Diametric and spatial structure of wood species of economic importance in the Amazon

Abstract

The objective of this study was to evaluate the diametric structure and spatial pattern of four timber species of economic importance in the Amazon. The study was carried out in nine Work Units of 100 ha each, inserted in the Annual Production Unit n° 8 of the Forest Management Unit Samambaia, belonging to the Mixed Cooperative of the Tapajós National Forest, Belterra municipality. Data were collected through a 100% inventory, with Cartesian coordinates mapping of all species with a diameter of 1.30 m equal to or greater than 20 cm. Diametric structure of the species was obtained through cluster and discriminant analyzes. From these structures five functions of probability density (Weibull-3P, Gamma, Normal, Lognormal and Exponential) were tested. The fit was assessed using the Kolmogorov-Smirnov test, 95% probability and histograms. Spatial pattern was obtained through Ripley's K-function. The species showed a diametric distribution tending to normal, which suggests regeneration problems, probably caused by low seed production, unfavorable edapho-climatic conditions or reduction of pollinating fauna. Hymenaea courbaril presented a random spatial pattern, while Manilkara huberi and Handroanthus serratifolius exhibited aggregate patterns. Mezilaurus itauba presented a pattern varying in relation to distance, that is, random for distances less than ± 100 m, aggregated up to approximately 825 m and random up to 1,500 m. Probably species dispersal syndromes and soil and climatic conditions of PAU affected the results reported in this study. © 2021 University of Sao Paolo. All rights reserved.