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Le maraîchage urbain joue un rôle très important dans la sécurité alimentaire et la résorption du chômage. Cependant, l’intensification des pratiques culturales peuvent altérer les propriétés physicochimiques des sols et réduire les rendements. La présente étude avait pour but de caractériser les pratiques culturales maraîchères à Brazzaville et de déterminer leur influence sur les propriétés physicochimiques des sols. Dans les sites retenus, des enquêtes structurées ont été menées auprès des maraîchers et des échantillons de sol ont été prélevés suivant des transects. Les analyses physiques et chimiques des sols ont été réalisées suivant les procédures courantes de laboratoire. Les résultats obtenus ont montré que les pratiques culturales dans les sites étudiés sont intensives. Les sols étudiés sont sableux à plus de 95%, acides, pauvres en matière organique et ont une CEC relativement faibles. Cependant on relève une sursaturation en bases échangeables sur l’ensemble des sites. Ainsi, cette sursaturation serait liée à l’intensification des pratiques culturales. Urban market gardening plays a very important role in food security and the reduction of unemployment. However, intensification of soil use can alter soil properties and reduce yields. This study aims to characterize vegetable farming practices in Brazzaville and to determine their influence on soil properties. In the selected sites, structured questionnaire was conducted among market gardeners and soil samples were taken following transects. Soil physical and chemical analyses were carried out following lab common procedures. The results showed that the cultivation practices in the sites studied are intensive. The soils studied are more than 95% sandy, acidic, low in organic matter and have a relatively low CEC. However, there is an oversaturation in exchangeable bases on all sites. Thus, this oversaturation would be linked to the intensification of cultural practices.

Ce travail a pour objet de contribuer à la connaissance de l’orpaillage et de ses impacts dans l’environnement forestier du secteur de Souanké au Nord-Ouest de la République du Congo. La méthodologie est basée sur l’inventaire des types et des caractéristiques des exploitations, et sur une évaluation des impacts environnementaux observés à l’aide de la grille de Fecteau et des analyses au spectrophotomètre. La télédétection a servi à l’évaluation de la dégradation forestière. Occupant 18 sites sur les 20 identifiés, l’exploitation artisanale reste dominante (soit 90%) par rapport à celle semi-industrielle. L’exploitation artisanale est pratiquée par des Congolais et certains étrangers (Camerounais, Tchadiens, Ouest africains, Congolais de la RDC) organisés en équipes légères tandis que l’exploitation semi-industrielle est pratiquée par des sociétés chinoises. Les impacts négatifs relevés sur l’environnement du secteur sont : dégradation du couvert végétal, perturbation du milieu, excavations, stagnation des eaux et asphyxie des plantes, éboulements, modification du paysage, tas de graviers et morts terrains abandonnés, augmentation de la turbidité des eaux, perturbation du régime d’écoulement des cours d’eau, risques d’accident. Les impacts identifiés pour l’orpaillage semi-industriel et l’orpaillage artisanal sont respectivement : majeurs (50% vs 31%), moyens (29% vs 15%), mineurs (21% vs 54%). La turbidité est supérieure à 500 NTU du point de lavage jusqu’à 1000 m en aval dans les sites mécanisés alors qu’elle décroit rapidement en aval des sites traditionnels. La superficie forestière dégradée par les activités d’orpaillage est évaluée à 934 ha sur 13.912 ha, soit un taux de 6.7%.

The study was conducted in Brazzaville, and data collection covers the period from May to June 2017. The methodology is based on literature review and floristic and equipment inventory. Nine green spaces spread over two out of nine townships in the capital city. Four are located in Bacongo and five in Poto-Poto. According to the classification standards, 5 squares and 4 gardens were studied. Except for one square, all the others, including the gardens, are planted with trees. The equipment inventory lists 183 benches, including 63.83% permanently and/or partially in the sun, 4 playgrounds, no games for children, and 3 cultural monuments. The flora and health of the trees stands shows 186 trees and 279 shrubs, all corresponding to 26 species. An examination of the health status reveals that 57% of trees show anthropogenic injuries. Floral analysis shows that exotic plants (76.92%) predominate over local plants (23.07%). The average basal area of trees in all green spaces is 1.95 m2·ha−1. The diametric structure is erratic within all green spaces, with a dominance of large diameter subjects. This leads to poor natural regeneration of woody plants. The green spaces in Brazzaville, which are very unevenly distributed within the urban fabric, do not meet the international standards disseminated by the World Health Organization (WHO) and do not fully play their biodiversity conservation and recreational and ecological functions. History of green spaces in Brazzaville states that no creation was born after independence. The existing land has been reduced in size, and the new land has been used for other purposes.

