Stockholms universitet logo, länk till startsida

Salim BelyazidUniversitetslektor

Om mig

Vänligen se engelsk sida.


I urval från Stockholms universitets publikationsdatabas

  • A Combined Measurement and Modelling Approach to Assess the Sustainability of Whole-Tree Harvesting—A Swedish Case Study

    2021. Cecilia Akselsson (et al.). Sustainability 13 (4)


    The demand of renewable energy has increased the interest in whole-tree harvesting. The sustainability of whole-tree harvesting after clear-cutting, from an acidification point of view, depends on two factors: the present acidification status and the further loss of buffering capacity at harvesting. The aims of this study were to investigate the relationship between these two factors at 26 sites along an acidification gradient in Sweden, to divide the sites into risk classes, and to examine the geographical distribution of them in order to provide policy-relevant insights. The present status was represented by the acid neutralizing capacity (ANC) in soil solution, and the loss of buffering capacity was represented by the estimated exceedance of critical biomass harvesting (CBH). The sites were divided into three risk classes combining ANC and exceedance of CBH. ANC and exceedance of CBH were negatively correlated, and most sites had either ANC < 0 and exceedance (high risk) or ANC > 0 and no exceedance (low risk). There was a geographical pattern, with the high risk class concentrated to southern Sweden, which was mainly explained by higher historical sulfur deposition and site productivity in the south. The risk classes can be used in the formulation of policies on whole-tree harvesting and wood ash recycling.

    Läs mer om A Combined Measurement and Modelling Approach to Assess the Sustainability of Whole-Tree Harvesting—A Swedish Case Study
  • Simulation of water and chemical transport of chloride from the forest ecosystem to the stream

    2021. Giuliana Zanchi (et al.). Environmental Modelling & Software 138


    The study evaluates the biogeochemical model ForSAFE-2D, designed to simulate water and chemical transport from the forest to the stream, by simulating the hydrology and the transport of the chemical tracer chloride (Cl-) along a forest hillslope in Northern Sweden. The simulated Cl- exports were in balance with the simulated inputs but measurements suggested a net release of Cl- from the catchment. Underestimated deposition inputs (deposition peaks and possibly dry deposition) were probably and partially responsible for this mismatch. However, we could not exclude that other soil biogeochemical processes omitted in ForSAFE-2D could also contribute to Cl- exports from the catchment. The study showed that ForSAFE-2D is a promising tool to better understand the factors that regulate the chemical export from the forest to the stream. The results also confirmed that there are limitations in using Cl- as a tracer in forest ecosystems.

    Läs mer om Simulation of water and chemical transport of chloride from the forest ecosystem to the stream
  • The bio-based economy, 2030 Agenda, and strong sustainability – A regional-scale assessment of sustainability goal interactions

    2021. Therese Bennich (et al.). Journal of Cleaner Production 283


    Policy-makers face the challenge of assessing and implementing sustainability measures, while also dealing with parallel and sometimes conflicting policy agendas, long-term policy impacts, and contested interpretations of sustainability. To support evidence-based decision-making in this context, this paper presents the results from an integrated assessment of sustainability goal interactions. Links between the bio-based economy, the 2030 Agenda, and the so-called strong sustainability paradigm were explored in a regional-scale case. The analysis focused primarily on developments in the forestry and energy sectors. Direct trade-offs and synergies as well as broader systemic impacts were identified. The results show how goals from the bio-based economy, 2030 Agenda and strong sustainability paradigm are mutually interacting. Positive interactions were found within two clusters of goals, offering coherent and synergetic transition pathways within these. The first cluster encompasses developments toward intensified forestry, renewable energy, and closed-loop production systems. The second pathway supports diversified forestry and protection of critical natural capital. However, while internally coherent, trade-offs were identified between these goal clusters, demonstrating the difficulty in simultaneously making progress on goals belonging to different sustainability agendas. The results also stress the need for disaggregation and long-term assessments to identify trade-offs and synergies. Finally, the analysis highlights the theoretical potential but practical challenges of implementing the bio-based economy and 2030 Agenda in a way that adheres to strong sustainability. The analytical framework used in the present study may be adapted and applied to other decision-making contexts. It is particularly useful in settings characterized by uncertainty and unstructured problem spaces.

