Estratégias de invasão de Hedychium coronarium J. König (Zingiberaceae)
Costa, Rosane Oliveira
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The invasion of natural ecosystems by exotic species threats world biodiversity, causing competitive exclusion of native species and loss of ecological interactions, compromising ecosystem functions and services. Invasive species often resist to environmental variations and are capable to develop strategies that increase their competitive ability. Hedychium coronarium J. König (Zingiberaceae) is an herbaceous macrophyte native from Himalaya, considered an aggressive invader on Americas. We investigated its dominance mechanisms and the effects on associated terrestrial and aquatic communities. We evaluated 1) the effect of intraspecific competition (rhizomes density) on sprouting and growth of aerial and subterraneous parts of H. coronarium on different light conditions; 2) the interspecific competition, by estimating the seedling growth of a native tree species (Anadenanthera macrocarpa) on the presence/absence of the invader; 3) the phytotoxicity of the essential oil from H. coronarium rhizomes on the germination of native riparian tree species; and 4) the toxicity of aqueous extract of H. coronarium rhizomes on aquatic organisms (algae, macrophyte, cladoceran, insect and fish). H. coronarium showed similar performance and occupation capacity on opened and shaded environments, suggesting the existence of a compensation mechanism of resource allocation on different light and density conditions. The presence of H. coronarium harmed the growth of A. macrocarpa seedlings independently of the removal of aerial part of the invader. The secondary compounds of essential oil of H. coronarium rhizomes affected the germination of native riparian tree species. The aqueous extract was toxic for all tested aquatic organisms, indicating possible alterations on trophic chain dynamic of invaded aquatic ecosystems. Our results suggest that H. coronarium use different invasion strategies and impose multiple negative effects on native communities, highlighting their high invasion potential and capacity of promote ecosystem changes.