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.
2009
Forfattere
Nicholas Clarke O. Janne Kjønaas Wenche Aas Kjell Andreassen Isabella Børja Harald Bratli Susanne Eich-Greatorex Toril Drabløs Eldhuset Kjersti Holt Hanssen Holger Lange Tonje Økland Ingvald Røsberg Trine Aulstad Sogn Volkmar TimmermannSammendrag
In Norway, it is planned to double the stationary use of bioenergy from all sources by up to 14 TWh before 2020, with much of this increase coming from forest resources, including residues like branches and tops (which are not much used today) being removed after tree harvest. This removal will reduce the supply of nutrients and organic matter to the forest soil, and may in the longer term increase the risk for future nutrient imbalance, reduced forest production, and changes in biodiversity and ground vegetation species composition. However, field experiments have found contrasting results (e.g. Johnson and Curtis 2001; Olsson et al. 1996). Soil effects of increased biomass removal will be closely related to soil organic matter (SOM) dynamics, litter quality, and turnover rates. The SOM pool is derived from a balance between above- and below-ground input of plant material and decomposition of both plants and SOM. Harvest intensity may affect the decomposition of existing SOM as well as the build-up of new SOM from litter and forest residues, by changing factors like soil temperature and moisture as well as amount and type of litter input. Changes in input of litter with different nutrient concentrations and decomposition patterns along with changes in SOM decomposition will affect the total storage of carbon, nitrogen and other vital nutrients in the soil. To quantify how different harvesting regimes lead to different C addition to soil, and to determine which factors have the greatest effect on decomposition of SOM under different environmental conditions, two Norway spruce forest systems will be investigated in the context of a research project starting in 2008/2009, one in eastern and one in western Norway, representing different climatic and landscape types. At each location, two treatment regimes will be tested: Conventional harvesting, with residues left on-site (CH) Aboveground whole-tree harvest, with branches, needles, and tops removed (WTH). Input of different forest residues will be quantified post harvest. Soil water at 30 cm soil depth will be analysed for nutrients and element fluxes will be estimated to provide information about nutrient leaching. Soil respiration will be measured, along with lab decomposition studies under different temperature and moisture regimes. Long term in situ decomposition studies will be carried out in the WTH plots using three different tree compartments (needles, coarse twigs, fine roots) decomposing in litter bags, in order to determine their limit value. The structure of the fungal community will be determined by soil core sampling and use of molecular techniques allowing qualitative and quantitative estimation. Understorey vegetation will be sampled to determine the biomass, and the frequency of all vascular plants, bryophytes and lichens will be estimated. After harvesting, replanting will be carried out. Seedling survival, causes of mortality and potential damage, growth, and needle nutrients will be monitored. Results from these studies will be used to identify key processes explaining trends observed in two series of ongoing long-term whole-tree thinning trials. We shall combine knowledge obtained using field experiments with results of modelling and data from the Norwegian Monitoring Programme for Forest Damage and National Forest Inventory. This will help us to predict and map the ecologically most suitable areas for increased harvesting of branches and tops on a regional scale based on current knowledge, and to identify uncertainties and additional knowledge needed to improve current predictions.
Sammendrag
European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] μm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) μm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 μm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used.
Forfattere
Carl Gunnar Fossdal Igor A. Yakovlev Ari M. Hietala Halvor SolheimSammendrag
To identify differentially expressed genes of the white-rot fungus Heterobasidion parviporum subtractive cDNA libraries were constructed using suppressive subtraction hybridization (SSH) technique with RNA extracted from an advanced stage of decay area and from colonization front next to the reaction zone of the stem of a mature Norway spruce trees. Besides cytochrome P450s and proteins with unknown function, the SSH libraries constructed contained genes involved in basic cellular processes, andcell wall degradation. To examine the role of selected candidate genes three trees, showing a variable degree of wood decay, were used for real-time RT-PCR profiling of candidate genes. In the decay transition areas the study revealed activity centers that showed remarkable similarity in the transcript profiles of monitored genes.
Forfattere
Nadeem Yaqoob Carl Gunnar Fossdal Jan Karlsson Benedicte Riber Albrectsen Halvor SolheimSammendrag
Due to the great economic losses caused by the root and butt-rot pathogen Heterobasidion annosum, development of efficient control measures is warranted. H. annosum a necrotroph colonize the Norway spruce from inside and is responsible for 100s of millions of Euros losses annually. Considerable clonal variation has been recorded for Norway spruce in resistance towards H. annosum, but the defence mechanisms contributing to host resistance against both necrotrophic and biotrophic fungi remain poorly understood. The recent genome sequencing of Populus has made the genus a model to facilitate tree genetics. Genome-wide transcript profiling of Populus tremula upon pathogen attack will now be used, and homologues of Norway spruce genes to defence genes up-regulated in Populus will be identified. Two aspen clones (23 and 72) from the SwAsp collection (Luquez 2007) were used in the present study. Plants were propagated from tissue culture and kept in greenhouse under un-manipulated conditions. To study the host defence mechanisms, the rust (Melampsora magnusiana Wagner) and a bluestain fungus were used as a biotrophic and necrotrophic fungus respectively. Melampsora spores solution was applied to the underside of the leaf. To control for sectoriality six leaves were infected on each plant. To ensure high humidity and avoid cross contamination, plastic bags were wrapped around infected leaves. Leaves above infected leaves (10, 9, and 8) were harvested respectively 1, 3 and 14 days after inoculation. Initial results from microarray data indicate a clear separation between two Aspen clone (23 and 72) lines. For line 23 the response to biotroph and necrotroph seems to be similar. Whereas the response for line 72 is divergent for the treatments as they go in opposite direction. The controls show that there is an initial difference in the 2 lines (controls are separated). What are the genes that make biotrohic and necrotrophic treatment of 72 look so different will be worked out from microarray data. Differential expression of defense genes in biotrohic and necrotrophic treatment will be verified further with quantitative real time PCR. Chemical analysis of Aspen leaves gave less phenolic compounds as plants were kept in greenhouse. HPLC will be carried out after reaching some conclusion from microarray data analysis.
Forfattere
Åke Olson Mikael Brandström Kajsa Himmelstrand Mårten Lind Magnus Karlsson K. Lunden Kerstin Dalman Heriberto Vélëz Björn Canbäck Francis Martin Halvor Solheim Carl Gunnar Fossdal Pierre Rouzé Yao-Cheng Lin Matteo Garbelotto Ursula Kües Igor V. Grigoriev Andrea Aerts Erika Lindquist Jeremy Schmutz Jan StenlidSammendrag
The genome sequence of the conifer rot root pathogen Heterobasidion annosum was generated at JGI with 8.23 X coverage. The nuclear genome assembles in 39 scaffolds of total 33.7 Mbp estimated to cover 98.1% of the complete genome. We predicted 12,270 genes with an average length of 1,617 bp and exon number and length of 5.54 and 250 bp respectively. About 50% (5999) of the predicted genes could be validated by EST support with the 40,807 EST´s generated with in the project. The genome has a GC content of 52.0% and very little repetitive sequences with 2,895 SSR per mega base. The physical genome is congruent with the genetic linkage map, and most of the linkage groups have been possible to anchor to the 18 largest scaffolds.
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Forfattere
Anna Lewandowska-Sabat Siri Fjellheim Per Winge Atle M. Bones Torfinn Sparstad Carl Gunnar Fossdal Jorunn Elisabeth Olsen Odd Arne RognliSammendrag
No abstract has been registered