Diversité végétale urbaine et estimation du stock de carbone : cas de la commune du Plateau Abidjan, Côte d’Ivoire

La réduction du dioxyde de carbone par les arbres est un important service écosystémique pour le bien-être humain. Dans les milieux urbains, ce processus est souvent négligé ou mal connu. La présente étude, réalisée au Plateau, à Abidjan, a permis d’évaluer la diversité des espèces végétales et le taux de carbone stocké par les arbres. Des jardins, des boulevards ainsi que l’espace de la gare Sud des bus, ont été les sites inventoriés. La présence/absence des espèces végétales ainsi que les circonférences de tous les individus d’arbres de dbh ≥ 10 cm, ont été notées. Au total 91 espèces végétales ont été recensées dont, Milicia regia, endémique et menacée d’extinction, pouvant éveiller la prise de conscience de l’environnement, peut être qualifiée d’emblématique.Dans l’ensemble des espaces, l’équivalent CO2 stocké par individu d’arbre est de 388,9 Kg ; ce qui témoigne du rôle compensatoire des espèces arborescentes, dans les émissions du dioxyde de carbone issu des activités anthropiques. L’ensemble des espaces étudiés, constitue donc un écosystème représentatif de la ville d’Abidjan.Mots-clés : biodiversité urbaine, service écosystémique, bien être humain, Côte d’Ivoire

Spatial Distribution of Cedrela Odorata Smaller Trees Affects Forest Regeneration in Exotic Tree Plantations in Central Côte d’Ivoire

Cedrela odorata L. was introduced as a possible forest restauration species in classified forests at Côte d’Ivoire. Because of its demonstrated invasive behavior in other tropical forests, this study aimed to assess the impact of Cedrela odorata on the regeneration of spontaneous plant species in tree plantations. On the base of Cedrela odorata larger tree densities, two types of forest plantation were considered: Type I (240 stems/ha) and Type II (176 stems/ha). In these plantations, plots with 0.25 ha were chosen to locate each tree with dbh ≥ 2.5 cm, in an orthonormal reference. The tree density, the basal area, the species richness, the Shannon diversity index and the rank-abundance curves were determined considering smaller and larger trees. The horizontal spatial arrangement and Ripley’s K function were performed to understand the spatial relationship between Cedrela odorata smaller trees and those of spontaneous species. The results shown lower spontaneous plant species richness (15-20 species) and diversity (1.15 - 1.43); the dominance of Cedrela odorata smaller trees (43.02 – 62.95 % of all stems). The Cedrela odorata smaller trees and those of other species have dependent spatial distributions; expressed by a spatial repulsion between the two groups up to a distance of 18 m in the most densified forest plantation. This repulsion was related to an aggregated distribution of Cedrela odorata smaller trees in plantation with higher tree density. The study suggests a 170-stems/ha (or lower) of Cedrela odorata planting density for biodiversity establishment improvement outcomes in forest plantations.

Identification and Validation of EST-Derived Molecular Markers, TRAP and VNTRs, for Banana Research

The advent of high-throughput sequencing technology has generated abundant information on DNA sequences for the genomes of many plant species. Expressed Sequence Tags (ESTs), which are unique DNA sequences derived from a cDNA library and therefore representing genes transcribed in specific tissues or at some stage of development, are one type of DNA sequences highly available today for many important crop species. Molecular markers are used for bridging DNA sequence information with particular phenotypes and are useful tools for genotyping germplasm collections and also for tagging genes involved in desirable agronomic traits. In this sense, there is always a strong demand for suitable marker techniques to better utilise existing sequence information. A transcriptome database from banana (Musa spp.), DATAMusa, containing 42,724 ESTs from 11 different cDNA libraries and encompassing approximately 24 Mb of DNA sequence, was used in this study for the design of primers to PCR-amplify two types of EST-derived molecular markers, Variable Nucleotide Tandem Repeat (VNTR) and Target Region Amplification Polymorphism (TRAP). These primers were then validated against a panel of 14 diploid Musa genotypes and produced 32 (VNTR) and 119 (TRAP) alleles. Used separately or together, both types of markers were able to discriminate Musa genotypes from different genome background (A or B genomes). The TRAP alleles identified were derived from only one EST, while the VNTR alleles were derived from 12 unigenes. Based on the results of this study, EST-derived markers can be an important source of polymorphism to be used in genetic diversity and gene discovery studies in banan

Stratégies et potentiel d’invasion des massifs forestiers par Hopea odorata Roxb. (Dipterocarpaceae) : cas du Parc National du Banco en Côte d’Ivoire

