Estudo da ocorrência e caracterização dos castanhais nas encostas do platô Almeidas - Mineração Rio do Norte, Porto Trombetas, PA

Abstract

This study aimed to locate and characterize the Brazil nuts tree on the slopes of the plateau Almeida Mineração Rio do Norte, Porto Trombetas, PA and study the occurrence and Biometric of the Brazil nut trees of each area, within the National Forest Saracá-Taquera, managed by IBAMA, where is installed the project for the mining of bauxite of Mineração Rio Norte S/A company, in the District of Porto Trombetas, Oriximiná (PA). The identification of areas was made with information of chestnuts trees from neighboring communities. In each area was made a central ath in the direction of greater length, where the wooden markers were laced every 100 m. On each point were opened side trails until the last nut found. Landmarks were placed at that point with the distance of central path and geographic coornates in UTM, Datum "Sth Amrcn 69." The perimeter and area of each were calculated and plotted on a map of the plateau Almeida. The forest inventory of 100% of Brazil nut trees in categories Adult and Natural Regeneration was done with the demarcation of areas of 20 m long by 50 m wide on the right and left side in each row. Were measured the total height of the trunk, the circumference at breast height (CAP) and the diameters of the crown in the way North-South and East-West. Were calculated for each area, the number of Brazil nut trees, percentage of occurrence, number of trees/ha (density), average of total height and the trunk, DBH, crown diameter, basal area per tree, the stem volume per tree. Analyses of variance were performed with different number of observations and averages compared by Tukey test at 5% probability of the data of variables measured and calculated. The nuts areas found were Veado Pequeno with 4.93 ha,Veado Grande with 32.19 ha, Josefa with 26.95 ha, Tauari with 47.39 ha, Viana with 12.92 ha, Pedra with 31.50 ha, Moreira with 39.08 ha,Paiol with 68.00 ha and Severino with 19.96 ha, totaling 282.92 ha. The density ranged from 2.98 to 5.84 individuals/ha; the height from 36 to 19.5 m; the DAP from 53.95 to 139.43; the crown diameter from 14.68 to 23.66 m, resulting in a coverage of 1803.63 m2/ha with Brazil nut trees; the basal area from 1.15 to 1.80 m2/tree and 2.41 m2 to 8.53 m2/ha, the height of the trunk from 25,15 to 12.24 m and the trunk volume from 29.01 to 7.26 m3. The absence or low frequency of Brazil nut trees in the Seedling class indicates that the nuts trees areas need management and planting of seedlings in gaps and/or in places more opened to ensure the existence of individuals in various stages of development of the species.