SOME GENETIC-ASPECTS OF HUMAN INTERVENTION IN FOREST REGENERATION - CONSIDERATIONS BASED ON EXAMPLES FROM AN EXPERIMENT IN NORTHERN SWEDEN

Some genetic consequences of forest regeneration methods are discussed based on results from an 11-year-old experiment with Scots pine in no rthern Sweden. The experiment comprises two environments (seed-trees a nd clear-felling), two regeneration methods (planting and sowing) and four seed sources (local seeds from the seed trees, northern stand see ds and two seed orchard crops). Seed source was important compared wit h environment and regeneration method for the occurrence of empty cult ivation quadrats (2 x 2 m). In relative terms it was less important fo r growth. There was no indication that progenies of the local trees we re best suited for the locality. There was no evident positive effect of the higher selection caused by higher.mortality and release thinnin g in some entries compared with others. Hence, a higher selection afte r sowing than after planting could not be shown to have positive effec ts. The variance between half sib families was a small share of the to tal variance, and thus the number of parents is probably unimportant f or variance of tree height or seedling survival in a forest. Progenies from the seed orchards grew fast, but the mortality was higher than f or the stand progenies. There was no significant genotype X environmen t interaction. There was a significant genotype x method interaction; seed orchard progeny were better for sowing than for planting.