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

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 theoreticalunbiasednessoftheestimatorsforPDSinallforms.Inaddition,whilethereissomedifferenceinvariance 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.