| 1. |
- Akselsson, Cecilia, et al.
(författare)
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Can increased weathering rates due to future warming compensate for base cation losses following whole-tree harvesting in spruce forests?
- 2016
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 128:1-2, s. 89-105
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Tidskriftsartikel (refereegranskat)abstract
- Whole-tree harvesting, i.e. harvesting of stems, branches and tops, has become increasingly common during recent decades due to the increased demand for renewable energy. Whole-tree harvesting leads to an increase in base cation losses from the ecosystem, which can counteract recovery from acidification. An increase in weathering rates due to higher temperatures is sometimes suggested as a process that may counteract the acidifying effect of whole-tree harvesting. In this study the potential effect of increasing temperature on weathering rates was compared with the increase in base cation losses following whole-tree harvesting in spruce forests, along a temperature gradient in Sweden. The mechanistic model PROFILE was used to estimate weathering rates at National Forest Inventory sites at today’s temperature and the temperature in 2050, as estimated by two different climate projections. The same dataset was used to calculate base cation losses following stem-only and whole-tree harvesting. The calculations showed that the increase in temperature until 2050 would result in an increase in the base cation weathering rate of 20–33 %, and that whole-tree harvesting would lead to an increase in base cation losses of 66 % on average, compared to stem-only harvesting. A sensitivity analysis showed that moisture changes are important for future weathering rates, but the effect of the temperature change was dominating even when the most extreme moisture changes were applied. It was concluded that an increase in weathering rates resulting from higher temperatures would not compensate for the increase in base cation losses following whole-tree harvesting, except in the northernmost part of Sweden.
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| 2. |
- Akselsson, Cecilia, et al.
(författare)
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Critical biomass harvesting - Applying a new concept for Swedish forest soils
- 2018
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 409, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of forest harvesting to base cation losses and soil acidification has increased in recent years in Sweden, as the demand for bioenergy has increased and the sulphur deposition has decreased. Thus, new policy tools are required to evaluate the progress of the recovery from acidification, and as a basis for forest management recommendations. In this study we introduce and test a concept, Critical biomass harvesting. The concept builds on the concept Critical loads, which has been used world-wide for several decades as a bridge between science and policies related to transboundary air pollution and acidification. The basis for the concept is an acidity mass balance, with sources and sinks of acidity. A critical limit defines the highest acceptable acidification status of the water leaving the root zone. Based on the critical limit, the highest allowed biomass harvesting can be calculated, keeping the other parameters constant. In this study the critical limit was set to ANC (Acid Neutralizing Capacity) = 0. Nitrogen was assumed to be affecting acidity only if it leaches from the root zone. The critical biomass harvesting was calculated for almost 12000 National Forest Inventory sites with spruce and pine forest, using the best available data on deposition, weathering and nitrogen leaching. The exceedance of critical biomass harvesting was calculated as the difference between the estimated harvest losses and the critical biomass harvesting. The results were presented as median values in merged catchments in a catchment database, with totally 2079 merged catchments in Sweden. According to the calculations, critical biomass harvesting was exceeded in the southern half of Sweden already at stem harvesting in spruce forests. Whole-tree harvesting expanded the exceedance area, and increased the exceedance levels in southern Sweden. The exceedance in pine forest was lower and affected smaller areas. It was concluded that the concept of critical biomass harvesting can be successfully applied on the same database that has been used for critical load calculations in Sweden, using basically the same approach as has been extensively applied, evaluated and discussed in a critical load context. The results from the calculations in Sweden indicate that whole-tree harvesting, without wood ash recycling, can be expected to further slow down recovery, especially in the most acidified parts of the country, in the southwest.
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| 3. |
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| 4. |
- Akselsson, Cecilia, et al.
