample preparation as well as ring measurement were carried out following a particular approach based on the use of GIS tools (Geographic Information System). The species-site chronology was constructed from the cross-dated individual growth-ring series. The comparison of this chronology with time-series of local precipitations revealed that annual growth-ring is positively related to prepicitation during the rainy season but at different months: precipitation during the early rainy season (april to may) associated to the growing for M. excelsa and precipitations at the end of the rainy season (september to october) for P. elata. In the current context of sustainable forests management, it would be highly recommended to develop such studies on other species in order to better understand the response of forest ecosystems to possible climate change. &nbsp

This paper assesses the response of Pericopsis elata trees to silvicultural operations conducted in abandoned plantations settled between 1972 and 1975 in the East and South regions of Cameroon. Trees quality and DBH were evaluated before and 6 years after 2009 thinning. The silvicultural treatment of thinning improved the quality (physiognomy), the annual diameter increment and the stand basal area of trees. The average percentage of winding trees dropped from 82.8% in 2009 before thinning to 44.1%, six years later after thinning (2015). The most important average diameters were observed in thinned plots (27.3 ±10.4 cm - 30.5 ±10.0 cm) compared to non-thinned plots (22.9±13.2 cm-23.3±10.8 cm). Thinned plots gained at least 6 cm in diameter in 6 years, which is trice compared to the 2 cm observed in the non-thinned plots. The average annual diameter increment was 0.45 cm/year in thinned plots against 0.34 cm/year in non-thinned plots in the same period. Thinned plots have gain at least 6 m²/ha in the stand basal area against 1 m²/ha for non-thinned plots.

Ghana is on the verge of exhausting its timber resources and has embarked on reforestation. However, the establishment of pure stands of high value indigenous tree species such as Odum ( Milicia excelsa and M. regia ), Mahogany ( Khaya and Entandrophragma species) and Kokrodua ( Pericopsis elata ) were not successful as a result of insect pest and disease problems. These failures, together with the need to establish plantations partly account for the widespread planting of teak ( Tectona grandis ), cedrela ( Cedrela odorata ) and other introduced tree species. Disease outbreaks in Tectona grandis , Cedrela odorata and Ceiba pentandra have been observed with the expansion of plantation estates. A study was therefore conducted to identify key diseases occurring in tree plantations, determine their distribution and evaluate management strategies to contain them. Diseases encountered include root rot caused by Armillaria hemii on T. grandis and Cedrela odorata , leaf spot and dieback on Ceiba pentandra seedlings and saplings caused by Colletotrichum capsici, Fusarium solani and Lasiodiplodia theobromae , stem canker on Eucalyptus spp. caused by Botryosphaeria sp. and leaf blight caused by a Calonectria species. Management of these diseases will require training of foresters on tree health issues, quarantine and silvicultural practices and initiation of sound breeding and selection programmes.

To develop silvicultural guidelines for high-value timber species of Central African moist forests, we assessed the performance of the pioneer Milicia excelsa (iroko, Moraceae), and of the non-pioneer light demander Pericopsis elata (assamela, Fabaceae) in logging gaps and in plantations in highly degraded areas in south-eastern Cameroon. The survival and size of each seedling was regularly monitored in the silvicultural experiments. Differences in performance and allometry were tested between species in logging gaps and in plantations. The two species performance in logging gaps was significantly different from plantations and concurred with the expectations of the performance trade-off hypothesis but not with the expectations of species light requirements. The pioneer M. excelsa survived significantly better in logging gaps while the non-pioneer P. elata grew significantly faster in plantations. The high mortality and slow growth of M. excelsa in plantations is surprising for a pioneer species but could be explained by herbivory (attacks from a gall-making psyllid). Identifying high-value native timber species (i) with good performance in plantations such as P. elata is of importance to restore degraded areas, and (ii) with good performance in logging gaps such as M. excelsa is of importance to maintain timber resources and biodiversity in production forests.