The study aimed at evaluating the natural regeneration of some characteristic species in the Loukaya peri-urban forest was carried out in Brazzaville, over three surveys of one hectare each. The botanical inventory of the 23 species monitored covers the subjects of 2 ≤ d0.20 < 10 cm and d1.30 ≥ 10 cm. The study shows 1255 individuals of which 68.27% are 2 ≤ d0.20 < 10 cm. While being tropophilic and mesophilic, this ecosystem is pauciflorous and paucispecific. The phytoecological data show that this formation, which is a link in the African dense humid forest, presents values far below those known elsewhere; while being faithful to the forests of the Cataractes Plateau. As for the rate of natural regeneration, this index is greater than or equal to 100 for 69.56% of the taxa. Sarcochores and heliophytes are the taxa that best support this natural regeneration. This high rate of regeneration would be correlated with the high level of anthropization, whose large canopy gaps are accompanied by a flow of light conducive to the installation of seedlings.

The relationship between ecosystem services and urban phytodiversity is being studied in the Moukonzi-Ngouaka district of Brazzaville. Urban forestry, a source of well-being for the inhabitants, is associated with socio-cultural foundations. The surveys concern flora, ethnobotany, socio-economics and personal interviews. The 60.30% naturalized flora is heterogeneous and closely correlated with traditional knowledge. The Guineo-Congolese endemic element groups are 39.27% of the taxa, of which 3.27% are native to Brazzaville. Ethnobotany recognizes 48.36% ornamental taxa; 28.36% food taxa; and 35.27% medicinal taxa. Some multiple-use plants are involved in more than one field. The supply service, a food and phytotherapeutic source, provides the vegetative and generative organs. Of the 52.31% of recognized taxa, 33.45% essentially provide leaves and 18.50% fruits. The main obsession of plant introduction being 1) food and phytotherapeutic, and 2) aesthetic, obscures other ecosystem services such as fuelwood and income, provided by NTFPs, pillars of poverty alleviation.

Ce travail a pour objet de contribuer à la connaissance de l’orpaillage et de ses impacts dans les écosystèmes forestiers du secteur de Souanké au Nord-Ouest de la République du Congo. La méthodologie est basée sur l’inventaire des types et des caractéristiques des exploitations, et sur une évaluation des impacts environnementaux observés à l’aide de la grille de Fecteau et des analyses au spectrophotomètre. La télédétection a servi à l’évaluation de la dégradation forestière. Occupant 18 sites sur les 20 identifiés, l’exploitation artisanale reste dominante (soit 90%) par rapport à celle semi-industrielle. L’exploitation artisanale est pratiquée par des Congolais et certains étrangers (Camerounais, Tchadiens, Congolais de la RDC et des ressortissants des pays Ouest africains,) organisés en équipes légères tandis que l’exploitation semi-industrielle est pratiquée par des sociétés chinoises. Les impacts négatifs relevés sur l’environnement du secteur sont : dégradation du couvert végétal, perturbation du milieu faunique, excavations, stagnation des eaux et asphyxie des plantes, éboulements, modification du paysage, amoncellements de graviers et morts-terrains, augmentation de la turbidité des eaux, perturbation du régime d’écoulement des eaux, risques d’accident. Les impacts identifiés pour l’orpaillage semi-industriel et artisanal sont respectivement : majeurs (50 % vs 31%) ; moyens (29% vs 15%) ; mineurs (21% vs 54%). La turbidité est supérieure à 500 UTN du point de lavage jusqu’à 1000 m en aval dans les sites mécanisés alors qu’elle décroit rapidement en aval des sites traditionnels. La superficie forestière dégradée par les activités d’orpaillage est évaluée à 934 ha sur 13.912 ha, soit un taux de 6.7%. The aim of this work is to contribute to the knowledge of gold artisanal mining and its impacts in the forest ecosystems of Souanké sector in the northwest of the Republic of Congo. The methodology is based on an inventory of the types and characteristics of mining operations, and on an assessment of the environmental impacts observed using the Fecteau grid and spectrophotometer analyses. Remote sensing was used to assess forest degradation. Of the 20 sites identified, 18 are dominated by artisanal mining (90%) compared to semi-industrial mining. Artisanal mining is carried out by Congolese and some foreigners (Cameroonians, Chadians, West Africans, and Congolese from the DRC) and organized in small teams, whereas semi-industrial mining is carried out by Chinese companies. The negative impacts noted on the environment of the sector are degradation of the vegetation cover, environmental disturbance, excavations, stagnation of water and asphyxiation of plants, landslides, modification of the landscape, heaps of gravel and dead land abandoned, increase in water turbidity, disturbance of the flow regime of watercourses, risks of accidents. The impacts identified for semi-industrial and artisanal gold mining are respectively: major (50% vs. 31%), medium (29% vs. 15%), and minor (21% vs. 54%). Turbidity is above 500 NTU from the washing point to 1000m downstream in mechanized sites, whereas it decreases rapidly downstream in artisanal sites. The forest area degraded by gold mining activities is estimated at 934 ha out of 13,912 ha, corresponding to a rate of 6.7%.

