Effect of southern pollination on the survival and growth of seed orchard progenies of northern Scots pine ( Pinus sylvestris) clones

Abstract

The growth and survival of background pollinated progeny of northern Scots pine clones from seed orchard located in southern Finland was examined at an age of 10–15 years and compared with the respective performance of seedlings from local natural stands. The material consisted of 33 progeny tests located in northern Finland within the original areas of the clones. Although no clear difference was observed between the height growth of the two groups, the survival was significantly lower in the seed orchard material (35%) than in the local stand material (56%). The relative survival (seed orchard vs. local entries) decreased steadily along with the decrease in the effective temperature sum of the trial sites, and was relatively small in the northernmost trials. The results indicate that the totally background pollinated seed from southwards-transferred, young seed orchards even can be used for reforestation in southern and central Lapland, at least in areas located at relatively low altitudes. The decrease in background pollination levels owing to the ageing of these orchards will increase the potential use of this seed. Using only those orchards containing the northernmost clones, combined with selective harvesting of the most hardy portion of the clones, is proposed as a means of further improving the adaptedness of planting material for northern conditions.