While most past studies have emphasized the relationships between specific forest stands and edaphic factors, recent observations in Central African moist forests suggested that an increase of slash-and-burn agriculture since 3000–2000 BP (Before Present) could be the main driver of the persistence of light-demanding tree species. In order to examine anthropogenic factors in the persistence of such populations, our study focused on Pericopsis elata, an endangered clustered timber species. We used a multidisciplinary approach comprised of botanical, anthracological and archaeobotanical investigations to compare P. elata patches with surrounding stands of mixed forest vegetation (“out-zones”). Charcoal samples were found in both zones, but were significantly more abundant in the soils of patches. Eleven groups of taxa were identified from the charcoals, most of them also present in the current vegetation. Potsherds were detected only inside P. elata patches and at different soil depths, suggesting a long human presence from at least 2150 to 195 BP, as revealed by our charcoal radiocarbon dating. We conclude that current P. elata patches most likely result from shifting cultivation that occurred ca. two centuries ago. The implications of our findings for the dynamics and management of light-demanding tree species are discussed.

Rationale The genus Pericopsis includes four tree species of which only Pericopsis elata (Harms) Meeuwen is of commercial interest. Enforcement officers might have difficulties discerning this CITES-listed species from some other tropical African timber species. Therefore, we tested several methods to separate and identify these species rapidly in order to enable customs officials to uncover illegal trade. In this study, two classification methods using Direct Analysis in Real Time (DART™) ionization coupled with Time-of-Flight Mass Spectrometry (DART-TOFMS) data to discern between several species are presented. Methods Metabolome profiles were collected using DART™ ionization coupled with TOFMS analysis of heartwood specimens of all four Pericopsis species and Haplormosia monophylla (Harms) Harms, Dalbergia melanoxylon Guill. & Perr. Harms, and Milicia excelsa (Welw.) C.C. Berg. In total, 95 specimens were analysed and the spectra evaluated. Kernel Discriminant Analysis (KDA) and Random Forest classification were used to discern the species. Results DART-TOFMS spectra obtained from wood slivers and post-processing analysis using KDA and Random Forest classification separated Pericopsis elata from the other Pericopsis taxa and its lookalike timbers Haplormosia monophylla, Milicia excelsa, and Dalbergia melanoxylon. Only 50 ions were needed to achieve the highest accuracy. Conclusions DART-TOFMS spectra of the taxa were reproducible and the results of the chemometric analysis provided comparable accuracy. Haplormosia monophylla was visually distinguished based on the heatmap and was excluded from further analysis. Both classification methods, KDA and Random Forest, were capable of distinguishing Pericopsis elata from the other Pericopsis taxa, Milicia excelsa, and Dalbergia melanoxylon, timbers that are commonly traded.

Pericopsis elata (Fabaceae) is a highly commercial species of semi-evergreen wet forests in central and western Africa. Its exploitation began in the second half of the 20th century because of its highly valued wood on the international market. Because of its low potential for natural regeneration, it is now considered an endangered species by IUCN and listed in Appendix II of CITES. No action was taken on the identification of good mother tree to enable good production of seedlings suitable for the management of logged forests of this species. Hence the need for new scientific investigation with a view to obtaining the missing information which would allow an unambiguous decision on the threats to the species. The objective of this study, which was conducted from November 2015 to July 2016, was to determine the diameter classes with the highest seed germination rate and the highest viability of the seedling seedlings at four months after sowing. To determine the germination rate, 100 seeds were tested for each diameter class. After germination, the seedlings were monitored for 120 days at the end of which the viability rate was calculated for each diameter class. Seeds from mother tree of the highest diameter classes [60-70cm[, [70-80cm[, [80-90cm[ and [90-100cm[ recorded the best germination rates with respectively 36, 42, 30 and 36%. The simple regression between germination rate and seed diameter classes is significant at the 5% probability threshold. The highest seedling viability rate of 98% is obtained with mother tree the diameter class [70-80cm[. However, it should be noted that the simple regression between plant viability and seed diameter classes have a fairly good relationship.Read Complete Article at ijSciences: V62017041256 AND DOI: http://dx.doi.org/10.18483/ijSci.1256