Background : The rainforest is a source of particularly diversified natural goods and services, satisfying at least 80% of the population's needs. Notwithstanding the intimate link between population and biodiversity, anthropogenic pressure and its corollaries, such as global climate change, have led to a specific and genetic erosion of about 30% over the last three decades. The major causes of these are, in the case of the Congo, anarchic urbanization, construction of physical communication infrastructures without an environmental and social impact assessment; and unbridled collection of medicinal plants for commercial purposes. The loss of biodiversity is a clear sign of unsustainable use of natural resources, which the traditional societies depends on for their livelihoods. Methods : Our study conducted at Mvouandzi, sub-prefecture of Kayes (Congo), is based on the ethnobotanical knowledge survey and floristic inventory. The informants, aged between 15 and 50 years or more comprised 25 men and 43 women who possess plant secrets. Prior to fieldwork, we reviewed existing literature that provided information on the status of inventoried species, their phytogeographic distribution, and known uses within their range. The ethnobotanical knowledge survey took place in two phases, namely: work with focus groups and conducting personalized interviews with the informants; and the collection of samples coupled, when possible, to the participatory approach. Results : The floristic inventory lists 81 useful species, corresponding to 72 genera and 43 families. Some species are multi-purpose, and 26 of the 60 medicinal plants inventoried are specifically associated with the traditional pharmacopoeia. 36 species are multi-purpose and the others 15 intervene specially in food, 26 in phytotherapy, and 5 in handicrafts. The high values of the ethnobotanical indices (the ethnobotanical use value (VU), the informant consensus factor (CFI), and the level of fidelity (NF)) show a strong involvement of these taxa in the daily life of this traditional society. Sociological analysis reveals that the level of ethnobotanical knowledge is proportional to the subjects’ age and in this matter, women excel in the exploitation of empirical knowledge. Conclusions : The Kouni community possesses a sophisticated ethnobotanical knowledge, which is a fundamental part of socio-cultural base of the Kouni community and an important cultural asset of Congolese nation. However, the Kouni community is shrinking due to rural exodus. Therefore, documenting the existing traditional knowledge is the first priority to preserve the Kouni cultural diversity. Keywords : Congo, Mvouandzi, ecosystem services, traditional knowledge, phytodiversity.

