Seed bank composition and floristic diversity of an inselberg in the semiarid region of Paraiba, Brazil

ABSTRACT The objective of this study was to evaluate the seed bank composition and floristic diversity, as well as the degree of vegetation similarity at different altitudes (base, middle, and top layers) of the Espinho Branco Inselberg, Patos, PB, Brazil. Forty-seven litterfall-soil samples (0-5 cm soil layer) were collected and placed on 95 perforated plastic trays to allow drainage of excess irrigation water. The trays were identified and distributed on benches in a shaded environment in the forest nursery at the Federal University of Campina Grande (UAEF/CSTR/UFCG), with a sunlight reduction factor of 50%. The emerged plants were classified by popular names, grouped according to family, genus, species, and plant type (herbaceous, sub-shrub, shrub, tree, and climber). Diversity and richness were evaluated using the Shannon-Weaver diversity and the Pielou equitability indices, and the similarity was determined using the Jaccard Index. The floristic composition of the collected samples showed 4,616 individuals from 40 families, 96 genera, and 111 species. The family Fabaceae had the highest number of species, followed by Euphorbiaceae, Malvaceae, and Poaceae. The predominant plant type was herbaceous. Cyperaceae, Onagraceae, and Poaceae were the most representative families in number of individuals. The Shannon-Weaver diversity and Pielou equitability indices were 2.92 and 0.62, respectively, and the Jaccard index was 0.93; the base layer had the greatest floristic richness. This work contributes with information to further researches on floristic diversity and richness and improves scientific studies in this field. RESUMO O presente estudo objetivou avaliar a composição e diversidade florística do banco de sementes e verificar o grau de similaridade dessa vegetação nas diferentes porções altitudinais (Base, Porção Mediana e Topo) do Inselbergue Espinho Branco no município de Patos-PB. Foram coletadas 47 amostras de serapilheira+solo na profundidade de 0-5 cm, distribuídas em 95 bandejas plásticas perfuradas, para permitir a drenagem do excesso de água de irrigação. Estas foram identificadas e distribuídas nas bancadas do ambiente sombreado do viveiro florestal do CSTR com fator de redução solar de 50%. As plantas emergidas foram classificadas pelo nome popular, agrupadas de acordo com a família, gênero, espécie e a forma de vida. A diversidade e a riqueza foram avaliadas utilizando o Índice de Shannon-Weaver e o Índice de equabilidade de Pielou, enquanto