Efeito de diferentes intensidades de corte seletivo sobre a regeneração natural de cerrado

Abstract

This study aimed at evaluating the effects of selective cut intensities on the natural regeneration of cerrado senso stricto and the effect of time on the dynamics of natural regeneration. The experiment was conducted, in an area of cerrado senso stricto, in northwestern Minas Gerais state. The following treatments were utilized: Check (T), clear cut (CR), selective cut system with a reduction of 50, 60, 70 and 80% of the basal area, maintaining a 20% reduction in the original value of De Lioucourt’s quocient (T50, T60, T70, T80) and a reduction of 50, 60, 70, and 80% in the basal area, maintaining a 20% addition in De Lioucourt’s quocient (T50q, T60q, T70q, T80q). The treatments were established in 1 ha plots, in three blocks. The plots for data collection of natural regeneration (60x1 m) were located in the center of each plot of the management treatment. Data about height were collected and the botanical identification of the individuals was done before the establishment of the treatments and one month and 8 months after this. An analysis of covariance was performed for the following variables: number of individuals, number of species, average height, number of dead individuals and number of recruited individuals. An analysis of variance was also proceeded to detect the effect of time after exploitation on the dynamics of natural regeneration. The chief results were: the natural regeneration of shrub- tree vegetation were not affected by the levels of cuttings; the arithmetic means of height, the number of individuals and the number of species were not affected by time after the exploitation; dynamics of the number of recruited individuals in natural regeneration and also the number of dead individuals was affected by time after exploitation of shrub - tree stratum; recruitment and mortality behaved inversely, while recruitment decreases with time, mortality presented a sharp increase after exploitation.