L’étude de la diversité floristique des ptéridophytes est menée au sein de l’écosystème forestier urbain de Brazzaville, très anthropisé et dont la flore, notamment les ptéridophytes, est mal connue. L’inventaire floristique itinérant ressort 24 espèces représentant à 19 genres et 11 familles dont les Polypodiaceae rassemblent 83,33 % des taxons. Des taxons recensés, Pteris vittata connu d’ailleurs est nouvellement identifié au Congo. En rapport avec le type d’habitat, les épiphytes sont prépondérants avec 6 espèces réparties dans 2 familles Polypodiaceae (83,3 %) et Davalliaceae (16,7 %). La flore des milieux humides compte 5 espèces regroupées dans quatre familles ainsi qu’il suit : Adiantaceae (20 %), Athyriaceae (40 %), Schizaeaceae (20 %), Blechnaceae (20 %). Les Ptéridophytes terrestres regroupent 3 espèces, avec une prédominance des Dennstaedtiaceae (66,66 %). Cette distribution met en évidence deux groupes : (i) un groupe d’espèces dites bioindicateurs écologiques parfaits, spécialisées à un biotope bien défini et satisfaisant à des exigences écologiques particulières ; (ii) le second est constitué de taxons (non bio-indicateurs) presque indifférents aux conditions du milieu. Au regard des adaptations développées, de la diversité et spécificité des biotopes occupés, et des services bioécologiques reconnus aux Ptéridophytes, ils n’en constituent pas moins un bon matériel didactique et/ou support des enseignements des sciences de la vie. L’analyse phytogéographique révèle que l’élément à large distribution (75 % de taxons) domine l’élément endémique (25 %). L’aménagement des voiries en général et la dégradation de l’écosystème forestier urbain, suite aux actions anthropiques récurrentes et de niveau d’intensité plus élevé, impactent fortement le développement des populations de ptéridophytes dans la ville de Brazzaville. study of the floristic diversity of pteridophytes is carried out in the urban forest ecosystem of Brazzaville which is very damaged by anthropogenic actions and whose flora, in particular the pteridophytes are poorly known. The itinerant floristic inventory results in 24 species representing 19 genera and 11 families with 83.33 % of the taxa Polypodiaceae. From the listed taxa, Pteris vittata already known elsewhere has been recently identified in the Congo. In relation to habitat type, epiphytic are predominant with 6 species in 2 Polypodiaceae families (83.3 %) and Davalliaceae (16.7 %). The wetland flora has 5 species grouped in four families as follows : Adiantaceae (20 %), Athyriaceae (40 %), Schizaeaceae (20 %), Blechnaceae (20 %). Terrestrial pteridophytes Group 3 species, with a predominance of Dennstaedtiaceae (66.66 %). This distribution shows two groups : (i) a group of species known as ecological bio-indicators Perfect, specialized in a well-defined biotope and meeting specific ecological requirements ; (ii) The second is made up of taxa (non-bio-indicators) that are almost indifferent to environmental conditions. In view of the adaptations developed, the diversity and specificity of the occupied Biotopes, and the bio-ecological services recognized in the pteridophytes, they are nevertheless a good teaching material and/or support of the teachings of the sciences of the Life. Phytogeographic analysis reveals that the large-distribution element dominates (75 % of taxa) dominates the endemic element (25 %). The development of the public urban roads in general and the degradation of the urban forest ecosystem, as a result of recurrent anthropogenic actions and higher levels of intensity, strongly impact the growth of pteridophytes populations in the city of Brazzaville.

Set as a reserve in 1938 by the general governor of French Equatorial Africa (AEF), the Patte d’Oie forest covered originally 240 ha of which deforestation now isolates three statements for a total area of 95 ha, thus less than 39% of the original area. Originally a perish-urban forest, it has now become intra-urban, and shelters three statements of natural forests, administrative buildings, plantations of Pinus sp. and Eucalyptus sp., an arboretum dedicated to the wet dense forests of the Congo Basin, the sporting and university installations and a zoological park. The Patte d’Oie forest and the four others which completely disappeared (the Tsieme, the Corniche, the Glaciere and the Tchad) from urban space, these four forest statements have not been the object of an in-depth study. Before this study, the phytoecological data on the three forest statements were partial and generalized from studies carried on less than 1000 m2. Moreover, they do not make any difference between the natural forest an...

