The study looked at how different types of forests in the Rhodope Mountains affect the growth of beech trees. They cut down 40 dominant beech trees and studied their growth patterns. They found that the way the forests develop influences the height and volume growth of the trees. Beech trees in mixed forests with pine trees can grow just as tall and big as those in pure beech forests, even in less productive areas, up to 50 years old. This shows that the environment in which the trees grow plays a big role in their growth, regardless of the site's productivity.