Age-dependent changes in needle-fascicle dynamics of Pinus sylvestris (L.)

Age-dependent dynamics of needle fascicles on the main stem of Scots pine t rees in Estonia and Finland were investigated by the needle trace method. M ean fascicle longevity increased with tree age. Fascicle pool size, fascicl e production and shedding were not related to tree age for trees less than 50 yrs old. Thereafter, the mean values of these characteristics declined l inearly. Thus, younger trees had more fascicles attached to the stem, but f ascicle survival in the third and fourth age classes tended to be greater i n older trees. A short-term pattern of variation in dynamics was seen: high er values in the rates of fascicle shedding and production. and in the quot ient of fascicle loss, in any one year were regularly followed by lower val ues in the following year.