Distribution of Lihtuanian Scots pine trees according to breeding categories and their seed production in seed stands

In addition to other traits, value of stands for breeding can be evaluated according to the number of plus trees and productive trees. According to this property, stands with the highest value for breeding are located in eastern Lithuania. Trees start to differentiate into breeding categories at the juvenile stage: in Scots pine stands on Pinetum myrtillosum sites, at the age of 6to 8 years and in Scots pine stands on Pinetum vacciniosum sites, at age of 10 to 12 years. According to radial increment, the trees start to differentiate into selection categories of productive, medium and minus trees, which often remain in these categories until mature age. The following four types of radial increment of trees were distinguished: (1) fast growth at the juvenile stage, followed by a gradual decrease, (2) fast growth at the juvenile stage, followed by a stable growth from age 20 to 30 years, (3) slow growth at the juvenile stage, followed gradual increase, (4) unstable growth all the time. In Lithuania, abundant seed yield used to occur in three to four year intervals. Populations with abundant flowering may produce approximately 10 kg of seeds (filled and empty) per ha, while the populations with weak flowering - 1 to 2 kg per ha. In mature Scots pine stands of stocking level ca 0.7, 6to 8% of the seeds are produced by plus trees, 24% by productive trees, 55 to 60% by trees of medium productivity and 10% by minus trees. Being suppressed, minus trees produce 2% of the seeds only.