The effects of four silvicultural methods notably Layon, Blanc-Etoc (BE), Martineau and assisted natural regeneration (ANR) have been compared on the dendrometric traits of Pericopsis elata Harms and Entandrophragma cylindricum Sprague planted in 1938 in Yangambi for controlling anthropogenic activities (agricultural deforestation and forest degradation) threatening the species to extinction added to difficult natural regeneration. The sustainable pedo-silvicultural system will preserve Yangambi biosphere reserve. In case of variance analysis significance; the non-parametric test of Kruskal Wallis and the test of Tukey Honest Significant Differences were applied to separate the traits means. Results have revealed that the three plantation methods were significantly different from ANR. BE, Martineau and Layon have determined the Gaussian shape for P. elata diametric structures while Layon, Martineau and ANR presented the inversed J shape for E. cylindricum. BE method convenes for plantations of the two species whose trait values were higher than those of other methods. The difference was significant between the widest average breast height diameter (DBH) of 44.49±10.63cm with the total height mean of 24.46±4.45m for P. elata and DBH of 29.63±11.59cm with the total height mean of 22.04±5.80m for E. cylindricum. The differences were also identified respectively for the two species regarding the basal areas with 25.54±5.6 against 9.474±1.67 m2/ha, the aboveground biomasses with 318.81±77.2 against 94.315±11.59t/ha and the loose volumes with 45069.49±12219.30 against 14 471.348±3 645.692m3/ha. The Layon method did not have significant effect on the E. cylindricum, but has influenced the DBH, AGB and basal area of P. elata. The least productive method ANR has expressed a convenient natural regeneration inversed J shape for the two species, as related to Yangambi reserve preservation.

In central Africa, most of the timber species require high light at the seedling stage for survival and growth. Forest managers face a regeneration shortage of these light-demanding timber species. To achieve long-term sustainability, there is a need for enrichment methods combining low cost and high species performance. The aim of this study was to assess the performance of Pericopsis elata seedlings in enriched logging gaps in Cameroon. Over five years, the survival and size of each seedling was monitored in 27 logging gaps that were either left without maintenance or cleared. Gaps were relatively small with an average total area of 155 m2. We found that planted seedlings of P. elata performed well in logging gaps. Even without any maintenance 61% of the planted seedlings survived after five years with an average annual diameter increment of 0.28 cm. P. elata appeared to be a good candidate species for enrichment in logging gaps. We demonstrated that the seedlings of P. elata tolerated a wide range of soil conditions but that their performance was strongly influenced by light availability (gap clearance), suggesting potentially improved performance of P. elata in high light environments such as in plantation or larger gaps.

Pericopsis elata (Fabaceae) is a tall tree of high commercial value of the moist semi-deciduous African forests. As a result of decades oflogging it is now considered as threatened and listed on the IUCN Red List and CITES Appendix II, even though essential biologicalparameters controlling its population dynamics remain unknown. This study aims at improving the knowledge of the species’ ecologicalparameters, and at assessing the impact of selective logging on its populations in an 118,052 ha forest in Cameroon. After inventoryingthe species in 1432 ha, mortality and growth were assessed over continuous 5- and 2-yr periods in unlogged and logged areas, respec-tively. Phenology was monitored in the unlogged forest during 5 yr. The population structure shows high relative abundance of trees inmedium size categories. Mean annual diameter increments in both environments did not differ significantly between unlogged andlogged areas. P. elata is a deciduous species that flowers at the end of the main dry season. The minimum reproduction and effectiveflowering diameters were 32 and 37 cm, respectively. Fruit maturation took place during 7 mo. With a minimum logging diameter of90 cm, the recovery rate computed over a 30-yr period was > 100 percent. Selective logging harvested only 12.1 percent of the totalnumber of seed trees and had little influence on the species’ biological parameters. Securing sufficient regeneration as a post-loggingaction is probably the most important consideration for achieving long-term sustainability.Abstract in French is available in the online version of this article.