    Läs mer om The bio-based economy, 2030 Agenda, and strong sustainability – A regional-scale assessment of sustainability goal interactions
  • The Effect of Nitrogen Fertilization on Tree Growth, Soil Organic Carbon and Nitrogen Leaching-A Modeling Study in a Steep Nitrogen Deposition Gradient in Sweden

    2021. Klas Lucander (et al.). Forests 12 (3)


    Nitrogen (N) fertilization in forests has the potential to increase tree growth and carbon (C) sequestration, but it also means a risk of N leaching. Dynamic models can, if the important processes are well described, play an important role in assessing benefits and risks of nitrogen fertilization. The aim of this study was to test if the ForSAFE model is able to simulate correctly the effects of N fertilization when considering different levels of N availability in the forest. The model was applied for three sites in Sweden, representing low, medium and high nitrogen deposition. Simulations were performed for scenarios with and without fertilization. The effect of N fertilization on tree growth was largest at the low deposition site, whereas the effect on N leaching was more pronounced at the high deposition site. For soil organic carbon (SOC) the effects were generally small, but in the second forest rotation SOC was slightly higher after fertilization, especially at the low deposition site. The ForSAFE simulations largely confirm the N saturation theory which state that N will not be retained in the forest when the ecosystem is N saturated, and we conclude that the model can be a useful tool in assessing effects of N fertilization.

    Läs mer om The Effect of Nitrogen Fertilization on Tree Growth, Soil Organic Carbon and Nitrogen Leaching-A Modeling Study in a Steep Nitrogen Deposition Gradient in Sweden
  • Catchment export of base cations

    2020. Martin Erlandsson Lampa (et al.). SOIL 6 (1), 231-244


    Soil mineral weathering is one of the major sources of base cations (BC), which play a dual role in forest ecosystems: they function as plant nutrients and buffer against the acidification of catchment runoff. On a long-term basis, soil weathering rates determine the highest sustainable forest productivity that does not cause acidification. It is believed that the hydrologic residence time plays a key role in determining the weathering rates at the landscape scale. The PROFILE weathering model has been used for almost 30 years to calculate weathering rates in the rooting zone of forest soils. However, the mineral dissolution equations in PROFILE are not adapted for the saturated zone, and employing these equations at the catchment scale results in a significant overprediction of base cation release rates to surface waters. In this study, we use a revised set of PROFILE equations which, among other features, include retardation due to silica concentrations. Relationships between the water transit time (WTT) and soil water concentrations were derived for each base cation, by simulating the soil water chemistry along a one-dimensional flow path, using the mineralogy from a glacial till soil. We show how the revised PROFILE equations are able to reproduce patterns in BC and silica concentrations as well as BC ratios (Ca2+/BC, Mg2+/BC and Na+/BC) that are observed in the soil water profiles and catchment runoff. In contrast to the original set of PROFILE equations, the revised set of equations could reproduce the fact that increasing WTT led to a decreasing Na+/BC ratio and increasing Ca2+/BC and Mg2+/BC ratios. Furthermore, the total release of base cations from a hillslope was calculated using a mixing model, where water with different WTTs was mixed according to an externally modeled WTT distribution. The revised set of equations gave a 50% lower base cation release (0.23 eqm 2 yr 1) than the original PROFILE equations and are in better agreement with mass balance calculations of weathering rates. Thus, the results from this study demonstrate that the revised mineral dissolution equations for PROFILE are a major step forward in modeling weathering rates at the catchment scale.

    Läs mer om Catchment export of base cations
  • Reviews and syntheses

    2020. Roger D. Finlay (et al.). Biogeosciences 17 (6), 1507-1533


    Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and meso-cosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance trans-portation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C : N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the systemic effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.

