Southern Swedish Forest Research Center


Southern Swedish Forest Research Center

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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.

Nasholm T.,Swedish University of Agricultural Sciences | Nasholm T.,Umea Plant Science Center | Hogberg P.,Swedish University of Agricultural Sciences | Franklin O.,International Institute For Applied Systems Analysis | And 8 more authors.
New Phytologist | Year: 2013

Symbioses between plant roots and mycorrhizal fungi are thought to enhance plant uptake of nutrients through a favourable exchange for photosynthates. Ectomycorrhizal fungi are considered to play this vital role for trees in nitrogen (N)-limited boreal forests. We followed symbiotic carbon (C)-N exchange in a large-scale boreal pine forest experiment by tracing 13CO2 absorbed through tree photosynthesis and 15N injected into a soil layer in which ectomycorrhizal fungi dominate the microbial community. We detected little 15N in tree canopies, but high levels in soil microbes and in mycorrhizal root tips, illustrating effective soil N immobilization, especially in late summer, when tree belowground C allocation was high. Additions of N fertilizer to the soil before labelling shifted the incorporation of 15N from soil microbes and root tips to tree foliage. These results were tested in a model for C-N exchange between trees and mycorrhizal fungi, suggesting that ectomycorrhizal fungi transfer small fractions of absorbed N to trees under N-limited conditions, but larger fractions if more N is available. We suggest that greater allocation of C from trees to ectomycorrhizal fungi increases N retention in soil mycelium, driving boreal forests towards more severe N limitation at low N supply. © 2013 New Phytologist Trust.

Ohlson M.,Norwegian University of Life Sciences | Brown K.J.,Geological Survey of Denmark | Brown K.J.,Natural Resources Canada | Birks H.J.B.,University of Bergen | And 6 more authors.
Journal of Ecology | Year: 2011

Global wildfire activity and biomass burning have varied substantially during the Holocene in both time and space. At the regional to continental scale, macroclimate is considered to be the predominant control regulating wildfire activity. By contrast, the role of forest tree composition is often considered as a subsidiary factor in studies addressing temporal variation in regional wildfire activity. Here, we assemble a spatially comprehensive data set of 75 macroscopic charcoal records that reflect local burning and forest landscapes that are spread over a substantial part of the European boreal forest, spanning both oceanic and continental climates. We show that the late-Holocene invasion of Norway spruce Picea abies, a new forest dominant in northern Europe, significantly reduced wildfire activity, thus altering forest disturbance dynamics at a subcontinental scale. Synthesis. Our findings show that a biotic change in the local forest ecosystem altered the fire regime largely independent of regional climate change, illustrating that forest composition is an important parameter that must be considered when modelling future fire risk and carbon dynamics in boreal forests. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.

Nordlander G.,Swedish University of Agricultural Sciences | Hellqvist C.,Swedish University of Agricultural Sciences | Johansson K.,Forestry Research Institute of Sweden | Johansson K.,Southern Swedish Forest Research Center | Nordenhem H.,Swedish University of Agricultural Sciences
Forest Ecology and Management | Year: 2011

Successful regeneration of conifer forests by planting is, in large parts of Europe, highly dependent on the effective suppression of damage caused by the pine weevil Hylobius abietis. We investigated the effectiveness of various combinations of control measures against pine weevil damage under boreal forest conditions in Sweden. In particular, we aimed to determine whether satisfactory regeneration could be obtained without the use of insecticides. The experimental study was established on ten new clear-cuts in each of three consecutive years. We studied the use of chemical and physical methods to protect seedlings directly, and investigated the influence of seedling type, age of clear-cut, and a number of soil factors as affected by preparation of the planting site, on the mortality and level of damage suffered by protected and unprotected seedlings. After two seasons, mortality due to pine weevil was 16% among unprotected seedlings, 6% for seedlings treated with the insecticides cypermethrin or imidacloprid, and less than 1% for those physically protected by a coating of Conniflex. However, the Conniflex, which consists of fine-grained sand embedded in a flexible acrylate matrix, was applied manually, and this may have enhanced its effectiveness compared to that achieved during large-scale, commercial application. Two types of containerized Norway spruce seedlings, which differed mainly in their stem diameter (average 2.6. mm and 3.5. mm), were used in the experiments. Among the unprotected seedlings, the narrower stemmed type was more frequently attacked (34% vs. 28%) and killed (19% vs. 12%) by pine weevil. Mortality caused by pine weevil among unprotected seedlings was higher on 1-year-old than on 2-year-old clear-cuts (20% vs. 12%). Soil preparation around unprotected seedlings had a substantial effect on the proportion attacked and killed by pine weevil as well as on the total mortality, with the highest level of feeding damage and mortality occurring on seedlings in undisturbed humus, and the lowest levels occurring on seedlings planted in pure mineral soil (26% vs. 7% for unprotected seedlings). This study demonstrates that acceptable levels of seedling survival can be achieved in regenerations of North European boreal forest without the use of insecticides. Mortality of unprotected seedlings can be reduced to acceptable levels if they are mostly planted in pure mineral soil. Damage can be further reduced by using seedlings with a somewhat larger stem diameter. Insecticides or a physical barrier of Conniflex alone appear to provide a sufficient level of protection. © 2011 Elsevier B.V.

