Bruno de Foucault

Environmental and wood biophysical variabilities in teak plantations in Togo (West Africa).

Abstract This survey addresses the influences of ecological factors on wood biophysical properties of teak wood in plantation in Togo. On national scale, these plantations are discriminated in six ecological groups using a correspondence factor analysis. The same analysis applied to the wood biophysical properties permits to discriminate Togolese teak in six groups also. Within these six biophysical groups, wood density ranged from 600 to 800 kg/m3. Mesurements of colour permit to classify these plantations in three categories. Natural durability of these plantations varies from highly durable to durable. At Tchorogo forest site scale, a survey using synusial approach to phytosociology permitted to describe three phytocoenoses with different productivity index which are Icacina senegalensis phytocoenose, Ressantia indica phytocoenose and Daniellia oliveri phytocoenose.

Contribution à une caractérisation de la végétation de la forêt de Ngotto (République Centrafricaine)

Abstract One part of Ngotto forest (south-west of Central—African Republic) was studied by the synusial approach in an unpublished thesis; eleven associations, ten subassociations and one provisional community were identified and described. The new syntaxa are validated here according to the International code of phytosociological nomenclature.

Caractéristiques structurelles et écologiques des phytocénoses de sous-bois des plantations privées de teck du département de l’Atlantique (Sud-Bénin, Afrique de l’Ouest)

Abstract Structural and ecological characteristics of private Teak plantations in the Atlantic Department, South Benin, were studied according to the synusial approach of phytosociology in order to contribute to the sustainable management of the plantations. The study of dendrometric characteristics of Teak plantations was done by establishing two temporal plots, each of 1 are. In each plot, the stem girth of the trees and the total height of three mean trees were measured. A total of 99 vegetal synusias has been described, then combined into 18 phytocoenoses. Ecological characteristics are also studied.

Nouvelles réflexions sur les lois qualitatives du monde végétal et leur valeur heuristique

Summary As in quantitative laws of classic physics, the qualitative laws of the vegetal world (botany, plant sociology) constitute preferential bridges between some areas a priori without report (flora, vegetation on one hand, ecology, geography, dynamics…on the other hand). One gives an inventory of these multiple laws and one shows how it is possible to use them to acquire various informations from limited data. These laws have therefore a high heuristic value, intervening for example in the elaboration of synsystematic keys and in «paleo-plant sociology».

Diversités floristique et biogéographique des cédraies d'Algérie

Abstract The flora of Algerian cedar forests is studied. More than 500 species of vascular plants are listed, in about sixty families, belonging to various chorological types and characteristic habitats with a high patrimonial value. The analyses of rarity, endemic species richness and biogeographic value of this flora confirm its originality. The threats on this flora are put in evidence. The accent is also put on the priority actions of conservation to be led within these populations of cedars, endemic of the centre and west North Africas mountains.

The Psychotria vogeliana-community in the spontaneous undergrowth of teak (Tectona grandis L. f.) plantations in south-Benin: ecological and sllvicultural indicatory values

Abstract The spontaneous undergrowth of teak (Tectona grandis L. f.) plantation in Djigbé forest (south Benin) has been studied. The Psychotria vogeliana-community is identified from ten representative phytosociological relevés. This community is an indicator of sandy plateau soils generally associated with the least productive plantations. Its composed of 91 species with a mean of 32 species per relevé. The study of distribution spectra reveals the abundance of phanerophytes, secondary forest species and phytogeographically widespread species; they represent respectively 86%, 48% and 50% of the total number of species. The analysis of species diversity indicates that the Psychotria vogeliana-community is somewhat diversified, but the species abundance is weakly balanced (2.1 for Shannon-Wiever index and 0.48 for evenness index).

Contribution à la connaissance de l'écologie d'Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) et de Pistia stratiotes L. (Araceae) dans la région maritime orientale du Togo

Abstract The water plans of the Togolese East maritime region are all invaded by floating weeds. Phytosociological study of these ones show two communities: Lemno paucicoctatae-Pistietum stratioitis, a Myriophyllum spicatum community. Eichhornia crassipes is quite rare despite its presence on the Lomé lagoon and on the Mono river. Water chemical analysis show that values of conductivity, hydrotimetric title (TH), chloride ions and phosphate ions measured at a youthful stage of Pistia were lower than those measured with its death. The reverse phenomenon is observed for nitrate and ammonium ions. Feeble values of conductivity, TH and chlorides favourish nitrates and ammonium assimilation by floating species. Statistical analysis of the hydro-chemical parameters permit to classify these water biotopes in ponds, swamps, streams and lagoons.

Analyse phytogéographique comparative des savanes et des forêts de Ngotto (République Centrafricaine)

Abstract After several investigations on the savanna and forest of Ngotto (Central African Republic), we propose a phytogeographical interpretation of our data on the systematic (level family), the biological forms, the dispersion of diaspores and phytogeographical elements spectra. These spectra are given regarding both formation type (savanna, forest) to appreciate their originality. Then, a comparaison is driven in order to set up the differences between these two formations.

Phytocénose à Mallotus oppositifolius et Macrosphyra longistyla dans le sous—bois des plantations privées de teck (Tectona grandis) de la commune d'Abomey-Calavi, Sud-Bénin

Abstract A study has been undertaken in the natural undergrowth of private teak plantations in Abomey—Calavi using the synusial approach to phytosociology. Pedological and topographical factors and private teak plantation production within plant communities have been studied. Mallotus oppositifolius and Macrosphyra longistyla community is identified on acid clayey—sandy soils. It is composed of eight vegetal synusia and represents the fourth stage growth of the vegetation succession in the study area. Mean diameter of teak in this plant community varied between 5.7 cm and 15.8 cm while the mean height is between 6.5 m and 13 m and, the basal area between 10.7 m2/ha and 18.9 m2/ha. This community is indicative of the most productive forest sites of the municipality.

Quelques données ethnobotaniques sur la flore togolaise

à Lomé (Togo) ont permis de recenser 141 espèces utilisées dans le traitement de 174 affections dont les plus fréquentes sont : paludisme, anémie, ulcère gastrique, troubles de conception, hémorroïdes, toux, rhumatisme et constipation. 41 recettes ont pu être enregistrées. Les plantes sont employées isolement ou en association. Différents organes ou parties de plantes sont utilisés dans les différents remèdes. La plupart des revendeurs sont des femmes. La connaissance des vertus des plantes est transmise généralement de parents à enfants, oralement et par apprentissage.