Development of a sampling strategy for young stands of Eucalyptus sp. using geostatistics

Abstract

This work evaluated the potential of a geostatistical interpolator for defining strata and for comparing the stratification generated by the interpolator with stratification based on data records, on the basis of sampling error. Data were collected from a clonal stand of eucalyptus encompassing 164.08 haof area and located in the municipality of Aracruz, Espírito Santo state. In 2003, 49 plots were allocated and in 2004 another 50 plots were distributed systematically in the area. In 2005, all plots were remeasured. The characteristic evaluated each measurement year was ‘volume outside bark’. Spherical and exponential models were fitted to the experimental semivariograms using the maximum likelihood method. The selected model, following the Akaike Information Criterion, was the exponential model. Based on degree of spatial dependence (SD) it was possible to assess the spatial continuity structure of the characteristic of interest. The variable ‘volume outside bark’ was found to be spatially structured in all measurement years and the degree of spatial dependence varied according to forest age. This indicates that statistical analyses should consider the spatial component in the inference process at the ages considered in this study, in particular area classification based on yield. Results showed that the geostatistical interpolator can be used for establishing strata and locating permanent sample plots in young stands of Eucalyptus sp.