Caracterização fitossociologica de um fragmento de floresta estacional decidual relacionado ao gradiente de altitude em Macaíba-RN

Abstract

The delimitation of Deciduous Forests should be done including several aspects, such as soil, relief and vegetation. In the Brazilian Northeast, the Decidual Seasonal forest occurs in a contact zone between the Caatinga, the Cerrado and the Atlantic Forest, being narrow and transitional bands. In the RN there is a forest versatility between these ecosystems. The altitude variation is an important factor of changes in vegetation patterns, however not deeply studied in national and local forests. The study was carried out in an area of deciduous forest in the county of Macaíba, which was divided into 4 zones with a difference of 19 m of altitude between them, floristic and phytosociological data were collected. A total of 449 individuals distributed in 69 species, 49 genus and 36 families were inventoried. Fabaceae family was the most representative one with 11 species and 164 individuals, followed by Myrtaceae (10 species and 98 individuals) and Malpighiaceae (4 species and 10 indivisuals). Chamaecrista ensiformis (Vell.) H.S. Irwin & Barneby, Guapira laxa (Netto) Furlan e Zanthoxylum syncarpum Tul species obtained the higher indexes Fr: 50, 45 e 50 e VI: 25,11%; 17,09% e 19,58% , repectively. No species occurred along the entire gradient, with a constant input and output of taxa, DCA values was -0,851 e -6,8794, the indexes de of J’0,8432 , (C) 0,9533 E H’3,532; C2 presented the best values for all analyzed indexes evidencing an excellent stage of conservation and phytosanation related to the Atlantic Forest. Ci and C4 in spite of the distance they present Phytophysiognomy of Caatinga and Cerado; While C3 presents taxa of wide distribution among the national biomes. Thus a significant dissimilarity in the vegetative structure is observed in a smooth and continuous way.