Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2008
Sammendrag
Pine Wood Nematode (PWN, Bursaphelenchus xylophilus) is the causal organism of Pine Wilt Disease (PWD), the worst forest pest of Japan. In Europe PWN is known to exist in Portugal. The Norwegian Food Safety Authority (Mattilsynet) is concerned about the plant health risks and the consequences to the society if PWN should establish in Norway. Mattilsynet needs a scientific assessment of the proposed measures in a contingency plan for PWN. Mattilsynet also needs the risks connected with recent spread of PWN in Portugal to be evaluated before possible changes can be made in the current phytosanitary policy of Norway. On this background Mattilsynet requested a pest risk assessment of PWN from the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM). To answer the request, VKM commissioned a draft pest risk assessment report from the Norwegian Institute for Agricultural Sciences and Environmental Research (Bioforsk). A working group appointed by VKM’s Panel on Plant Health (Panel 9) has been involved during Bioforsk’s work on the report. VKM’s Panel 9 has used the report as a basis for VKM’s opinion. The current document answers Part 1 of Mattilsynet’s request, and was adopted by Panel 9 on a meeting 3rd September 2008. VKM’s Panel 9 gives the following main conclusions of the risk assessment: The PRA area of this assessment is Norway. PWN is not known to occur in Norway. With present trade pattern the probability of entry of PWN into Norway is expected to be high. The most probable pathway for entry of PWN into Norway would be wood packaging material (WPM). The probability that PWN will establish and spread in Norway is considered as high. With regard to the so-called Pest Free Areas (PFAs) of Portugal, the criteria given in ISPM No. 4 (FAO 1995) for establishing and maintaining PFAs have not been met, and the data available is not sufficient to confirm the existence of PFAs. Acceptance of untreated conifer wood from all parts of Portugal will result in a very high probability of entry and a high probability of establishment and spread of PWN and its vector to Norway. Uncertainty factors: To the best of our knowledge PWN is absent from the PRA area. The beetle M. sutor is regarded as a potential vector or PWN, but this has so far not been demonstrated in nature. The currently low vector densities may retard establishment of the PWN and PWD, but it will probably not stop establishment in a longer perspective. Lack of information on the dynamics of PWN populations in cool climates complicates estimates of the spread of the nematode and PWD. Custom routines may fail in their detection of PWN. Import of a seemingly harmless material might therefore pose an unknown risk. WPM follows consignments of all kinds and is a good example of a hazardous material, which often escapes plant health inspections. Detailed assessments of economic consequences of a possible establishment and spread of PWN in Norway, the effects of global warming and other climate changes on the probability for PWD outbreaks, and the effect of possible phytosanitary measures, will be given in Part 2.
Forfattere
Mari Mette TollefsrudSammendrag
Norway spruce (Picea abies), a conifer of the boreal forest, is one of the ecologically and economically most important forest tree species in Europe. It is naturally distributed into two disjunct ranges, one northern and one southern. In this thesis, genetic variation in Norway spruce populations has been investigated to obtain a comprehensive understanding of how its genetic structure has been shaped by Quaternary climate changes, hybridization with Siberian spruce (P. obovata), present-day ecological marginality and adaptive changes. Recently compiled fossil records of Norway spruce have moreover been used for inference of glacial refugia and the direction of migration routes. In Paper I, we combine fossil pollen data with a dataset of the maternally inherited, seed-dispersed mitochondrial (mt) marker nad1 obtained from 369 populations (4876 trees) to infer glacial refugia, postglacial colonization routes and the genetic consequences of range contractions and expansions. The combined data suggest that Norway spruce survived in at least seven refugial areas from which it expanded in the Holocene. These were the Russian plains, south-eastern Alps, southern Bohemian Massif including its southern foreland, northern Dinaric Alps, northern Carpathians, southern Carpathians and south-west Bulgarian mountains. Siberian spruce survived the last glacial maximum east of the Ural Mountains, separated from the refugia of Norway spruce (Paper III). Genetic diversity in Norway spruce showed an overall decrease from the oldest regions towards the younger regions. The different refugia had, however, contrasting genetic structuring and there were large differences in the genetic patterns along the different colonization routes. In the Alps, for example, diversity decreased over very short distances, whereas diversity in northern Europe was maintained over large distances. In Paper II we obtained a deeper insight into the genetic structuring of the northern European populations by analyzing nuclear microsatellite variation. Very little differentiation was revealed across the northern European range, manifesting high levels of past and present gene flow. Despite little differentiation, the microsatellite structure corroborated the mtDNA-based hypothesis of expansion out of one large Russian refugium along two separate migration routes, one northwestern route through Finland into northern Scandinavia and one southwestern route across the Baltic Sea to southern Scandinavia. In the south, microsatellite diversity was largely maintained from east to west, suggesting that pollen flow has efficiently counteracted the loss of diversity following colonization. Towards the northern climatic margin, nuclear microsatellite diversity decreased and inbreeding increased, probably