three k-tree distance and fixed-sized plot designs were used for estimating tree density in sparse oak forests. these forests cover the main part of the zagros mountain area in western iran. they are non-timber-oriented forest but important for protection purposes. the main objective was to investigate the statistical performance of k-tree distance and fixed-sized plot designs in the estimation...

The properties of a variable area sampling technique, by which the observer varies the searchradius to obtain approximately a prescribed number of woody plants in each tier measured, were determined by (i) comparison of fixed area and variable area sampling of a computer-mapped shrub population; (ii) comparison of results from fixed area and variable area sampling of woody plants exceeding abou...

Because different tree parameters are of differing importance, and have different variability, efficiency in sampling would suggest that some of the principle variables be subsampled. One convenient way to do this is to sample different numbers of items at the same sample locations. This paper is a review of some current techniques in subsampling for measured values, especially with Variable Pl...

A new distance-based estimator for forest regeneration assessment, the mean distance method, was developed by combining ideas and techniques from the wandering quarter method, T-square sampling and the random pairs method. The performance of the mean distance method was compared to conventional 4.05 square meter plot sampling through simulation analysis on 405 square meter blocks of a field sur...

Variable plot sampling has been widely used for many years. It was recognized, early in its application, that the process of getting stand volume could be divided into two components, counting trees to get basal area per unit area and measuring trees to get volume/basal area ratios (VBARs). It was further recognized that these two components had different amounts of variation and therefore shou...

Double sampling plan is an examination with a certain parameter, so it cannot decide about manufactured products whose portion parameter ( ) is not certain. The main goal of this survey is to introduce double variable plan when  is indefinite to examine manufacturing products when concerned characteristics are normally distributed. Plan parameters are achieved by an optimization manner. Sum of ...

We investigated the effect of plot-based and unrestricted (plot-less) sampling on an inventory of amegadiverse taxon, spiders, in an Afrotropical forest for the purpose of species richness estimates. We also investigated the efÞciency of human-based sampling methods and the effect of allocation of sampling effort to different samplingmethods to cover asmanymicrohabitats as possible. In the 10-d...