%0 Journal Article
%A Duchateau, E.
%A Longuetaud, F.
%A Mothe, F.
%A Ung, C.
%A Auty, D.
%A Achim, A.
%T Modelling knot morphology as a function of external tree and branch attributes
%B Canadian Journal of Forest Research
%D 2013
%V 43
%P 266-277
%N 3
%X Existing models for describing knot morphology are typically based
on polynomial functions with parameters that are often not biologically
interpretable. Hence, they are difficult to integrate into tree growth
simulators due to the limited possibilities for linking knot shape
to external branch and tree characteristics. X-ray computed tomography
(CT) images taken along the stems of 16 jack pine (Pinus banksiana
Lamb.) trees and 32 black spruce (Picea mariana (Mill.) B.S.P.) trees
were used to extract the three-dimensional shape of 3450 and 11 276
knots from each species, respectively. Using a nonlinear approach,
we firstly fitted a model of knot geometry adapted from a Weibull
function. Separate equations were used to describe both the curvature
and the diameter of the knot along its pith. Combining these two
equations gave an accurate representation of knot shape using only
five parameters. Secondly, to facilitate the integration of the resulting
model into a tree growth simulator, we extracted the parameters obtained
for each knot and modelled them as functions of external branch and
tree characteristics (e.g., branch diameter, insertion angle, position
in the stem, tree height, and stem diameter). When fitted to a separate
data set, the model residuals of the black spruce knot curvature
equation were less than 2.9 mm in any part of the knot profile for
75% of the observations. The corresponding value from the diameter
equation was 2.8 mm. In jack pine, these statistics increased to
5.4 mm and 3.2 mm, respectively. Overall, the ability to predict
knot attributes from external tree- and branch-level variables has
the potential to improve the simulation of internal stem properties.
%2 Export Date: 7 May 2013
Source: Scopus
CODEN: CJFRA
:doi 10.1139/cjfr-2012-0365
%( 00455067 (ISSN)
%K Curvature equation, Insertion angles, Nonlinear approach, Polynomial
functions, Three-dimensional shape, Tree characteristics, Weibull
functions, X-ray computed tomography, Computerized tomography, Morphology,
Separation, Weibull distribution, Forestry, coniferous forest, functional
morphology, growth modeling, height determination, stem, Weibull
theory, Anatomy, Forestry, Separation, Statistical Distribution
%# Luc
%Z timestamp=(2013.05.07)
%U http://www.scopus.com/inward/record.url?eid=2-s2.0-84875852337&partnerID=40&md5=11ee56f8a67476e519e7ee31d3dbd5ab
%F DuchateauLonguetaudMotheEtAl2013
%3 BibTeX type = ARTICLE