Pericopsis elata is a timber tree with a high commercial value used as hardwood in the Congo basin forest. It is considered a threatened species by the International Union for Conservation of Nature (IUCN) and classified in 1992 in the annex II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The natural regeneration of P. elata is problematic; an increase in knowledge concerning its ecology, productivity, and potentials could significantly contribute to the sustainable exploitation of the species and improve its silviculture. Despite the irregularity of silvicultural treatment, Kienke south and Ndeng ndeng plantation, respectively situated in the south and east region of Cameroon, show acceptable survival rates. These rates are estimated at 91% in parcel P75 planted at 884 stems/ha and 69% in parcel P746 with a density of 192 stems/ha. Tree mortalities were mainly attributed to edaphic and climatic factors. The best performances of tree diameter growth were...

Traditionnellement, les études paléoécologiques menées en Afrique centrale ont documenté l’évolution de la végétation, en particulier le rôle du climat dans le façonnage des paysages forestiers tropicaux. Ces études restent néanmoins peu nombreuses, en raison des conditions d’accès au terrain et de la grande diversité en matière d’espèces végétales. En outre, la relation entre l’homme et son environnement y demeure un champ d’investigation relativement récent. Conduite dans une optique pluridisciplinaire, entre archéologie et écologie, cette thèse s’intéresse aux activités humaines passées dans le nord du bassin du Congo et à leur impact sur les forêts telles que nous les voyons aujourd’hui. L’analyse du cadre spatio-temporel des activités anthropiques dans l’Intervalle de la Sangha montre l’ampleur du manque de connaissances sur cette présence humaine. Elle souligne également l’absence d’occupations humaines entre ~1300 et 600 BP dans la zone d’étude. Une méthodologie est donc proposée pour combler ces lacunes, basée sur l’acquisition et l’analyse statistique des restes botaniques carbonisés trouvés dans les sols. Les résultats montrent une opposition spatiale entre espaces domestiques et agricoles. La combinaison d’endocarpes de palmier à huile carbonisés et de tessons de céramique indiquerait la présence de villages, tandis que la présence de charbons de bois supposerait davantage l’existence de champs. Par ailleurs, le rassemblement et l’analyse d’importants jeux de données (i. e. paléoécologiques, archéologiques, historiques et dendrologiques), centrés sur l’Intervalle de la Sangha et couvrant le dernier millénaire, soulignent l’effet des changements d’usage des terres sur la régénération de quatre populations d’arbres héliophiles actuellement exploités pour leur bois (Erythrophleum suaveolens, Pericopsis elata, Terminalia superba et Triplochiton scleroxylon). Les résultats mettent particulièrement en exergue le rôle de la colonisation européenne à partir de la deuxième moitié du 19e siècle dans ces changements, et le déficit de régénération de ces populations d’héliophiles depuis cette période. Ainsi, ce travail souligne l’importance de la chronologie, de l’identification des activités humaines passées au sein des forêts denses humides et de l’impact de l’histoire humaine récente sur les paysages forestiers d’Afrique centrale. Enfin, nous identifions plusieurs lacunes et proposons des pistes de recherche, notamment en direction des gestionnaires forestiers.

Seven methanol extracts of seven plants from seven plant families were screened for antimalarial properties. The plants were identified and selected from Gboko and Kastina-Ala local government areas in the Tivland ethnobotany in the Middle Belt Zone of Nigeria. Methanol plant extracts were evaluated for in vitro. antimalarial properties using the lactate dehydrogenase technique, with a multiresistant strain of Plasmodium falciparum. K1. Quantification of activity was by estimation of the concentration of extracts that inhibited 50% growth of parasite (IC50) in µg/ml. Of the seven plants screened, Erythrina senegalensis. DC (Leguminosae), Pericopsis elata. Harms (Papilionaceae), and Bridelia micrantha. Benth (Fabaceae) had IC50 values of 99.7, 124.8, and 158.7 µg/ml, respectively. Nauclea latifolia. SM (Rubiaceae) extract exhibited the least activity in the assay with an IC50 value of 478.9 µg/ml.

