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Accueil du site → Doctorat → Allemagne → 2020 → Understanding the dynamics of even-aged stands of Brutia pine (Pinus brutia Ten.) in the coastal region of Syria based on a distance-independent individual-tree growth model

Technische Universität Dresden (2020)

Understanding the dynamics of even-aged stands of Brutia pine (Pinus brutia Ten.) in the coastal region of Syria based on a distance-independent individual-tree growth model

Tammam Suliman

Titre : Understanding the dynamics of even-aged stands of Brutia pine (Pinus brutia Ten.) in the coastal region of Syria based on a distance-independent individual-tree growth model

Auteur : Tammam Suliman

Université de soutenance : Technische Universität Dresden

Grade : Doctor rerum silvaticarum (Dr. rer. silv.) 2020

Résumé partiel
The correct assessment of resources is a key condition for ensuring the sustainable supply of forest resources. In Syria, sustainable forest management is limited, because there is practically not enough knowledge on how to determine an annual growth, how future developments can be predicted, how the site productivity and the optimal rotation age can be accurately estimated, or which thinning regime is best suitable. To cover these gaps and to answer the questions, objective of the work is to develop an individual-tree growth model based on real-time series. Methodology and results : The study analyzed existing inventory data that came from 61 plots (51 for modeling and 10 for validation). The data used to develop the individual tree growth model could be categorized into four groups : Measured and calculated individual trees, variables describing the growth, measured plot variables, calculated stand variables.e.g. Stand basal area, stand volume, mean stand height…. Plot-wise equations for tree height, crown diameter and crown length were used to model the missing data values. The also analyzed the factors affecting the individual tree growth : competition and the site index. The study analyzed the competition using a set of distance-dependent and independent competition indices. The results found it that distance-independent and dependent competition indices have a consistent negative impact on tree basal area increment. On another hand, competition stimulates a little the height increment before start decreasing as competition increases. The best distance-independent indices were candidate for further modeling. Site index which is a measure of potential site productivity and it is defined in this work as stand dominant height at given age. The study tested 10 equations. Sloboda equation was confirmed as most appropriate for site index characterization of Pinus brutia stands in Syria. Then, the study tested the statistical models for describing the important life processes of single trees which consists of growth and mortality equations. Growth equations included diameter increment, height increment, crown ratio and generalized height-diameter equation. The study developed diameter increment equation as function of tree size, site characteristics (site index and geo-climatic variation OGV), and competition variables. The equation showed good performance for explaining the variations in diameter increment, where the coefficient of determination (R2) was 0.58. One supplementary equation for diameter increment equation was fitted without geo-climatic variation (OGV) and showed similar performance. XVIII The study developed two individual tree height increment equations : linearized height increment in similar way to that developed to diameter increment, and the second equation is Modifier-Potential height increment by achieving Nagel‟s equation (1999).

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