A growth and yield projection system for a tropical rainforest in the Central Amazon, Brazil

The aim of this study was to develop and apply an implicit yield model based on the Weibull probability density function for the predictions of yield by diameter class for a logged tropical rainforest located in the center of Amazon. The study area is located in the Tropical Forest Experimental Station, 90 km from the urban center of Manaus, AM, Brazil. The data came from 12 permanent 1 ha plots, logged at three levels of basal area removal intensities. In each plot all individuals with DBH ⩾ 10 cm between 1990 and 2009 were measured annually. Functions were used to describe the dynamics of tree abundance (recruitment and mortality), basal area, summed diameters per hectare, and a new statistic for classification of forest yield, in order to estimate the sample moments of minimum, average and quadratic mean diameter in 2009. The Weibull diameter distribution was fitted using the method of moments and validated by data collected in 2009. The inclusion of variables that reflect the productive potential in the proposed model facilitates the evaluation of forests that have undergone changes in its structural characteristics in the different sites. The use of an alternative technique for classification led to a better understanding of the management regimes applied to the forests under analysis. The proposed model proved efficient by the Kolmogorov-Smirnov test, and thus may be used in updating inventory statistics, calculations of annual cut and in planning forest by companies that work in uneven aged and mixed forests in different sites of the Amazon.