Prospection survey and harvest optimization aiming at the management sustainability of a submontane semideciduous seasonal forest / Inventário de prospecção e otimização da colheita visando a sustentabilidade do manejo de uma floresta estacional semidecidual submontana

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

Among the activities which form a forest management system, harvest is the most expensive one, and when it is carried out with no planning it causes severe damages to the forest structure. To perform a low impact exploitation, that is, to minimize damage to the natural regeneration, that is, to minimize damage to the natural regeneration and remaining trees, a detailed survey of the area to be managed must be done. The main objective of this work was to propose harvest optimization of a semideciduous seasonal forest, based on a new methodology of prospection survey with an arboreous mapping. In a unit of annual production of 24.25 ha, 2,707 arboreous individuals were surveyed, with DBH ≥ 20 cm, and their data of quantitative and qualitative freatures, besides their geographic coordinates (UTM) were kept in a geographic referred databank. The prospection survey analyses included the technical viability and the determination of cost of the proposed method. In addition to the floristic composition and the phytosociologic structure, an analysis of the internal structure and diametric structure, basal area and volume was also done. With these results various simulations of cutting alternatives were made, based on the legislation in force in the State of Minas Gerais, Brazil. All data surveyed were kept in a geographic information system (SIG) which helped in the operational planning and in the harvest stock optimization. The prospection survey methodology, based on the use of digital equipment for distance measurement, showed to be feasible. The accuracy required in the determination of the position of the trees, as well as the relief conditions, dense understory and great presence of vines, influenced directly the prospection survey outcome, which were of 442 m per day for trail opennings, and of 0.80 ha per day for the prospection survey carry out. The cost of trail openning and prospection survey were of US$35.69 and US$89.43 per hectare, respectively. The harvest stand, with 24.25 ha, presented 158.01 m2 of basal area and 1,032.29 m3 of commercial volume, that is, 6.5 m2/ha and 42.6 m3/ha, respectively. The forest presents a typical secondary formation, with a great number of species of low values of VC, followed by few species of high values of VC. From the 68 species identified, 10 (14.7%) were classified as pioneers, 42 (61.8%) were classified as initial secondary, and 14 (20.6%) were classified as late secondary. The proposed cutting intensity provided 566.08 m3 of commercial volume in the area fo 24.25 ha, or 23.3 m3/ha. The sustainable yield forest management plan recommended (PMFRS), registered in the IEF/MG, for this same stand, that a commercial volume of 37.26 m3/ha, or 903.5 m3 should be harvested, that is, a harvest of 59% above the volume provided by means of the prospection survey. The modelling of the forest structure in a geographic information system allowed the simulation of a harvest alternative, which was based both on the determination of a maximum reduction of 60% of basal area, by species and diametric class, as well as on the concern of the damages that this harvest could cause to the canopy and clearance formations. Moreover, the plan allowed the presentation of critical areas places with the occurrence of vines, bamboo, grasses and socky emergences and seed trees. These measures are required by the laws that rule the forest management.

ASSUNTO(S)

botânica manejo florestal administração plant communities floresta sistemas de informação geográfica geographic information systems mata atlantica comunidades vegetais exploração botany madeira wood exploration medição forest management forest measurement mata atlântica

ACESSO AO ARTIGO

Documentos Relacionados