Influence of Anthropization on the Diversity of Woody Vegetation in Muskuwaari Transplanted Sorghum Field in the Sudano-Sahelian Zone of Cameroon

Transplanted sorghum is a staple food crop and represents an important part of cereal production in the Far North region. Its cultivation has led to profound agrarian changes and environmental landscape. The main objective of the study carried out from 2017 to 2019 in the Far North area was aimed to study the influence of anthropization on the diversity of woody vegetation, its management and conservation of the transplanted sorghum landscape in the Sudano-Sahelian zone. Population surveys in six (06) villages and floristic surveys through 50 m2 plots in two soil types in these villages were conducted. The results show that the use of herbicide, cutting down and stump removal of woody plants, essential in most cases, have led to profound changes in the Kare with the invasion of the fields by weed plants, post-harvest soil denudation and the disappearance of plant biodiversity. The exploitation of sorghum led to a reduction in the number of woody species from 20 to 9 at the start to the end of the study respectively. Similarly, the average species density decreased over time. The disappearance of 17 individuals was recorded on the clay soil type and 12 on the hydromorphic soil type during the 2 years. Faced with this threat, the practice of agroforestry (4 to 11%), reduction in the use of chemicals (24.19 to 40.32%), abolish harvesting of green wood (0 to 3.33%) and plough to limit the action of fire have been proposed as alternative measures for sustainable exploitation of transplanted sorghum

Phytodiversité et séquestration de carbone des parcs agroforestiers à Borassus aethiopum Mart. (Arecaceae) en zone soudano-sahélienne du Cameroun

Borassus aethiopum, better known as the African dwarf palm, is a recognized tropical species in Africa. It is of great importance for the ecological balance and plays a multifunctional role for the communities surrounding the parks. This study aims to assess the floristic richness and carbon sequestration capacity of these parks in the district of Poli in the North Cameroon region. Ethnobotanical surveys and floristic inventories were carried out in three villages. Five sites, two cultivated and three fallow, were sampled. Allometric and cylinder volume equations were used to estimate the amount of carbon. The populations of the Vallée de rôniers are aware of the benefits they derive from these parks. The regeneration of this essence is done naturally. Fallowed areas are more diverse (31 species) and denser (317 stems per hectare) compared to cultivated areas (25 species, 123 stems per hectare density). The cultivated plots, however, have larger basal areas (11.24 square meter). Five species show high ecological importance indices (Borassus aethiopum, Piliostigma thonningii, Entada africana, Adansonia digitata, Sarcocephalus latifolius, Ficus sycomorus, Annona senegalensis). The park sequesters an average of 86.65 tons of carbon per hectare. The ecological and economic value linked to this quantity of carbon is 317.72 tons of carbon dioxide per hectare and 1766535 FCFA respectively. The value of this species contributes to the subsistence of populations and is an asset for its conservation and rational management. These parks are important reservoirs of biodiversity and play a fundamental role in meeting the needs of the local population. agroforestry parks, Borassus aethiopum, floristic diversity, carbon stock, Cameroo

Phytodiversité et séquestration de carbone des parcs agroforestiers à Borassus aethiopum Mart. (Arecaceae) en zone soudano-sahélienne du Cameroun

Borassus aethiopum plus connu sous le nom de palmier nain africain, est une espèce tropicale répandue en Afrique. Elle est d'une grande importance pour l'équilibre écologique et joue un rôle multifonctionnel pour les communautés environnantes des parcs. Cette étude vise à évaluer la richesse floristique et la capacité de séquestration de carbone de ces parcs de l’arrondissement de Poli dans le Nord du Cameroun. Les enquêtes ethnobotaniques et les inventaires floristiques ont été menés dans trois villages. Cinq sites, dont deux cultivés et trois en jachères, ont été échantillonnés. Les équations allométriques et de volume de cylindre ont été utilisées pour estimer la quantité de carbone. Les populations de la Vallée de rôniers sont conscientes des bénéfices qu’elles tirent de ces parcs. La régénération de cette essence se fait naturellement. Les zones misent en jachère sont plus diversifiée (31 espèces) et plus dense (317 tiges par hectare) comparées à celles cultivées (25 espèces, 123 tiges par hectare de densité). Les parcelles cultivées présentent cependant, des surfaces terrières plus importantes (11,24 mètres carrés). Cinq espèces présentent des indices d’importance écologique élevés (Borassus aethiopum, Piliostigma thonningii, Entada africana, Adansonia digitata, Sarcocephalus latifolius, Ficus sycomorus, Annona senegalensis). Le parc séquestre en moyenne 86,65 tonnes de carbone par hectare. La valeur écologique et économique liée à cette quantité du carbone est de 317,72 tonnes de dioxyde de carbone (CO2) par hectares et 1766535 FCFA respectivement. La valeur de cette espèce contribue à la subsistance des populations et constitue un atout en faveur de sa conservation et de sa gestion rationnelle. Ces parcs constituent d’importants réservoirs de biodiversité et jouent un rôle fondamental dans la satisfaction des besoins de la population locale.Borassus aethiopum, better known as the African dwarf palm, is a recognized tropical species in Africa. It is of great importance for the ecological balance and plays a multifunctional role for the communities surrounding the parks. This study aims to assess the floristic richness and carbon sequestration capacity of these parks in the district of Poli in the North Cameroon region. Ethnobotanical surveys and floristic inventories were carried out in three villages. Five sites, two cultivated and three fallow, were sampled. Allometric and cylinder volume equations were used to estimate the amount of carbon. The populations of the Vallée de rôniers are aware of the benefits they derive from these parks. The regeneration of this essence is done naturally. Fallowed areas are more diverse (31 species) and denser (317 stems per hectare) compared to cultivated areas (25 species, 123 stems per hectare density). The cultivated plots, however, have larger basal areas (11.24 square meter). Five species show high ecological importance indices (Borassus aethiopum, Piliostigma thonningii, Entada africana, Adansonia digitata, Sarcocephalus latifolius, Ficus sycomorus, Annona senegalensis). The park sequesters an average of 86.65 tons of carbon per hectare. The ecological and economic value linked to this quantity of carbon is 317.72 tons of carbon dioxide per hectare and 1766535 FCFA respectively. The value of this species contributes to the subsistence of populations and is an asset for its conservation and rational management. These parks are important reservoirs of biodiversity and play a fundamental role in meeting the needs of the local population. agroforestry parks, Borassus aethiopum, floristic diversity, carbon stock, Cameroo

