A social-ecological perspective on ecosystem vulnerability for the invasive creeper coralita (Antigonon leptopus) in the Caribbean: A review

Abstract

The Caribbean islands are a hotspot for biodiversity, harboring 2.3% of the world's endemic plant species on just 0.18% of the earth surface. Due to habitat degradation, invasive species are considered a major environmental problem on these islands. The vine coralita (Antigonon leptopus Hook. & Arn.) is the most abundant invasive species on the Dutch Caribbean island of St. Eustatius. Forming thick, monospecific carpets, it is seen as a threat to biodiversity. Insight is needed as to the ecological and social factors that influence the local ecosystem's vulnerability for invasion by A. leptopus. We used a Social-Ecological Systems framework for a literature review to answer our research questions: 1) What is currently known about the social and ecological factors that make an ecosystem vulnerable for invasions by invasive species and A. leptopus in particular? 2) How much empirical evidence is provided to back up the claims made in the reviewed literature? and 3) Which research and management priorities can be identified for St. Eustatius based on this analysis? Our review yielded 46 relevant documents, of which only 21 were peer-reviewed scientific articles. We assessed the level of empirical support for each of the factors mentioned in the reviewed literature and used these to shape our conceptual Social-Ecological model. Three major factors appeared to be responsible for the vulnerability of ecosystems for A. leptopus invasion: overgrazing by feral animals (16 papers), anthropogenic disturbance (19) and climate change (6). Empirical evidence for the relation between A. leptopus invasion and social and ecological factors is scarce: only anthropogenic disturbance and overgrazing were supported by quantitative data (three papers each). Our literature review also indicates that the invasion of A. leptopus on St. Eustatius is more a symptom than a cause in itself. Efforts to manage coralita by chemical or manual removal are futile if not combined with active vegetation restoration and grazer exclusion. Conservation efforts have led to an increase in forested areas on the island, in which coralita is not present. More experimental research is needed to inform policy and management decisions, preferably on the effects of feral grazer exclusion and shading by native trees on the recovery of natural vegetation in areas now dominated by coralita.