due to smaller effective population size and more limited pollen production in the north, promoting mating among relatives. In Paper III, we investigated genetic differentiation between Norway spruce and Siberian spruce with mtDNA and chloroplast (cp) DNA markers. Chloroplast DNA is paternally inherited and spread with both seeds and pollen. We found two main genetic groups with both types of markers, corresponding to the two species and associated with separate refugia west (Norway spruce) and east (Siberian spruce) of the Ural Mountains. The Ural Mountains do not constitute a major barrier to gene flow. mtDNA haplotypes of Norway spruce were found east of the Ural Mountains, and extensive paternal introgression from Siberian spruce to Norway spruce was suggested across the Ural Mountains. Extensive pollen flow is in agreement with the homogenization observed in both the chloroplast (Paper III) and the nuclear (Paper II) gene pool of northern European Norway spruce. Pollen flow mainly occurs from Siberian spruce to Norway spruce, and Siberian spruce thus disperses westwards through paternal introgression. With the mtDNA marker nad1, it is possible to trace the origin of central European and northern European trees with a simple assay. In Paper IV, we determined the origin of trees in Norway spruce plantations. This was done prior to a greenhouse experiment recording the timing of terminal bud set of seedlings of different origins. We found that seedlings of central European origin from seeds produced in Norway had on average a bud set more similar to local Norwegian seedlings than to central European seedlings from seeds produced in central Europe. This suggests that the progenies of trees of central European provenances growing in Norway may have a rapid adaptation to the northern climate. Norway spruce thus not only has a fast and extensive migratory capacity but also a fast adaptative capacity, which may facilitate its altitudinal migration as climate warming proceeds.
Sammendrag
Achieving multifunctionality on a parcel of land, or in a landscape as a whole, requires a delicate balance between the different functions. This is particularly so when one of the desired functions is agricultural production. This paper examines the special challenges involved when cultural landscapes are protected by law. Norwegian `Landscape Protection Areas` are intended to preserve the landscape character of special landscapes. Ideally these landscapes should preserve ecological functions, whilst at the same time allowing for recreation and tourism, and the economic returns to ensure continued use of the landscape in the future. Balancing these functions is fraught with difficulties. The former agricultural systems that shaped these cultural landscapes may no longer be viable from the perspective of food production, and biodiversity is notoriously bad at paying for itself. Are the farmers that own the land willing to take on new roles as landscape managers rather than food producers? And who will pay for this? We present results of a questionnaire to farmers that own or manage farmland in Landscape Protection Areas. Of the 893 respondents, almost a quarter claimed that their farm business had been negatively affected by landscape protection. Niche products or alternative income possibilities had not been realised. We found a generally negative attitude towards municipal authorities and 24 % of respondents were strongly against the establishment of new Landscape Protection Areas, even if the State paid compensation for their economic loss. Based on results of the study we suggest that major improvements to the protection system could be made simply by improving communication between management authorities and farmers and involving farmers in making management plans.
Forfattere
Igor A. Yakovlev Daniel Kwaku A. Asante Carl Gunnar Fossdal Jouni Partanen Olavi Junttila Øystein JohnsenSammendrag
The initiation of growth and dormancy represents critical ecological and evolutionary trade-offs between survival and growth in most perennial plants and represents one of the most basic adaptations of trees to their environment. It is likely that they regulates differently: apical bud set and dormancy induction regulates by perception of short-day signal, but bud burst regulates mostly by temperature signals. We tried to dissect these processes on phenotypical and molecular levels. Seedlings for dormancy analysis were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two SSH cDNA libraries, forward and reverse, representing genes predominantly expressed in plants after short day (SD) treatment (going to bud set) and continue growing at LD. Subtracted libraries had been partially sequenced for candidate genes seeking. Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs in LD library were represented by photosynthesis related genes and just nearly 6% in SD library. High differences were found in RNA synthesis and RNA processing, protein degradation, defense and transporting genes and also in transposable elements. Each library contains large number of unknown genes (mostly in SD). So obtained subtracted libraries is a good source of candidate genes, differently expressed during regulation of bud set. Bud burst initiation was studied on grafts from 15- and 30-year old Norway spruce within 3 time-points during autumn in natural (outdoor) and “forcing” (1 week, 12 h light and 20°C constant) conditions using earlier developed candidate genes (Yakovlev et al., 2007). We used quantitative RT–PCR to study the expression patterns of 58 chosen genes related for bud set and 34 genes – for bud burst. By the experiment conditions we could study only delayed genes and constitutively expressed early genes. Among the candidate genes found, the most interesting ones were the transcription factors, calcium censors, signaling, cold- and water stress related genes. The putative role of the studied genes in development regulation bud set and bud burst is discussed.
