TAILIEUCHUNG - Báo cáo khoa học: "Modelling resin production distributions for Pinus Pinaster Ait using two probability functions"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Modelling resin production distributions for Pinus Pinaster Ait using two probability functions. | 369 Ann. For. Sci. 57 2000 369-377 INRA EDP Sciences Original article Modelling resin production distributions for Pinus Pinaster Ait using two probability functions Nikos Nanosa Wubalem Tadessea Gregorio Monteroa Luis Gilb and Ricardo Aliaa a Centro de Investigacion Forestal CIFOR-INIA Apdo 8111 28080 Madrid Spain b Unit of Physiology and Genetics ETSI Montes 28040 Madrid Spain Received 12 April 1999 accepted 10 February 2000 Abstract - The Weibull and the Chaudhry-Ahmad probability density functions were used to model resin production distributions for maritime pine stands. Maximum likelihood was used for parameter estimation. Data were collected during one season in two sets of plots. Set 1 consisted of two 50-tree and one 100-tree plots. Bootstrap re-sampling showed that the Weibull parameters had smaller estimation errors for small sample sizes. Set 2 consisted of thirty-seven 10-tree plots. No significant differences in the fit of the density functions were detected. Parameters of both models were found to be well correlated with the mean plot production as well as with the within plot coefficient of variation. The results did not reveal any major differences between the Weibull and the Chaudhry-Ahmad probability functions. The most appropriate model should be chosen at later stages when parameters of both functions are regressed against easily measured stand attributes. resin production distribution Pinus pinaster Weibull Chaudhry and Ahmad modelling Résumé - Modélisation de la distribution de production de résine pour Pinus pinaster Ait au moyen de deux lois de probabi-lité. La distribution de la production de résine de peuplements de pin maritime est modélisée par les fonctions de densité de probabi-lité de Weibull et de Chaudhry-Ahmad La méthode du maximum de vraisemblance est utilisée pour l estimation des paramètres. Les données ont été mesurées dans deux groupes de placettes pendant une saison de récolte. Pour le premier groupe qui est composé de deux

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