Comparison of three sampling methods in the characterization of cork oak stands for management purpose

M.J. Paulo, M. Tomé, A. Otten, A. Stein

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)

Abstract

The cork oak (Quercus suber L.) is an evergreen oak that has the ability to produce a continuous layer of cork tissue which regenerates after being removed. Cork oak stands can be diverse in structure. Young stands are often regularly spaced, whereas older stands usually show clustering and can be mixed with other species. Farmers assessing cork value use a zigzag sampling procedure within a stand. In this study we compare zigzag sampling with two other sampling methods, fixed-radius plot sampling and n-tree distance sampling, using a model for the costs of sampling. We used data from two cork oak stands in Portugal as well as data from six types of simulated stands. We found that zigzag is the poorest sampling method, as in most situations it produces estimators with larger bias and larger standard errors than that produced by the other two procedures. Fixed-radius plot sampling and n-tree distance sampling produce comparable results; however, fixed-radius plot sampling is preferred because it produces unbiased estimators
Original languageEnglish
Pages (from-to)2295-2303
JournalCanadian Journal of Forest Research
Volume35
Issue number10
DOIs
Publication statusPublished - 2005

Keywords

  • competition measures
  • predicting growth
  • point process
  • distance
  • trees

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