(författare)
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Weathering rates in Swedish forest soils
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:22, s. 4429-4450
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Forskningsöversikt (refereegranskat)abstract
- Soil and water acidification was internationally recognised as a severe environmental problem in the late 1960s. The interest in establishing “critical loads” led to a peak in weathering research in the 1980s and 1990s, since base cation weathering is the long-term counterbalance to acidification pressure. Assessments of weathering rates and associated uncertainties have recently become an area of renewed research interest, this time due to demand for forest residues to provide renewable bioenergy. Increased demand for forest fuels increases the risk of depleting the soils of base cations produced in situ by weathering. This is the background to the research programme Quantifying Weathering Rates for Sustainable Forestry (QWARTS), which ran from 2012 to 2019. The programme involved research groups working at different scales, from laboratory experiments to modelling. The aims of this study were to (1) investigate the variation in published weathering rates of base cations from different approaches in Sweden, with consideration of the key uncertainties for each method; (2) assess the robustness of the results in relation to sustainable forestry; and (3) discuss the results in relation to new insights from the QWARTS programme and propose ways to further reduce uncertainties. In the study we found that the variation in estimated weathering rates at single-site level was large, but still most sites could be placed reliably in broader classes of weathering rates. At the regional level, the results from the different approaches were in general agreement. Comparisons with base cation losses after stem-only and whole-tree harvesting showed sites where whole-tree harvesting was clearly not sustainable and other sites where variation in weathering rates from different approaches obscured the overall balance. Clear imbalances appeared mainly after whole-tree harvesting in spruce forests in southern and central Sweden. Based on the research findings in the QWARTS programme, it was concluded that the PROFILE/ForSAFE family of models provides the most important fundamental understanding of the contribution of weathering to long-term availability of base cations to support forest growth. However, these approaches should be continually assessed against other approaches. Uncertainties in the model approaches can be further reduced, mainly by finding ways to reduce uncertainties in input data on soil texture and associated hydrological parameters but also by developing the models, e.g. to better represent biological feedbacks under the influence of climate change.
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| 5. |
- Belyazid, Salim, et al.
(författare)
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Assessing the Effects of Climate Change and Air Pollution on Soil Properties and Plant Diversity in Northeastern US Hardwood Forests : Model Setup and Evaluation
- 2019
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 230:5
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Tidskriftsartikel (refereegranskat)abstract
- The integrated forest ecosystem model ForSAFE-Veg was used to simulate soil processes and understory vegetation composition at threesugar maple, beech, yellow birchhardwood forest sites in the Northeastern United States (one at Hubbard Brook, NH, and two at Bear Brook, ME). Input data were pooled from a variety of sources and proved coherent and consistent. While the biogeochemical component ForSAFE was used with limited calibration, the ground vegetation composition module Veg was calibrated to field releves. Evaluating different simulated ecosystem indicators (soil solution chemistry, tree biomass, ground vegetation composition) showed that the model performed comparably well regardless of the site's soil condition, climate, and amounts of nitrogen (N) and sulfur (S) deposition, with the exception of failing to capture tree biomass decline at Hubbard Brook. The model performed better when compared with annual observation than monthly data. The results support the assumption that the biogeochemical model ForSAFE can be used with limited calibration and provide reasonable confidence, while the vegetation community composition module Veg requires calibration if the individual plant species are of interest. The study welcomes recent advances in empirically explaining the responses of hardwood forests to nutrient imbalances and points to the need for more research.
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| 6. |
- Belyazid, Salim, et al.
(författare)
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Water limitation can negate the effect of higher temperatures on forest carbon sequestration
- 2019
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Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 138:2, s. 287-297
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Tidskriftsartikel (refereegranskat)abstract
- Climate change will bring about a consistent increase in temperatures. Annual precipitation rates are also expected to increase in boreal countries, but the seasonal distribution will be uneven, and several areas in the boreal zone will experience wetter winters and drier summers. This study uses the dynamic forest ecosystem model ForSAFE to estimate the combined effect of changes in temperature and precipitation on forest carbon stocks in Sweden. The model is used to simulate carbon stock changes in 544 productive forest sites from the Swedish National Forest Inventory. Forest carbon stocks under two alternative climate scenarios are compared to stocks under a hypothetical scenario of no climate change (baseline). Results show that lower water availability in the future can cause a significant reduction in tree carbon compared to a baseline scenario, particularly expressed in the southern and eastern parts of Sweden. In contrast, the north-western parts will experience an increase in tree carbon stocks. Results show also that summer precipitation is a better predictor of tree carbon reduction than annual precipitation. Finally, the change in soil carbon stock is less conspicuous than in tree carbon stock, showing no significant change in the north and a relatively small but consistent decline in the south. The study indicates that the prospect of higher water deficit caused by climate change cannot be ignored in future forest management planning.
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| 7. |
- Bennich, Therese, et al.