National audience; Because of their dominant role in the global carbon cycle, changes in tropical forest dynamics can affect the pace of the climate changes.Today, the only estimation of tropical tree growth comes from permanent plot networks. However, their installation is still much too recent (i.e. beginning of the 80’s for the oldest stations) to provide long enough temporal series to answer primordial, yet unsolved questions. Is tropical tree growth controlled by climate variations? Are tropical forests showing long-term changes of their productivity as temperate forests do? What are the impacts of the global changes on tropical forest functioning? An even more basic question is still fully unsolved: how old are tropical trees? Nevertheless, not any sustainable exploitation and management of the tropical forest resources is conceivable without knowing the age of the harvested trees. The dendrochronology approach (i.e. the study of annual rings in trees) was remarkably successful in solving these questions for temperate climate trees. The retrospective analysis of tree growth patterns not only gives direct access to the age of the trees, but allows reconstructing the past effects of the environment on tree physiology over decades or even centuries. However, insurmountable difficulties to identify annual growth rings in most tropical trees (due to nearly constant growth rates over the year) prevented dendrochronologists from using the classical method of ring width measurements. As we urgently need to understand the effects of the ongoing changes in climate and atmosphere on tropical forest, it appears especially important to develop new techniques for tropical dendrochronology. The objective of the project was to evidence the existence of cyclic chemical signals in tropical wood that could compensate for the lack of visible growth rings. The potential of dendrochemical analysis for emphasizing reliable markers of seasonal cycles was tested on trees of known age from three different species: two major long-lived species of the Guianan-Amazon tropical wet forest (Dicorynia guianensis, Sextonia rubra) and one from the equatorial African forest (Pericopsis elata). The analyses were performed at the DiffAbs beamline using synchrotron monochromatic X-ray beam of energy 18.1 keV. For each wood sample, the radial distribution of 17 elements was analyzed from the bark to the pith with a 300 μm spatial resolution using a Silicon Drift Detector. The results showed that these ringless tropical trees, by displaying seasonal variations in wood element composition, can yet keep an archive of their past growth. Compared to the only previous report established on one single tree, the current study, based on 13 trees, constitutes a much more robust assessment.

This scoping paper analyzes the governance of trade in timber-producing species regulated by CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) in light of the Convention's increasing relevance as a tool to control transnational timber trade. The CITES regulatory framework is outlined as it relates to tree species, along with the compliance mechanisms developed to build range state capacity for implementing trade controls in relation to tropical timber species and to apply sanctions to countries that fail to take recommended action to resolve implementation problems. The study describes stricter domestic measures developed by consumer countries, most notably the EU, to control imports of CITES-listed species, including trees, as well as additional regulatory frameworks designed by importing countries to exclude illegal timber from their markets. It also examines the implications for CITES of regional economic integration given the Convention's dependence on national border controls, with a focus on experience in the EU and trends in Asia. Key findings from three case studies of how CITES has approached governance of trade in valuable timber-producing species - ramin (Gonystylus spp.) from Asia, afrormosia (Pericopsis elata) from Central and West Africa and bigleaf mahogany (Swietenia macrophylla) from Latin America - are presented and other potential case studies identified. The study concludes by identifying priority areas where further research could contribute towards catalyzing positive change to strengthen the governance of transnational timber trade, and ultimately towards the survival of tree species traded illegally and unsustainably.

Heartwood decay is one of the major pathological constraints affecting the quality and marketable volume of tropical timber. A study on its behavior was conducted on Pericopsis elata in order to contribute to its sustainable management in Cameroon. Tree susceptibility to heartwood decay was evaluated using three diameter classes, based on allometric equations between decayed and healthy trees. Wood samples and visible macromycetes were taken from living and felled trees with an auger. Isolation of microfungi was performed on potato dextrose agar medium and their identification was based on the morphological and microscopic characteristics of the mycelium and conidia with reference to identification keys of mycology. Identification of macromycetes was based on their morphological characteristics as described in reference books on macromycetes identification. Results show that diameter class ]110, 120[ presented highly significant (P

