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Open AccessArticle

An Improved Weise’s Rule for Efficient Estimation of Stand Quadratic Mean Diameter

1
Faculty of Forestry, Technical University in Zvolen, Zvolen 96053, Slovakia
2
Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague 6 165 21, Czech Republic
3
National Forest Centre––Forest Research Institute in Zvolen, Zvolen 96053, Slovakia
4
Institute of Forest Ecology, Slovak Academy of Sciences, Zvolen 96053, Slovakia
*
Author to whom correspondence should be addressed.
Academic Editor: Maarten Nieuwenhuis
Forests 2015, 6(8), 2545-2559; https://doi.org/10.3390/f6082545
Received: 1 June 2015 / Revised: 20 July 2015 / Accepted: 22 July 2015 / Published: 27 July 2015
The main objective of this study was to explore the accuracy of Weise’s rule of thumb applied to an estimation of the quadratic mean diameter of a forest stand. Virtual stands of European beech (Fagus sylvatica L.) across a range of structure types were stochastically generated and random sampling was simulated. We compared the bias and accuracy of stand quadratic mean diameter estimates, employing different ranks of measured stems from a set of the 10 trees nearest to the sampling point. We proposed several modifications of the original Weise’s rule based on the measurement and averaging of two different ranks centered to a target rank. In accordance with the original formulation of the empirical rule, we recommend the application of the measurement of the 6th stem in rank corresponding to the 55% sample percentile of diameter distribution, irrespective of mean diameter size and degree of diameter dispersion. The study also revealed that the application of appropriate two-measurement modifications of Weise’s method, the 4th and 8th ranks or 3rd and 9th ranks averaged to the 6th central rank, should be preferred over the classic one-measurement estimation. The modified versions are characterised by an improved accuracy (about 25%) without statistically significant bias and measurement costs comparable to the classic Weise method. View Full-Text
Keywords: quadratic mean diameter; diameter dispersion, sample quantile; rule of thumb; simulation; European beech; forest inventory quadratic mean diameter; diameter dispersion, sample quantile; rule of thumb; simulation; European beech; forest inventory
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Sedmák, R.; Scheer, Ľ.; Marušák, R.; Bošeľa, M.; Sedmáková, D.; Fabrika, M. An Improved Weise’s Rule for Efficient Estimation of Stand Quadratic Mean Diameter. Forests 2015, 6, 2545-2559.

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