Articles by Tore Skrøppa

After a presentation of basic biodiversity concepts, reviews are made of studies reporting genetic implications of tree improvement activities: seed treatments, seedling production, provenance transfers, plus tree selection, seed production in seed orchards and progeny testing.

Several of the activities may influence the genetic structure and diversity of the planted forests. The general conclusion is, however, that planted forests are at least as genetically diverse as the natural stands that they replace. The diversity in forest management and use is best assurance for the future adaptability of the forests.

• Skrøppa, E-mail: ts@mm.unknown

This paper summarises the main topics and conclusions from the joint meeting of two IUFRO working parties, S2.04-02, Breeding theory and progeny testing, and S2.02-16, Seed orchards, held in Tuusula, Finland on September 10–15, 1991. It concludes the main topics that need more research in these disciplines and future trends in the research.

• Roulund, E-mail: hr@mm.unknown
• Skrøppa, E-mail: ts@mm.unknown

Progenies from open pollinated cones collected in natural populations of Norway spruce (Picea abies (L.) Karst.) distributed along two altitudinal transects in Mid-Norway were tested in the nursery, in short term tests and in long-term field trials. The populations showed clinal variation related to the mean annual temperatures of the populations, with the earliest bud flush and cessation of shoot elongation and lowest height at age nine years for the high altitude populations. Within population variation was considerable as the narrow sense heritability for these traits was 0.67, 0.31 and 0.09 in one transect and 0.55, 0.18 and 0.14 in the other transect, respectively. Lammas shoots occurred in the short term trials with large variation in frequency between years. There was significant family variation for this trait, but also interactions between populations and year. The variance within populations was considerably larger in the populations from low altitude compared to the high-altitude populations. Significant genetic correlations between height and phenology traits and damage scores indicate that families flushing early and ceasing growth late were taller. Taller families also had higher frequencies of damages. Selection of the top 20% families for height growth in short term tests at age nine years gave a simulated gain of 11% increased height growth at age 18 years in long term trials at altitudes similar to those of origin of the populations. The gain was negative when high altitude populations were selected based on testing in the lowland.

• Skrøppa, Norwegian Institute of Bioeconomy Research, P.O. Box 115, 1431 Ås, Norway E-mail: tore.skroppa@nibio.no
• Steffenrem, E-mail: as@nn.no

• Skrøppa, Norwegian Forest and Landscape Institute, Box 115, 1431 Ås, Norway E-mail: tore.skroppa@skogoglandskap.no
• Solheim, Norwegian Forest and Landscape Institute, Box 115, 1431 Ås, Norway E-mail: halvor.solheim@skogoglandskap.no
• Steffenrem, Norwegian Forest and Landscape Institute, Box 115, 1431 Ås, Norway E-mail: arne.steffenrem@skogoglandskap.no