The long-lived pioneer species Pericopsis elata is one of the rare tropical timbers on the list of the Convention on International Trade of Endangered Species, supporting the need for accurate and reliable growth data. In one planted and one natural forest in the Democratic Republic of Congo, respectively four and 37 Pericopsis stem disks were collected. The tree-ring series of planted trees were used to confirm annual tree-ring formation. For the natural forest, a tree-ring chronology with 24 stem disks ranged from 1852 up to 2008. This chronology was compared with time-series of local precipitation, resulting in a significant correlation with the second half of the rainy season (September–November). This seasonal precipitation was related with sea surface temperatures of the West Indian Ocean. Higher precipitation during El Niño years corresponded with higher tree-ring indices but differences were not significant. In addition, pointer years were rare and did not have a consistent link with extreme climatic conditions. The existence of annual tree rings encourages further tree-ring analyses of P. elata and other flagship timber species in order to further document climate-growth responses and to provide the long-term framework that is needed for sustainable management planning.

Objectives : This article examines the diametric growth of 4 commercial species, with poor natural regeneration, exploited in eastern Cameroon. The species are Erythrophleum suaveolens (tali), Mansonia altissima (bete), Pericopsis elata (assamela) and Triplochiton scleroxylon (ayous). Methodology and results : For this purpose, permanent monitoring growth devices constituted by permanent circuits were installed. After 3 years of annual measurements of the tree diameter, a periodic diametric medium growth of 0.68 cm / year for E. suaveolens , 0.37 cm / year for M. altissima , 0.32 cm / year for P. elata and 0.70 cm / year for T. scleroxylon was obtained. Considering the periodic medium growth of two diameter classes below the minimum diameter for logging, a new replenishment rate for the 4 species was calculated. Conclusion and application of findings :These replenishment rates were compared to the replenishment rate obtained using the diametric growth set by the Cameroonian government. There is an overestimation of the possibilities by the administration for M. altissima and T. scleroxylon and an underestimation of the possibilities in the case of E. suaveolens . For P. elata , the replenishment rate obtained in this study permanent devices is substantially similar to those calculated with the diametric growth proposed by the Cameroonian state. The results of this study will serve as a reference to the sustainable management of species with low diametric growth by raising their minimum logging diameter. For species with low natural regeneration as those considered in this study, silvicultural measures should be proposed. Keywords : commercial timbers; management plan; diametric growth; permanent devices; replenishment rate.

Summary 1 Seed germination in light and dark, and responses to irradiance and light quality, were tested in shadehouse experiments for 19 West African tropical forest tree species representing a wide range of ecological types. Germination in forest gaps of different size was tested for 11 species. 2 Percentage germination was reduced in the dark only for three small-seeded species that are common in forest soil seed banks: Musanga cecropioides, Nauclea diderrichii and Milicia excelsa. Percentage germination of the other 16 species, including four widely regarded as ‘pioneers’, was unaffected. 3 Effects of different irradiances in shadehouses, where the seeds were watered, were significant for some species, but there was no consistent pattern. Irradiance effects in forest gaps, where the seeds received only natural wet season rainfall, were more widespread and substantial, and were most commonly shown as a depression of percentage germination at high irradiance. 4 Effects of light quality (neutral vs. green shade; red : far-red = 0.43) were insignificant at 5% irradiance in shadehouses for all species except Nauclea diderrichii. In growth chamber experiments, the low energy response was only evident at 1.0 µmol m–2 s–1 (

