Composição florística e estrutural da vegetação de restinga do Estado do Piauí

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Restinga is vegetation settled upon quartzpamnents of the quaternary and its floristic composition is considered an extension of Atlantic Forest or adjacent ecosystems. The present thesis brings two works released in the restingas of the State of Piauí, whose coast belongs to the septentrional portion of the northeastern coast. This study is divided in two chapters. The first one had the aim of verifying if the restingas of Piauí present floristic composition originated in its adjacent ecosystems (Caatinga, Cerrado) or caatinga-cerrado transition. This work brings the survey of the areas situated in the municipalities of Ilha Grande, Parnaíba and Luiz Correia, which belong to the Área de Preservação Ambiental do Delta do Parnaíba. The collections were made between july/2005 and june/2007. The study about distribution of woody species was based upon the lists of other surveys in northeastern restingas. A matrix of absence/presence was set up in order to calculate multivariate analysis (UPGMA-group average) and the jaccard index, determining the floristic similarity and comparing with data from other restingas and adjacent ecosystems. 213 species from 53 botanical families were found, from which 11,4% were woody species exclusive of the studied restingas. The predominant life-form (43,65%) was nanofanerophyites, similar to what occurs in other Brazilian restingas. The most representative families were Fabaceae (45 spp.), Euphorbiaceae (15 spp.) and Bignoniaceae (10spp.). Their physiognomies are similar to the other Brazilian restingas (grasslands, scrubs and forests). The survey presented species that are common in other areas, just like Cyperus maritimus, Remirea maritima, Guettarda platypoda, Manilkara triflora, Abrus precatorius, Matelea maritima, and others. The study of similarity pointed out that the area resembles more the other northeastern restingas, intrinsically connected to the Atlantic Forest in its composition, than the ecosystems adjacent to it. The second chapter deals with the vegetation structure and its relation with the chemical and physical composition of the soil, in the same areas used in the floristic study. The tested hypothesis was that the soil factors influence in the structure of each of the restingas from Piauí in different ways, besides they present a structural pattern similar to the other northeastern restingas. The point-centered quarter method was used to the study of structure. Soil samples of the area were collected in order to determinate their chemical and physical variables. Profiles of each area were built, what demonstrated the predominant structure. Using the canonical correspondence analysis, the soil variables were compared to the found species. The studied restingas presented similar physiognomies to the ones in the other northeastern restingas, with a lower Shannon Diversity Index. The canonical analysis made possible to conclude that the species distribution was influenced by some soil factors.

ASSUNTO(S)

vegetação costeira piauí(br) botanica flora riqueza vegetação de restinga estrutura lenhosa restinga

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