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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2004

Abstract

During the last thirty years the interest for the use of selective cutting in the sub-alpine spruce forests of Norway has increased. However, there have been very few investigations on the post harvesting development after such cuttings. Four plots in irregular Norway spruce (Picea abies (L.) Karsten) dominated forests on semi-fertile sites in Northern Norway have been the subjects of a case study.We performed a reconstruction of the stand development by means of biometric assessments and ring widths measurements of all standing trees. Tree ages, stand structure, growth and recruitment were examined. Even though a hypothetical reverse J-curve for the present diameter distribution was identi- fied, the four plots were even-aged. Growth reactions indicate that most of the present sawtimber trees were established after heavy dimension cuttings in the late 19th century.The recruitment situation is characterized as satisfying in one of four plots. The post harvesting mean volume increment on the plots have been about two thirds of the potential yield estimated from site indices and maximum mean annual increment in regular stands. Managing strategies for irregular spruce forest stands are briefly discussed.

Abstract

Automatic heartwood detection will improve the ability to produce timber of prescribed properties and increase sawmill revenues. In fresh crosscuts, evaporation cools the surface more in the moist sapwood than in the drier heartwood areas.In this semi-industrial investigation, infrared exposures of 180 pine sawlogs were analysed. An algorithm was established to determine the heartwood diameter fraction in a digital temperature profile through the crosscut. Top end heartwood diameter could then be computed automatically by multiplying top end diameter (measured by a traditional log scanner) with the heartwood fraction calculated from an infrared exposure taken at an arbitrary end.The temperature gradient between the heart- and sapwood indicated the accuracy of the method. A promising application would be to use the heartwood fraction to estimate mean annual ring width and other related wood properties, and to use the temperature gradient to indicate the log freshness.

Abstract

Twenty-two highly variable SSR markers were developed in Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] from five SSR-enriched genomic libraries. Fifteen PCR primer pairs amplified a single codominant locus, while seven primer pairs occasionally amplified two loci. The Mendelian inheritance of all 22 SSRs was confirmed via segregation analyses in several Douglas-fir families. The mean observed heterozygosity and the mean number of alleles per locus were 0.855 (SE=0.020) and 23 (SE=1.6), respectively. Twenty markers were used in genetic linkage analysis and mapped to ten known linkage groups. Because of their high polymorphism and unambiguous phenotypes, 15 single-locus markers were selected as the most suitable for DNA fingerprinting and parentage analysis. Only three SSRs were sufficient to achieve an average probability of exclusion from paternity of 0.998 in a Douglas-fir seed orchard block consisting of 59 parents.

Abstract

We estimated time from death to fall (standing time) of Norway spruce (Picea abies (L.) Karst.) snags in a submountainous old-growth forest in south-central Norway, applying four calculation methods to 124 dendrochronologically cross-dated still-standing snags and 64 fallen logs. The calculation methods consistently estimated expected standing time of snags at 26–34 years, with a median of 16–21 years and 20% of snags standing for >48–58 years. The survival function from all methods took the approximate form of a negative exponential, with a 3%–4% annual fall rate for snags. In the distribution of time since death, a small peak in dead trees 20–30 years ago (late 1970s) coincides with a historic epidemic of bark beetles. The method using only time since death of still-standing snags appears to be the most feasible for estimating total standing time of snags in old-growth forests with constant tree mortality.

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Abstract

Polyphenolic parenchyma cells (PP cells) in Norway spruce (Picea abies (L.) Karst.) stem phloem play important roles in constitutive and inducible defenses. To determine whether anatomical and molecular changes in PP cells are correlated with tree resistance, we infected two Norway spruce clones with the pathogenic fungus Ceratocystis polonica (Siem.) C. Moreau. The fungus induced significantly different lesion lengths in the two clones, indicating that one clone was more resistant to the fungus (short lesions) than the other (long lesions). After infection, the cross-sectional area of PP cells and their vacuolar polyphenol bodies increased in the three most recent annual rings of PP cells in both clones. The more resistant clone had larger PP cells with denser polyphenol bodies than the less resistant clone, whereas the less resistant clone accumulated relatively more polyphenols after infection. Compared with the less resistant clone, the more resistant clone contained higher starch concentrations before infection that were reduced more quickly after infection before returning to original values. Low transcript levels of chalcone synthase were detected in uninfected tissues of both clones, but the levels increased dramatically after infection. Transcript levels were higher and peaked 6 days earlier in the more resistant clone than in the less resistant clone. The activity of at least one highly basic peroxidase isoform was greatly enhanced after infection, and this increase occurred earlier in the more resistant clone.

Abstract

Conifers have evolved constitutive and inducible defense mechanisms to help in both wound healing and defense against attack by bark beetles and other organisms. These defenses include oleoresin, phenolics, and static structures in secondary phloem, such as lignified cells and calcium oxalate crystals, that create physical barriers. We used a phylogenetic approach to investigate the defense anatomy of conifer stems of 13 species from five families following treatment with methyl jasmonate (MJ), a compound that induces defense responses in stems of several Pinaceae species.Methyl jasmonate induced a response similar to wounding except that the response was not accompanied by lesion formation, necrosis or a hypersensitive response. In the Pinaceae species studied, MJ induced polyphenolic parenchyma (PP) cell activation and xylem traumatic resin duct (TD) formation. Members of the Taxodiaceae, which are not known to produce large quantities of resin, showed massive xylem TD formation and surface resinosis following MJ treatment.Treatment with MJ caused members of the Araucariaceae and Cupressaceae to form axial phloem resin ducts but not xylem ducts, whereas Podocarpaceae species showed no induction of resin-producing structures. All species treated with MJ showed phenolic deposition in PP cells, and early lignification of phloem fibers was observed in most of the non-Pinaceae species.We conclude that, although evolution of resin-producing structures occurred independently in conifer lineages, MJ seems to induce resin production regardless of tissue location, as well as inducing deposition of phenolic compounds. Co-evolution of conifer defensive strategies and bark beetle pests is discussed.