Jurģis Jansons

Jurģis Jansons
Latvian State Forest Research Institute "Silava"

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29
Publications
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299
Citations

Publications

Publications (29)
Article
Full-text available
In any forest stand, the theoretically modelled output of sawlogs (the most valuable roundwood assortments) will differ from what is actually obtained. The aim of this study was to assess whether it is possible to characterise this difference by site properties or forest inventory parameters for birch, black alder, and aspen. We compared theoretica...
Article
Full-text available
The overall increase of ungulate populations in modern Europe has contributed to conflicts in national economies, particularly between game management and the forestry sector. This study assessed damage risks to young pine (Pinus sylvestris L.), spruce (Picea abies (L.) H. Karst.) and aspen (Populus tremula L.) stands at two spatial scales. One lev...
Preprint
Full-text available
In any forest stand, the theoretically modelled output of sawlogs (the most valuable roundwood assortments) will differ from what is actually obtained. The aim of this study was to assess whether it is possible to characterize this difference by site properties or inventory parameters of forest element for birch, black alder and as-pen. The differe...
Article
Full-text available
Whether intraspecific phenotypic variation in saprobic fungi may be driven by the host of origin has received little attention. We addressed this issue by testing hypotheses using the model system Phlebiopsis gigantea , a wood destroying fungus associated with Picea abies and Pinus sylvestris , among others, and widely employed in practical forestr...
Article
Full-text available
Heterobasidion root rot is one of the most economically important conifer diseases in the Northern Hemisphere, and stump removal is considered to be one of most effective control methods. However, the impact of stump removal on the diversity of mycorrhizal and soil fungi should be evaluated. From 2011 to 2012, a stump removal trial was established...
Article
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Scots pine (Pinus sylvestris L.) is one of the most widespread and economically most important tree species in Latvia. Scots pine forest health and element flow changes have been monitored in Latvia within the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with assessment of crown...
Article
Because intensive forestry favors the spread of Heterobasidion spp., increasing amounts of decayed Norway spruce (Picea abies) wood in forest stands should be taken into account in the management of commercial forests. Spruce wood colonized by Heterobasidion spp. ensures fruit body formation, which increases the risk of new infections by basidiospo...
Article
Full-text available
As one of the most abundant tree species in the hemiboreal zone, birch is important from both commercial and biodiversity perspectives. While old-growth deciduous stands are important for biodiversity conservation with an emphasis on deadwood availability, the role that deadwood in these stands plays in carbon sequestration remains unclear. We stud...
Article
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Land use and land use change calculation matrix is one of the most important parts of the national greenhouse gas (GHG) inventory in land use, land use change and forestry (LULUCF) sector providing information of an overall summary and changes in land use at a national level over a specified period of time. Information on land use and land use chan...
Article
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Norway spruce (Picea abies L. Karst.) is an important species in Latvia both ecologically and economically, and has been subjected to silvicultural management in Latvia since at least the middle of the 19th century. Forest regeneration activities starting in the 1960s resulted in the establishment of spruce stands with uncertified and often undocum...
Article
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This study investigated the origins and spread patterns of Heterobasidion root disease in three Pinuscontorta Dougl. ex Loudon plantations established on forest and agricultural land and subjected to three different management scenarios. Trees with decline symptoms and stumps remaining from the previous rotation were sampled for fungal isolations....
Article
Full-text available
Key message Volume predictions of sample trees are basic inputs for essential National Forest Inventory (NFI) estimates. The predicted volumes are rarely comparable among European NFIs because of country-specific dbh-thresholds and differences regarding the inclusion of the tree parts stump, stem top, and branches. Twenty-one European NFIs implemen...
Article
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Today, when anthropogenic pressure on natural ecosystems promotes degradation of natural habitats and facilitates distribution of alien species, local disturbances such as forest management become more significant in relation to alien plant species expansion. The aim of this study was to investigate the impact of forest road and drainage network re...
Article
Full-text available
The aim was to investigate relative susceptibility of stumps of spruce and pine to airborne infections by Heterobasidion following pre-commercial thinnings. The proportions of infected stumps and colonized stump surface areas were analysed in 16 forest stands. In total, 746 spruce and 1063 pine stumps were sampled, and 184 and 105 infected stumps,...
Article
Full-text available
The aim of the research was to assess distribution of organic soils in farmlands for the time period between 1990 and 2015, as well as to carry out a recalculation of GHG emissions from organic soils in grassland and cropland. We evaluated the area of typical organic soils using digitized soil maps created between 1960s and 1980s there were 183,000...
Article
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The objective of this study was to investigate basic density and its within-stem variation by studying 84 European aspen stems from 28 forest stands in Latvia. The studied forest stands covered all age classes from young stands to matured forests in representative growth conditions of European aspen. The densities of 2722 wood and 1022 bark specime...
Article
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We studied field performance of containerised Pinus sylvestris and Picea abies seedlings of different provenances. Shoot height, needle chemical composition, root collar diameter, root mycorrhization and mycorrhizal species composition were evaluated after four growing seasons following outplanting. The results showed that in general spruce had bet...
Article
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Notable amounts of wood ash containing plant macro and micronutrient elements in balanced proportions are produced in Latvia. If bioenergy production source product is plant material, and facilities are operating well, then 'side product' fermentation residues or wood ashes should not contain elements in toxic concentrations. Wood ash contains P an...
Article
The importance of wood biomass as a source of bioenergy at wider scales, i.e. for a centralized production of heat and electricity, is increasing. Hence, precise estimates of biomass are necessary for the calculation of available resources and carbon budget. Mathematical models based on easily measurable variables can notably facilitate the estimat...
Article
Due to the dieback caused by ascomycete Hymenoscyphus fraxineus, common ash (Fraxinus excelsior L.) regeneration currently occurs only naturally and is crucial for existence of the species. Hence, in this study, we assessed the success of the natural regeneration and health condition of common ash in 90 diverse young stands. Additionally, the age s...
Article
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Norway spruce is commonly regenerated by planting and disc trenching is by far the most widely used soil preparation method in Latvia; however, in specific site conditions other methods might be beneficial. Therefore aim of our study was to assess influence of spot mounding on early growth and tending of Norway spruce in hemiboreal forests. Spot mo...
Article
Full-text available
Stem cracks are damaging for timber quality and can reduce the monetary value of a tree both directly and indirectly: serving as gateway for fungal infections. Aim of the study was to assess the influence of tree dimensions and seed origin on the frequency of stem crack for Norway spruce. The study was carried out in two contiguous provenance trial...
Article
Full-text available
In the last decade the populations of large game as moose and red deer have increased in Latvia, and the risk of damage to forest stands has increased simultaneously. The aim of this study was to evaluate the extent of bark stripping wounds, decay incidence and associated fungi in 30-year-old Picea abies stems damaged by big game. In total, 90 tree...
Article
The structure of 2 to 9-year-old natural origin broadleaved stands is analyzed, using the method of component analysis. The stands under study represent natural regrowth of trees in fertile cutovers of dry mineral, wet mineral, wet peatland, drained mineral, and drained peatland forest growing conditions. For analyzing the internal structure of you...

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