Seftigen K.,Gothenburg University | Linderholm H.W.,Gothenburg University | Drobyshev I.,Southern Swedish Forest Research Center | Drobyshev I.,University of Québec | Niklasson M.,Southern Swedish Forest Research Center
International Journal of Climatology | Year: 2013

In this study, we present the first regional reconstruction of summer drought for southeastern Sweden. The June-July standardized precipitation index (SPI) was reconstructed over the period 1650-2002 based on Pinus sylvestris L. tree-ring width data, where the reconstruction could account for 41.6% of the total variance in the instrumental record over 1901-2002. Our reconstruction suggests an overall wet 18th century and a dry 19th century. The most outstanding pluvial phase in the pre-instrumental period took place in the mid-1720s and lasted over 50 years, while multi-decadal periods of below average moisture conditions were reconstructed in the 1660s-1720s, 1800s-early 30s, and in the 1840s-50s. Several of these dry spells have previously been found in reconstructions from Sweden and Finland, indicating that our reconstruction reflects large-scale moisture anomalies across eastern Fennoscandia. Comparison of the SPI estimates with mid-tropospheric pressure patterns suggests that summertime drought is associated with positive pressure anomalies over British Isles and the North Sea, while an eastward movement of the Icelandic low-pressure systems over the western part of central Fennoscandia results in wetter than normal June-July conditions over the region of interest. © 2012 Royal Meteorological Society.

Linderholm H.W.,Gothenburg University | Bjorklund J.A.,Gothenburg University | Seftigen K.,Gothenburg University | Gunnarson B.E.,Swedish University of Agricultural Sciences | And 5 more authors.
Climate of the Past | Year: 2010

Fennoscandia has a strong tradition in dendrochronology, and its large tracts of boreal forest make the region well suited for the development of tree-ring chronologies that extend back several thousands of years. Two of the world's longest continuous (most tree-ring chronologies are annually resolved) tree-ring width chronologies are found in northern Fennoscandia, with records from TornetrCurrency signsk and Finnish Lapland covering the last ca. 7500 yr. In addition, several chronologies between coastal Norway and the interior of Finland extend back several centuries. Tree-ring data from Fennoscandia have provided important information on regional climate variability during the mid to late Holocene and have played major roles in the reconstruction of hemispheric and global temperatures. Tree-ring data from the region have also been used to reconstruct large-scale atmospheric circulation patterns, regional precipitation and drought. Such information is imperative when trying to reach better understanding of natural climate change and variability and its forcing mechanisms, and placing recent climate change within a long-term context. © 2010 Author(s).

Stromgren M.,Swedish University of Agricultural Sciences | Hedwall P.-O.,Southern Swedish Forest Research Center | Olsson B.A.,Swedish University of Agricultural Sciences
Forest Ecology and Management | Year: 2016

