A comprehensive comparison of perpendicular distance sampling methods for sampling downed coarse woody debris

Abstract

Many new methods for sampling down coarse woody debris have been proposed in the last dozen or so years. One of the most promising in terms of field application, perpendicular distance sampling (PDS), has several variants that have been progressively introduced in the literature. In this study, we provide an overview of the different PDS variants and comprehensive comparison of their associated estimator performance. Additionally, two new variants and their estimators are introduced to the existing pool. Simulations are used to determine the efficiency of competing protocols and associated estimators. The simulation results corroborate the theoretical unbiasedness of the estimators for PDS in all forms. In addition, while there is some difference in variance among the protocols, the overall difference is small, and depends on the attribute to be estimated. Therefore, the choice of which PDS variant to use in field applications will depend on the field conditions and attributes to be estimated. © 2012 Published by Oxford University Press on behalf of the Institute of Chartered Foresters, 2012.