The urban vegetation of Brazzaville, formerly dominated by the natural forest and savannah, changed radically under the anthropic pressures. The horizontal extension and the development of the city are the principal reasons of the change. These combined effects led to the reduction in local floristic diversity and the explosion of an immigrant flora in the surface of the city. The inventory of the urban arborescent flora shows that it is composed of 98% non‑native allochtonous species among which 30% come from the local flora, but non‑native of Brazzaville. The introduction of the foreign species to Congo and in particular to Brazzaville, announced since the 1880s, continues nowadays without any control. Some taxa having passed in the collective memory are considered, by a meat deal of citizens, like natural of the area. This vision is consolidated by the mark of a good tendency to naturalization. An analysis of the behaviour of different introduced taxa raises that the majority of the species were not naturalized, in spite of a perfect adaptation. From the introduced species, some of them have completely disappeared from the new territory (Aleurites moluccana, Hymenaea courbaril, Schizolobium parahybum, Jacaranda mimosifolia, Berlinia brunellii and Symphonia globulifera). On the other hand, another is in the process of disappearance because the individuals reached the senescence (Delonix regia). This flora which is very heteroclite comes from several areas of which America and Asia would be considered as the first providers with 76% taxa. The Guineo‑Congolese flora accounts for 24% inventory., La végétation urbaine de Brazzaville, autrefois dominée par la forêt naturelle et la savane, s’est transformée radicalement sous la pression anthropique. L’extension horizontale et le développement de la cité en sont les principales raisons. Ces effets conjugués ont conduit à la diminution de la diversité floristique locale et à l’explosion d’une flore allochtone dans l’aire de la ville. L’inventaire de la flore arborescente urbaine montre qu’elle se compose à 98 % d’espèces allochtones, dont 30 % proviennent de la flore locale, mais non native de Brazzaville. L’introduction des espèces étrangères au Congo et notamment à Brazzaville, signalée depuis les années 1880, se poursuit de nos jours sans le moindre contrôle. Certains taxons étant passés dans la mémoire collective sont considérés, par bon nombre de citoyens, comme natifs de la région. Cette vision est confortée par la marque d’une bonne tendance à la naturalisation. Une analyse du comportement des différents taxons introduits relève que la plupart des espèces ne se sont pas naturalisées, en dépit d’une parfaite adaptation. Parmi les espèces introduites, une frange d’entre elles a complètement disparu de cet espace (Aleurites moluccana, Hymenaea courbaril, Schizolobium parahybum, Jacaranda mimosifolia, Berlinia brunellii et Symphonia globulifera). Par contre, une autre (Delonix regia) est en voie d’extinction avec des individus sénescents. Cette flore, très hétéroclite, provient de plusieurs régions dont l’Amérique et l’Asie seraient les premières pourvoyeuses avec 76 % des taxons. La flore guinéo‑congolaise contribue à peine à 24 % de l’inventaire., Kimpouni Victor,Mbouba Sonia Danielle,Motom Marcel. Étude de la flore allochtone arborescente et foresterie urbaine à Brazzaville (Congo). In: Le Journal de botanique, n°79, 2017. Septembre. pp. 73-92.

The flora of the Patte d’Oie forest of Brazzaville is studied according to three plots of 0.5 ha, corresponding each to one of the islet, currently constituting it. With an original area of 240 ha, put in reserve in 1938, the natural forest of the Patte d’Oie of Brazzaville covers 95 ha, less than 39% compared to initial area. Because the other main forests of Brazzaville have disappeared without delivering their biodiversity, this study is the first one which emphasizes the flora of this single ecosystem of Congo. The total floristic inventory revealed 459 trees of dbh≥10 cm on 1.5 ha; it is an average of 306 trees?ha?1. 31 species are listed for 17 families, and the best represented of which (Fabaceae, Euphorbiaceae and Rubiaceae) have a diversity varying from 13% to 19% of the inventory and a tree number oscillating from 15% to 36%. The Shannon (H') biological diversity index of the three plots is of 2.6 on average, for a maximum diversity (H'max) average of 2.9 versus an average true diversity of 15. The Pielou index is on average 0.9, whereas that of Simpson is 0.9. The coefficients of similarity of Jaccard (41.4% to 57.1%) and of the coefficient of S?rensen (58.5% to 72.7%) show the variations in the floristic composition. The followed ecological parameters show that this ecosystem is very few diversified compared to the tropical wet dense forests on the one hand, and, on the other hand, a non constant floristic composition is not. The analysis of the diametric structure by plot and the dominant and/or characteristic species give erratic curves, evidence of an insufficiency of the regenerative potential. Indeed, approximately 70% of the species are characteristic of the disturbed ecosystems (Macaranga sp.,Caloncoba welwitschii,Hymenocardia ulmoides,and Anthocleista sp.).

Phytoecological analysis of the woody flora of High Sangha (Republic of Congo). The flora of the High Sangha, just like that of Congo as a whole, develops in the corridor of the “Sangha River” of Guineo-Congolian area. Still badly known, it is studied according to a North-eastern South-western floristic gradient, corresponding to a phytogeographical distribution extending from the Atlantic element (Nigero-Cameroono-Gabonese) to the Cameroono-Congolese element. On both side of the Sangha River, the surface of study is subdivided in three sectors whose central zone is the floristic junction between South-west and the North-East. The inventory of the individuals of dbh ≥ 10 cm counts 387 species of which 12 mark the South-western sector, 18 for the North-eastern sector and six for the central sector. The vertical distribution distinguishes three layers from unequal importance, of which the percentage of species oscillates from 24 to 42%. Floristic diversity, interpreted by the indices of biological ...

