TREE SPECIES COMPOSITION AND STRUCTURE IN AN AREA REPRESENTATIVE OF \u201cACURI FOREST\u201d AT PANTANAL MATOGROSSENSE, BRASIL

Visando contribuir para o maior conhecimento deste tipo florestal pantaneiro, apresenta-se resultado de levantamento flor\uedstico-estrutural realizado em \ue1rea vulgarmente denominada de \u201cMata com Acuri\u201d, localizada na RPPN SESC Pantanal (Munic\uedpio de Bar\ue3o de Melga\ue7o - MT, Brasil - 16\uba45\u2019 S; 56\uba15\u2019 W). Os dados flor\uedsticos foram obtidos a partir de coletas sistem\ue1ticas de material bot\ue2nico f\ue9rtil e vegetativo efetuadas na \ue1rea amostral e entorno desta. Para coleta de dados estruturais, a \ue1rea foi subdividida em 100 parcelas cont\uedguas de 10 m x 10 m. Dentro de cada uma destas parcelas, todos os indiv\uedduos arb\uf3reos com di\ue2metro a altura do peito igual ou superior a 5,0 cm e palmeiras foram identificados, mensurados e mapeados, utilizando-se o sistema de coordenadas. Foram amostrados 1224 indiv\uedduos ha-1, representativos de 44 esp\ue9cies, 43 g\ueaneros e 27 fam\uedlias; \uedndice de diversidade H\u2019 = 1,613 (var. 0,003514). Fam\uedlias com maior diversidade: Fabaceae (9 spp.), Sapindaceae e Anacardiaceae (3 spp. cada), Bignoniaceae, Malvaceae, Moraceae e Rubiaceae (2 spp. cada). Dentre as esp\ue9cies amostradas, 39% eram perenif\uf3lias; 32% semidec\uedduas e 29% dec\uedduas. Do total de indiv\uedduos arb\uf3reos amostrados (n = 440), 51% eram dec\uedduos; 23% semidec\uedduos e 26% perenif\uf3lios. Attalea phalerata foi a esp\ue9cie que com maior valor de import\ue2ncia (VI = 121,62), devido \ue0 sua alta densidade (64% do total de indiv\uedduos amostrados), frequ\ueancia (100%) e elevad\uedssima \ue1rea basal (74,10 m2.ha-1). Com valores subsequentes registraram-se Anadenanthera colubrina , Triplaris americana e Phyllostylon rhamnoide (VI = 35,41; 28,51; 18,5, respectivamente). A \ue1rea estudada foi identificada como bastante peculiar em rela\ue7\ue3o a outros locais representativos de Floresta Estacional, especialmente pela presen\ue7a massiva de Attalea phalerata e aus\ueancia de representantes de Myrtaceae. A grande representatividade de esp\ue9cies pioneiras em associa\ue7\ue3o \ue0 elevada densidade de indiv\uedduos dentro desta categoria sucessional refor\ue7a o car\ue1ter de forma\ue7\ue3o transicional da Mata com Acuri. Em fun\ue7\ue3o da alta porcentagem de esp\ue9cies dec\uedduas e semidec\uedduas registradas para a \ue1rea de estudo, classificou-se esta como sendo representativa de Floresta Estacional Decidual.Aiming to contribute to the better understanding of this kind of Pantanal forest, the results from a floristicstructural survey performed in a 1ha plot commonly classified as \u201cAcuri Forest\u201d, located at RPPN SESC Pantanal (Municipality of Bar\ue3o de Melga\ue7o - MT, Brazil - 16\uba45\u2019S; 56\uba15\u2019W) are presented. The floristic data were obtained from systematic collection of botanical material on the studied area and surroundings. The structural data were obtained from a one ha plot, divided into 100 contiguous sub-plots (10m x 10m). Inside these sub-plots, all arboreal individuals with diameter at breast high equal or greater than 5.0 cm, including palms, were identified, measured and mapped, using a coordinate system. 1224 individual ha-1 were sampled, representing 44 species, 43genus and 27 families; diversity index H\u2019= 1.613 (var. 0.003514). The highest diversity families were Fabaceae (9 spp.), Sapindaceae e Anacardiaceae (3 spp. each), Bignoniaceae, Malvaceae, Moraceae e Rubiaceae (2 spp. each). Among the sampled species, 39 % were evergreen; 32 % semideciduous and 29% deciduous. Considering the tree individuals total (n = 440), 51 % were dec\uedduos; 23% semideciduous and 26% evergreen. Attalea phalerata was the species with the highest structural value (VI= 121.62), due to its high density (64% of the total sampled individuals), frequency (100%) e and very high basal area (74.10 m2 ha-1). On second level of importance were Anadenanthera colubrina , Triplaris americana and Phyllostylon rhamnoide (VI= 35.41; 28.51; 18.5 respectively). The studied area was identified as very peculiar comparatively with other Seasonal Forest areas, especially because the Attalea phalerata massive density and absence of Myrtaceae representatives. The high representation of pioneer species in association with high density of individuals within this successional category reinforces that Mata com Acuri represents an early successional stage or a transitional stage. Based on the great percentage of deciduous and semi-deciduous species recorded for the area of study, it was classified as being representative of Deciduous Forest