Depending on the general or specific objectives, for the improvement of forest species and to assess performance of proveniences in different environmental conditions, it is necessary to install comparative trials. These comparative trials include descendants of Forest Genetic Resources (RGF) from three provenance regions (A, B, C) of the Republic of Moldova, and are being intended to monitor the performance of descendants over time. The performance of descendants will be evaluated through different statistical approaches of biometric parameters. The study of comparative cultures will contribute to establish over time most adapted and stable proveniences for region where permanent trials are installed. The selection of most adapted proveniences is the first mandatory stage in any tree improvement program, because in addition to estimating provenances ability to adapt, are also evaluated quantitative traits such as growth performances and wood quality and plasticity