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
Authors
Tore SkrøppaAbstract
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Authors
Bernt-Håvard Øyen Petter NilsenAbstract
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.
Authors
Peder Gjerdrum Olav HøibøAbstract
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Authors
Peder Gjerdrum Olav Albert HøibøAbstract
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.
Authors
G.T. Slavov G.T. Howe Igor A. Yakovlev K.J. Edwards K.V. Krutovskii G.A. Tuskan J.E. Carlson Steven H. Strauss W.T. AdamsAbstract
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.
Authors
Atle WibeAbstract
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