Provider: Ingenta Connect
Database: Ingenta Connect
Content: application/x-research-info-systems
TY - ABST
AU - Leites, Laura P.
AU - Robinson, Andrew P.
TI - Improving Taper Equations of Loblolly Pine with Crown Dimensions in a Mixed-Effects Modeling Framework
JO - Forest Science
PY - 2004-04-01T00:00:00///
VL - 50
IS - 2
SP - 204
EP - 212
KW - natural resources
KW - forestry
KW - forestry science
KW - Max and Burkhart taper equation
KW - natural resource management
KW - forestry research
KW - environmental management
KW - Pinus taeda
KW - forest
KW - forest management
KW - sources of variation
KW - crown variables
KW - forest resources
N2 - A mixed-effects modeling framework was applied to Max and Burkhart's (1976) (MB) taper equation for loblolly pine (*Pinus taeda* L.). The advantages of such a strategy over ordinary least squares were: (1) more accurate specification of the correlation structure of the data
and (2) the ability to assess the potentially explainable variation at the tree level. Significant relationships were established between tree-level crown dimensions and parameter estimates. The study data comprised 197 plantation-grown loblolly pine trees of 10 different ages in Uruguay.
Four versions of MB were evaluated: (1) the original equation, (2) the original equation fitted with mixed effects, and two adapted versions: (3) the first included crown variables and fixed effects, (4) the second included crown variables and mixed effects. The crown variables were tree-level
crown length and crown length ratio. The best of the four competing equations included both of the crown variables as well as tree-level random effects, suggesting that some linear tree-level variability may yet be explained by variables not considered in this study. Testing on an independent
validation data set did not show over-fitting problems. For prediction purposes, the equations with added crown variables were more precise but not less biased. FOR. SCI. 50(2):204–212.
UR - http://www.ingentaconnect.com/content/saf/fs/2004/00000050/00000002/art00006
ER -