Forestry Research Institute of Sweden

Uppsala, Sweden

Forestry Research Institute of Sweden

Uppsala, Sweden
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Rytter L.,Forestry Research Institute of Sweden | Rytter R.-M.,Rytter Science
Forest Ecology and Management | Year: 2017

Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) has recently been introduced commercially in the Nordic and Baltic forestry. The hybrid is suitable for biomass production under high latitude conditions and the productivity is promising. Regeneration may be based on vigorous root sucker sprouting. Management strategies for root sucker stands are important for the outcome, but are still under development. Our study examined dynamics, productivity and sustainability of root sucker generations with three different management regimes: 4-year rotation (4YR), 8-year rotation (8YR) and intended 16-year rotation (8+YR), which was halfway in this study. Thinning measures were performed in the two longest rotations, i.e. corridor cleaning in 8YR, and corridor cleaning followed by thinning to ca 1100–1200 stems ha−1 in the 8+YR rotation. The study comprised a mid-term evaluation eight years after clear cutting of the initial planted stand. Total woody biomass production during eight years was 98.3, 92.6 and 87.2 Mg DM ha−1 in the 4YR, 8YR and 8+YR treatments, respectively, but without significant differences. Mean annual increment (MAI) raised rapidly and reached a level of 10–12 Mg DM ha−1 year−1 in all regimes two years after clear cutting. Stem diameter development was strongly promoted by thinning measures and height development was also positively affected by reduced stand density. Sustainability in biomass production is essential when relying on sprouting after harvest. We could not see any productivity decline in the two consecutive 4-year cycles included. Thinning measures often cause a decreased production until canopy closure is reached, but our study showed no decrease, which may be due to the very rapid growth of root sucker stands. The root sucker number was 77,000–124,000 ha−1 after the first season. Self-thinning was reached after one year leading to a rapid reduction in living shoots in unthinned plots where the share of dead shoots constituted 46–56%, but only 5.0–9.1% of biomass, at the end of the 4-year rotations. We concluded that different management strategies affected biomass production weakly, but influenced diameter development strongly, which suggests a large flexibility where different management strategies may be selected for various purposes without substantial initial loss of biomass. © 2017 Elsevier B.V.

Rosner S.,University of Natural Resources and Life Sciences, Vienna | Karlsson B.,Forestry Research Institute of Sweden
Trees - Structure and Function | Year: 2011

The aim of this study was to investigate bending stiffness and compression strength perpendicular to the grain of Norway spruce (Picea abies (L.) Karst.) trunkwood with different anatomical and hydraulic properties. Hydraulically less safe mature sapwood had bigger hydraulic lumen diameters and higher specific hydraulic conductivities than hydraulically safer juvenile wood. Bending stiffness (MOE) was higher, whereas radial compression strength lower in mature than in juvenile wood. A density-based tradeoff between MOE and hydraulic efficiency was apparent in mature wood only. Across cambial age, bending stiffness did not compromise hydraulic efficiency due to variation in latewood percent and because of the structural demands of the tree top (e. g. high flexibility). Radial compression strength compromised, however, hydraulic efficiency because it was extremely dependent on the characteristics of the "weakest" wood part, the highly conductive earlywood. An increase in conduit wall reinforcement of earlywood tracheids would be too costly for the tree. Increasing radial compression strength by modification of microfibril angles or ray cell number could result in a decrease of MOE, which would negatively affect the trunk's capability to support the crown. We propose that radial compression strength could be an easily assessable and highly predictive parameter for the resistance against implosion or vulnerability to cavitation across conifer species, which should be topic of further studies. © 2010 Springer-Verlag.

Audy J.-F.,Laval University | D'Amours S.,Laval University | Ronnqvist M.,Norwegian School of Economics and Business Administration | Ronnqvist M.,Forestry Research Institute of Sweden
International Journal of Production Economics | Year: 2012

Interest has been raised by the recent identification of potential savings through collaborative planning in logistics operations. Even though substantial savings can be realized, two key questions exist: (i) how should potential savings be divided among a group of collaborating companies and (ii) among potential collaborating companies, how should collaborating group(s) be formed? These two questions are studied in a specific context: among potential collaborating companies; a subset, denoted the leading companies, performs collaborative planning on behalf of the others and together, they initiate formation of a collaborating group. We use the concept of a business model to detail such context. Based on the literature on network formation where potential savings are modelled by a cooperative game, four business models are explored in four different subsets of leading companies. We propose a network model as a method to determine the stable collaborating group in each computation. A case study including eight forest companies is described and analyzed. Results show that very different solution characteristics can be achieved depending on the business model selected. © 2011 Elsevier B.V.