SUMMARY We studied hemiparasitism in Okoubaka aubrevillei Pellegr. & Normand (Santalaceae), an uncommon West African rainforest tree of widespread distribution (Ivory Coast to Zaire) which attains heights of up to 40 m. It has a very large seed (mean fresh mass of 101 g), and slow accumulation of biomass characteristic of seedlings of shade- tolerant rainforest trees. 0. aubrevillei seedlings became hemiparasitic within 6 months when grown next to seedlings of the tree species Entandrophragma angolense (Wel.) DC., Pericopsis elata (Harms) Van Meeuwen, Pterygota macrocarpa K. Schum., and Tieghemella heckelii Pierre ex Chev. P. macrocarpa, and the nitrogen- fixing legume, P. elata were most infected. Characteristically for hemiparasites, midday leaf water potentials in 0. aubrevillei were at -2 MPa lower than those of the host seedlings. Stomatal conductance, however, was low, with a maximum of 111 mmol m2 s-1. After 1 yr, no significant effects of the hemiparasitism were observed on the growth of 0. aubrevillei or on its nutrient status as measured by foliar element concentrations. By contrast, the two most infected host species showed increased mortality and/or reduced growth. Foliar element concentrations were not, however, affected in host plants of the surviving species. Although the resources of a large seed might enable seedlings of 0. aubrevillei to grow independently from hosts for prolonged periods, their simultaneous strong effect on the mortality and growth of host seedlings might point to an alternative competitive function of hemiparasitism. Key words: Foliar nutrients, hemiparasite, leaf water potential, rain forest tree, stomatal conductance.

PREMISE OF THE STUDY Microsatellite loci were developed in the endangered Pericopsis elata using a combination of low-cost procedures. METHODS AND RESULTS Microsatellite isolation was performed simultaneously on three distinct species through a newly available procedure that associates multiplex microsatellite enrichment and next-generation sequencing, allowing the rapid and low-cost development of microsatellite-enriched libraries through the use of a 1/32nd GS-FLX plate. Genotyping using M13-like labeling in multiplexed reactions allowed additional cost savings. From 72 primers selected for initial screening, 21 positively amplified P. elata, and 11 showed polymorphism with two to 11 alleles per locus and a mean value of 5.4 alleles per locus. CONCLUSIONS These microsatellite loci will be useful to further investigate the level of genetic variation within and between natural populations of P. elata in Africa.

Pericopsis elata is an African forestry species commercialized under the vernacular names afrormosia or assamela. It is one of the principal species commonly exploited for timber in the Democratic Republic of Congo (DRC) and in a lesser extent in Cameroon and Congo. In view of its sustainable resource exploitation, the species is in centre of numerous polemics notably in the European Union. It is one of the rare commercialized species that produce wood, since 1992, as listed in the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) annex II specifying that “the exploitation of afrormosia necessitate the deliverance and a prior presentation of exploitation permit”. The most important reserves of afrormosia are found in DRC. This doctoral thesis presents the ecology of this particular tree and its behaviour regarding forestry exploitation. It allows to inform the international organisms such as CITES as well as the national policy-makers on the vulnerability of afrormosia and to propose appropriate measures that can avoid future unsustainable/unregulated exploitation activities/Pericopsis elata est une espèce forestière africaine commercialisée sous les noms d’afrormosia ou d’assamela. Elle est une des principales espèces exploitées pour le bois d’œuvre en République Démocratique du Congo (RDC) et dans une moindre mesure au Cameroun et au Congo. Elle est au centre de nombreuses polémiques, notamment dans l’Union européenne, en ce qui concerne la durabilité de son exploitation. C’est une des rares espèces commerciales productrice de bois d’œuvre listée, depuis 1992, dans l’Annexe II de la CITES (Convention sur le commerce international des espèces en danger d’extinction) qui spécifie que « L'exportation d'un spécimen d'une espèce inscrite à l'Annexe II nécessite la délivrance et la présentation préalables d'un permis d'exportation ». Les plus grandes réserves d’afrormosia se trouvent en RDC. Cette thèse de doctorat porte sur l’écologie de cet arbre et sur son comportement vis-à-vis de l’exploitation forestière. Elle permet d’informer les organismes internationaux comme la CITES et les décideurs nationaux sur la vulnérabilité de l’afrormosia et de proposer des mesures à prendre pour que l’espèce ne soit pas menacée par une exploitation mal conduite et non régulée, Doctorat en Sciences, info:eu-repo/semantics/published

