Análise de sobrevivência e qualidade de um plantio de Eucaliptos spp. em estágio inicial na Zona da Mata Norte de Pernambuco

Abstract

The forest inventory is an essential tool for accurate forestry planning, with the aim of obtaining a homogeneous forest in the future with good expressiveness in terms of diameter and height. The study area was a sugar-alcohol company located in the Zona da Mata Norte region of Pernambuco, in the municipality of Tracunhaém. In order to have a quality forest, it is necessary to periodically monitor the stand from the time the seedlings are planted in the field until they are harvested. The aim of this study was to assess the survival and quality of Eucalyptus hybrids (Eucalyptus urophylla x Eucalyptus camaldulensis) using two sampling methods, using the Pv50% uniformity index. The inventory was carried out at 3 months and 14 months using the circular plot and systematic line sampling methods. The planting was done at a spacing of 3m x 3m in an area close to a community that used it to dispose of its solid waste. Systematic sampling was carried out by randomly establishing the start of the systematic sampling sequence and followed the sequence established for data collection. The sampling per plot was 6 meters long and 113m² in area. The data obtained made it possible to generate information on the percentage of survival, planting failures and mortality, with the systematic line sampling method performing more efficiently, as it generates reliable information when it comes to observing trends in a forest. Survival by systematic sampling at 3 months ranged from 85% to 66% survival, and at 14 months 78% to 63%, while the circular plot method at 1 month had a percentage of 94% to 100% survival and at 14 months 72% to 99%. The study showed satisfactory sampling sufficiency, with a 9% sampling error being admissible, and a coefficient of variation of 43%, showing high variability in the volume of samples. The uniformity index Pv50% of the plots had 37% uniformity, indicating that the silviculture applied to the areas did not provide equal growing conditions for the hybrids. When analyzing the sampling methods based on the analysis of variance statistics, it was possible to see that the systematic sampling method was significant and more efficient for carrying out a survival inventory.