Forfattere
Øystein Johnsen Igor A. Yakovlev Daniel Kwaku A. Asante Anne Eskild Nilsen Harald Kvaalen Carl Gunnar FossdalSammendrag
In forest trees, environmental conditions during the reproduction can greatly influence progeny performance. We here suggest that temperature during zygotic embryogenesis and seed maturation regulates an “epigenetic memory” in the progeny, involving differential expression of genes that may regulate bud phenology, cold acclimation and embryogenesis in Norway spruce. Conditions colder than normal advance the timing whilst temperatures above normal delay the onset of these processes. The altered performance lasts for many years. The seedlings actually remember the temperatures and photoperiod prevailing during zygotic embryogenesis and seed maturation. We show for the first time that regenerated plants, cloned through somatic embryogenesis, express a memory of the temperatures applied during embryo development whilst growing in a common greenhouse environment. The warmer the in vitro temperature applied, the later the regenerated plants formed terminal buds in the common environment the second growth season. The differences were very large, and similar in size to a provenance separation of 4 – 6 degrees of latitude. To study a molecular mechanisms of a memory from embryo development identical crosses were performed, seed were produced in different temperature regimes (cold and warm embryonic history) and seedling were grown under long day (LD = continuous light) and short day (SD = 12 h night) conditions. We have prepared two subtracted cDNA libraries, forward and revers, representing genes predominantly expressed in plants growing from seeds obtained after embryogenesis in cold environment (CE) and warm environment (WE) after short day treatment (going to bud set). Annotation reveals considerable differences in studied transcriptomes. More than 50% of contigs were unknown. So obtained subtracted libraries is a good source of candidate genes. We used quantitative RT–PCR to study the expression patterns of 34 chosen candidate genes. Just two putative genes among them with no matching in the Database and one reverse transcriptase show constitutively differential expression in progeny from CE and WE
Forfattere
Per Otto Flæte Kjell VadlaSammendrag
Concern about environmental impacts of chemical wood preservatives has resulted in increased interest for natural wood durability. The natural durability of sapwood of most species is generally low, while heartwood can be more resistant to biodeterioration. For the sawmill industry various lumber products require certain diameters and lengths of the logs in addition to requirements for wood properties. When utilising the heartwood, it is therefore important to acquire information already in the forest about which trees that can be suitable for logs with a predefined heartwood diameter and length. The main objectives of this work was to study the variation in heartwood diameter along the stem of Scots pines (Pinus sylvestris L.), and to develop a model for predicting heartwood diameter profiles based on variables that can easily be measured in the forest.....
Forfattere
Arne SteffenremSammendrag
Wood based products come from a renewable resource playing an important part of the carbon cycle and are therefore regarded environmentally friendly compared to many other alternatives. We might therefore expect a more intensive use of the timber resource in the future. An increase in the supply and net value of timber products from a given area requires more intensive and cost efficient forest management. However, a faster growth rate in general and an increase in the juvenile wood proportion specifically, might come in conflict with the desirable wood quality. Tree breeding programs for Norway spruce (Picea abies L. Karst.) aim to follow up the general demands by providing forestry with plant materials that have superior growth and high wood quality. It is therefore important to establish a better knowledge of the potential of improving wood quality characters in this species through breeding. Characteristics important for structural strength and dimensional stability in conifers are wood density, spiral grain, microfibril angle (MfA) in the S2 layer in the secondary cell wall, branch characteristics and stem straightness. We have studied the genetic variation and correlation patterns for these traits and the direct end-use performance of clearwood samples in terms of stiffness (MOE) and strength (MOR) in four studies of Norway spruce (Paper I-IV). Wood quality traits of defect free wood were studied in Paper I and II. The materials used were 28 and 29 year old progeny trials planted in South East Norway on fertile soils. Significant genetic variation was found for wood density, MfA and spiral grain in both studies (p < 0.05). MOE and MOR, measured by static bending, were studied in one of the materials and the genetic variation was found to be highly significant (p < 0.01). There was also significant genetic variation (p < 0.05) in MOE estimated (MOEest) from wood density and the x-ray diffractometry pattern from the S2 layer obtained by SilviScan®-3. Genetic parameters were estimated in Paper II with large standard errors. The parameters must therefore be used with caution and preferably with support from other studies. We could confirm earlier studies of high genetic variation and low genotype by environment interactions (GxE) for wood density and spiral grain. Parameter estimates for MfA and MOEest, from one site, suggest that these are under moderate to strong genetic control in Norway spruce. Phenotypic correlations between growth traits (height and diameter growth) and wood quality traits were negative for wood density, positive for MfA and negative for MOEest. Genetic relationships showed the same trends for diameter growth, but not for height growth. The genetic and environmental variation in branch characteristics (Paper III and IV) were studied in three sets of progeny trials that were 22, 28 and 29 years old from planting. Stem straightness was studied in the 22-year old trial only. The branch diameter was highly influenced by site index and spacing. Number of branches formed and stem straightness seems to be under stronger genetic control. Individual tree heritabilities for growth traits, branch diameter and stem straightness were estimated in the 22-year old progeny trial planted at two sites. The trials were planted with different spacing, which allowed us to study genotype by spacing interactions. Heritability for growth traits and branch diameter across sites were moderate (0.14 - 0.19) compared to the higher values found for stem straightness (0.28). GxE, and thereby genotype by spacing interactions were not important for any of the traits. Heritability for number of branches, estimated from one of the sites, was 0.24. There was a strong and positive genetic correlation between growth traits and branch diameter. The presence of genetic variation for most wood quality traits suggests that these can be improved by tree breeding. However, genetic correlations with growth traits indicate that selection solely for growth might have adverse effects on wood quality. It is therefore important to balance the gain in growth and wood quality. Implementation of several adversely correlated traits in a breeding program reduces its efficiency. It is therefore essential that tree breeding, silvicultural practices and forest industrial needs interact when developing tree breeding programs to obtain an optimal strategy for selection and utilization of improved plant materials.
