tailieunhanh - Báo cáo lâm nghiệp: "Variables influencing cork thickness in spanish cork oak forests: A modelling approach"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Variables influencing cork thickness in spanish cork oak forests: A modelling approach. | Ann. For. Sci. 64 2007 301-312 INRA EDP Sciences 2007 DOI forest 2007007 301 Original article Variables influencing cork thickness in Spanish cork oak forests A modelling approach Mariola Sanchez-Gonzalez Rafael Calama Isabel Canellas Gregorio MONTERO Centro de Investigation Forestal INIA Ctra. de La Coruna km 7 5 28040 Madrid Spain Received 27 March 2006 accepted 15 June 2006 Abstract - In this study we evaluate the influence of different variables on cork thickness in cork oak forests. For this purpose first we fitted a multilevel linear mixed model for predicting average cork thickness and then identified the explanatory covariates by studying their possible correlation with random effects. The model for predicting average cork thickness is described as a stochastic process where a fixed deterministic model explains the mean value while unexplained residual variability is described and modelled by including random parameters acting at plot tree plot X cork harvest and residual within-tree levels considering the spatial covariance structure between trees within the same plot. Calibration is carried out by using the best linear unbiased predictor BLUP theory. Different alternatives were tested to determine the optimum subsample size which was found to be appropriate at four trees. Finally the model was applied and its performance in the estimation of cork production was tested and compared with the cork weight model traditionally used in Spain. cork thickness mixed model calibration Quercus suber L. Résumé - Variables influenẹant l épaisseur du liège dans les forêts de chênes-lièges espagnoles une proposition de modélisation. Dans cette étude nous avons mesuré l influence de diverses variables sur l épaisseur du liège des forêts de chênes-lièges. Dans ce but nous avons d abord appliqué un modèle linéaire mixte pour prédire l épaisseur moyenne du liège et on a alors identifié les co-variables explicatives pour expliquer leur possible correlation avec des .