Resume La diversite floristique de deux lots de vergers traditionnels de ± 20 et ± 40 ans est etudiee en fonction du degre de l’activite anthropique. Mis en place en savane, les vergers de ± 20 ans sont entretenus, alors que ceux de ± 40 ans sont abandonnes depuis plus d’une vingtaine d’annee. L’inventaire recense 24 especes dont 21% sont communes aux deux lots de vergers. Les densites moyennes respectives sont de 94 ± 3,46 pieds.ha-1 et 102 ± 2 pieds.ha-1. Les coefficients de similarite de Jaccard et de Sorensen discriminent les deux lots, alors que les indices de diversite de Shannon (0,79 ± 0,38 et 0,93 ± 0,02) et de Simpson (5,63 ± 1,05 et 13,74 ± 1,79) soulignent leur faible diversification. Quant a l’indice de Pielou (0,42 ± 0.17 et 0,46 ± 0.02), il marque une dominance dans les deux cas. Les donnees phytogeographiques caracterisent l’element de base Guineo-Congolais (29,16%), quoique que l’on note une dominance des especes allochtones (50%) de distribution pantropicale.

Cette contribution a l’etude des plantes a effets psychotropes et toxiques du Congo (Brazzaville) met en relief 11 especes appartenant a la flore sauvage (64 %) et au cortege allochtone (36 %). Elle traduit le niveau de connaissances des communautes autochtones et allochtones sur l’exploitation de la biodiversite vegetale. Le centre d’interet porte sur les aspects ethnobotaniques, notamment les parties utilisees, le mode d’usage et les effets induits sur le comportement des individus, suite a leur prise. Quoique plusieurs de ces plantes sont largement usitees en pharmacopee traditionnelle, les raisons des prises vont des faits volontaires pour les plantes psychotropes, aux accidentelles pour les alimentaires. L’utilisation des plantes allochtones (ornementales) devoile des usages secondaires ou primaires meconnus des populations congolaises. Eu egard a la severite des intoxications induites par ces plantes, particulierement Datura cf. fastuosa, Tetracarpidium conophorum, Tabernanthe iboga et Dioscorea spp., des comportements nouveaux sont observes au sein des communautes sur leur mode de gestion.

The study, conducted in the city of Dolisie, provides an overview of plant diversity, ethnobotanical and ecosystem services, people's expectations and perceptions of urban forestry. It is based on the botanical inventory and interviews involving city managers and populations. A total of 34 species belonging to 26 genera and 17 families have been recorded with a fruit tree dominance. The role and importance of trees in urban areas is well perceived by the population. Gender and education level influence urban forestry preferences and expectations. Men with at least a secondary level of education exploit the aesthetic aspects of the environment, while women and individuals with at most a primary level like food, phytotherapeutic and financial aspects. The 10 urban forestry properties identified constitute three categories whose ethnobotanical use values stand out: supply services with 1.96 and regulation services with 1.97. A gender and educational level analysis reveals differences, sometimes significant, in the ethnobotanical use value of a property. As for the level of fidelity, it is carried by the same taxa, especially fruit trees, both in food and phytotherapy. At a time when humanity is suffering from the harmful effects of climate change, the value of urban forestry is undeniable in mitigating the heat islands generated by our cities.

The spatial analysis of the flora of the peri-urban forest of Djoumouna has been conducted in Brazzaville, Congo. Data collection, conducted from April to August 2017, is based on a floristic inventory of 75 plots of each 400 m2 (20 m x 20 m). The study shows 898 trees of dbh ≥ 10 cm corresponding to 106 species and 36 families. The number of individuals per plot averages 11.97 ± 0.42 feet/plot while the number of species per plot averages 7.37 ± 0.30. The land used by projecting the trunk sections is on average 0.74 ± 0.05 m2/plot. The Jaccard similarity coefficient between plots is between 0 and 75% while the average Skewness is 1.26 ± 0.11. The average Shannon index is 1.77 ± 0.05 per plot with an average maximum diversity of 1.93 ± 0.04. The average Pielou index is 0.91 ± 0.01. The absolute diversity index averages 6.54 ± 0.29 while α-Fisher averages 11.44 ± 1.39. The average value of the Green index is -0.04 ± 0.01 and finally 7.55% of taxa have a rarefaction index of species between 40 and 77% compared to 92.45% where this index varies from 81 to 99%. The upward hierarchical classification and the AFC highlight the presence of floristic subfacies resulting from taxa independence. Since most species have a density of less than 1 tree.ha-1, the floristic composition is heterogeneous, resulting in insufficient natural regeneration and low resilience of this ecosystem threatened with extinction in the very short term.

