Composição florística e estrutura da comunidade arbustivo-arbórea de um trecho de floresta submontana na vertente sudeste do Parque Estadual da Ilha Grande, Angra dos Reis / RJ

Abstract

The study has as purpose to evaluate the floristic and structural composition of shrub-arboreal component in the submontane forest patch within the Atlantic Rain Forest domain with different stages of natural regeneration, in the southeast slope at the State Park of Ilha Grande, RJ. For the floristic studies were realized unsystematic samples in different parts in this slope. The species list was complemented with the conference at herbarium collections of the Rio de Janeiro (FCAB, GUA, HB, HRJ, R, RB, RBR, RFA, RFFP e RUSU) and with the results obtained of phytosociological studies. The conservation status of recorded species was verified for the Brazilian Flora. 34 plots of samples were set out for the phytosociological studies, totaling 1.02 ha of sampled area. All shrubby-arboreous individuals with DAP ≥ 5 cm were registered and, after identification, were deposited in the Herbarium of the Universidade do Estado do Rio de Janeiro (HRJ). The statistical package FITOPAC 2.1. was used for data analysis. The similarity between the remaining investigated in this study and fourteen others from different areas of Rio de Janeiro, of llha Grande's itself or not, was evaluated using the similarity coefficient of Sorensen; by Unweighted Pair Group Method with Arithmetic Mean (UPGMA) criterion and by the auto-resampling method for the structure of groups; by using the programs PAST v1.34 and Multiv 2.4. From the survey in herbariums and from floristic and phytosociological inventories carried in this paper, were examined 3,470 registers: 1,778 of the survey in herbariums, 1,536 of phytosociological and 156 of floristic studies. These registers corresponded to 606 species or morpho-species of Angiosperms and one of Pteridophyte. The results revealed the existence of 22 species threatened by extinction for Brazilian Flora. From among which, seven are exclusive of phytosociological sampling: Abarema cochliacarpos (Gomes) Barneby & J.W. Grimes, Chrysophyllum flexuosum Mart., Ficus pulchella Schott ex Spreng., Macrotorus utriculatus Perkins, Myrceugenia myrcioides (Cambess.) O.Berg, Rudgea interrupta Benth and Urbanodendron bahiense (Meisn.) Rohwer. In phytosociological study, were inventoried 1,536 individuals of 217 species, subordinate to 53 families. The Shannon diversity indices (H ') calculated was 4,702 nats/ind and equability (J) of 0.874. The ten families with highest richness were: Myrtaceae (31 spp.), Rubiaceae (21), Fabaceae (17), Lauraceae (12), Euphorbiaceae (11), Monimiaceae (8), Melastomataceae (7), Sapindaceae (7), Sapotaceae (6) and Annonaceae (6). The 10 highest values for species importance were for Chrysophyllum flexuosum (3,43%), Lamanonia ternata Vell. (3,40%), Hyeronima alchorneoides Allemão (2,83%), Actinostemon verticillatus (Klotzsch) Baill. (2,55%), Psychotria brasiliensis Vell. (2,55%), Eriotheca pentaphylla (Vell.) A. Robyns (2,28%), Guatteria australis A. St.-Hil. (2,12%), Mabea brasiliensis Müll. Arg. (2,04%), Miconia prasina (Sw.) DC. (1,89%) and Rustia formosa (Cham. & Schltdl. ex DC.) Klotzsch (1,82%). Were sampled 27% species represented by only one individual. The Floristic analyzes evaluated from the Sorensen Similarity Index indicated as the main variables for the formation of blocks, the different values of diversity for the areas and the phytogeographical distribution of species. The results obtained along with data from ecological groups, for individuals of the phytosociology, indicated a higher percentage of secondaries tardy individuals sampled. It Concludes that the study area is a secondary forest in regeneration intermediate stage, with great richness of species, many of which with relevant ecological importance