Logging effects on mangroves vegetation diversity in the Sanaga River estuary

In recent decades, there has been a significant reduction in mangrove vegetation cover. Anthropogenic activities are increasingly affecting this ecosystem, even in protected areas. This study aimed to assess the impact of logging on the floristic composition and structure of mangrove vegetation in the Sanaga river estuary. The study was conducted in six mangrove areas of the Douala-Edea National Park. Plots measuring 25m x 25m were established every 20m along open transects perpendicular to the main tidal channels to inventory all species. Trees with a circumference greater than 15cm were identified and their heights were measured in each plot. The number and circumference of all stumps were also identified. The impact of logging was characterised by stump abundance, number of associated species, and density of Acrostichum aureum and Nypa fruticans. Seven of the eight characteristic mangrove species of the African Atlantic coast were encountered, with the exception of Conocarpus erectus. Out of the six investigated sites, three were slightly disturbed and three were moderately disturbed. The Shannon-Weaver diversity index ranged from 1.13 to 1.88, while the mean abundance varied from 400 ± 67.9 to 656 ± 90.5 ind. ha-1. The mean diameter ranged from 7.8 ± 6.7 to 22.5 ± 11cm, and the mean height of trees ranged from 4.8 ± 2.8 to 17.5 ± 8.2m. Many young individuals are being exploited (diameter of the stumps less than 10 cm) . Human activities have impacted the structure of the mangroves, with logging being the main cause of degradation of this ecosystem.