Sampling methods and geostatic for estimate of number of stems and volume of Eucalyptus grandis plantations

Abstract

The objectives of this work were to estimate the number of stems and wood volume per unit of management, by Simple Random Sampling (ACS) and geostatistic interpolator, for circular and row plots in three sample intensities; in order to compare the estimates obtained by the application of different methods, with the observed value (census) of each unit of management. The study area included four stands of Eucalyptus grandis, totaling 104.71 ha at ages varying from three to four years, belonging to Ripasa S/A Cellulose and Paper Company. Stem number of each stand was counted using digital aerial pictures. The evaluation of the accuracy of the estimate of the stem number and volume were made by accuracy matrix. The space prediction of the stem number and of volume, in each stand, were done by krigage with simulation in each stand. There was significant difference among the appraised methods for stem number in the three sample intensities. In the highest sample intensities the methods that involved circular plots were more precise than the row plot. In the sample intensity 1:10, the row plots were more precise than the circular ones. For the variable volume, the F test was not significant for the two highest sample intensities (1:4 and 1:7) and in the highest intensity there was statistical difference among the methods. Through the accuracy matrix for stem number as for volume, the most exact methods were those based on circular plots and for the intensity 1:10, the methods based on linear plots were more precise.