Study On Site Index And Dominant Height Growth Model Of Chinese Fir Plantations

The site index method is a common way for forest site quality evaluation,and dominant height is an important parameter in the site index model.With data of 65 permanent sample plots and stem analysis of 20 dominant individual trees,21 dominant height growth models were totally derived from Richards?Lundqvist-Korf and Hossfeld functions by the algebraic difference approach(ADA)?generalized algebraic difference approach(GAD A)and age-independent method for Chinese Fir plantations in Jiangle national forest farm in Fujian Province.Two or three best-fitted models were selected to test the prediction effect of each method.Among the selected models,the best one was determined based on synthetic comparison of statistical and biological features.The main conclusions were summarized as follows:1?The best model was identified as model M3 of six models developed with ADA method,which was derived from Lundqvist-Korf functions with a as free parameter.The site index curves generated with model M3 were anamorphic with variable asymptotes2?The best model was identified as model E5 of six models developed with GADA method,which was derived from Hossfeld functions with a=b1+X?b=b2/X as free parameters.The site index curves generated with model E5 were polymorphic and sigmoid with variable asymptotes3?The best model was identified as model S7 of nine models developed with age-independent method,which was derived from Hossfeld functions with a as expand parameter of stand factors.And the prediction accuracy of the model increases with the decrease of parameter ?t.4?When comparing the models established by the three methods,in general,the age-independent models were best,followed by the GADA models,and the last were the ADA models.But the age-independent models were not dynamic equations which could not generate site index curves.Therefore,it is recommended to use an age-independent model to predict Chinese fir dominant height growth;If the site index curves are to be made for Chinese fir plantations,a flexible GADA model is a better choose,which is consistent with the biological characteristics of Chinese fir growth.