Journal Article

practical look at the variable area transect

Dobrowski, Solomon Z., Murphy, Shannon K.

2006

Overview

The variable area transect (VAT) is a plotless density estimator that has received little attention in the ecological literature despite having potentially robust estimation properties. VAT allows for density estimations without the lengthy search times associated with other plotless density estimators. In spite of this, little has been written about the effect of varying transect widths on its density estimation properties or on the practical implementation of the VAT in field settings. An artificial population sampler was used to examine the effect of transect width on density estimates obtained using the VAT. Three transect widths were chosen corresponding to the mean object size, the largest object size, and twice the size of the largest object. Transect width had a marked effect on the quality of the density estimation, with the largest transect width resulting in significant negative biases in estimation. For the narrowest width, most estimates were within 10% of the true value for a nonrandomly distributed population. The practical considerations of choosing a VAT transect width are enumerated.

• Publisher: Ecological Society of America
• Subject: Animal and plant ecology / Animal, plant and microbial ecology / Biological and medical sciences / Computer Simulation / Density / Density estimation / Ecology / Ecosystem / Estimation bias / Estimators / Fundamental and applied biological sciences. Psychology / General aspects / methodology / Models, Biological / plotless density estimator / Population Density / Population distributions / population ecology / Population estimates / research methods / sampling / Sampling bias / Search time / transect surveys / variable area transect