INFLUENCE OF ENVIRONMENTAL VARIABLES ON THE TREE COMMUNITY STRUCTURE AND FLORISTIC PATTERNS IN A MONTANE ARAUCARIA FOREST FRAGMENT IN LAGES, SANTA CATARINA STATE

O objetivo deste trabalho foi caracterizar a composi\ue7\ue3o flor\uedstica e a estrutura do componente arb\uf3reo de um fragmento de Floresta Ombr\uf3fila Mista Montana e avaliar a influ\ueancia de vari\ue1veis ambientais sobre os padr\uf5es encontrados. A \ue1rea de estudo situa-se no munic\uedpio de Lages, SC, \ue0s margens do Rio Caveiras (27\ub051'19.20\u201dS e 50\ub010'33,39\u201dW). O levantamento da vegeta\ue7\ue3o e das vari\ue1veis ambientais (caracter\uedsticas qu\uedmicas e f\uedsicas dos solos, relevo e cobertura do dossel) foi realizado em 50 parcelas permanentes de 20x10 m, alocadas de forma sistem\ue1tica estratificada no fragmento. Todas as \ue1rvores vivas com circunfer\ueancia 65 15,7 cm (medidas a 1,30 m do solo - CAP) foram mensuradas (CAP e altura) e identificadas. Foi calculado o valor de import\ue2ncia (VI) das esp\ue9cies encontradas, realizada a ordena\ue7\ue3o das parcelas em fun\ue7\ue3o da abund\ue2ncia das esp\ue9cies, por meio da analise de NMDS (Nonmetric multidimensional scalling) e plotadas a posteriori as vari\ue1veis ambientais significativas no diagrama de ordena\ue7\ue3o. Foram amostrados 1.843 indiv\uedduos, que totalizaram uma \ue1rea basal de 36,45 m2/ha, distribu\ueddos em 37 fam\uedlias bot\ue2nicas, 63 g\ueaneros e 92 esp\ue9cies. As tr\ueas esp\ue9cies com os maiores valores de VI foram Araucaria angustifolia (Bertol.) Kuntze, Lithraea brasiliensis Marchand e Jacaranda puberula Cham. As vari\ue1veis que apresentaram maior correla\ue7\ue3o com a estrutura e a composi\ue7\ue3o flor\uedstica do componente arb\uf3reo foram o pH, o desn\uedvel m\ue1ximo da parcela e o teor de Mg.This study aimed to characterize the floristic composition and structure of the tree component of a montane Araucaria Forest fragment and to assess the influence of environmental variables on the patterns observed. The study area was located in the municipality of Lages, Santa Catarina state, close to the margin of the Caveiras River. The vegetation and the environmental variables (physical and chemical soils characteristics, relief and canopy cover) were surveyed within 50, 20 x 10m, permanent plots allocated systematically stratified in the forest fragment. All trees with circumference at breast height (CBH) 65 15,7 cm were measured (CBH and height) and identified. The importance values (IV) of the found species were calculated, the plots and species were ordinated by an analysis of NMDS (Nonmetric Multidimensional Scaling), according to the abundance of species, and the significant environmental variables plotted \u201ca posteriori\u201d in the ordination diagram. One thousand, eight hundred and forty-three (1,843) individuals were sampled, which added up to a total basal area of 36.45 m2, distributed in 37 botanical families, 63 genera and 92 species. The three species with the highest values of VI were Araucaria angustifolia (Bertol.) Kuntze, Lithraea brasiliensis Marchand and Jacaranda puberula Cham. The variables that showed the higher correlation with the tree component structure and floristic composition were the pH, the plot highest declivity and the Mg content