Harvesting stumps after clear-cutting can increase bioenergy supplies and thus reduce needs for fossil fuels, but more knowledge is required about associated changes in greenhouse gas emissions from forest soils to assess the climatic impact of extracting stumps for this purpose. The soil disturbance caused by harvesting stumps may alter soil processes, including N mineralization. N availability is an important determinant of emissions of the potent greenhouse gases N2O and CH4. Effects of stump harvest on these gases are largely unknown. Therefore, they were explored in this study by monitoring differences in N2O and CH4 emissions associated with different types of disturbance during two years following stump harvest and site preparation (as well as their overall effects) at three mesic sites, using the chamber technique. N2O emissions at two of the sites were affected by the type of soil disturbance, but not at the other site. At one site, the N2O emissions were highest from undisturbed soil and mounds and significantly lower from mixed soil, bare mineral soil and wheel ruts. At this site the emission rates were clearly correlated with N availability across the disturbances. At the second site showing significant treatment effects, N2O emissions were higher from the bare mineral soil after site preparation than from other types of disturbed soil. At the third site there were no significant N2O emissions, possibly due to reductions in nitrogen availability caused by the fast establishment of vegetation at that site. The CH4 fluxes included both uptakes and losses, but were generally low following all types of soil disturbances, although they were substantial from wheel ruts and soil pits. In conclusion there were no, or minor, between-treatment differences in N2O and CH4 emissions. Furthermore, the radiative forcing potential of these emissions was small compared to mean CO2 emissions from Swedish clear-cuts. Thus, our results indicate that stumps can be harvested without causing elevated emissions of N2O and CH4 on mesic sites. The effects on wetter sites remain to be illuminated. © 2016 Elsevier B.V.

Johansson K.,Southern Swedish Forest Research Center | Nilsson U.,Southern Swedish Forest Research Center | Orlander G.,Sodra Forest Owner Association
Forestry | Year: 2013

Scarification is the most common measure to improve the planting environment in Sweden. However, different scarification methods give varying results. During the early 1990s, a nation-wide experiment with 10 field installations was established in order to test the effect of several scarification methods, including two intensities of soil inversion and mounding, on growth of planted Norway spruce seedlings and in comparison with no scarification (i.e. control). Eighteen growing seasons after planting, a higher seedling survival was found following soil inversion (77 per cent for normal and 76 per cent for intensive) compared with mounding (67 per cent) and control (57 per cent). The mean height of the planted trees across all sites 18 years after planting was 413 and 430 cm following normal and intensive soil inversion, respectively, 424 cm after mounding and 346 cm in the control. The difference in height between the scarification treatments and the control corresponded to a time gain of ∼4 years of growth after 18 years. However, the length of the leading shoot was not affected by scarification after 14-18 years, indicating that scarification did not affect growth beyond the establishment phase. Scarification reduced variation in height of the planted trees. On scarified plots, the number of naturally regenerated trees increased with more than 100 per cent to reach a mean value of 2300 stems per hectare. © 2012 Institute of Chartered Foresters. All rights reserved.

This paper analyzes trends and possible future developments in global wood-product markets and discusses implications for the Swedish forest sector. Four possible futures, or scenarios, are considered, based on qualitative scenario analysis. The scenarios are distinguished principally by divergent futures with respect to two highly influential factors driving change in global wood-product markets, whose future development is unpredictable. These so-called critical uncertainties were found to be degrees to which: (i) current patterns of globalization will continue, or be replaced by regionalism, and (ii) concern about the environment, particularly climate change, related policy initiatives and customer preferences, will materialize. The overall future of the Swedish solid wood-product industry looks bright, irrespective of which of the four possible futures occurs, provided it accommodates the expected growth in demand for factory-made, energy-efficient construction components. The prospects for the pulp and paper industry in Sweden appear more ambiguous. Globalization is increasingly shifting production and consumption to the Southern hemisphere, adversely affecting employment and forest owners in Sweden. Further, technical progress in information and communication technology (ICT) is expected to lead to drastic reductions in demand for newsprint and printing paper. Chemical pulp producers may profit from a growing bio-energy industry, since they could manufacture new, high-value products in integrated bio-refineries. Mechanical pulp producers cannot do this, however, and might suffer from higher prices for raw materials and electricity.© 2011 by the authors; licensee MDPI, Basel, Switzerland.

Promotion of renewable energy sources in Europe is foreseen to result in a dramatic increase in the demand for woody biomass. This paper assesses whether wood resources in the European Union (EU) will support future demand. Possible implications for countries with ample forest resources and a well-developed forest industry, such as Sweden, of an expected mounting demand pressure are discussed. Other drivers of change in global wood product markets posing challenges for the forest sector in general are also addressed. These drivers are reviewed and, together with the results from the EUwood project and econometric wood market models, analyzed as to their impacts on the Swedish forest sector. Demand is foreseen to vastly exceed the potential supply of woody biomass in Europe, putting a tremendous pressure on the Swedish forest resource and necessitating trade-offs between different ecosystem services. Further, projections suggest that Sweden will decrease in importance in production as well as consumption terms for all wood products.

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