Geographical variation in phenology ofQuercus petraea(Matt.) Liebl andQuercus roburL. oak grown in a greenhouse

Twenty-three provenances of Quercus robur and four of Quercus petraea were tested in a nursery indoor provenance trial. The provenances were sampled in the northern region of Europe. The study revealed large provenance variation in growth, flushing and leaf yellowing. Provenances from Finland and Norway were slow growing compared with those from Denmark, which showed slower growth than Polish, German, Dutch and British provenances. Northern provenances had a slightly significant earlier flushing than southern provenances. Provenances from the Netherlands and the British Isles ceased growth significantly later than provenances from Finland, Norway and Sweden. No significant correlations were revealed between leaf yellowing and growth, flushing and growth or length of growing season and growth, but provenances with late leaf yellowing tended to have higher growth. Provenance and family variation were compared among five Danish provenances. High population differentiation of quantitative traits Q ST values were found for phenology and low values for growth. The study confirms that the adaptive potential for Q. robur is very high. The implications for the movement of forest reproductive material and gene conservation are discussed.