Modelling the Form Factor of Pinus brutia Ten. Trees Grown in Rabiaa Forests - Northern Lattakia


Abstract in English

Estimation of tree and stand volume is a key calculation for productive forest management (de Miguel et al., 2012). A precise estimation of tree volume needs to take the variation in bole forms into account while calculation, this can be done by estimating tree form factor. This study aims to construct a mathematical model to calculate the form factor of brutia pine trees grown in the regions of Rabiaa in northern Latakia. The form factor model can help foresters to precisely estimate the volume of tree and forest stands. During the period 2008-2011, 72 pine trees of various ages and sizes, located in natural stands of different densities and site qualities, were felled. Diameters at different heights of the felled trees were measured; trees volumes and volumes of equivalent cylinders were calculated, and consequently the values of tree form factor were computed. The dataset was randomly split into two parts, 75% (55 trees) of the data for constructing form factor model and 25% (17 trees) for model validation. A form factor model was obtained using the non-linear regression equations in the statistical program SPSS. Value of the coefficient of determination adjusted (R²adj) was about 0.81. The model has been validated using several statistical methods, the relative bias ( e%) was ca. 17.9%, while the value of model accuracy ) % x m ) was 22.9 %. In order to obtain lower value of model relative bias and higher value of accuracy it’s recommended to use a larger database comprising all distribution areas of pine in Syria.

References used

BOYDAK, M. Silvicultural characteristics and natural regeneration of Pinus brutia Ten. – a review. Plant Ecology, No. 171, 2004, 153–163
DE-MIGUEL, S. MEHTÄTALO, L. SHATER, Z. KRAID, B. & PUKKALA, T. Evaluating marginal and conditional predictions of taper models in the absence of calibration data. Canadian Journal of Forest Research, No. 42, 2012, 1383–1394
MUHAIRWE, C.K. Tree form and taper variation over time for interior lodgepole pine. Canadian Journal of Forest Research, No. 24, 1994, 1904–1913

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