According to environmental factors: Light conditions In the understorey of a forest, the apical meristem of the main stem of young tree edifies short annual shoots which bear some small branches with a differed development. The tree form have a tendancy to be tabular. Individuals growing in full sun show a pyramidal form of the crown (Individuals of Cedrus atlantica in the understorey and in open place.  .) According to genetic factors Studies which were carried out in provenance field trials (installed by the participant P1-1) allowed to observe variations of architectural features between species and provenances for young individuals. The polycyclism rate and the vigour gradient of branches on the annual shoots varies between Cedrus atlantica and C. libani . The polycyclism rate changes between the Lebanese and Turkish provenance of C. libani. Between Turkish provenance, a variation of branch form may be observed. In this case, the young individuals in some provenance possess more or less horizontal branches and in other provenance, they have straightened branches ( ). Growth rate is generally higher for C. atlantica and C. libani of Turkey that for C. libani of Lebanon.   | 