Before this study, the ligneous flora of the Cataracts plate was known only very partially. It was limited to the savannah species of the shrubby layer and an unpublished floristic statement (1950) of about thirty forest species. As for the principal wood (14 species) interested by the forest industry, data are available since the year 2005, within the framework of the inventory of the forest unit of installation Loamba which integrates the forests of our zone of investigation. With the present stage of knowledge, it is inventoried 153 woody species being distributed in 42 families whose floristic diversity varies from 0.65 to 13.07%. As in the African tropical forests, the families best represented are Fabaceae, Euphorbiaceae, Malvaceae and Rubiaceae. In spite owing to the fact that the Cataracts plate evolve in the Guineo-Congolese—Zambezienne transition zone, the phytogeographical analysis shows that the element base is dominated by the guineo-Congolese species (59.86%). The floristic composit...

The forest facies with Aucoumea klaineana of the Congolese littoral has a very heterogeneous floristic diversity in its specific composition, space and life period. Though A. klaineana is the characteristic element and dominating of this facies, its dynamics knows a regressive evolution in correlated to the development stage. To the present stage of his dynamics, one passes gradually from an almost monospecific facies with A. klaineana to a facies with variable heterogeneous complexity. A. klaineana is the dominant species with 46.4% of stand, followed by Trichilia heudelotii, Carapa procera and Sacoglottis gabonensis (22% of 1,186 individus having d.b.h. ≥ 10 cm in the experimental plot). Like the local forests, the studied facies highlights Fabaceae with an index of relative diversity of 18.31%. Lastly, a concomitant analysis of the calculated ecological indices and forest dynamics observed underlie that the facies monospecific is only one short transitional stage. This stage is recognized as b...

The ethnobotanical study carried out at Madingou (4°16' S, 13°33' E) focuses on medicinal plants of the savannah zone. The survey used personal interviews and focus groups. Informants consisted of the inhabitants, whose age varies from 18 to 60 years or more. A total of 80 plant species were cited in the traditional pharmacopoeia. These plants are used in 66 recipes for treating 43 different diseases and symptoms, grouped in 11 major affiliations following the disease and symptoms sphere. Infectious and parasitic diseases is the most important group (23.25%), followed by the ill-defined symptoms and signs (13.95%) and the digestive system (11.63%). Five modes of administration were noted. The most preferred being the oral voice (38.75%). Among the 7 types of plant parts cited, leaves (65%) are preponderant. 8 modes of preparation were cited, the decoction (23.75%) being the most common. Of the 80 species listed, Allium sativum, Persea americana, Solanum nigrum, are among the medicinal plants most commonly used in Africa. Of the remaining species, 9 have been the subject of phytochemical studies all over the world. Ethnobotanical data show that a number of taxa, the medicinal properties of which are proved elsewhere, exist in the region and are not exploited, such as Millettia laurentii. Several species inventoried cover more than one aspect of indigenous knowledge, they are referred to as multipurpose plants and therefore the most vulnerable of the anthropic influences.

Les ilots forestiers de la Patte d’Oie a Brazzaville sont etudies suivant trois releves de 0,5 ha, correspondant chacun a un ilot. Mise en reserve en 1938, l’aire originelle est passee de 240 ha a 95 ha, soit moins de 39% de cette surface. A la difference des massifs forestiers qui ont disparu, sans livrer leur biodiversite, cette etude valorise cet ecosysteme unique au Congo. L’inventaire du sous-bois des trois ilots revele 120 especes et 47 familles dont les Rubiaceae (25,6 a 34,2%) dominent les Fabaceae (5,9 a 13,9%). La densite des especes caracteristiques varie de 0,7 a 60 arbres.ha-1. L’indice de diversite biologique de Shannon (H’) est en moyenne de 1,9 ± 0,3 pour les ligneux, contre 3,5 ± 0,25 pour la flore totale. La diversite maximale (H’ max ) moyenne des ligneux est de 3,5 ± 0,1 et de 5,3 ± 0,01 pour la biodiversite globale. La moyenne de l’indice de Pielou des ligneux est de 0,5 ± 0,07 et de 0,7 ± 0,05 pour la flore totale. Quant a l’indice de Simpson, sa moyenne est de 0,5 ± 0,1 pour les ligneux et de 0,9 ± 0,03 pour la flore globale. Les coefficients de similarite de Jaccard varient respectivement pour les ligneux et la flore globale de 52 a 62% et de 50 a 55,6% ; alors que ceux de Sorensen oscillent de 69,2 a 77,6% et de 66,7 a 71,4%. Les differents indices montrent que cet ecosysteme possede une faible diversite floristique qui s’accompagne d’une heterogeneite et d’une dominance dans la composition floristique. Les especes dominantes etant typiques du sous-bois, la regeneration naturelle accuse un deficit dans le recrutement des classes de diametre, ce qui affecte sa dynamique et donc son maintien a long terme. Mots cles : Congo ; diversite floristique ; coefficient de similarite ; ecosysteme forestier urbain ; indice de diversite biologique.

