Table 1 Definitions of key terms

Random subset: Trees randomly selected from forest stands that have reached the selection age. These are both phenotyped and genotyped, and their pedigree is subsequently reconstructed. The primary aim of this subset is to yield an unbiased estimation of genetic variances.

Top phenotypic subset: Trees preselected for their superior phenotypic performance from forest stands that have reached the selection age. These, too, undergo genotyping and pedigree reconstruction. Their breeding values, which serve as the selection criterion, are computed using genetic variances derived from the random subset.

Candidate population: Individuals from the top phenotypic subset that are available for possible inclusion in the breeding arboretum.

Core subset: A collection of the breeding arboretum’s reproductively active genotypes (grafts) producing genetically superior forest reproductive material. These represent the highest-performing members of the candidate population.

Reservoir subset: A group of candidate trees that are on track to join the core subset once they attain reproductive age. These trees have already been grafted and are currently situated in the breeding arboretum.