Odzala National Park Research Articles

Biotopes et diversite des groupes phytogeographiques dans la flore du Parc National d'Odzala (Congo-Brazzaville)

This work is the first analysis of the totality of the plant biodiversity inventories made in the Odzala National Park. It deals especially with habitat diversity and phytogeographical groups based ou the correctly determined species of the curent flora. The global taxonomic list consists of 1141 species belonging to 125 families. Forest habitat is the most diversified with 806 species reaching 71% of the total, of wich 537 belong to the foret de terre ferme. Grassy habitat includes 335 species reaching 29% of the total, 143 species belonging to the savanna. At the phytogeographical groups level, the basic Guineo-Congolian element is the most important with 666 species (58% of the flora). Species with very broad geographical area follow with 271 species (24% of the flora). Correlation between habitat and phytogeographical groups has been established. The predominance of the basic Guineo-Congolian element in forest sites where the human influence is lesser displays the stability of these habitats. The importance of species with very broad geographical area in grassy habitats illustrates the secondary or substitution character of these sites, mainly created by human activities.

Status and conservation of primates in Odzala National Park, Republic of the Congo

AbstractA survey of diurnal primate populations was carried out in Odzala National Park, Republic of the Congo, over 3 months in 1994 and 2 months in 1995. The park contains a high diversity and species-specific abundance of primates, and has the highest number of diurnal primates (10 species) in the forest block of Central Africa. Eight species of monkey: greater whitenosed monkeyCercopithecus nictitans, moustached monkeyCercopithecus cephus, crowned guenonCercopithecus pogonias, De Brazza's monkeyCercopithecus neglectus, talapoinMiopithecus talapoin, white-cheeked mangabeyCercocebus albigena, agile mangabeyCercocebus galeritusand guerezaColobus guereza, as well as gorillaGorilla g.gorillaand chimpanzeePan t.troglodyteswere sighted in the survey. Monkey species richness was highest in dense inundated forest and thicket, with all eight species occurring in these habitats, whereas only four species were found interra firmaforest (consisting of the park's two main habitats, open-canopy Marantaceae forest and closed-canopy primary forest). Three of the four species (C. nictitans, C. cephusandC. albigena) present interra firmaforest were most abundant in closed-canopy primary forest (1.4,1.0 and 0.6 groups per km, respectively) while the fourth (C. pogonias) was most abundant in open-canopy Marantaceae forest. Gorilla nests were most abundant in open-canopy Marantaceae forest (12.1 nests per km), while chimpanzee nests were mostly found in closed-canopy primary forest and Marantaceae forest (14 and 12 nests per km, respectively). Odzala has the highest recorded densities of western lowland gorilla (mean = 5.4 individuals per sq km) and chimpanzee (mean = 2.2 individuals per sq km) in Central Africa. The high densities of gorillas and chimpanzees may be a result of the high productivity of the forest and low poaching pressure. Conservation measures to ensure the maintenance of conditions in the area, such as educational programmes, are suggested.

Status and conservation of primates in Odzala National Park, Republic of the Congo

Status and conservation of primates in Odzala National Park, Republic of the Congo

Hybridization in paradise flycatchers (Terpsiphone Rufiventer, T. batesi and T. viridis) in Ondzala National Park, Northern Congo

Dowsett-Lemaire, F. 1999. Hybridization in paradise flycatchers (Terpsiphone rufiventer; I: batesi and I: viridis). in Odzala National Park, Northern Congo. Ostrich 70 (2); 123–126 The Redbellied and Bates's Paradise Flycatchers Terpsiphone rufiventer and I: batesi are widely distributed in the rain forests of the Guineo-Congolian Region. They have similar ecological requirements, usually identical songs and in Gabon, Congo and parts of Cameroon at least appear to be mainly allopatric. However, the two species meet in the forest/savanna mosaic of NW Congo (Odzala) where T. rufiventer inhabits only swamp forest and T: batesi both swamp and closed-canopy dryland forest. Eight of 23 birds (35%) occupying territories in swamp forest were found to be hybrids. Territories are defended against congeners as well as conspecifics. In dryland forest, however, some T: batesi have developed a very different song-type which is not understood by birds from swamp forest. It is possible that T: batesi came into contact with T. rufiventer at Odzala through the current expansion of the dryland forest. One of the hybrid males sang like African Paradise Flycatcher I: viridis, occupied a territory at the edge of swamp forest (a situation more typical of I: viridis) andMayhave been a multiple hybrid.

Forest elephant paths and movements at the Odzala National Park, Congo: the role of clearings and Marantaceae forests

The role of forest clearings and Marantaceae forest on elephant movement at the Odzala National Park was studied by describing and mapping elephant paths. Three types of paths were distinguished based on their direction, length, width, elephant activity and the types of forests they cross. They were called boulevards, foraging paths, and clearing alleys. All paths explored were heavily used. Boulevards are used for travelling over long distances (up to 34 km) and for linking up rapidly favourite sites such as clearings. Foraging paths mainly run through the medium‐density Marantaceae forests which provide elephants with both herbaceous foods and tree fruit. Clearing alleys form a dense network of tracks around clearings. This network could be a result of an anti‐predatory monitoring behaviour of elephants before entering the clearings where they have long experienced heavy poaching. The heavy trampling which results from the elephant activity could contribute to the maintenance of clearings by preventing germination and seedling survival of the numerous seeds dispersed in their dung.

Large mammals at forest clearings in the Odzala National Park, Congo

Nous avons exploré 36 clairières incluses dans les forêts du Parc National d’Odzala au Congo. Treize espèces de mammifères y ont été observées, dont les plus fréquentes étaient les éléphants, les buffles, les gorilles, les sitatungas, les bongos, les potamochères et les hylochères. Sur la clairière de Maya Nord, les taux de présence des buffles dans la journée était de 7 1 %, celle des éléphants de 37 % et celle des gorilles de 34 %. Plus de 100 éléphants ont été dénombrés simultanément, ainsi qu’un groupe de 25 buffles tandis que la présence simultanée de deux groupes de gorilles a été observée à plusieurs reprises et qu’un groupe de 17 sitatungas résidait en permanence sur la clairière. Les différences dans le taux de fréquentation des clairières résultent pro parte de l’influence du braconnage des éléphants qui touche plus fortement les clairières situées à proximité des rivières. Les clairières sont essentiellement visitées par les animaux pour la collecte des sels minéraux trouvés dans l’eau, le sol et les végétaux. Elles jouent sans doute un rôle fondamental dans le maintien des fortes densités de populations observées dans la région notamment pour les éléphants et les gorilles. Elles constituent en outre des sites d’observation remarquables. Elles sont cependant des sites idéaux pour le braconnage. Les clairières les plus riches se trouvant hors des limites du PNO, l’extension de ces limites semble une priorité.