Development of design unbiased estimators for the restricted k-tree sampling techniques PCM (point-centered quarter method) and T-square sampling

• Applicant: Professor Dr. Christoph Kleinn
• Subject Area: Forestry
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 82429971

k-tree sampling is frequently applied in ecological sampling; less so in forest inventory for the concern of unbiasedness. A design-unbiased estimator had recently been developed (Kleinn and Vilčko 2006), using inclusion zones that quantify the per-tree selection probability - but that are laborious to determine in the field (higher order Voronoi diagrams). That estimation approach shall be further developed in this project for restricted k-tree sampling; that is to the point-centered-quarter method and to the T-square sampling technique. New approaches are required, the higher order Voronoi diagrams do not apply. Also, we wish to clarify the following research questions for both unrestricted and restricted k-tree sampling:Can the selection probability be approximated by regressing them to easily measurable inter-tree distances at the sample point?How compares the unbiased estimator for restricted/unrestricted k-tree sampling to fixed area plots in terms of precision for different point patterns?Can tree mapping be optimized by an integrated field computing and measurement system?Theoretical analyses and simulation studies on real data will be carried and also field testing. The results will be equally important for forest inventory sampling and for ecological sampling.

• DFG Programme: Research Grants