Composite Estimation for Forest Inventories Using Multiple Value Groups and Strata

Abstract

Abstract Due to economic and political pressures placed on timber production, information from timber inventories needs to be broken down into information on particular value groups, which are groupings based on individual tree characteristics. Thus estimates of totals and variances need to be computed for individual value groups, all value groups combined, and any collection of value groups. A method for reporting these estimates using a variance-covariance matrix is given. This is followed by two examples of the estimation of totals and variances for value groups applied to a population comprising two strata. Poisson (3P) and sample-tree sampling are used in the first and second strata, respectively. These examples are included to highlight important estimation considerations. A worked example based on an artificial population is also given. The population for the worked example is divided into two strata, with three value groups in each stratum. 3P and sample-tree sampling are used in the first and second strata. South. J. Appl. For. 20(2):103-109.