Assessment of crown height-diameter distribution in pedunculate oak (Quercus Robur) and the performance of regression models

In the stands of pedunculate oak (Quercus robur) located in the north, center, and south of the Republic of Moldova, a study focusing on the relationship between crown height and diameter was conducted. The analysis of the trees height-diameter crown distribution revealed an increase in the complexity of the stand structure along the north-south ecological gradient. Simultaneously, within these distributions, phenotypic variability in the height-diameter characteristic of tree crowns was observed. The statistical fit of the relationship between tree crown height and diameter was assessed by analyzing 25 regression models and selecting those that demonstrated good performance for the data describing the relationship. A more precise adjustment of the data was identified as a function of increasing complexity in the distribution of the investigated feature. The best results in this context were obtained for the experimental data regarding the relationship between the height and crown diameter of the trees in the southern area, in the Baimaclia Forest District, compared to the other areas.