Diversité Et Structure Floristiques Sous Des Peuplements d’Acacias Australiens En Zone Forestière De La Côte d’Ivoire

Since thirty years, four Australian Acacias species are introduced and studied in Anguédédou Research station. The station research is located in evergreen forest in the south of Côte d'Ivoire. The objective of the introduction of these species, is to rehabilitate degraded grounds and fallow after growing. The study aims at appreciating the impact of Acacia species on floristic diversity and the regeneration of forest species. For collecting data, we use quadrat method (35 x 50 m and 6 x 6 m).This method permitted the inventory of 212 species on 1.05 ha. Among these species, 1.89 % are Ivorian endemic species and 11.32 % are endemic of West African flora. The flora under the different species of Acacia are relatively diversified and dense. The majority of plant inventoried under Acacia species have small diameters. The highest specific richness average per plots (36 m2) were noted in the 11 years old parcels of Acacia mangium (26.20±2.34) and 27 years old parcels of Acacia auriculaeformis (25.40±2.34) and Acacia crassicarpa (30.60±2.34). The mean values of diameters (dbh ≥ 2.5 cm) fluctuate from 2.94±0.56 cm for the 8 years old stands of Acacia mangium to 8.09±0.56 cm for the 27 years old settlements of Acacia crassicarpa. The results show that leguminous trees can be used for recolonization of the deforested areas in order to rebuild quickly their plant biodiversity

Insectes ravageurs et champignons parasites associés au dépérissement des peuplements de Tectona grandis (teck) régénérés à Téné, zone semi-décidue de Côte d’Ivoire

Les rejets de souche de teck sont l’objet d’attaque par des ravageurs et champignons capables de freiner leur croissance et développement. L’objectif est d’identifier les insectes ravageurs et les champignons parasites associés au dépérissement des rejets de teck régénérés à partir des souches. Au plan méthodologique, les ravageurs ont été caractérisés par repérage et exploration des dégâts corticaux et sous-corticaux des rejets de teck. Les champignons ont été isolés à partir des racines de rejets présentant des symptômes d’infection fongique. Les résultats ont mis en évidence la présence des termites (g. Ancistrotermes), des criquets puants (Zonocerus variegatus) et des coléoptères (Xyleborus aquilus). L’isolement et l’identification fongiques ont montré les espèces, Phellinus noxius, Fusarium verticilioides et les genres, Fusarium, Trichoderma, Penicillium et Aspergillus. Phellinus noxius, reconnu comme agent de pourriture brune racinaire provoque le dépérissement puis la mort des rejets de teck.© 2015 International Formulae Group. All rights reserved.Mots clés: Rejet de souche de teck, termites, criquets, coléoptères, champignons, dégâtsEnglish Title: Ravager insects and fungi associate to dieback of stand of Tectona grandis (teak) regenerate at Téné, semi deciduous zone of Côte d’IvoireEnglish AbstractSprouts of tools were attacked by ravagers and fungi capable to stop their growth and development. The objective of this work is to identify ravager insects and parasitizes fungi associate to dieback of sprouted from  tools of Teak. Methodologically, ravagers were characterized by search and exploration of cortical and subcortical damages of teak. Fungi were isolated from roots of sprout of stool presenting symptom of fungical infection. Results showed the presence of termites (g. Ancistrotermes), stinking crickets (Zonocerus variegatus) and beetles Xyleborus aquilus). Isolation and identification revealed the presence of fungal species Phellinus noxius, Fusarium verticilioides and genius, Fusarium, Trichoderma, Penicillium and Aspergillus. Phellinus noxius, known like agent of brown root rot incite dieback and sprouts death.© 2015 International Formulae Group. All rights reserved.Keywords: Sprouted from tools of teak, termites, crickets, beetles, fungi, damag

CHARACTERIZATION OF THE NATURAL FLORA OF THE UNDERSTORY OF THE RUBBER PLANTATIONS IN SOUTHERN COTE D’IVOIRE: CASE OF THE RUBBER PLANTATIONS OF THE CNRA ANGUEDEDOU

