Métodos de regeneração da acacia mangium willd

Abstract

The increase in forest stands of exotic species is gradually growing worldwide due to several economic and environmental benefits. There are few studies on the best methods of regenerating forest stands of these species to find a more accessible and profitable method. In Brazil, the planting of exotic forest species grows every year, with emphasis on the exotic species Acacia mangium. The objective of this work was to compare the productive performance of A. mangium plantations regenerated by planting seedlings and conducting the regeneration of the soil seed bank. The study was carried out at the company Litiara Indústria de Cerâmicas do Amazonas Ltda., located on the AM-010 highway, in the rural area of the municipality of Itacoatiara (Am). Three stands of the company were evaluated, established via two regeneration methods: planting seedlings, at 12 and 24 months of age, and spontaneous regeneration of the soil seed bank at 27 months of age. The stands at 24 and 27 months of age were measured within five circular plots with a radius of 12.62 m (area of 500 m2), and the 12-month-old plots were measured in five rectangular plots of 20 x 25 m (area of 500 m2). The sampling system used was simple random. In each plot, the values of circumference at breast height (CBH), total height (At) and number of living trees were measured. Then, the values of diameter at breast height (DBH), density of trees per hectare, individual volume and volume per hectare were calculated. The mean values of diameter at breast height (12.95 cm), total height (11.66 m), individual volume (0.075 m3) and volume per hectare (107.25 m3) were higher in the stand regenerated by planting seedlings at 24 months of age. However, in the spontaneously regenerated stand, a higher mean value of tree density per hectare (4032 trees) was observed. Although the individual volume per tree was reduced in spontaneous regeneration (0.021 m³), the high density of trees promoted a high volume per hectare (84.21 m3). The regeneration of A. mangium stands can be carried out either by planting seedlings or by regenerating the soil seed bank. These results increase the possibilities of regeneration of stands of this species, especially for small producers who do not have a high investment capacity for planting seedlings.