Sciage De Rebuts De Tectona Grandis L. F. (Teck)

Les rebuts de billons de teck abandonnés dans les parcelles après exploitation, sont taxés de faibles diamètres et de faible rendement au sciage. Le travail réalisé vise à montrer la similitude de ces valeurs entre les rebuts et les billons de premier choix. Sept cent (700) rebuts de billons de teck de 24 ans, sélectionnés en zone de forêt dense semi-décidue, ont été cubés et sciés en usine avec un plateau technique adapté aux bois de petits diamètres. Les résultats obtenus montrent que les diamètres moyens des rebuts de billons étudiés sont faibles et gravitent autour de la classe 15/19 cm à 37%, autour de la classe 20/24 cm à 44% (majoritaire), autour de la classe 25/29 cm à 15% et autour de la classe 30/34 cm à seulement 3%. Ces valeurs, bien que faibles, sont du même ordre de grandeur que celles des billons de premier choix de même âge ou d’âge proche. Le rendement brut sciage obtenu est de 38,12% qui est faible mais également similaire à celui des billons de teck de premier choix. Ce rendement chute de 4 à 7% en éliminant l’aubier pour améliorer la qualité des débités. Les rebuts de billons de teck présentent des diamètres et des rendements sciages faibles mais similaires à ceux des billons de premier choix. Les quantités abandonnées dans les parcelles prenant de plus en plus de l’ampleur, les rebuts offrent ainsi une bonne opportunité de valorisation de matière première à l’échelle industrielle par un plateau technique fixe ou mobile. Discarded teak logs in post-harvest plots are taxed with small diameters and low sawing yield. The work carried out aims to show the similarity of these values between the rejects and the logs of first choice. Seven hundred rejects of 24-year-old teak logs, selected in semi-deciduous dense forest zone, were cubed and sawed at the factory with a technical platform adapted to small diameter woods.The results obtained show that the average diameters of the discarded teak logs studied are low and revolve around the 15/19 cm class at 37%, around the 20/24 cm class at 44% (majority), around the 25/29 cm class at 15% and around the class 30/34 cm at only 3%. These values, although low, are of the same order of magnitude as those of firstgrade logs of the same age or near age.The gross sawing yield obtained is 38.12% which is low but also similar to that of the first choice teak logs. This yield drops by 4 to 7% by eliminating the sapwood to improve the quality of the sawn timber. Discarded teak logs have low lumber diameters and yields, but are similar to those of high grade logs. The quantities left in the plotstaking more and more scale, the rejects thus offer a good opportunity for raw material valorization on an industrial scale by a fixed or mobile technical platform

Dynamique et structure de la flore de la Savane Protégée des Feux dans la Réserve Scientifique de Lamto (Centre de la Côte d’Ivoire)

This work that is one of the first of its kind in Unburned Savannah in Lamto, center of Ivory Coast, intends to characterize the vegetation in terms of dynamic evolution and plant structure, 53 years after its protection from fires. Surfaces plot, linear surveys and itinerant methods were used to collect floristic data. The diversity and the wealth of flora, as well as the structure of the different types of vegetation has been analyzed. 176 plant species belonged to genera 143 kinds and 49 families were indentified. The most important families are the Leguminosae (14.77 %), Rubiaceae (13.63 %) and Apocynaceae (10.79 %). About 15.37 % (27 species) of this flora represents the particular statute species. Among the inventoried species, 11 are exploitable species or exploited as timber of which ten are forest species. Due to richnes of its flore and flora dynamic, the Unburned Savannah must be protected. Based on an ascending hierarchical classification performed by using 11 linear surveys, this study has demonstrated the existence of a floristic variability to three groups

Tree allometry and stand structure in dryland forests relics of northern Côte d’Ivoire

The contribution of dryland forests in West Africa to carbon stocks remains poorly documented due to the lack of appropriate allometric models and inventory data. In this study, we gathered such data for dryland forest relics of northern Côte d’Ivoire. Inventory data were used to determine and sample the dominant species, and to characterize the stand structure. Destructive biomass data were used to develop local mixed-species allometric models for estimating tree aboveground biomass (AGB) and test the validity of existing allometric models, and to characterize the stand structure (including carbon stock). A total of 118 tree species belonging to 102 genera and 36 families were inventoried in 41 plots of 25 × 25 m (625 m² each, totalling 2.56 ha) sampled in three sites in the Korhogo department. Among them, seven predominant species, including one exotic, were selected for destructive sampling in one site, the Lataha Forest Research Station. Destructive biomass data for 34 trees belonging to these dominant species and with diameter at breast height between 6 and 41 cm were used to fit allometric equations specific to this forest type and to test the predictions of existing equations earlier developed for the global tropics and for African dry forests. Six equations integrating three predictors, stem diameter (D), total tree height (H) and wood specific gravity (ρ) were developed and the models with the three predictors showed the best performance. Pantropical models significantly over-estimated tree AGB by 20 % while models developed for African dry forests provided reliable estimates, suggesting a specific allometry of trees in dryland forest relics that needs to be further explored.. With our best AGB model, a quantity of 141.26 ± 92.72 tDM.ha−1 was estimated confirming that these dryland forest relics are important carbon stocks for this region where open vegetation dominates. This study constitutes an important contribution for the carbon accounting programs related to the implementation of REDD+ initiatives in Côte d’Ivoire