Invasive Species Compendium

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Abstract

Aquatic vegetation of the wetlands of the high micro-basin of the Estero creek, San Ramon de Alajuela, Costa Rica.

Abstract

The vegetation composition study is a key aspect in assessing the ecological condition of aquatic ecosystems. The wetlands of the high watershed of the quebrada Estero in San Ramón of Alajuela, Costa Rica, are a conservation priority, though there are no previous studies on the plant biodiversity. The objective of this study was to examine the taxonomic composition of aquatic flora of this micro watershed. The study was conducted between July and September 2014. Eight sampling points were selected along the quebrada Estero. Band transects of 10 squares of 1 m2 were made to determine the plant species present and their abundance (percentage cover). A total of 13 families and 32 species were found, of which 11 are strictly aquatic, seven semiaquatic and 15 flood-tolerant. Most were flowering plants (six dicots, 25 monocots) and a species of green algae. The most diverse families were Poaceae (12 species) and Cyperaceae (7). According to lifeform, 29 were emergent, two floating and one submerged. Five were considered exotic. Coix lacryma-jobi and Leersia hexandra showed abundance values of 27% and 25% respectively, which were classified as frequent, others are rare. The site with the highest richness was Pantanol with 12 species, followed by the Embalse el Porvenir with 11 species. Both sites also showed high levels of diversity (H′: 1.41 and 1.85) and low dominance (D′0.42 and 0.2 respectively). The Pantano2 and Pantano3 sites are the most similar, with three common species (S=0.67), while the most different was Quebrada2, sharing only one species with Pantanol. In conclusion, the plant diversity of these ecosystems is important because it retains typical elements of Costa Rica's wetlands so they must be preserved. However, the presence of exotic dominant species and low richness in some wetlands suggest some degradation processes, therefore measures should be taken for their protection, management and recovery.