Phytosociology of the arborescent-arboreal component of a seasonal forest in Uruguai River Valley, Southern Brazil/ Fitossociologia do componente arborescente-arboreo de uma floresta estacional no vale do Rio Uruguai, Sul do Brasil

The degradation status of the forests in western Santa Catarina state reflects in a reduced number of conserved areas that enable studies on forest communities diversity and structure in order to create strategies for ecosystems preservation, management and restoration. The objective of this study was to describe the diversity and structure of a forest remnant of Seasonal Submontane Deciduous Forest located in the municipality of Sao Joao do Oeste, Santa Catarina state. For the inventory, we demarcated 102 sampling units of 10 x 10 m, continuously arranged in a grid of 6 x 17 plots, in which all plants of the arborescent-arboreal sinusiae with perimeter at breast height (PBH) [greater than or equal to] 15 cm were sampled. We surveyed 1441.18 living trees and 93.14 standing dead plants per ha. The 79 species found belong to 61 genera and 33 families. Sorocea bonplandii, Nectandra megapotamica, Inga marginata, Ocotea diospyrifolia and Trichilia claussenii presented the highest importance value indexes. The Shannon diversity index (H') was 3.21 and the Pielou equability (J') was 0.735. The vertical structure of the vegetation sampled was divided into treelets (2-11 m), canopy (12-17 m) and emerging trees (18-25 m). The studied forest fragment is an important reference ecosystem for the implementation of strategies for preservation, management and restoration of seasonal forests. Keywords: woody component; forest structure; submontane subformation; Seasonal Deciduous Forest. O status de degradacao das florestas no oeste catarinense repercute em um numero pequeno de areas conservadas que possibilitem estudos sobre diversidade e estrutura de comunidades florestais, a fim de criar aporte teorico para estrategias de preservacao, manejo e restauracao ecossistemica. O objetivo do presente estudo foi descrever a diversidade e a estrutura de um remanescente de Floresta Estacional Decidual Submontana localizado no municipio de Sao Joao do Oeste--SC. Para o inventario, foram demarcadas 102 unidades amostrais de 10 x 10 m, dispostas em uma grade continua de 6 x 17 parcelas, nas quais foram amostradas todas as plantas da sinusia arborescente-arborea com PAP [greater than or equal to] 15 cm. Ocorreram 1441,18 arvores vivas e 93,14 plantas mortas em pe/ha. As 79 especies encontradas pertencem a 61 generos e 33 familias. O indice de diversidade de Shannon (H') foi de 3,21 e o indice de equabilidade de Pielou (J')foi de 0,735. A estrutura vertical da vegetacao amostrada foi d