An analysis of stand-level size distributions of decay-affected Norway spruce trees based on harvester data

We studied size distributions of decay-affected Norway spruce trees using cut-to-length harvester data. The harvester data comprised tree-level decay and decay severity recordings from 101 final felling stands, which enabled to analyze relationships between size distributions of all and decay-affected trees. Distribution matching technique was used to transfer the size distribution of all trees into the diameter at breast height (DBH) distribution of decay-affected trees.publishedVersio

Ultrasonic-Standing-Wave-Crystallized Oleogels Characterized via Oscillatory Rheology

Ultrasonic standing waves, have been shown by our research group, to change the mechanical properties of crystallizing monoglyceride oleogels, which are viscoelastic lipid-based materials featuring a 3D network of structuring molecules. Oleogels are a potentially healthier alternative to traditional fats, such as butter, margarine, and shortenings. Here, we continue our research on ultrasonic-standing-wave-treated oleogels by investigating their mechanical properties through linear and non-linear oscillatory shear rheology. We found that the mechanical response of the treated oleogels is more elastic at lower strains and more viscous at higher strains when compared to reference samples, while the overall shape of the response curves remains similar. Through characterization of ultrasound-standing-wave-treated oleogels, we expand the previous knowledge of the state-of-the-art lipid-based materials.Peer reviewe

Progression of Ash Dieback in Norway Related to Tree Age, Disease History and Regional Aspects

Ash dieback, caused by the ascomycete Hymenoscyphus fraxineus, has been spreading throughout Europe since the early 1990s, threatening European ash at a continental scale. Little is known about the development of the disease in individual forest trees and in different age classes. In this study we monitored ash dieback on trees of different diameter classes in five permanent plots in ash stands in south-eastern Norway from 2009 to 2016, and from 2012 to 2016 in three plots in western Norway with a shorter disease history. Our results showed that more than 80% of the youngest and more than 40% of the intermediate future crop trees in the plots in south-eastern Norway were dead by 2016, while the disease development in large, dominant trees was slower. Although less damage has been observed in the plots in western Norway, the trend for the juvenile trees is the same as in south-eastern Norway with rapidly increasing damage and mortality. Most dead trees in south-eastern Norway were found at sites with high soil moisture and showed symptoms of root-rot caused by Armillaria species. Infected trees, both young and old ones, are weakened by the disease and appear to be more susceptible to other, secondary pathogens, especially under unfavourable site conditions.publishedVersio

Using laser micro-dissection and qRT-PCR to analyze cell type-specific gene expression in Norway spruce phloem

The tangentially oriented polyphenolic parenchyma (PP) and radially organized ray parenchyma in the phloem are central in the defense of conifer stems against insects and pathogens. Laser micro-dissection enables examination of cell-specific defense responses. To examine induced defense responses in Norway spruce stems inoculated with the necrotrophic blue-stain fungus Ceratocystis polonica, RNA extracted from laser micro-dissected phloem parenchyma and vascular cambium was analyzed using real-time RT-PCR (qRT-PCR) to profile transcript levels of selected resistance marker genes. The monitored transcripts included three pathogenesis-related proteins (class IV chitinase (CHI4), defensin (SPI1), peroxidase (PX3), two terpene synthesis related proteins (DXPS and LAS), one ethylene biosynthesis related protein (ACS), and a phenylalanine ammonia-lyase (PAL). Three days following inoculation, four genes (CHI4, PAL, PX3, SPI1) were differentially induced in individual cell and tissue types, both close to the inoculation site (5 mm above) and, to a lesser degree, further away (10 mm above). These resistance marker genes were all highly induced in ray parenchyma, supporting the important role of the rays in spruce defense propagation. CHI4 and PAL were also induced in PP cells and in conducting secondary phloem tissues. Our data suggests that different cell types in the secondary phloem of Norway spruce have overlapping but not fully redundant roles in active host defense. Furthermore, the study demonstrates the usefulness of laser micro-dissection coupled with qRT-PCR to characterize gene expression in different cell types of conifer bark.publishedVersio

Substrate-specific transcription of the enigmatic GH61 family of the pathogenic white-rot fungus Heterobasidion irregulare during growth on lignocellulose

The GH61 represents the most enigmatic Glycoside Hydrolase family (GH) regarding enzymatic activity and importance in cellulose degradation. Heterobasidion irregulare is a necrotizing pathogen and white-rot fungus that causes enormous damages in conifer forests. The genome of H. irregulare allowed identification of ten HiGH61 genes. qRT-PCR analysis separate the HiGH61 members into two groups; one that show up regulation on lignocellulosic substrates (HiGH61A, HiGH61B, HiGH61D, HiGH61G, HiGH61H, and HiGH61I) and a second showing either down-regulation or constitutive expression (HiGH61C, HiGH61E, HiGH61F, and HiGH61J). HiGH61H showed up to 17,000-fold increase on spruce heartwood suggesting a pivotal role in cellulose decomposition during saprotrophic growth. Sequence analysis of these genes reveals that all GH61s except HiGH61G possess the conserved metal-binding motif essential for activity. The sequences also divide into groups having either an insert near the N terminus or an insert near the second catalytic histidine, which may represent extensions of the substrate-binding surface. Three of the HiGH61s encode cellulose-binding modules (CBM1). Interestingly, HiGH61H and HiGH61I having CBM1s are up-regulated on pure cellulose. There was a common substrate-specific induction patterns of the HiGH61s with several reference cellulolytic and hemicellulolytic GHs, this taken together with their low transcript levels on media lacking lignocellulose, reflect the concerted nature of cell wall polymer degradation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00253-012-4206-x) contains supplementary material, which is available to authorized users

Species selection in areas subjected to risk of root and butt rot: applying Precision forestry in Norway

Norway’s most common tree species, Picea abies (L.) Karst. (Norway spruce), is often infected with Heterobasidion parviporum Niemelä & Korhonen and Heterobasidion annosum (Fr.) Bref.. Because Pinus sylvestris L. (Scots pine) is less susceptible to rot, it is worth considering if converting rot-infested spruce stands to pine improves economic performance. We examined the economically optimal choice between planting Norway spruce and Scots pine for previously spruce-dominated clear-cut sites of different site indexes with initial rot levels varying from 0% to 100% of stumps on the site. While it is optimal to continue to plant Norway spruce in regions with low rot levels, shifting to Scots pine pays off when rot levels get higher. The threshold rot level for changing from Norway spruce to Scots pine increases with the site index. We present a case study demonstrating a practical method (“Precision forestry”) for determining the tree species in a stand at the pixel level when the stand is heterogeneous both in site indexes and rot levels. This method is consistent with the concept of Precision forestry, which aims to plan and execute site-specific forest management activities to improve the quality of wood products while minimising waste, increasing profits, and maintaining environmental quality. The material for the study includes data on rot levels and site indexes in 71 clear-cut stands. Compared to planting the entire stand with a single species, pixel-level optimised species selection increases the net present value in almost every stand, with average increase of approximately 6%.Species selection in areas subjected to risk of root and butt rot: applying Precision forestry in NorwaypublishedVersio