    Läs mer om Reviews and syntheses
  • Revisiting the Contested Role of Natural Resources in Violent Conflict Risk through Machine Learning

    2020. Marie K. Schellens, Salim Belyazid. Sustainability 12 (16)


    The integrated character of the sustainable development goals in Agenda 2030, as well as research in environmental security, flag that sustainable peace requires sustainable and conflict-sensitive natural resource use. The precise relationship between the risk for violent conflict and natural resources remains contested because of the interplay with socio-economic variables. This paper aims to improve the understanding of natural resources’ role in the risk of violent conflicts by accounting for complex interactions with socio-economic conditions. Conflict data was analysed with machine learning techniques, which can account for complex patterns, such as variable interactions. More commonly used logistic regression models are compared with neural network models and random forest models. The results indicate that a country’s natural resource features are important predictors of its risk for violent conflict and that they interact with socio-economic conditions. Based on these empirical results and the existing literature, we interpret that natural resources can be root causes of violent intrastate conflict, and that signals from natural resources leading to conflict risk are reflected in and influenced by interacting socio-economic conditions. More specifically, the results show that variables such as access to water and food security are important predictors of conflict, while resource rents and oil and ore exports are relatively less important than other natural resource variables, contrasting what prior research has suggested. Given the potential of natural resource features to act as an early warning for violent conflict, we argue that natural resources should be included in conflict risk models for conflict prevention.

    Läs mer om Revisiting the Contested Role of Natural Resources in Violent Conflict Risk through Machine Learning
  • Water limitation can negate the effect of higher temperatures on forest carbon sequestration

    2019. Salim Belyazid, Zanchi Giuliana. European Journal of Forest Research 138 (2), 287-297


    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.

    Läs mer om Water limitation can negate the effect of higher temperatures on forest carbon sequestration
  • Weathering rates in Swedish forest soils

    2019. Cecilia Akselsson (et al.). Biogeosciences 16 (22), 4429-4450


    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.

    Läs mer om Weathering rates in Swedish forest soils
  • Dynamic modelling of weathering rates - the benefit over steady-state modelling

    2019. Veronika Kronnäs, Cecilia Akselsson, Salim Belyazid.


    Weathering rates are of considerable importance in estimating the acidification sensitivity and recovery capacity of soil and are thus important in the assessment of the sustainability of forestry in a time of changing climate and growing demands for forestry products. In this study, we modelled rates of weathering in mineral soil at two forested sites in southern Sweden included in a monitoring network, using two models. The aims were to determine whether the dynamic model ForSAFE gives comparable weathering rates to the steady-state model PROFILE and whether the ForSAFE model provided believable and useful extra information on the response of weathering to changes in acidification load, climate change and land use. The average weathering rates calculated with ForSAFE were very similar to those calculated with PROFILE for the two modelled sites. The differences between the models regarding the weathering of certain soil layers seemed to be due mainly to differences in calculated soil moisture. The weathering rates provided by ForSAFE vary seasonally with temperature and soil moisture, as well as on longer timescales, depending on environmental changes. Long-term variations due to environmental changes can be seen in the ForSAFE results, for example, the weathering of silicate minerals is suppressed under acidified conditions due to elevated aluminium concentration in the soil, whereas the weathering of apatite is accelerated by acidification. The weathering of both silicates and apatite is predicted to be enhanced by increasing temperature during the 21st century. In this part of southern Sweden, yearly precipitation is assumed to be similar to today's level during the next forest rotation, but with more precipitation in winter and spring and less in summer, which leads to somewhat drier soils in summer but still with increased weathering. In parts of Sweden with a bigger projected decrease in soil moisture, weathering might not increase despite increasing temperature. These results show that the dynamic ForSAFE model can be used for weathering rate calculations and that it gives average results comparable to those from the PROFILE model. However, dynamic modelling provides extra information on the variation in weathering rates with time and offers much better possibilities for scenario modelling.

    Läs mer om Dynamic modelling of weathering rates - the benefit over steady-state modelling
  • Assessing the Effects of Climate Change and Air Pollution on Soil Properties and Plant Diversity in Northeastern US Hardwood Forests

    2019. Salim Belyazid (et al.). Water, Air and Soil Pollution 230 (5)


    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.

    Läs mer om Assessing the Effects of Climate Change and Air Pollution on Soil Properties and Plant Diversity in Northeastern US Hardwood Forests
  • Effects of whole-tree harvesting on soil, soil water and tree growth - A dynamic modelling exercise in four long-term experiments

    2019. Martin Erlandsson Lampa (et al.). Ecological Modelling 414


    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.

    Läs mer om Effects of whole-tree harvesting on soil, soil water and tree growth - A dynamic modelling exercise in four long-term experiments
  • Aluminium and base cation chemistry in dynamic acidification models - need for a reappraisal?

