(Bijalwan, 2010) ; 428 stems∙ha−1 in 95 species in a rainforest of Xishuangbana, China (Lu et al., 2010) . African tropical forests have shown densities of 434 stems (≥10 cm dbh) in mixed tropical forest, and 340 stems in a monodominant forest in Cameroun (Lewis et al., 2013) ; 387 stems in 94 species in a strict nature reserve in southwest Nigeria (Adekunle et al., 2013) . The stem densities are indeed similar and comparable with that of other tropical forests across the globe. These densities vary across the sites mainly due to the variations in disturbance regimes and capacities of each landscape to regrow after disturbance cycles. This on the other hand is responsible for the variations in basal area of the stems in each site.

Species richness of the ecosystem though varied, were generally low. This low species richness feature is however consistent with other freshwater swamp forests (Lugo et al., 1988; Scarano et al., 1997; Teixeira et al., 2011; Kurtz et al., 2013) due to environmental constraints associated with the ecosystem. The flooding regime that is associated with the ecosystem which inundates the soil exerts selective pressure on the composition and the structure of the ecosystem (Kurtz et al., 2013) . Since the flood free environments required to facilitate reproduction and shallow water to prevent water-logging of seedlings or gas exchange (Lugo et al., 1998) are barely guaranteed for the ecosystem, it affects its richness and composition such that only those species with higher tendencies of adaptation could thrive in the ecosystem. Similar studies (Kurtz et al., 2013) reported lower species richness of the forests compared to the drier adjacent soil or forest locations.

As the ecosystem continues to undergo regimes of natural and anthropogenic disturbances, they provide gaps in the canopies of the forests and provide basis for regeneration and species diversity across the landscape. Such events go on to create opportunities for the addition of new species to the ecosystem and in turn facilitate the reinforcement and maintenance of the tree diversity in the ecosystem (Nakagawa et al., 2013) .

5. Conclusion

The study documented an array of composition found across the ecosystem according to their respective abundance in the ecosystem. Their stem densities were similar with those of other tropical forest ecosystems, while their diversity increased with disturbance across the ecosystem. The ecosystem is characterized by general low species richness, as in other freshwater swamp forests in the Neotropics. This implies that the loss of any single species in the ecosystem poses a great threat to species’ existence and conservation, and in turn, puts the ecosystem at the risk of ecosystem collapse. Furthermore, as the species diversity and rarity of the ecosystem are more associated with disturbed locations more than the intact zones, effective conservation of the ecosystem should be focused not only on the intact forest locations with higher basal area per hectare, but also on the disturbed locations whose higher species’ value is vital for the stability of the ecosystem.

Appendix 1

Table A1. Species importance values for all the forest sites.

Appendix 2

Table A2. Family importance values of the forest sites.

NOTES

*ORCID ID: https://orcid.org/0000-0003-2635-6948.

Conflicts of Interest

The authors declare no conflicts of interest.

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