RT Journal Article
T1 Fitting and calibrating a multilevel mixed-effects stem taper model for maritime pine in NW Spain
A1 Arias Rodil, Manuel
A1 Castedo Dorado, Fernando
A1 Cámara Obregón, Asunción
A1 Diéguez Aranda, Ulises
K1 Maritime Pine
AB Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction
PB PLOS
YR 2015
FD 2015
LK http://hdl.handle.net/10347/21822
UL http://hdl.handle.net/10347/21822
LA eng
NO Arias-Rodil M, Castedo-Dorado F, CámaraObregón A, Diéguez-Aranda U (2015) Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain. PLoS ONE 10 (12): e0143521. doi:10.1371/journal.pone.0143521
NO The corresponding author was in receipt of an FPU grant (AP2012-05337) from the Spanish Ministry of Education, Culture and Sport, http://www.mecd.gob.es/. This work was also supported by project no. AGL2008-02259/FOR from the Spanish Ministry of Science and Innovation, http://www.idi.mineco.gob.es/; and project nos. CN-07-094 and SVPA-13-ECOEMP-58 from the Government of the Principality of Asturias, http://www.asturias.es/
DS Minerva
RD 24 abr 2026