Almqvist C.,Forestry Research Institute of Sweden
Canadian Journal of Forest Research | Year: 2013

Reducing generation turnover in breeding programs should increase the genetic gain per unit time. This could potentially be achieved by topgrafting, since it can be used to induce strobili production in young plant material. I therefore studied the effect of the interstock clone on the vitality and strobili production of topgrafts in Pinus sylvestris L. over 4 years. The experiment consisted of 20 interstock clones × 3 ramets per interstock × 10 topgrafts per ramet, giving a total of 600 topgrafts. There were large differences in topgraft survival rates among the different interstock clones, ranging from 60% to 93% in the spring of the experiment's fourth year. Analysis of variance (ANOVA) revealed that both the interstock and the topgraft had significant effects on female and male topgraft strobili production. The effect of the ramet within the interstock was small on topgraft vitality but was large and significant on strobili production. The interaction between interstock and topgraft was not significant for topgraft vitality and male strobili production for any of the studied years, but it was significant two out of four years for female strobili production. No relationship was found between female strobili production on the interstocks and their capacity to induce female strobilis on topgrafts, but there was a weak relationship between strobili production on the interstocks and their capacity to induce male strobilis on topgrafts. Overall, the results indicate that topgrafting could, with appropriate interstock clones, effectively decrease the time to strobili production compared with conventional grafting using young rootstocks in P. sylvestris, but suitable interstock clones will have to be identified by screening tests. © 2013 Published by NRC Research Press.

Rytter L.,Forestry Research Institute of Sweden
Forest Ecology and Management | Year: 2013

Early management of hardwood stands is important if the goal is to produce high-quality timber and it may also reduce the rotation period. Both effects are favourable for the economic outcome of hardwood forestry. Eight young hardwood stands, dominated by either birch (Betula pendula Roth and B. pubescens Ehrh.), black alder (Alnus glutinosa (L.) Gaertn.), aspen (Populus tremula L.) or lime (Tilia cordata Mill.), in need of precommercial thinning, were identified in southern Sweden. The aim was to assess the effect of delayed thinning and thinning intensity on retained trees under north European conditions. Three treatments were applied: (1) 5. years delayed thinning, (2) standard thinning, and (3) strong thinning to 2/3 the stand density of treatment 2. Retained trees were followed during 11. years and showed that delayed thinning resulted in smaller crowns and slower diameter development than in the thinned alternatives. There were only minor differences between standard and strong thinning. After thinning the trees of the delayed thinning alternative showed partial recovery of the crowns. There were no longer any significant differences in green crown base height although differences in green crown radius and crown ratio remained between the delayed and the other two thinning alternatives. Furthermore, diameter growth rate of the delayed thinning trees recovered to about the same level as for trees with earlier thinning. However, differences in diameter and in the ratio diameter:height persisted, indicating that diameter loss in the early rotation phase cannot be compensated for later. It is concluded that early precommercial thinning lead to better early diameter growth than delayed thinning but also that young stands with late thinning can recover in diameter growth rate resulting in shifted but parallel diameter growth curves. © 2013 Elsevier B.V.

Lindholm E.-L.,Swedish University of Agricultural Sciences | Berg S.,Forestry Research Institute of Sweden | Hansson P.-A.,Swedish University of Agricultural Sciences
European Journal of Forest Research | Year: 2010

In a case study, seven different procurement chains of forest energy in Sweden were modelled and the environmental performance was calculated from a Life Cycle Assessment (LCA) perspective. The systems differed with respect to geographical location, the technology employed and resource use (stumps or logging residues). The energy output/input ratio of chips from residues and stumps was in the range 21-48, and the greenhouse gas emissions were 1.5-3.5 g CO2-eq/MJ chips. The systems in southern Sweden were generally more efficient than similar systems in northern Sweden. The forest energy systems based on bundles and stumps rely on immature technologies which have the potential to be improved should there be technical developments of the systems. © 2010 Springer-Verlag.

Almqvist C.,Forestry Research Institute of Sweden
Scandinavian Journal of Forest Research | Year: 2013

Reducing the generation turnover increases the genetic gain in a breeding programme. Topgrafting, new genetic material being grafted into the crown of ramets of reproductive mature trees, can deliver this aim since it is able to induce strobili production in young material of conifers. To this end, I studied the effect of scion age (seedlings of 4-6 years from seed) on topgraft vitality/survival, and female and male strobili production in Pinus sylvestris (L.) over 5 years. The seedlings' growing environment prior to topgrafting had a significant impact on topgraft vitality, with more vital topgrafts obtained from potted seedlings than from seedlings grown in raised nursery beds. However, the growth environment had no clear effect on female or male strobili production. In the second year, after grafting up to 76% of the topgrafted seedlings had female strobili. Vitality increased with age of the seedling from which the scions were collected, but differences in both female and male strobili production were only marginal. The position of the topgraft within the interstock crown influenced both vitality and strobili production, with higher vitality and greater male strobili production in low positions and greater female strobili production in high positions. Based on these results, breeders should perform topgrafting as soon as the seedlings have enough scions for planned crossing activities. © 2013 Copyright Taylor and Francis Group, LLC.