Le caractère envahissant et la germination de l’espèce Hopea odorata Roxb. (Dipterocarpaceae) ont été étudiés dans la forêt de l’Anguédédou et dans la périphérie du Parc National du Banco en Côte d’Ivoire. Le but est de démontrer le potentiel d’invasion et la capacité de reproduction de cette espèce exotique. Les résultats obtenus dans la forêt d’Anguédédou indiquent que Hopea odorata présente un taux de germination de 30%. Cette plante présente un fort taux de recouvrement (65%), une densité  élevée (12 292,31 individus/ha) avec un nombre considérable de jeunes plants qui totalisent 97,62% du nombre d’individus recensés de l’espèce. C’est une espèce très régulière et agressive dans la zone où elle est plantée. A la périphérie du Parc National du Banco, Hopea odorata  présente un recouvrement moyen de 10,17%, une densité de 6 480 individus/ha constitués essentiellement de jeunes plants. Les résultats démontrent la capacité de cet arbre à se disperser et à coloniser la  périphérie du Parc National du Banco et pourrait contribuer à son caractère envahissant.Mots clés : Arbre non-indigène invasif, biologie des populations, écologie de l’invasion, invasion biologique, invasion par les arbres

Value-adding post harvest processing of cooking bananas (Musa spp. AAB and ABB genome groups)

Cooking bananas (including plantains) are among the major commodities used in Sub Saharan Africa to combat food insecurity. It is estimated that more than 30% of the banana production are lost afterharvest. The losses are mostly due to the rapid ripening of the fruits, poor handling, inadequate storage and transportation means, and poor knowledge of food processing options. Processing the fresh fruits into food products with a longer shelf life can provide a major outlet to use surpluses and to exploit a greater number of marketing options. In this paper, we provide ingredients and recipes for food products made by the International Institute of Tropical Agriculture (IITA) from its improved hybrids of cooking bananas to decrease post harvest losses, diversify the industrial potentials of bananas, and add value to farmers’ products. Some of these processing methods can be used by farmers and ruralentrepreneurs in their communities to ensure food security and raise their incomes, or upgraded by the private sector in a value chain approach to curb production losses in bananas.Keywords: Bananas, food security, post harvest, food processing, value additio

Déterminismes De La Dynamique De La Forêt Des Marais Tanoé-Ehy (Sud-Est, Côte d'Ivoire)v

Objective: The Tanoé-Ehy Forest (FMTE) has been identified as a top priority site for primate conservation in West Africa. Pending the completion of the measures of its final classification in protected area, anthropic pressures are constantly nibbling the types of habitat that the FMTE contains. The objective of the present study was to analyze the spatial and temporal evolution of this forest from 1986 to 2016. The study consisted in mapping and following through Landsat satellite images from 1986, 2000, and 2016 the dynamics of the land use that constitute the FMTE. To better understand the underpinnings of this evolution, based on anthropogenic threats, surveys were carried out in the five villages closest to the forest. Treatments show a 10% degradation of swamp forest area to degraded forests in 30 years. The habitats temporarily flooded forests remained intact during this 30 years period, reflecting efforts to maintain the integrity of the FMTE. Surveys have shown that the types of pressure and their intensity vary from peripheral villages. Overall, this involves wood harvesting and hunting. In view of the importance of the FMTE in terms of a particular ecosystem and the conservation of biodiversity, it is desirable and urgent that, in addition to awareness-raising campaigns for local populations, the process of its final ranking be accelerated to end its degradation

Diversity Analysis of Elite Maize Inbred Lines Adapted to West and Central Africa Using SSR Markers

Seventeen elite maize inbred lines of West and Central Africa adaptation with tropical and temperate x tropical origin were investigated for diversity at 18 SSR loci in non-coding regions of the maize genome, alongside two temperate inbred lines (B73 and Mo17), perennial teosinte (Zea diploperennis) and gamagrass (Tripsacum dactyloides). A total of 174 alleles were detected with a range of 5 to 15 alleles per maker and an average of 9.7 alleles per locus. Polymorphic information content (PIC) ranged from 0.29 in umc1226 to 0.92 in bnlg2122 with an average of 0.75. Relationships between heterotic groups and groups based on SSR data were quite varied for the lines studied. Primarily, the SSR markers grouped the lines on the basis of their origin, with three instances of a pair of heterotic lines clustering together; one pair of temperate origin and the other two tropical vs temperate x tropical. Four inbred lines (CMR 19, CMR 20, CMR 21, and CMR 26), belonging to three heterotic groups were, however, differentiated by SSR data. The markers showed potential for use in managing inbred lines germplasm adapted to West and Central Africa, particularly for classifying inbred lines for which records of ancestry are not readily available and for exploiting the heterosis known for tropical vs. temperate x tropical crosses

