Select issue
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
1950-1959
1940-1949
1926-1939
Acta Forestalia Fennica
1992-1999
1984-1991
1974-1983
1968-1973
1953-1968
1933-1952
1913-1932
Articles containing the keyword 'non-circularity'
Category : Research article
article id 924,
category
Research article
(2012).
On non-circularity of tree stem cross-sections: effect of diameter selection on cross-section area estimation, Bitterlich sampling and stem volume estimation in Scots pine.
Silva Fennica
vol.
46
no.
5B
article id 924.
https://doi.org/10.14214/sf.924
Keywords:
basal area;
Scots pine;
stem volume;
forest mensuration;
cross-section;
non-circularity;
Bitterlich sampling
Abstract |
View details
|
Full text in PDF |
Author Info
In the common methods of forest mensuration, including stem volume models and Bitterlich sampling, stem cross-sections are assumed to be circular. In nature this assumption is never exactly fulfilled. Errors due to non-circularity have been presumed to be small and unimportant but studied little: theoretical and empirical studies exist on cross-section area estimation, but errors in stem volume estimation have not been investigated at all, and errors in Bitterlich sampling are theoretically known only for stand basal area estimation. In the theoretical part of this study, we developed methods for quantifying the systematic and sampling errors that 22 common ways of selecting diameter within non-circular cross-sections induce (i) in area estimates by the circle area formula, (ii) in stand total estimates by Bitterlich sampling, and (iii) in stem volume estimates by a volume equation, by a cubic-spline-interpolated stem curve, and by a generalised volume estimator. In the empirical part, based on the digital images of 709 discs taken at 6–10 heights in 81 Scots pine stems from different parts of Finland, we investigated the variation in cross-section shape, and demonstrated the magnitude of the errors presented in the theoretical part. We found that non-circularity causes systematic overestimation of area and volume, and inflicts potentially systematic error on stand total estimates by Bitterlich sampling. In our data these effects were small, but the finding is not generalisable due the skewed size distribution and poor geographical representativeness of the data. We recommend using diameter derived from girth for both tree and stand level estimation, as it involves no sampling error and produces clearly the most stable systematic errors.
-
Pulkkinen,
E-mail:
minna.pulkkinen@iki.fi
Click this link to register to Silva Fennica.
If you are a registered user, log in to save your selected articles for later access.
Your selected articles
Send to email
Send to email
Fraysse J. Y.,
Crémière L.
(1998)
Nursery factors influencing containerized Pinus ..
Silva Fennica
vol. 32
no. 3
article id 686
(remove)
| Edit comment
Silva Fennica ·
Finnish Society of Forest Science
