Wetlands invaded by Pneumatopteris afra (Christ.) Holttum are less diverse and more threatened than non-invaded ones in Nigeria.
We compared the diversity indices of wetlands invaded by a fern, Pneumatopteris afra, and those that were not invaded. Six wetlands chosen for this study were each the size of 500×500 m2 which included 3 invaded and 3 non-invaded wetlands. A total of 240 quadrats of size 1.5×1.5 m2 were established at all sites for estimation of abundance and diversity indices. A total of 1634 individual plants of 9 species were observed at the invaded sites while 1032 individuals of 14 species were observed at the non-invaded sites. The non-invaded sites exhibited significantly higher diversity indices than the invaded ones. Non-invaded sites are richer and more diverse than the invaded sites. None of the plant species at the non-invaded sites exhibited strong dominance over others. The lower species diversity of the invaded sites is also an indicator of the threat level posed on the wetlands by P. afra.