Ladivania Medeiros do Nascimento

Composição florística de um trecho de vegetação arbustiva caducifólia, no município de Ibimirim, PE, Brasil

Com o objetivo de contribuir para o conhecimento da estrutura taxonomica e identidade floristica da vegetacao arbustiva caducifolia das chapadas sedimentares do semi-arido de Pernambuco, foi realizado o levantamento da flora angiospermica de uma area situada no municipio de Ibimirim, PE. Em 343 coletas, foram identificados 139 taxons, distribuidos em 92 generos e 38 familias. As familias com maior riqueza foram: Euphorbiaceae, Fabaceae, Caesalpiniaceae e Mimosaceae com 42% e 33% das especies e generos, respectivamente. A partir da analise de 831 especies listadas em 15 levantamentos floristicos, distribuidos em 19 areas (Ceara, Pernambuco, Piaui e Sergipe), identificou-se que o maior numero de especies em comum ocorreu com levantamentos localizados em chapadas sedimentares e caatingas instaladas no cristalino, e o menor, com o levantamento de cerrado no Estado do Piaui. A partir dos aspectos floristicos, funcionais e grau de deficiencia hidrica da area de estudo, a vegetacao foi considerada como pertencente a caatinga.

Natural forest regeneration in abandoned sugarcane fields in northeastern Brazil: floristic changes

Surveys were undertaken to examine the floristic changes during secondary succession in three areas of 12 and three of 20-year-old secondary forests in Pernambuco State, Brazil. Two hundred and six species were identified, with 136 being found in the 12-year-old secondary forest and 161 species in the 20-year-old forest. Fabaceae and Myrtaceae were the most important families, increasing in species numbers with regeneration age. Of the 216 species, 115 were trees, 48 shrubs, 16 herbaceous plants, and 24 woody lianas, without significant differences between the two regeneration site ages. NMDS analysis revealed a formation of two floristic groups, distinguishing secondary and mature forests, with a further division within secondary forests in accordance with the time since abandonment. Similarity analysis ANOSIM confirmed the significance of the groups, which had floristic composition significant distinct (R=0.96) and 63% of dissimilarity (SIMPER). However, the sharing of 68 arboreal species between the secondary and mature forests suggests a floristic convergence. DCA analysis of the arboreal component as well as the other plant habits suggested that the separation of the subgroups is correlated with physical and chemical variables of the soils. All of these results indicate that, within the chronosequence analyzed, the velocity and direction of the floristic composition during secondary succession was influenced not only by the time of their abandonment, but also by a wide range of environmental variables.