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Reykjavík, Iceland

Elefsen S.E.,Agricultural University of Iceland | Frey P.,French National Institute for Agricultural Research | Frey P.,University of Lorraine | Sverrisson H.,Icelandic Forest Research | Hallsson J.H.,Agricultural University of Iceland
European Journal of Plant Pathology | Year: 2014

The basidiomycete Melampsora larici-populina causes foliar rust on Populus species from the sections Aigeiros and Tacamahaca, causing reduction in biomass production and economic losses. In the present study, samples of Icelandic M. larici-populina were collected for analysis of genetic diversity and population structure. A total of 439 isolates, collected at 15 locations, and analysed using 22 microsatellite markers were compared to data from French M. larici-populina populations. Twenty-one of the loci analysed were polymorphic, with an average of 3.4 alleles per locus. The mean observed and expected heterozygosities for all populations were 0.35 and 0.38. Evidence was found for a substructure within the Icelandic population with three subpopulations being the most likely scenario with low levels of gene flow. The population structure seen here is most likely shaped by both isolation and genetic drift as well as repeated events of colonization. In the future it can therefore be expected that regional poplar rust genotypes in Iceland change by two different modes; on one hand by transport of spores within the country and on the other hand by repeated colonization events. The results reported here underline the importance of closely monitoring the development of fungal diseases in Iceland, and to carefully select for resistance in Icelandic plant breeding programs. © 2014 Koninklijke Nederlandse Planteziektenkundige Vereniging. Source


Sigurdsson B.D.,Agricultural University of Iceland | Medhurst J.L.,University of Tasmania | Wallin G.,Gothenburg University | Eggertsson O.,Icelandic Forest Research | Linder S.,Southern Swedish Forest Research Center
Tree Physiology | Year: 2013

The growth responses of mature Norway spruce (Picea abies (L.) Karst.) trees exposed to elevated [CO2] (CE; 670-700ppm) and long-term optimized nutrient availability or elevated air temperature (T E; ±3.9°C) were studied in situ in northern Sweden in two 3year field experiments using 12 whole-tree chambers in ca. 40-year-old forest. The first experiment (Exp. I) studied the interactions between CE and nutrient availability and the second (Exp. II) between CE and T E. It should be noted that only air temperature was elevated in Exp. II, while soil temperature was maintained close to ambient. In Exp. I, C E significantly increased the mean annual height increment, stem volume and biomass increment during the treatment period (25, 28, and 22%, respectively) when nutrients were supplied. There was, however, no significant positive CE effect found at the low natural nutrient availability. In Exp. II, which was conducted at the natural site fertility, neither C E nor TE significantly affected height or stem increment. It is concluded that the low nutrient availability (mainly nitrogen) in the boreal forests is likely to restrict their response to the continuous rise in [CO2] and/or TE. © 2013 The Author. Source


Zlatanov T.,Forest Research Institute Sofia | Schleppi P.,Swiss Federal Institute of forest | Velichkov I.,Forest Research Institute Sofia | Hinkov G.,Forest Research Institute Sofia | And 4 more authors.
Forest Ecology and Management | Year: 2013

Components of structural diversity of abandoned chestnut (Castanea sativa Mill.)-dominated and co-dominated forests along an altitudinal gradient in the Belasitsa mountain region of Southwest Bulgaria were evaluated, including: (i) tree species composition; (ii) differentiation in diameter, height and age; (iii) tree crown defoliation and light transmission; and (iv) regeneration composition and abundance. Competition between tree species and its influence on current stand structure were analysed. Lack of management had triggered rapid structural and successional development in formerly chestnut mono-dominated forests which have now been invaded by midseral and later seral vegetation dominated by European beech (Fagus sylvatica L.) and sessile oak (Quercus petraea Liebl.). Distribution of sample plots according to diameter differentiation for chestnut showed positive differentiation values (dominance of chestnut with respect to other species) in 43 of a total of 46 plots sampled. Structure is much more balanced in terms of height differentiation. In the absence of management, chestnut blight has been a major stress factor and is likely an important driver of chestnut decline. The proportion of chestnut trees infected by chestnut blight disease exceeded 80% in 28 plots. Nearly one third (31%) of all sampled trees were characterized by a degree of defoliation of more than 60%. Despite the low levels of light at the forest floor, the density of the regeneration stratum was relatively high (averaging 19,300ha-1). An important finding is the retained regeneration potential of chestnut (31% of all seedlings). Chestnut seedlings, however, appeared to be poorly adapted to shading and rapidly declined in density and growth while seedlings of most competitors survived longer and dominated the regeneration stratum. © 2012 Elsevier B.V. Source