Sammendrag
In European forests, standings stocks are currently increasing and are higher than ever during the last decades. This is due to a multitude of reasons; human impacts such as reduced logging or the abandonment of agricultural land are clearly among them. However, data from intensive monitoring plots reveal an increased growth even in the absence of direct human intervention. For this study, we used a set of 363 such plots from 16 European countries, which are a subset of the ICP-Forests Level II plots, and are typically rectangular areas with a size of 0.25 ha. We investigated the influence of environmental factors on forest growth. In particular, the role of nitrogen, sulphur and acid deposition, temperature, precipitation and drought was elucidated. The study focussed on the tree species Norway spruce, Scots pine, common beech and European as well as sessile oak. We used existing information on site productivity, stand age and stand density to estimate expected growth. Relative tree growth was then calculated as the ratio between actual growth, obtained within a five years observation period, and expected growth. The site productivity incorporates past environmental conditions and was either computed from site index curves, where we distinguished Northern, Central and Southern Europe variants, or was taken from expert estimates. The models explained between 18% and 39% of the variance. Site productivity and stand age were positively and negatively related to actual growth, respectively. The results indicated consistently a fertilizing effect from nitrogen deposition, with roughly one percent increase in site productivity per kg of nitrogen deposition per ha and year, most pronounced for plots having soil C/N ratios above 25. We also found a positive albeit less clear relationship between relative growth and summer temperatures. Other influences were uncertain. In particular, we cannot conclude on detrimental effects on growth from sulphur and acid deposition or from drought periods.
Forfattere
Erlend Ystrøm Haartveit Per Otto FlæteSammendrag
Wood from different tree species is commonly similar in visual appearance but still have considerable differences in machining and wood properties. Even heartwood and sapwood from the same tree species may be difficult to separate visually, but the wood properties important for the quality of the final products may differ. Hence, within the forest products industry there is a great need to non-destructively evaluate wood quality prior to and during manufacturing in order to ensure effective allocation of raw material, and to obtain consistent and well defined quality of the end products. Near infrared spectroscopy is a promising technique because it requires minimal, if any, sample preparation and provides results rapidly, even when used on intact, opaque biological samples. In this paper we use near infrared spectroscopy combined with multivariate statistical analyses for classification of wood types. Case I considers heartwood and sapwood from Scots pine. On freshly cut wood heartwood and sapwood are visually similar, but the wood properties differ. Case II considers wood from tree different species of spruce, Norway spruce, Sitka spruce and Lutz spruce. The species have differences mechanical and machining properties. NIR spectra were recorded directly on solid wood surfaces. The multivariate statistical analyses were based on partial least squares methodology and resulted in successful classification of wood types in both cases. All models were validated using test set validation. In both cases the result showed that near infrared spectroscopy and multivariate statistics can be used to develop well-performing prediction models for classification of visually similar wood types.
Sammendrag
This paper reports the results from a study of modulus of elasticity (MOE) and modulus of rupture (MOR) of 42 small clear specimens prepared from 300 year old roundwood floor girders containing high levels of NaCl at Bryggen in Bergen, Norway. NaCl concentration was 6.5 % of the dry matter of the wood. MOE and MOR were 25 % lower than the values obtained from a reference material with equivalent annual ring width and density. The considerable reduction of MOE and MOR should be taken into consideration in conservation of load-bearing wooden structures that have been exposed to NaCl.