Valeurs écologiques et économiques des écosystèmes de la Réserve de Faune du Dja sous l'influence des effets anthropiques

Abstract

Protected areas are a land-use mode that promotes the maintenance of vegetation cover and are the foundation of all biodiversity conservation strategies. This study was carried out with the presumption that 1) the biological wealth of the Dja Wildlife Reserve (DWR) can generate significant revenues for the State and neighboring populations, 2) the DWR has high potential for sequestration and carbon storage for forthcoming decades, 3) there are no drivers of degradation in the DWR. In this study, the ecological and economic values of DWR ecosystems and the anthropogenic effects that influence them were evaluated. These were: 1)characterizing the vegetative cover of the DWR, 2) assessing the DWR's carbon sequestration and storage capacity, and 3) assessing the importance of DWR for the conservation of biodiversity, 4) to evaluate the economic value of the DWR and 5) characterize the human actions in the DWR. To achieve this, the satellite Landsat 8 images of the study area were processed using the ERDAS Imagine 2014 and ArcGis10.0 software to identify different types of vegetation cover and map the vegetation of the DWR. Field data were obtained from 50 transects in the five previously defined areas. The assessment of carbon sequestration and storage capacity was done using the allometric formula of Chave et al., (2014). According to the 2016 Finance law, the cutting down taxes and exit duties were deducted from the applicable Free On Board prices per m3 of wood exported by species and by zone and the forest yearly rental linked to the total area of the forest under exploitation. The potential of the species recognized as threatened on the 2016 International Union for the Conservation of Nature (IUCN) red list present in the DWR has been exploited to assess the importance of DWR for the conservation of biodiversity. A sample of 250 camps was studied. Thus, their areas were estimated and the measurements were taken in a control plot of the same area installed near the deforested area. The main results show a varied and very diversified vegetation cover with eleven (11)types of plant cover sitting on firm land (79.32%) and on hydromorphic soils (20.36%) with dominance of dense evergreen forests with high density (DHS b) representing nearly 39% of the vegetative cover of the DWR. The flora is very rich with two hundred and senventy (270) species belonging to fifty (50) families and one hundred and eighty seven 187 genera. Carbon sequestration and storage capacities in all types of vegetation cover are important with an average of 209.97 tC / ha including the below ground carbon. The DWR is home to thirty two (32) globally recognized endangered species listed on the 2016 IUCN Red List and therefore has significant biodiversity conservation power. The economic potential of exploitable and marketable timber resources estimated at XAF 14.23 billion per year for the State (public treasury) and XAF 394.5 million for decentralized local authorities and local populations. Degradation rate at the scale of the reserve is estimated at 3.6 ha / year (0.0051 %) where we should have 0 % to talk about zero degradation corresponding to an emission of 10.45 tones of CO2 per hectare. The average number of stems cut down for camp construction is estimated at 170 stems / ha of diameter class ≤ 20 while trapping remains the main cause of deforestation. The exploitation of the DWR can contribute 0.4% of the annual budget of the State and support local development with a contribution of about XAF 394.5 million per year and can continue to regulate the global climate if its covered remains maintained through sequestration and carbon storage. Despite its protection status, the DWR is subject to degradation. However, the DWR presents a great diversity of ecosystems and remains an ultimate conservation site for biodiversity in Cameroon and in the Congo Basin. As future prospects for this study, it would be important to remake it in other protected areas of Cameroon's forest zones with a focus on the economic value of ecotourism and the assessment of understories and soil carbon stocks.