    2018. Jon Petter Gustafsson (et al.).


    Long-term simulations of the water composition in acid forest soils require that accurate descriptions of aluminium and base cation chemistry are used. Both weathering rates and soil nutrient availability depend on the concentrations of Al3+, of H+, and of base cations (Ca2+, Mg2+, Na+, and K+). Assessments of the acidification status and base cation availability will depend on the model being used. Here we review in what ways different dynamic soil chemistry models describe the processes governing aluminium and base cation concentrations in the soil water. Furthermore, scenario simulations with the HD-MINTEQ model are used to illustrate the difference between model approaches. The results show that all investigated models provide the same type of response to changes in input water chemistry. Still, for base cations we show that the differences in the magnitude of the response may be considerable depending on whether a cation-exchange equation (Gaines-Thomas, Gapon) or an organic complexation model is used. The former approach, which is used in many currently used models (e.g. MAGIC, ForSAFE), causes stronger pH buffering over a relatively narrow pH range, as compared to state-of-the-art models relying on more advanced descriptions in which organic complexation is important (CHUM, HD-MIN PLQ). As for aluminium, a fixed gibbsite constant, as used in MAGIC, SMART/VSD, and ForSAFE, leads to slightly more pH buffering than in the more advanced models that consider both organic complexation and Al(OH)(3) (s) precipitation, but in this case the effect is small. We conclude that the descriptions of acid-base chemistry and base cation binding in models such as MAGIC, SMART/VSD, and ForSAFE are only likely to work satisfactorily in a narrow pH range. If the pH varies greatly over time, the use of modern organic complexation models is preferred over cation-exchange equations.

    Läs mer om Aluminium and base cation chemistry in dynamic acidification models - need for a reappraisal?
  • Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model - soil chemistry of three Swedish conifer sites from 1880 to 2080

    2019. Eric McGivney (et al.).


    Forest soils are susceptible to anthropogenic acidification. In the past, acid rain was a major contributor to soil acidification, but, now that atmospheric levels of S have dramatically declined, concern has shifted towards biomass-induced acidification, i.e. decreasing soil solution pH due to tree growth and harvesting events that permanently remove base cations (BCs) from forest stands. We use a novel dynamic model, HD-MINTEQ (Husby Dynamic MINTEQ), to investigate possible long-term impacts of two theoretical future harvesting scenarios in the year 2020, a conventional harvest (CH, which removes stems only), and a whole-tree harvest (WTH, which removes 100 % of the above-ground biomass except for stumps) on soil chemistry and weathering rates at three different Swedish forest sites (Aneboda, Gardsjon, and Kindla). Furthermore, acidification following the harvesting events is compared to the historical acidification that took place during the 20th century due to acid rain. Our results show that historical acidification due to acid rain had a larger impact on pore water chemistry and mineral weathering than tree growth and harvesting, at least if nitrification remained at a low level. However, compared to a no-harvest baseline, WTH and CH significantly impacted soil chemistry. Directly after a harvesting event (CH or WTH), the soil solution pH sharply increased for 5 to 10 years before slowly declining over the remainder of the simulation (until year 2080). WTH acidified soils slightly more than CH, but in certain soil horizons there was practically no difference by the year 2080. Even though the pH in the WTH and CH scenario decreased with time as compared to the no-harvest scenario (NH), they did not drop to the levels observed around the peak of historic acidification (1980-1990), indicating that the pH decrease due to tree growth and harvesting would be less impactful than that of historic atmospheric acidification. Weathering rates differed across locations and horizons in response to historic acidification. In general, the predicted changes in weathering rates were very small, which can be explained by the net effect of decreased pH and increased Al3+, which affected the weathering rate in opposite ways Similarly, weathering rates after the harvesting scenarios in 2020 remained largely unchanged according to the model.

    Läs mer om Assessing the impact of acid rain and forest harvest intensity with the HD-MINTEQ model - soil chemistry of three Swedish conifer sites from 1880 to 2080
  • Critical biomass harvesting - Applying a new concept for Swedish forest soils

    2018. Cecilia Akselsson, Salim Belyazid. Forest Ecology and Management 409, 67-73


    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.

