Genetic diversity is the cornerstone of biodiversity. As part of Measure 1 (M1 – “Biodiverse and resilient forests”) of the Action Plan for Switzerland's Biodiversity Strategy, Phase 2 (AP-SBS II, 2025–2030), the genetic diversity and population structure of five native tree species are to be quantified using whole-genome sequencing and evaluated in terms of their adaptability to future environmental conditions and their optimal use as a forest genetic resource. The focus is on rare tree species and their designated gene conservation areas throughout Switzerland, as well as on a drought-sensitive main tree species. In addition, the genetic diversity of the seeds of a rare tree species will be examined more closely in order to derive recommendations for seed production. The results obtained here will help to assess the genetic diversity and representativeness of main and secondary tree species in gene conservation areas and to identify possible over-representations and gaps in the existing network of gene conservation areas. The project thus makes an important contribution to the conservation and promotion of rare tree species and their genetic diversity, to the development of strategies for adaptive silviculture, and thus to ensuring that forests are as biodiverse and resilient as possible.