Wetlands invaded by Pneumatopteris afra (Christ.) Holttum are less diverse and more threatened than non-invaded ones in Nigeria

Abstract

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.

Keywords

• calopogonium mucunoides
• cyclosorus afer
• invasive plants
• lafia
• wetlands