Exploitation des fleurs de Ageratum conyzoides, Sida rhombifolia et Stylosanthes guianensis par Apis mellifera (Hymenoptera: Apidae) à Dang (Ngaoundéré, Cameroun)

A Dang (Ngaoundéré, Cameroun), d’avril à décembre 2015 et 2016, les fleurs de Ageratum conyzoides L., Sida rhombifolia L. et Stylosanthes guianensis (Aublet) Swartz ont été observées en vue de l’étude de l’activité de butinage de Apis mellifera L. Les fleurs de chacune de ces espèces végétales ont été prospectées deux jours par semaine, les mercredis et vendredis, entre 7h 00 et 18h 00, période subdivisée en trois tranches horaires (7h 00-11h 00, 11h 00-15h 00 et 15h 00- 18h 00). Les résultats montrent que les butineuses de A. mellifera fréquentaient intensément et régulièrement chacune de ces espèces végétales pour la récolte du pollen. Cette abeille prélevait fortement le nectar chez S. rhombifolia et S. guianensis. Chez A. conyzoides cette activité était faible. Le plus grand nombre de butineuses de A. mellifera simultanément en activité sur 1000 fleurs variait de 54 (A. conyzoides) à 125 (S. rhombifolia). Ageratum conyzoides, S. rhombifolia et S. guianensis sont des plantes apicoles fortement pollinifères pouvant être cultivées et protégées pour augmenter la production du pollen comme produit de la ruche. Sida rhombifolia et S. guianensis sont des plantes apicoles fortement nectarifères pouvant être cultivées et protégées pour accroitre la production du miel. Sur chacune de ces plantes, les ouvrières de A. mellifera transportaient le pollen de fleur en fleur et peuvent ainsi être considérées comme des pollinisateurs.Mots clés: Ageratum conyzoides, Sida rhombifolia, Stylosanthes guianensis, Apis mellifera, plante apicole, pollinisationEnglish AbstractAt Dang, from April to December 2015 and 2016, Apis mellifera L. workers foraging activity was studied on the flowers of three plants species, Ageratum conyzoides L., Sida rhombifolia L. and Stylosanthes guianensis (Aublet) Swartz. At Dang, the flowers of each plants species were observed two days per week, the Wednesdays and Fridays between 07h.00 and 18h.00, for recording the pollen and/or nectar foraging behaviour of A. mellifera workers. Results show that, A. mellifera harvested intensely and regularly the pollen of each plant species. In addition, S. rhombifolia and S. guianensis were also visited intensely and regularly for nectar; A. conyzoides was also visited for nectar but slightly. The greatest mean number of workers foraging simultaneously on the flower was 1 for each plant species, per 1000 varied from 54 (A. conyzoides) to 125 (S. rhombifolia). Apis mellifera workers visited the flowers of plants species others during foraging bouts. Consequently, A. conyzoides, S. rhombifolia and S. guianensis are highly polliniferous bee plants that can cultivated and protected to increase pollen production as a hive product. Sida rhombifolia and S. guianensis are highly nectariferous bee plants that can be cultivated and protected to increase the honey production. During foraging, A. mellifera workers carried pollen from flower to flower and improved pollination possibilities of each plant species and can thus be considered as pollinator.Keywords: Ageratum conyzoides, Sida rhombifolia, Stylosanthes guianensis, Apis mellifera, bee plant, pollinatio