Insights into Spatiotemporal Variations and Driving Factors of Net Primary Productivity of Terrestrial Vegetation in Africa

The net primary productivity (NPP) of vegetation is an important indicator to evaluate the quality assessment of terrestrial ecosystems and characterize the status of ecosystem carbon balance. In this paper, we analyzed the spatial-temporal dynamics changes and sustainability of NPP in Africa from 1981-2018 using NPP long time series data, and explored the influence of topographic, climatic and human activity factors on NPP changes. The results show that: (1) Most of the deciduous broadleaf and deciduous coniferous forest areas in the tropical rainforest and its north and south sides showed a highly significant increasing trend in NPP, while the Congo Basin, Gabon, Cameroon, Ghana, Nigeria, and Tanzania showed a highly significant decreasing trend in NPP under the influence of human activities; (2) Most of the deciduous broadleaf and deciduous coniferous forest areas in the tropical rainforest and its north and south sides showed a highly noticeable increase in NPP, while the Congo Basin, Gabon, Cameroon, Ghana, Nigeria, and Tanzania showed a highly significant decrease in NPP under the influence of human activities; (3) In terms of the overall impact of each driver on NPP changes, cumulative precipitation and average temperature changes have the greatest impact on NPP changes, while human activities and topographic changes have the least impact on NPP changes. Among the human activity factors, population density change can better measure the effect of human activity change on NPP change, while among the topography factors, elevation change can better measure the effect of topography change on NPP change. The results of this paper can provide a scientific basis for the sustainable development of ecology, agricultural production and socio-economy in Africa.