Objective: The study was conducted in the rubber plantations of the National Agricultural Research Centre (CNRA) of Anguédédou in the south of Côte d'Ivoire, to characterize the natural biodiversity of the undergrowth of rubber plantations, through the floristic composition and the evolution of the number of species according to the age of the plantations. Methodology and results: The methodology focused on the surface inventory. Thus, 36 surveys of 20 m x 10 m, or 200 m², were installed and inventoried through the rubber plantations of different age classes ([1 to 5 years], [6 to 10 years], [11 to 20 years] and [21 to 40 years]), abandoned rubber plantations and secondary forest. Regeneration was evaluated in plots with a 5 m (25 m²) coastline. The results have shown that rubber plantations are rich in 130 natural plant species. With the exception of rubber plantations from 1 to 5 years and especially of abandoned rubber plantations, the influence of this crop on the natural flora is felt in plantations from 6 to 10 years, with only 34 species. However, this flora evolves with the aging of the plantations. In abandoned plantations, 75 species were inventoried with a good presence of endemic species such as Chlamydocarya macrocarpa, Angylocalyx oligophyllus, Chassalia kolly, Mussaenda tristigmatica. There are also some rare and/or endangered species such as Albizia adianthifolia, Baphia nitida, Commelina benghalensis, Culcasia scandens, Gloriosa superba, Greenwayodendron suaveolens, Millettia zechiana and Milicia excelsa. The floristic similarity between abandoned rubber plantations and secondary forest, indicates a shift from abandoned rubber plantations to forest formations with high regeneration density, mainly in abandoned plantations. Conclusion and application: The study showed that the impact of rubber culture is felt on the natural flora of young rubber plantations. However, when plantations are abandoned, the environment becomes secondary forest. This investigation deserves to be carried out in other rubber plantations of other ecological zones of Côte d'Ivoire

Productivité maximale et âge d’exploitabilité technique de Tectona grandis (teck) en fonction de la fertilité des stations en Côte d’ivoire

Objectif : L’étude contribue à établir un modèle de gestion plus productif et qui valorise à court terme le reboisement du teck (Tectona grandis L. f.) en Côte d’Ivoire.Méthodologie et résultats : Le teck en provenance de Tanzanie, Thaïlande et Laos est mis en essai dans des placeaux temporaires de 3 zones écologiques en Côte d’Ivoire (forestières, préforestière, savane). Deux cents placeaux ont été mesurés pour élaborer le modèle de production. Le suivi expérimental s’est fait sur deux campagnes de mesure, de 1975 à 1980 et de 1980 à 1990. En fonction de la hauteur dominante et du diamètre d’exploitabilité des arbres, la classe de fertilité la plus élevée est obtenue en zone de forêt dense, la moyenne en zone préforestière et la plus faible fertilité en zone de savanes. En fonction des niveaux de fertilité des stations, les âges d’exploitabilité technique se situent entre 10 et 16 ans pour les zones de forêt dense avec des diamètres atteignant 20 à 25 cm et une productivité comprise entre 12 et 20 m3/ha/an. En zone de savanes, la productivité maximale, (6 m3/ha/an), est obtenue à 18 ans avec un diamètre d’exploitabilité moins important de 15 cm.Conclusion et application des résultats : la zone forestière dense caractérise au mieux la production maximale de bois avec un âge d’exploitabilité technique plus faible.Mots clés : Tectona grandis, classes de fertilité, âges d’exploitabilité technique, productivité maximale de bois, Côte d’Ivoire.Maximal productivity and technical exploitability age of Tectona grandis (teck) according tostations fertility in Côte d’IvoireABSTRACTObjective: The study aims to establish a management model for more production and which establishes short term teak reforestation in Côte d’Ivoire.Methodology and results: Teak from Tanzania, Thailand and Laos were planted in temporary plots of three ecological zones in Côte d’Ivoire (forest, transition, savanna). The experiment was observed on two campaigns, from 1975 to 1980 and 1980 to 1990. According to the dominant height and diameter’s exploitability of tree, the highest class fertility is obtained in closed forest zone, the average in transition forest area and the weakest fertility in savanna zone. According to the stations fertility levels, technical loggable ages of tree ranged from 10 to 16 years for closed forest with diameters reaching 20 and 25 cm and maximum wood productivity ranging between 12 and 20 m3/ha/year. In the savanna zone, maximum timber productivity, weaker (6 m3/ha/year), was obtained later at 18 years with a weakness diameter of exploitability of 15 cm.Conclusion and application of results: The closed forest zone characterizes better wood maximum productivity with a lower technical exploitability age.Keywords: Tectona grandis (teak), stations fertility classes, technical loggable ages, wood maximum productivity, Côte d’Ivoire