Estrutura da vegetação arbórea em um remanescente de floresta higrófila, Pontal do Araguaia-MT

Abstract

The swamp forest, known as "hygrophilous forest," "flooded gallery forest" or "semi-deciduous seasonal forest with permanent river influence" is a formation that is characterized by occurring in soil permanently soaked and restricted to small fragments along with other vegetative types. This work characterized the floristic richness and structure of the woody flora in a hygrophilous forest and defined the most important species of the community. The study was made in a hygrophilous forest with a total area of 20 square meters as reserve in private area, located in Pontal do Araguaia, Mato Grosso (15 ° 54 'S and 52 ° 16' W). The terrain presents little slope and presents shallow water table, which favors the occurrence of flooded places in the vicinity of well drained places, where natural perennial drainage lines are observed. Five 20 x 50 m (0.5 ha) plots were used. In each plot, all living or dead arboreal individuals with diameter ≥ 5 cm, measured at 1.30 m height (DBH), were included. In total, 692 individuals (657 live and 35 dead) were sampled from 20 families, 22 genera and 25 arboreal-shrub stratum species, with a total density of 1384 ind.ha-1 and a basal area of 18.801 m².ha-1. Of the 25 species, one is identified at the gender level and one at the family level. The diversity index (H ') was 2.35 nats.ind-1 and the equability (J) 0.73. The wealth appraiser Jackknife1 provided the value of 29.8 species, while Chao 2 estimated 26.5 species. The most numerous species were Protium heptaphyllum (Aubl.) (222 individuals), Tapirira guianensis Aubl. (90 individuals) and Qualea ingens Warm. (85 individuals), which together represent 57.36% of the total individuals. The species with the highest value of importance (IVI) and cover (IVC) was Protium heptaphyllum (Aubl.) (56.78; 49.43), followed by Qualea ingens Warm. (47.03, 39.68) and Ruizterania wittrockii (Malme) Marc.-Berti (39.75, 32.40). Protium heptaphyllum (Aubl.) was distinguished by the high number of individuals, while Qualea ingens Warm. and Ruizterania wittrockii (Malme) Marc-Berti were distinguished by the high size of the individuals sampled. Measures of floristic similarity were found between the forests of the present study and five other structures of Mato Grosso, Federal District and Minas Gerais. The six forests presented low values of floristic similarity among them, although some of them presented common species among the most abundant ones. It was concluded that generalist species increase the richness of the forest and the experts define dominance and density.