Precision and relative efficiency of sampling methods in teak

Abstract

This study aimed to compare three sampling methods: fixed area, Bitterlich, and Prodan, regarding accuracy and relative efficiency to estimate the variables: diameter at 1.30 m above soil level (DBH), number of trees, basal area, and volume. The limit of error established was 10% at probability level of 95%, using 30 plots for each method. Circumference at 1.30 m above soil level was measured, for conversion in DBH, with total time counted since the plots installation until the last tree measured. The most accurate sampling was the fixed area method, for estimation of DBH and number of trees per hectare, whereas the Bitterlich method was the most accurate for estimation of basal area and volume. Bitterlich method proved to be more efficient for estimation of all variables. It can be concluded that the accuracy is not directly associated with relative efficiency, and that less usual sampling.