Composition and ecological characteristics of the woody flora of Mindouli area (Congo). The study of the flora of Mpassa (Mindouli) emphasizes the richness of three woody ecosystems. The savannah flora of the region having been the subject of a specific and total research since the Sixties of the century spent, the floristic diversity of the woody formations remained ignored until now the inventory. This work highlights 112 species, developing in two natural ecosystems (the forest and savannah) and in anthropic formation. The analysis of the woody layer of savannah shows that three (Ochna cf. arenaria, Steganotaenia araliacea and Strychnos pungens) of the 15 species present, have a disseminated distribution. On the contrary, Syzygium guineense seems gregarious on the hills. As for forest formations, they have a low floristic diversity (4 to 48 species) and their composition varies from a valley to another, as the coefficient of similarity of Jaccard (4.35 to 25 %) shows it. The taxa usually found in these woody formations are Pentaclethra eetveldeana, Pseudospondias microcarpa and Musanga cecropioides. Their relative frequency oscillating from 7.36 to 6.13 %. The biological index of diversity of Shannon (H') confirms the small degree of diversity reached by these formations. It is on average of 0.84 ± 0.27 for a maximum diversity (H'max) average of 1.02 ± 0.32. As for the index of regularity (Eq), it tends towards 1 and its average is of 0.82 ± 0.15. The evolution of this index confirms that there is not particular predominance within these forest ecosystems. The diaspores types analyse shows a predominance of the sarcochores (78.2 %) from where importance of the zoochorie like principal mode of dissemination. The floristic imbalance of the various facies would be explained by the absence of the agents of dissemination and in this case, they are the mammals and of the pledged birds to the forest ecosystems, element of the co-evolution plants – animals., L’étude de la flore de Mpassa (Mindouli) met en valeur la richesse de trois écosystèmes ligneux. La flore savanicole de la contrée ayant fait l’objet d’une recherche spécifique et globale au cours des années 1960, la diversité floristique des formations ligneuses était méconnue avant cet inventaire. Ce travail met en relief 112 espèces, se développant dans deux écosystèmes naturels et semi-naturels (la forêt et la savane) et dans une formation anthropique. L’analyse de la strate ligneuse de la savane montre que trois espèces (Ochna cf. arenaria, Steganotaenia araliacea et Strychnos pungens) sur 15, ont une distribution très disséminée. Au contraire, Syzygium guineense reste grégaire sur les collines. Quant aux formations forestières, elles présentent une faible diversité floristique (4 à 48 espèces) et leur composition varie d’une vallée à une autre, comme le montre le coefficient de similarité de Jaccard (4,35 à 25 %). Les espèces communément retrouvées dans ces formations sont Pentaclethra eetveldeana, Pseudospondias microcarpa et Musanga cecropioides. Leur fréquence relative oscille de 7,36 à 6,13 %. L’indice de diversité biologique de Shannon (0,84 ± 0,27) confirme le faible degré de diversité atteint par ces formations. La diversité maximale (H’max) moyenne est de 1,02 ± 0,32 ; pendant que l’indice de régularité (Eq) tend vers 1 et sa moyenne est de 0,82 ± 0,15. L’évolution de cet indice confirme qu’il n’existe pas de dominance particulière au sein de ces écosystèmes forestiers. L’analyse des types de diaspores montre une dominance des sarcochores (78,2 %) d’où l’importance de la zoochorie comme principal mode de dissémination. Le déséquilibre floristique des différents faciès s’expliquerait par l’absence des agents de dissémination et dans le cas présent, il s’agit des mammifères et des oiseaux inféodés aux écosystèmes forestiers, maillons de la co-évolution plantes – animaux., Kimpouni Victor,Apani Ernest,Motom Marcel. Caractéristiques écologiques et composition de la flore ligneuse de la région de Mindouli (Congo). In: Le Journal de botanique, n°57, 2012. Mars. pp. 37-47.