LATITUDINAL AND ALTITUDINAL VARIATION OF BUD BURST IN WESTERN POPULATIONS OF SESSILE OAK (QUERCUS-PETRAEA (MATT) LIEBL)

Latitudinal and altitudinal variations of bud burst in western populat ions of sessile oak (Quercus petraea (Matt) Liebl) are examined. The p henology of bud burst in 50 populations of sessile oak has been studie d in four provenance tests located in France. The authors obtained lar ge variations between populations and these variations are linked to a ltitude, latitude and spring frost tolerance. The northern populations and those close to the sea level are the latest. These populations ar e more tolerant to the late spring frost. Due to the geographical stru cturation, which is linked to adaptative characters, we advise foreste rs to use sessile oak of local origins.