Produção de madeira em regime de talhadia na floresta estacional decidual

Abstract

The tobacco producing region of Rio Grande do Sul has a high demand for firewood for the curing of Virginia tobacco leaves. An example of species with features to supply the demand is Nectandra megapotamica which can be conducted by the coppice system for the production of firewood, and leaves for the extraction of essential oils. The objective of this study was to estimate the individual volume and biomass production for evaluating the technical viability of managing secondary forests under coppice system for the production of forest timber and non-timber products. Samples were collected on Agudo municipality in the central region of Rio Grande do Sul, in a secondary forest regenerated after the occurrence of clear-cutting of the pre-existing forest in in 1993, with removal of wood and reduction of residual biomass with fire and without soil disturbance, and cultivated a corn crop followed by fallow. A forest inventory was conducted to determine the floristic composition of the vegetation. All the trees were identified in the field, having been measured the CAP, the total height, commercial height, crown insertion height and eight canopy rays, guided by the cardinal and collateral points. Were slaughtered 16 individuals of Nectandra megapotamica, totaling 36 trunks. In each proceeded by a cubing Smalian method. Then we proceeded to separate the compartments of the biomass, which were measured with the aid of a balance of digital hook. To determine the dry mass, samples were collected, which were heavy on the spot and placed in plastic bags and taken to the Forest Management Laboratory of UFSM, which they were dried in an air forced circulation stove at a temperature of 72 ° C, until constant weight. The branches with CAP greater than 15.7 cm were used as sample for adjusting the amount of biomass and models. Also evaluated the regrowth of stumps, measuring height and CAP of the shoots, and the place of emergence of the same. At the forest inventory, 385 individuals were sampled, of which 25% have more than one stem. Nectandra megapotamica showed a percentage of 56% of individuals with more than a trunk, demonstrating that it can be conducted under the coppice system. It was found that the branches can be used as sample for volume and biomass studies because they showed similar behavior to the trees. Models were fitted that showed good fits to the data volume and biomass. Nevertheless, for the compartments of biomass canopy, the generated equations were less accurate due to the greater variation in the data. There was no difference in the production of wood and leaves in individuals with a trunk or multiple trunks. The production in the study area was 56.2 m³.0,23 ha-1, equivalent to 244 m³.ha-1. The coppice of native species can partially supply the demand for wood in the properties of the tobacco region. Finally, the management of secondary forests under coppice system for the production of forest products timber and non-timber is technically viable.