Leaf area and leaf dry biomass are key parameters linked to plant production and they are used in functional–structural plant models to simulate plant growth, but they are difficult to ascertain. Measuring leaf dimensions (length and width) to estimate them provides a non-destructive and rapid approach that can be used in the field. This was tested on teak (Tectona grandis) in Togo. Leaves were sampled to maximize variability in sizes along two categories of axes and at different ranks on the growth units. Two different equations were determined to estimate leaf area and dry biomass from leaf dimensions. The relation between leaf area (A) and the product of length (L) × width (Wi) was defined by the linear equation A = 0.60 × L × Wi whereas dry biomass (We) was predicted by a power law We = 0.004 × (L × Wi)1.11. This method could also be tested and applied to other species
Abstract:The accuracy of ten methods of scaling (Smalian, Huber, Newton, Neloï d, paraboloid, cone, paracone, cylinder, truncated cone and truncated Neloï d) was evaluated on logs of 0.5, 1, 2 and 3 m cut to different heights of 27 teak trees. For this purpose, the volumes estimated by the ten formulas were compared with real volumes obtained by the technique of xylometer. The results obtained showed that the method of Huber was more efficient to calculate the volume of logs throughout the stem when the length was 0.5 m. For the other length logs, it was also the best formula when the logs came from the base of the stem. The formulas of Newton and Smalian gave in the center and top of the stem, in the case of 1 m and 2 m logs, relatively similar results and were better than other methods of scaling. As might be expected, the dendrometric method (cylinder, paraboloid, Neloï d, cone) gave worse results regardless of the length of logs considered. With logs of 0.5, 1, 2 and 3 m long, truncated forms of cone and Neloï d could also be used without significant errors in estimating the volume of teak logs. The model scaling obtained for the entire tree OPEN ACCESS Diversity 2013, 5 100 expresses the logarithm of the volume against the logarithm of the diameter and the logarithm of height.
Key message A retrospective architectural analysis performed on planted teaks in Togo showed that the variation of wood radial properties were linked with tree ontogeny, and that these relationships depended on thinning practices and provenance. Context Variability in growth, flowering and forking in individual trees according to origin and/or thinning practices may affect wood structure and consequently impact wood physical properties. We tested this hypothesis in teak. Aims We sought evidence of: (1) origin effects (Togolese versus Tanzanian teak) on growth, flowering, cambial growth and wood properties; (2) thinning effects on these variables and (3) relationships between tree ontogeny and radial variations of wood properties. Methods A retrospective architectural analysis was used to draw stem growth and near infrared spectroscopy to assess radial variations of wood properties. Results Flowering reflects tree vigour and began at an earlier age in Togolese than in Tanzanian provenances. No differences were detected in regards to growth ring surface area, basic density and modulus of elasticity. Both systematic and selective thinnings improved growth without impacting the two latter properties. Stabilization of the growth ring area observed at 4 years old was associated with a decline in stem annual extension with a 1-year time lag. Conclusions Architectural analyses showed that radial growth was linked with tree ontogeny. This method can be extended to subsequent developmental stages, i.e. to older trees with economic interest, and used to determine architectural traits that are useful in tree selection. (Résumé d'auteur
L'analyse des indices cubitaux a montré qu'en dehors des abeilles de Dabou qui avaient une valeur moyenne de 2,28 ± 0,35, les abeilles de toutes les autres localités avaient des indices inférieurs à 2,10. Les résultats ont montré que les abeilles peuvent être classées selon la valeur de leur indice cubital, en trois groupes assez distincts. Cette étude ayant révélé une variation significative dans les caractères morphométriques de l'abeille au Nord-Est du Bénin, il importe d'adopter des stratégies appropriées pour la conservation de leur diversité.
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