Pericopsis elata is an African forestry species commercialized under the vernacular names afrormosia or assamela. It is one of the principal species commonly exploited for timber in the Democratic Republic of Congo (DRC) and in a lesser extent in Cameroon and Congo. In view of its sustainable resource exploitation, the species is in centre of numerous polemics notably in the European Union. It is one of the rare commercialized species that produce wood, since 1992, as listed in the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) annex II specifying that “the exploitation of afrormosia necessitate the deliverance and a prior presentation of exploitation permit”. The most important reserves of afrormosia are found in DRC. This doctoral thesis presents the ecology of this particular tree and its behaviour regarding forestry exploitation. It allows to inform the international organisms such as CITES as well as the national policy-makers on the vulnerability of afrormosia and to propose appropriate measures that can avoid future unsustainable/unregulated exploitation activities/Pericopsis elata est une espèce forestière africaine commercialisée sous les noms d’afrormosia ou d’assamela. Elle est une des principales espèces exploitées pour le bois d’œuvre en République Démocratique du Congo (RDC) et dans une moindre mesure au Cameroun et au Congo. Elle est au centre de nombreuses polémiques, notamment dans l’Union européenne, en ce qui concerne la durabilité de son exploitation. C’est une des rares espèces commerciales productrice de bois d’œuvre listée, depuis 1992, dans l’Annexe II de la CITES (Convention sur le commerce international des espèces en danger d’extinction) qui spécifie que « L'exportation d'un spécimen d'une espèce inscrite à l'Annexe II nécessite la délivrance et la présentation préalables d'un permis d'exportation ». Les plus grandes réserves d’afrormosia se trouvent en RDC. Cette thèse de doctorat porte sur l’écologie de cet arbre et sur son comportement vis-à-vis de l’exploitation forestière. Elle permet d’informer les organismes internationaux comme la CITES et les décideurs nationaux sur la vulnérabilité de l’afrormosia et de proposer des mesures à prendre pour que l’espèce ne soit pas menacée par une exploitation mal conduite et non régulée, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

En Afrique centrale, l’aménagement fores- tier repose sur une méthode de simulation de la production forestière peu précise, susceptible d’hypothéquer la durabilité de l’exploitation. L’objectif de cette étude est d’améliorer la prédiction de la crois- sance pour quatre essences commerciales importantes en Afrique centrale. Le dispo- sitif d’étude a été installé dans le Sud-Est du Cameroun et comporte 387 arbres : 136 assamela (Pericopsis elata), 54 moabi (Baillonella toxisperma), 124 sapelli (En- tandrophragma cylindricum), et 73 tali (Erythrophleum suaveolens). Le diamètre a été mesuré régulièrement entre 2009 et 2012. L’intensité de la compétition a été quantifiée à l’échelle d’une placette circu- laire de 20 m de rayon installée autour de chaque arbre focal. Les caractéristiques to- pographiques et hydrologiques ont été esti- mées à l’aide d’un système d’information géographique. La croissance a été modéli- sée en intégrant le diamètre des arbres et les conditions de croissance (indice de com- pétition et environnement local). Les valeurs d’accroissement utilisées actuellement au Cameroun ne sont pas différentes des va- leurs observées en forêt non perturbée par l’exploitation forestière pour l’assamela, le moabi et le tali, mais surestiment la crois- sance de 20 % pour le sapelli. Un modèle log-normal intégrant le diamètre des arbres et l’intensité de la compétition permet d’es- timer l’accroissement des quatre essences avec un coefficient de détermination (R2) va- riant de 0,092 pour l’assamela à 0,47 pour le moabi. Les variables topographiques et hydrologiques ne permettent pas d’amé- liorer significativement la qualité des pré- dictions. Ces modèles peuvent être utilisés pour prédire l’accroissement à partir des données d’inventaires forestiers d’aména- gement tels qu’ils sont réalisés en Afrique centrale, en vue d’améliorer la définition de paramètres de gestion tels que le dia- mètre minimum d’exploitation ou le taux de reconstitution pour les quatre essences étudiées.