Evaluation De La Diversité Et Estimation De La Biomasse Aérienne Des Arbres Du Jardin Botanique De Bingerville (District d’Abidjan, Côte d’Ivoire)

The Bingerville Botanical Garden is an urban green space which can contribute to the quality of the living environment and to attractivity of tourists in Abidjan city. Its floristic diversity and socio-economic and ecological benefits remain still unknown. The present study was conducted to assess botanical species diversity and the reduction of CO2 emissions in this space. Trees species with dbh ≥ 10 cm were recorded in 41 plots of 500 m² surveyed in four types of biotopes: two arboretums with 20 and 100 years old, one secondary forest with more than 100 years and a fallow of 20 years old. Floristic indices and aboveground biomass (AGB) were determined for each biotope. A total of 742 trees with dbh ≥ 10 were counted: 127 species. Preponderance species are Cassia siamea, Terminalia mantaly, Milicia excelsa and Ceiba pentandra in arboretums, Pentadesma butyracea and Acacia mangium in the secondary forest, Ficus exasperata and Borassus aethiopum in the fallow. Arboretums are richest (96 species), and they have more AGB (566.7 t/ha). The secondary forest has 71 species with an aboveground equal to 381.4 t/ha. The fallow is less rich (13 species) with an AGB of 21 t/ha. This study has shown the importance of Bingerville Botanical Garden in plant and fighting against climate change

Relations entre la diversité et la biomasse aérienne des espèces arborescentes dans les agroforêts traditionnelles à base de cacaoyers: Cas de la localité de Lakota (Côte d’Ivoire)

En matière de gestion durable des systèmes agroforestiers à base de cacao, il serait important de trouver un compromis pour à la fois conserver la biodiversité et les stocks de carbone ; ce qui constituerait une alternative écologiquement soutenable à l’agriculture conventionnelle. En Afrique sub-saharienne, peu d’études ont mis la lumière sur les relations éventuelles entre la biomasse végétale et la diversité biologique dans ces systèmes. La présente étude a permis de tester ces relations dans des agroforêts à cacao de Lakota en Côte d’Ivoire. Des cacaoyères et des forêts ont été inventoriées selon la méthode des transects à aire variable. Plusieurs indices floristiques, ont été calculés et la biomasse aérienne a été estimée, pour les espèces arborescentes de dbh > 2,5 cm. Au total, 215 espèces ont été dénombrées dans l’ensemble des biotopes dont 57,2 % en forêts anciennes, 50,2 % en forêts secondaires et 26 à 45 % dans les plantations. La biomasse aérienne des arbres sur pied dans les forêts anciennes est plus élevée (203,7 t ha-1) que dans les plantations où la biomasse baisse jusqu’à 90,2 t ha-1. Il n’existe pas de relations significatives entre la biomasse aérienne et la diversité des espèces dans les forêts. Dans les plantations âgées de plus de 15 ans, une forte diversité spécifique peut être bénéfique à 20 % dans l’augmentation de la biomasse sur pied. Les pratiques paysannes traditionnelle sen cacao culture peuvent donc garantircon comitamment, la diversité floristique et la biomasse qui est le facteur déterminant dans la séquestration du carbone.Mots Clés: Réchauffements climatiques, système agroforestier, Côte d’Ivoire, activité anthropiqueEnglish AbstractFor sustainable management of cocoa based agroforestry systems, it is important to find a tradeoff to conserve both biodiversity and carbon stock; which would be an ecologically sustainable alternative to conventional agriculture. In Sub-Saharan Africa, few studies have tested relationships between plant biomass and biodiversity in these systems. This study analysed these relationships in Cocoa based agroforest in Lakota area in Côte d’Ivoire. Cocoa farms and forest patches were inventoried using the variable-area transect method. We considered all trees species with dbh> 2.5 cm. Pearson correlation was used to test probable links between aboveground biomass and diversity indexes. We recorded a total of 215 tree species in all habitats, of which 57.2% were in old growth forests, 50.2% in secondary forests and 26-45% in cocoa farms. Biomass stock of old growth forests was greater (203.7 t ha-1) than in plantations, where it dropped to 90.2 t ha-1. There was no significant relationship between aboveground biomass and floristic indices in forests. In old plantations of over 15 years old, high species diversity could contribute up to 20% in the aboveground biomass. The conservation of floristic diversity in cacao based agroforestry systems may represent an important factor in mitigating global warming, through the storage of large amounts of carbon.Keywords: Climate change, cocoa based agroforestry system, Côte d’Ivoire, human activitie