EVALUATION OF DIFFERENT INTERVENTION LEVELS IN THE DEVELOPMENT OF THE BASAL AREA AND NUMBER OF TREES OF A BRAZILIAN SAVANA - STRICTO SENSU

Abstract

This study compared statistically the changes of the number of trees and the growth of basal area after 10 years of apllying different levels of intervention in the vegetation of the savannah “stricto sensu”. The data for accomplishment of this study were obtained in the Alvação farm, in Coração de Jesus county, north of the state of Minas Gerais. Evaluations were accomplished in 1986, 1996 and 1998 in 30 plots of 600m2 each installed in an area of 30ha subjected to 6 treatments. These consisted on: remotion of 50%, 70%, 80%, 90% and 100% of the basal area, besides the control, with 5 repetitions each. It was reccorded the number of trees and the basal area of the plants with circumference at 1,30m of height (CAP) larger or equal to 15,7 cm. This study was carried out to evaluate the development of the trees and the basal area after the treatments had been applied by using the analysis of variance in factorial design with subdivided plots in time. The main results were: the experiment implanted in 1986 was still in the growth phase, since the control plots presented increasing number of plants and basal area of 12,6% and 92,56% respectively for the measurement of 1996; among the applied treatment the clear cutting presented the largest percentage of increase in the number of trees; considering the variable number of trees per hectare it can be suggested a cutting cycle of 10 years, when 70% and 100% of basal area are removed. However, for a twelve years cutting cycle remotion from 50% to 100% of basal area can be adopted.