(författare)
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The Bio-Based Economy : Dynamics Governing Transition Pathways in the Swedish Forestry Sector
- 2018
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- A transition to a bio-based economy would entail change in coupled social-ecological systems. These systems are characterised by complexity, giving rise to potential unintended consequences and trade-offs caused by actions aiming to facilitate a transition process. Yet, many of the analyses to date have been focusing on single and predominantly technological aspects of the bio-based economy. The main contribution of our work is to the development of an integrated understanding of potential future transition pathways, with the present paper focusing specifically on terrestrial biological resources derived from the forestry sector in Sweden. Desired change processes identified include a transition to diversified forest management, a structural change in the forestry industry to enable high-value added production, and increased political support for the bio-based economy concept. Hindrances identified include the ability to demonstrate added values for end consumers of novel biomass applications, and uncertainty linked to a perceived high level of polarisation in the forestry debate. The results outline how these different processes are interrelated, allowing for the identification of high order leverage points and interventions to facilitate a transition to a bio-based economy.
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| 8. |
- Bennich, Therese, et al.
(författare)
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The Route to Sustainability-Prospects and Challenges of the Bio-Based Economy
- 2017
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 9:6
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Forskningsöversikt (refereegranskat)abstract
- The bio-based economy has been increasingly recognized in the sustainability debate over the last two decades, presented as a solution to a number of ecological and social challenges. Its premises include climate change mitigation, cleaner production processes, economic growth, and new employment opportunities. Yet, a transition to a bio-based economy is hampered by risk factors and uncertainties. In this paper, we explore the concept of a bio-based economy, focusing on opportunities of achieving sustainability, as well as challenges of a transition. Departing from an understanding of sustainability provided by the weak and strong sustainability paradigms, we first outline the definition and development of the bio-based economy from a theoretical perspective. Second, we use Sweden as an example of how a transition towards a bio-based economy has been evolving in practice. The review indicates that the proposed direction and strategies of the bio-based economy are promising, but sometimes contradictory, resulting in different views on the actions needed for its premises to be realized. Additionally, current developments adhere largely to the principles of the weak sustainability paradigm. In order for the bio-based economy to develop in accordance with the notion of strong sustainability, important steps to facilitate a transition would include acknowledging and addressing the trade-offs caused by biophysical and social limits to growth.
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| 9. |
- Bennich, Therese, et al.
(författare)
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Understanding the Transition to a Bio-Based Economy : Exploring Dynamics Linked to the Agricultural Sector in Sweden
- 2018
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing interest in the bio-based economy, evident in the policy domain as well as in the academic literature. Its proponents consider it an opportunity to address multiple societal challenges, and the concept has broad reach across different sectors of society. However, a potential transition process is also linked to areas of risk and uncertainty, and the need for interdisciplinary research and for the identification of potential trade-offs and synergies between parallel visions of the bio-based economy have been emphasized. The aim of this paper is to contribute to addressing this gap by using an approach combining tools for systems analysis with expert interviews. Focusing specifically on dynamics in the agricultural sector in Sweden, an integrated understanding of the social and ecological processes contributing to or hindering a transition in this area is developed, high order leverage points are identified, and potential impacts of proposed interventions explored. The paper also considers cross-sectoral linkages between the forestry and agricultural sectors.
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| 10. |
- Erlandsson Lampa, Martin, et al.
(författare)
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Effects of whole-tree harvesting on soil, soil water and tree growth - A dynamic modelling exercise in four long-term experiments
- 2019
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 414
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Tidskriftsartikel (refereegranskat)abstract
- Whole tree harvesting (WTH) following final felling of productive forests is increasingly promoted as a method to extract biomass for energy purposes. Despite its importance, there is a limited number of experimental studies investigating the impacts of WTH on forest ecosystem sustainability. Modelling studies have previously been carried out to complement and explain empirical observations from four long-term WTH experiments in Sweden. The literature shows a significant discrepancy between these studies, and open questions remain as to the fate of the base cations that are not removed in the absence of WTH. This study uses the integrated ecosystem model ForSAFE, which simulate a forest ecosystem's biogeochemical processes and the feedbacks between these processes, to trace the fate of base cations for the said four long-term WTH experiments. The study shows that the model generally captures the observed effects of WTH on the stocks of base cations in the biomass and in the soil. The modelled results were also used to map how the base cations removed through WTH would otherwise (if left at the site) have been distributed in the ecosystem. The results indicate that the soil organic pool may be more important to the long-term base cation balance than the exchangeable pool, and should receive more attention in future research.
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