ABSTRACT The distribution modeling in diameter classes is an important indicator of the potential use of a forest community, as well as the projection of future forest production. The objective of this study was to evaluate the diametric structure and to select probabilistic density functions for three woody species in forested arboreal Caatinga vegetation in Bahia, Brazil. The study was carried out in the Contendas do Sincorá National Forest in the state of Bahia, Brazil. A total of 16 plots of 20 x 20 m were installed and all individuals with diameter at breast height equal to or greater than 5.0 cm were measured. The three species with the highest population density (Commiphora leptophloeos, Manihot catinga and Patagonula bahiensis) were selected for analysis and modeling of the diametric structure. Four probabilistic density models were adjusted. The Akaike information criterion was used to select the best model. The results found indicated that the three species presented a decreasing type curve. The Log-Normal function best described the diametric distribution and it can be indicated to describe the diametric distribution and assist in making decisions about the management and conservation of these species. It is concluded that the Normal function was less adequate to represent the distribution of the studied species.

ABSTRACT Dynamics studies associated with prognosis can support planning actions for the conservation and sustainable use of forest resources. Therefore, the objective of this study was to evaluate the dynamics and predict the diameter structure using the Markov chain model for an area of caatinga forest submitted to different management practices. The study was carried out in the Contendas do Sincorá National Forest in the state of Bahia. Four treatments were installed, corresponding to three management systems and one control. Data was obtained measuring all individuals with a diameter greater than or equal to 5 cm. The measurements were performed at two moments in 2015 and 2018. The results indicated that the selective cut-by-diameter treatment had the lowest mortality rate and the highest recruitment rate. Predictions of the diameter structure using the Markov chain do not generally present statistical differences (α0.01) between the observed and expected frequencies for the year 2018. It was concluded that the basal area showed a tendency for recovery and growth in the treatments which involved suppression compared to the control, with no statistically significant differences among treatments until the moment after intervention.