Invasive Species Compendium

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Abstract

Floristic composition, diversity and its potential for future regeneration between native and exotic species in the caiman forest of Seychelles.

Abstract

This study was conducted in the Caiman forest on Mahé in the Seychelles - an important water catchment area that suffers from different land use activities and also from invasive species. The aim of this research was threefold: (i) to identify and document plant species in the Caiman forest, (ii) to assess the diversity of plant species, and (iii) based on available saplings, to make inference on future potential for regeneration. Considering the rugged terrain, existing paths were used as transects having first established that the species composition along paths was similar to that in the forest as a whole. Adult plants and saplings were inventoried across 8 sub-transects giving a total length of 1260 m. Twenty-six plant species belonging to 18 families were recorded in the study area, the majority belonging to the plant family Arcecaceae and Moraceae. Exotic species recorded a relatively higher diversity compared to native species across the three different altitude and dominated even on glacis habitats mostly located on steep slopes in Seychelles. Phoenicophorium borsigianum recorded the highest prominent value for both adult and sapling while species such as Swietenia macrophylla, Artocarpus heterphyllus, Pinus carbaea, Dillenia ferruginae, Ficus reflexa and Terminalia catappa had no identifiable saplings. In term of their potential for future regeneration, our study found out that exotic species have relatively higher potential for regeneration compared to native species in the Caiman forests. Without eradication programs and monitoring, the future composition of the Caiman forest is likely to be dominated by exotic species.