Icelandic Forest Research

Reykjavík, Iceland

Icelandic Forest Research

Reykjavík, Iceland
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Sigurdsson B.D.,Agricultural University of Iceland | Leblans N.I.W.,Agricultural University of Iceland | Leblans N.I.W.,University of Antwerp | Dauwe S.,Agricultural University of Iceland | And 19 more authors.
Icelandic Agricultural Sciences | Year: 2016

This article describes how natural geothermal soil temperature gradients in Iceland have been used to study terrestrial ecosystem responses to soil warming. The experimental approach was evaluated at three study sites in southern Iceland one grassland site that has been warm for at least 50 years (GO), and another comparable grassland site (GN) and a Sitka spruce plantation (FN) site that have both been warmed since an earthquake took place in 2008. Within each site type, five ca. 50 m long transects, with six permanent study plots each, were established across the soil warming gradients, spanning from unwarmed control conditions to gradually warmer soils. It was attempted to select the plots so the annual warming levels would be ca. +1, +3, +5, +10 and +20 °C within each transect. Results of continuous measurements of soil temperature (Ts) from 2013-2015 revealed that the soil warming was relatively constant and followed the seasonal Ts cycle of the unwarmed control plots. Volumetric water content in the top 5 cm of soil was repeatedly surveyed during 2013-2016. The grassland soils were wetter than the FN soils, but they had sometimes some significant warming-induced drying in the surface layer of the warmest plots, in contrast to FN. Soil chemistry did not show any indications that geothermal water had reached the root zone, but soil pH did increase somewhat with warming, which was probably linked to vegetation changes. As expected, the potential decomposition rate of organic matter increased significantly with warming. It was concluded that the natural geothermal gradients at the ForHot sites in Iceland offered realistic conditions for studying terrestrial ecosystem responses to warming with minimal artefacts.

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.

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.

Halldorsson G.,Soil Conservation Service of Iceland | Sigurdsson B.D.,Agricultural University of Iceland | Hrafnkelsdottir B.,Agricultural University of Iceland | Hrafnkelsdottir B.,Icelandic Forest Research | And 3 more authors.
Icelandic Agricultural Sciences | Year: 2013

This paper is a review of the history of the introduction of arthropod herbivore species to Iceland since the beginning of the 20th century. A total of 27 new arthropod herbivore species on trees and shrubs have become established in Iceland during this period. One of the introduced pest species, the pine woolly aphid, has been considered to be the major cause of the almost total eradication of the introduced Scots pine in Iceland. The rate of introduction was found to be highest during warm periods. Outbreaks of pests in birch woodlands were also found to be most severe during warm periods. Other pest species have shown changes in outbreak patterns since 1990. The consequences of these findings for isolated native forest ecosystems and a growing forest resource in Iceland are discussed.

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.

Alberdi I.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Inia | Alberdi I.,Polytechnic University of Mozambique | Michalak R.,UN Economic Commission for Europe | 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.

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.

Oddsdottir E.S.,Icelandic Forest Research | Oddsdottir E.S.,University of Helsinki | Oddsdottir E.S.,University of Iceland | Eilenberg J.,Icelandic Forest Research | And 5 more authors.
Agricultural and Forest Entomology | Year: 2010

Weevil larvae of the genus Otiorhynchus are a serious problem in agriculture and forestry, causing damage to a wide range of plant species, primarily by larval feeding on roots. Otiorhynchus larvae are a serious pest in forest plantations in Iceland, causing 10-20% mortality of newly-planted seedlings. We studied the effects of soil fungi on the survival of Otiorhynchus sulcatus larvae. The larvae were introduced into pots with birch seedlings grown in: (i) nursery peat; (ii) nursery peat inoculated with three different species of ectomycorrhizal fungi; (iii) nursery peat inoculated with insect pathogenic fungi; (iv) nursery peat inoculated with ectomycorrhizal fungi and insect pathogenic fungi; and (v) nursery peat inoculated with natural forest soil from Icelandic birch woodland. Larval survival was negatively affected by inoculation of: (i) the ectomycorrhizal fungus Laccaria laccata; (ii) the ectomycorrhizal fungus Cenococcum geophylum; (iii) the insect pathogenic fungus Metarhizium anisopliae; and (iv) forest soil. Inoculation with the ectomycorrhizal fungus Phialophora finlandia did not have any significant effect on larval survival. No significant synergistic effect was found between insect pathogenic and ectomycorrhizal fungi. It is concluded that ectomycorrhizal and insect pathogenic fungi have a significant potential in biological control of Otiorhynchus larvae in afforestation areas in Iceland. Further studies are needed to establish the effect of these fungi in the field and to analyse how mycorrhizal fungi affect root-feeding larvae. © 2010 The Authors. Journal compilation © 2010 The Royal Entomological Society.

Oddsdottir E.S.,Icelandic Forest Research | Oddsdottir E.S.,University of Helsinki | Oddsdottir E.S.,University of Iceland | Eilenberg J.,Copenhagen University | And 4 more authors.
Applied Soil Ecology | Year: 2010

We present novel findings highlighting the early effects of inoculation of downy birch (Betula pubescens Ehrh.) seedlings with factorial combinations of beneficial soil fungi, namely, ectomycorrhizal and insect pathogenic fungi, on Otiorhynchus spp. larval root herbivory under Icelandic field conditions.Birch seedlings were pre-treated with (1) a mixture of four ectomycorrhizal fungal species: Paxillus involutus (Batsch: Fr.) Fr., Telephora terrestris Ehrh.: Fr., Phialophora finlandia Wang & Wilcox. and Hebeloma sp., (2) the insect pathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin or (3) a combined inoculum that included the four ectomycorrhizal fungal species and M. anisopliae. Non-inoculated seedlings served as untreated controls. Inoculated and control seedlings were transplanted into soils at three different sites representing eroded land, birch woodland and heathland.Assessment following the first growing season indicated that the effects on Otiorhynchus spp. larval root herbivory and seedling productivity of pre-inoculation with the ectomycorrhizal fungal species mixture and the insect pathogenic fungus, M. anisopliae, were highly dependent on site and treatment. Inoculation with ectomycorrhizal fungi and M. anisopliae significantly reduced root herbivory in both the birch woodland and, in particular, the eroded land sites. In the heathland site, no or even negative effects on root herbivory were observed. However, potential synergistic effects of combined inoculation with both ectomycorrhizal fungi and M. anisopliae were not identified under these experimental conditions.Accumulated seedling mortality ascribed to root herbivory after three growing seasons showed a significant site dependent response, but no significant treatment effect was detected.The effects of ectomycorrhizal and insect pathogenic fungi on root herbivory are discussed and we conclude that significant, although mostly unidentified, interactions between the inoculated fungi and the naturally occurring soil microorganisms may explain these findings. Such interactions require further detailed investigation in order to develop an efficient strategy for soil inoculation with beneficial fungi. © 2010 Elsevier B.V.

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