Alberdi I.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Inia | Alberdi I.,Polytechnic University of Mozambique | Michalak R.,Forestry and Timber Section | Fischer C.,Swiss Federal Institute of forest | And 17 more authors.
Forest Policy and Economics | Year: 2016

The supply of wood in Europe on a sustainable basis is highly relevant for forestry and related policies, particularly in relation to (i) analysing global change mitigation strategies and carbon accounting (ii) establishing realistic forecasts and targets for wood resources, biomass and renewable energy and (iii) assessing and supporting strategies for an increased use of wood.Therefore, it is relevant to have robust information of the availability for wood supply. The main aim of this paper is to harmonize the concept of 'forest available for wood supply' (FAWS) at European level.The data employed in this study was acquired through two questionnaires. The first questionnaire, conducted under the framework of COST Action FP1001 and a second questionnaire was completed by national correspondents and members of the UNECE/FAO.The analysis showed that reasons for the exclusion of forest from FAWS are diverse. Legal restrictions and specifically 'Protected areas' are considered by 79% of the countries while very few countries consider economic restrictions.A new FAWS reference definition is provided and the consequences of using this new definition in eight European countries were analysed. Application of the proposed definition will increase consistency and comparability of data on FAWS and will result in decreasing the area of FAWS at a European level. © 2016. Source


Oddsdottir E.S.,Icelandic Forest Research | Oddsdottir E.S.,University of Helsinki | Oddsdottir E.S.,University of Iceland | Nielsen C.,Copenhagen University | And 5 more authors.
Icelandic Agricultural Sciences | Year: 2010

In Iceland, extensive afforestation programmes have been initiated, often involving the outplanting of nursery seedling stock on eroded land. In some areas high seedling mortality, to a large extent due to root damage caused by Otiorhynchus spp. larvae, has been reported. Even though recent studies have shown that inoculation with entomopathogenic and ectomycorrhizal fungi may reduce the effects of Otiorhynchus spp. on seedling mortality, information on the occurrence and distribution of these key fungal species in Icelandic soils is limited. The present study reports findings of a targeted survey on the occurrence and distribution of entomopathogenic fungi and birch (Betula pubescens) root symbiotic ectomycorrhizal fungi in Icelandic soils from key habitats representing birch woodland, heathland and degraded/eroded land. Entomopathogenic fungi were isolated from soil by baiting with Tenebrio molitor and Galleria mellonella larvae. Identification to species was achieved based on standard morphotyping of cultures that included conidiophores and conidia. Birch seedling root symbiotic ectomycorrhizal fungal distribution in eroded and birch woodland soil was determined following baiting with birch seedlings over 9 months and classification based on gross morphology. Significant lower frequency and diversity of both entomopathogenic and ectomycorrhizal fungi were detected in soil collected from eroded areas compared to soil from vegetated areas (birch and heathland). Three species of entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Isaria farinosa were present in soil samples collected from the birch woodland and heathland sites. In contrast, no insect pathogenic fungi were found in soil collected from the eroded sites. B. bassiana and M. anisopliae were recorded for the first time in Iceland. The incidence of mycorrhizal root tips was higher on seedlings grown in soil from birch woodland than in soil from eroded land and a higher diversity of ectomycorrhizal morphotypes was found in birch soil. The importance of these findings is discussed in relation to afforestation in Iceland. Source

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