Sustainable utilization evaluation is the basis for ensuring the sustainable exploitation of fisheries’ resources. This paper explores the changes in the mean trophic level of African marine fish catches during a 70-year period based on the statistical data on marine fisheries’ catches in Africa from 1950–2019, provided by the FAO in, order to determine the sustainable utilization of Africa’s fishery resources. The results indicate that although the marine fishery resources of African coastal countries have great variability, their exploitation has roughly gone through the stages of under-exploitation, rapid exploitation, and over-exploitation. Currently, marine fisheries in North and Central Africa are characterized by sustainable exploitation, while East, West, and Southern Africa are in a state of overfishing. The study implicates that African countries should establish a real-time monitoring system for marine fishery resources as soon as possible in order to dynamically grasp the actual changes in fish community structure due to fishing activities, ensure transparency in management and decision making, enact marine regulations to restrict massive fishing by overseas fleets, issue fisheries licenses cautiously, adopt conservative resource conservation policies, and enforce actions to achieve sustainable fisheries development.
The Mara River Basin of Africa has a world-famous ecosystem with vast vegetation, which is home to many wild animals. However, the basin is experiencing vegetation degradation and bad climate change, which has caused conflicts between people and wild animals, especially in dry seasons. This paper studied the vegetation greenness (VG), vegetation greenness trends (VGT), and their responses to climate change in dry seasons in the Mara River Basin, Africa. Firstly, based on Google Earth Engine (GEE) platform and Sentinel-2 images, the vegetation distribution map of the Mara River Basin was drawn. Then dry seasons MODIS NDVI data (January to February and June to September) were used to analyze the VGT. Finally, a random forest regression algorithm was used to evaluate the response of VG and VGT to temperature and precipitation derived from ERA5 from 2000 to 2019 at a resolution of 250 m. The results showed that the VGT was fluctuating in dry seasons, and the spatial differentiation was obvious. The greenness increasing trends both upstream and downstream were significantly larger than that of in the midstream. The responses of VG to precipitation were almost twice larger than temperature, and the responses of VGT to temperature were about 1.5 times larger than precipitation. The climate change trend of rising temperature and falling precipitation will lead to the degradation of vegetation and the reduction of crop production. There will be a vegetation degradation crisis in dry seasons in the Mara River Basin in the future. Identifying the spatiotemporal changes of VGT in dry seasons will be helpful to understand the response of VG and VGT to climate change and could also provide technical support to cope with climate-change-related issues for the basin.
This study investigates the spatio-temporal dynamics of Climate Potential Productivity (CPP) in Central Africa during 1901–2019 using the Thornthwaite Memorial model coupled with Mann–Kendall tests based on high spatial and temporal resolution data. The results demonstrate the climate–vegetation interactions under global warming: (1) Central Africa exhibited a statistically significant warming trend (r2 = 0.33, p < 0.01) coupled with non-significant rainfall reduction, suggesting an emerging warm–dry climate regime that parallels meteorological trends observed in North Africa. (2) Central Africa exhibited an overall increasing trend in CPP, with temporal fluctuations closely aligned with precipitation variability. Specifically, the CPP in Central Africa has undergone three distinct phases: an increasing phase (1901–1960), a decreasing phase (1960–1980), and a slow recovery phase (1980–2019). The multiple intersection points between the UF and UB curves indicate that Central Africa’s CPP has been significantly affected by climate change under global warming. (3) The correlation of CPP–Temperature was mainly positive, mainly distributed in the Lower Guinea Plateau and the northern part of the Congo Basin (r2 = 0.26, p < 0.1). The relationship of CPP–Precipitation showed predominantly a very strong positive correlation (r2 = 0.91, p < 0.01).