Rytter R.-M.,Forestry Research Institute of Sweden
Biomass and Bioenergy | Year: 2012

A large share, estimated at 12-25%, of the annual anthropogenic greenhouse gas emissions is attributed to global deforestation. Increasing the forested areas therefore has a positive impact on carbon (C) sequestration and mitigation of high atmospheric CO2 concentrations. Fast-growing species, such as willow and poplar, are of high interest as producers of biomass for fuel, but also as C sinks. The present study estimated the rate of C sequestration in biomass and soil in willow and poplar plantations. Calculations were based on above- and below-ground biomass production data from field experiments, including fine root turnover, litter decomposition rates, and production levels from commercial plantations. Accumulation of C in woody biomass, above and below ground, was estimated at 76.6-80.1 Mg C ha-1 and accumulation of C in the soil at 9.0-10.3 Mg C ha-1 over the first 20-22 years. The average rates of C sequestration were 3.5-4.0 Mg C ha-1 yr-1 in woody biomass, and 0.4-0.5 Mg C ha-1 yr-1 in the soil. If 400,000 ha of abandoned arable land in Sweden were planted with willow and poplar, about 1.5 Tg C would be sequestered annually in woody biomass and 0.2 Tg C in soils. This would be nearly one tenth of the annual anthropogenic emissions of C in Sweden today. These calculations show the potential of fast-growing plantations on arable land to mitigate the effect of high CO2 concentrations over a short time span. Knowledge gaps were found during the calculation process and future research areas were suggested. © 2011 Elsevier Ltd.

Stener L.-G.,Forestry Research Institute of Sweden
Scandinavian Journal of Forest Research | Year: 2013

Ash dieback damage was assessed and analysed on 16-22 year-old grafts in two ash seed orchards (Fraxinus excelsior L.). The grafts originated from 106 plus-tree clones selected from 27 stands in southern Sweden based on their phenotypes. The results obtained indicate that ash dieback disease is strongly genotypically controlled. There was considerable genotypic variation among individuals. None of the clones seemed to be totally resistant, but some exhibited reduced susceptibility and retained this resistance after 6 years under heavy infection pressure. Autumn phenology based on leaf coloration was subject to moderate genetic control (H2 = 0.19). The genetic correlation between autumn phenology and damage was weak to moderate (rG from 0.38 to 0.60) and positive, indicating that susceptible clones have a prolonged growing season. There was no evidence suggesting that stands differed in susceptibility. Together with the high heritability of resistance, strong age×age correlations and weak genotype×environment interactions, this suggests there is good scope for breeding less susceptible trees for the future. © 2013 Copyright Taylor and Francis Group, LLC.

Weslien J.,Forestry Research Institute of Sweden | Djupstrom L.B.,Forestry Research Institute of Sweden | Schroeder M.,Swedish University of Agricultural Sciences | Widenfalk O.,Forestry Research Institute of Sweden
Journal of Animal Ecology | Year: 2011

1.Priority effects have been hypothesized to have long-lasting impact on community structure in natural ecosystems. Long-term studies of priority effects in natural ecosystems are however sparse, especially in terrestrial ecosystems. 2.Wood decay is a slow process involving a high diversity of insect and fungus species. Species interactions that drive change in communities of insects and fungi during wood decay are poorly understood because of a lack of sufficient long-term studies. 3.In this paper, we followed the colonization and succession of wood-living insects and fungi on cut trees during 15years, from tree death and onwards, in a boreal forest landscape. We test the long-term priority effects hypothesis that the identity and abundance of species that colonize first affect the colonization success of later-arriving species. We also hypothesize that species interact in both facilitative and inhibitory ways, which ultimately affect habitat quality for a red-listed late-succession beetle species. 4.Possible causal associations between species were explored by path analysis. The results indicate that one bark beetle species, Hylurgops palliatus, and one wood-borer species, Monochamus sutor, which colonized the wood during the first year after cutting, influenced the occurrence of a rare, wood-living beetle, Peltis grossa, that started to emerge from the stumps about 10years later. The positive effects of Hylurgops palliatus and negative effects of M. sutor were largely mediated through the wood-decaying fungus species Fomitopsis pinicola. 5.The study shows that variable priority effects may have long-lasting impact on community assembly in decaying wood. The study also exemplifies new possibilities for managing populations of threatened species by exploring links between early, well-understood species guilds and late, more poorly understood species guilds. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society.

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