Distance-independent individual tree diameter-increment model for Thya (Tetraclinis articulata (VAHL.) MAST.) stands in Tunisia

• Autor(a) principal: Sghaier, T.
• Data de Publicação: 2013
• Outros Autores: Tomé, Margarida, Tomé, J., Sanchez-Gonzalez, M., Cañellas, I., Calama, R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/8178
• topic: age-independent growth model; difference equations; Tetraclinis articulata; Tunisia

Aim of study: The aim of the work was to develop an individual tree diameter-increment model for Thuya (Tetraclinis articulata) in Tunisia. Area of study: The natural Tetraclinis articulata stands at Jbel Lattrech in north-eastern of Tunisia. Material and methods: Data came from 200 trees located in 50 sample plots. The diameter at age t and the diameter increment for the last five years obtained from cores taken at breast height were measured for each tree. Four difference equations derived from the base functions of Richards, Lundqvist, Hossfeld IV and Weibull were tested using the ageindependent formulations of the growth functions. Both numerical and graphical analyses were used to evaluate the performance of the candidate models. Main results: Based on the analysis, the age-independent difference equation derived from the base function Richards model was selected. Two of the three parameters (growth rate and shape parameter) of the retained model were related to site quality, represented by a Growth Index, stand density and the basal area in larger trees divided by diameter of the subject tree expressing the inter-tree competition. Research highlights: The proposed model can be useful for predicting the diameter growth of Tetraclinis articulata in Tunisia when age is not available or for trees growing in uneven-aged stands.