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IMPACTS OF THE INVASION BY Cryptostegia madagascariensis Bojer ex Decne. (Apocynaceae Juss.) IN THE REMNANT OF CAATINGA IN THE TOWN OF IBARETAMA, CEARÁ STATE, BRASIL
Sousa, Flaubert Queiroga de; Andrade, Leonaldo Alves de; Xavier, Klerton Rodrigues Forte; Silva, Patrícia Cândido da Cruz & Albuquerque, Manoel Bandeira de
Abstract
Cryptostegia madagascariensis Bojer ex Decne. is a shrubby species capable of forming populational
massifs in several niches of caatinga and its related ecosystems, especially in the most humid sites, that may
change the characteristics of native vegetation, triggering the disappearance of autochthonous species. This
study aimed to identify the impacts caused by the invader on the floristic composition and the structure of
the shrub-arboreal component. Three areas of investigation were selected, they were termed by: Ambience
I – area with a high intensity of invasion, Ambience II – the transition area between I and III (medium
intensity), and Ambience III – area with a low intensity of invasion. For the inventory of those areas,
it was used the point-centered sampling method (Quarter Method), considering adults those plants that
presented the diameter at ground level (DGL) greater than or equal to 3 cm, and height greater than or equal
to 1m. For the evaluation of the structure the conventional phytosociological parameters were analyzed,
beyond indices of Diversity, Equitability and Environmental Impact of Exotics (IEIE). In the Ambience, I
Cryptostegia madagascariensis was responsible for 82% of density, while in the Ambiences II and III, the
density of the species was severally reduced (14.2% and 9.6%, respectively). The diversity, according to
the Shannon-Weiner index, was low for the Ambience I (0.85) and higher for the Ambiences II and III (2.67
e 2.50, respectively). Results demonstrate that Cryptostegia madagascariensis affects severely the diversity
and the structure of invaded communities, causing loss in the autochthonal biodiversity of caatinga.
Keywords
exotic species; biological invasion; semiarid.
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