    Läs mer om Critical biomass harvesting - Applying a new concept for Swedish forest soils
  • Modeling the forest phosphorus nutrition in a southwestern Swedish forest site

    2018. Lin Yu (et al.). Ecological Modelling 369, 88-100


    In this study, a phosphorus (P) module containing the biogeochemical P cycle has been developed and integrated into the forest ecosystem model ForSAFE. The model was able to adequately reproduce the measured soil water chemistry, tree biomass (wood and foliage), and the biomass nutrient concentrations at a spruce site in southern Sweden. Both model and measurements indicated that the site showed signs of P limitation at the time of the study, but the model predicted that it may return to an N-limited state in the future if N deposition declines strongly. It is implied by the model that at present time, the plant takes up 0.50 g P m(-2) y(-1) of which 80% comes from mineralization and the remainder comes from net inputs, i.e. deposition and weathering. The sorption/desorption equilibrium of P contributed marginally to the supply of bioavailable P, but acted as a buffer, particularly during disturbances.

    Läs mer om Modeling the forest phosphorus nutrition in a southwestern Swedish forest site
  • The Bio-Based Economy

    2018. Therese Bennich (et al.). Sustainability 10 (4)


    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.

    Läs mer om The Bio-Based Economy
  • Understanding the Transition to a Bio-Based Economy

    2018. Therese Bennich (et al.). Sustainability 10 (5)


    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.

    Läs mer om Understanding the Transition to a Bio-Based Economy
  • The Route to Sustainability-Prospects and Challenges of the Bio-Based Economy

    2017. Therese Bennich, Salim Belyazid. Sustainability 9 (6)


    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.

    Läs mer om The Route to Sustainability-Prospects and Challenges of the Bio-Based Economy
  • Can increased weathering rates due to future warming compensate for base cation losses following whole-tree harvesting in spruce forests?

    2016. Cecilia Akselsson (et al.). Biogeochemistry 128 (1-2), 89-105


    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.

    Läs mer om Can increased weathering rates due to future warming compensate for base cation losses following whole-tree harvesting in spruce forests?
  • Global topics and novel approaches in the study of air pollution, climate change and forest ecosystems

    2016. Pierre Sicard (et al.). Environmental Pollution 213, 977-987


    Research directions from the 27th conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems (2015) reflect knowledge advancements about (i) Mechanistic bases of tree responses to multiple climate and pollution stressors, in particular the interaction of ozone (O-3) with nitrogen (N) deposition and drought; (ii) Linking genetic control with physiological whole-tree activity; (iii) Epigenetic responses to climate change and air pollution; (iv) Embedding individual tree performance into the multi-factorial stand-level interaction network; (v) Interactions of biogenic and anthropogenic volatile compounds (molecular, functional and ecological bases); (vi) Estimating the potential for carbon/pollution mitigation and cost effectiveness of urban and periurban forests; (vii) Selection of trees adapted to the urban environment; (viii) Trophic, competitive and host/parasite relationships under changing pollution and climate; (ix) Atmosphere -iosphere-pedosphere interactions as affected by anthropospheric changes; (x) Statistical analyses for epidemiological investigations; (xi) Use of monitoring for the validation of models; (xii) Holistic view for linking the climate, carbon, N and O-3 odelling; (xiii) Inclusion of multiple environmental stresses (biotic and abiotic) in critical load determinations; (xiv) Ecological impacts of N deposition in the under-investigated areas; (xv) Empirical models for mechanistic effects at the local scale; (xvi) Broad-scale N and sulphur deposition input and their effects on forest ecosystem services; (xvii) Measurements of dry deposition of N; (xviii) Assessment of evapotranspiration; (xix) Remote sensing assessment of hydrological parameters; and (xx) Forest management for maximizing water provision and overall forest ecosystem services. Ground-level O-3 is still the phytotoxic air pollutant of major concern to forest health. Specific issues about O-3 are: (xxi) Developing dose response relationships and stomatal O-3 flux parameterizations for risk assessment, especially, in under-investigated regions; (xxii) Defining biologically based O-3 standards for protection thresholds and critical levels; (xxiii) Use of free-air exposure facilities; (xxiv) Assessing O-3 impacts on forest ecosystem services.

    Läs mer om Global topics and novel approaches in the study of air pollution, climate change and forest ecosystems

Visa alla publikationer av Salim Belyazid vid Stockholms universitet