Freshwater Swamp Forest Ecosystem in the Niger Delta: Ecology, Disturbance and Ecosystem Services

Freshwater swamp forests are wetland ecosystems of global importance, especially because they provide very valuable ecosystem services such as regulation of flood and maintenance of water quality, and provide suitable habitat for the conservation of wetland ecosystems (flora and fauna). Though they are hosts to important biodiversity as in other tropical ecosystems, their ecology, function and contribution to ecosystem services are poorly understood. With poor baseline data on this threatened ecosystem across the Niger Delta region and the entire West African region, this thesis explores its ecology, biogeography and the capacity to which this ecosystem sequester carbon, in a bid to better prioritize and inform effective conservation and management.
Floristic compositions of the ecosystem were varied in density, diversity and rarity across undisturbed, disturbed and transition (mangrove-freshwater) zones. A total of 138 species within 100 genera and 41 families of taxa were identified across the 24 one hectare forest plots; with variations in dominance according to each of the zones. With a stem density which ranged from 94 – 506 stems ha-1, the ecosystem was seen to be comparable with other tropical forest ecosystems, but were poorer in species richness as a result of the environmental constraints associated with the swamp. Though disturbance (local factors) influenced the pattern of species distribution to a great extent, environmental (regional factors) equally contributed to this variation.
Above ground carbon estimates (AGC) were also similar to other African forest ecosystems, with the estimates varying at the plot level mainly due to disturbance gradients. Other variables that contributed to AGC variations included the floristic composition (which were found to be more carbon dense towards the transition zones), tree structure and climatic variables. Other ecosystem services derived from the ecosystem (timber and non-timber forest products) were found to be a major source of sustenance and income generation at varying levels. Household usage and dependence on the forests were mainly influenced by the degrees of remoteness of each community, and whether each of the households had other alternative sources of livelihood. With a poor perception of decline in ecosystem services with usage, the forests has steadily shrunk and degraded.