| 1. |
- Aronsson, Per, et al.
(författare)
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An operational decision support tool for stump harvest
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A multi-criteria decision support tool was developed to optimise stump harvesting for energy in Sweden. The decision tool takes account of multiple, sometimes conflicting, criteria relating to stump harvest; energy and climate, economics, biodiversity, and soil and water. Data on harvested stems are used as primary input data in the tool. Such data are routinely collected in harvester computers. The tool effectively deals with mixed sets of data; quantitative harvest data are re-calculated to metric (e.g. stump biomass), and qualitative data (e.g. biodiversity implications) are incorporated. A digital terrain map derived from air-borne laser scanning provides basic data for estimating soil wetness, while digital maps of water courses, key habitats and protected areas, or other sensitive habitats, are used to identify potentially and practically harvestable stumps.In four sub-models, an index from 0 to 10 is calculated for each stump, with 0 representing ‘Not at all suitable’ and 10 ‘Highly suitable for extraction’. Through this, a stump of high value for wood-living species is assigned a low index in the biodiversity sub-model and a large, easily accessible stump is assigned a high index in the economic sub-model. When calculating the net index, the sub-indices can be weighted according to the preferences of the end-user.An energy and climate sub-model incorporates greenhouse gas (GHG) emissions from forest operations and the effect of advancing GHG emissions when stump biomass is incinerated instead of being left to decompose. In the economic sub-model the potential monetary return from each stump is calculated based on estimated revenue from harvested stump biomass and the costs of stump harvesting and forwarding operations (based on cost functions and GIS calculations of transport distances).The biodiversity sub-model considers four types of wood-dependent organisms (lichens, mosses, insects and fungi) in terms of their habitat requirements, vulnerability, sun exposure preferences, locality, etc. A panel of external experts has drawn up a grading scale of stump values for the different taxonomic groups. The proximity to key habitats and exposure to sunlight are derived from a spatial model.Soil and water issues are handled within a sub-model estimating the consequences for long-term soil fertility (nutrient cycling and soil compaction) and water (leaching of plant nutrients and mercury, and particle transport due to soil damage by heavy machinery).The tool offers the end-user possibilities to prioritise and plan for cost-effective stump harvesting, while minimising negative environmental impacts.
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| 2. |
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| 3. |
- Lagnelöv, Oscar, et al.
(författare)
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Cost analysis of autonomous battery electric field tractors in agriculture
- 2021
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Ingår i: Biosystems Engineering. - : Elsevier. - 1537-5110 .- 1537-5129. ; 204, s. 358-376
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Tidskriftsartikel (refereegranskat)abstract
- Interest in the electrification of agricultural vehicles is increasing along with growing interest in autonomous vehicles. Individual technologies have been well-explored, but not their combined use and the effects on agricultural fieldwork. In this study, cost analysis was conducted based on a simulated vehicle system with 50 kW self-driving battery electric drive (BED) tractors. The analysis included battery degradation due to cycling and the cost of inadequate machine capacity, as these factors are suspected to be problems for electric tractors. A dynamic discrete-event vehicle system model, a linear timeliness model and a one-dimensional battery cell ageing model were assumed. Costs obtained were compared with those of contemporary manned diesel-based systems. BED systems had equal or lower annual costs compared to conventional manned diesel-based systems; this was due to lower costs for fuel and maintenance, while providing adequate capacity and lower energy usage. Sensitivity analysis showed that operating costs were of greater significance than investment costs. The generally more expensive investment costs of BED systems were outweighed by the reduced operating costs for several different BED system systems. Battery degradation costs and timeliness were influential, but not sufficient to make the system uncompetitive. The synergistic effect of vehicular autonomy and BED outweighed several of the drawbacks of BED systems, such as frequent recharging, increased transport and reduced consecutive work time.
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| 4. |
- Lagnelöv, Oscar, et al.
(författare)
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Electric tractors – Sustainable and Profitable? Economic and environmental impact of autonomy and electric drivelines in agriculture
- 2022
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Ingår i: VDI reports. - : VDI Verlag. ; , s. 189-196
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Konferensbidrag (refereegranskat)abstract
- Vehicle electrification can be an effective emission-mitigating technology in heavy vehicles, including in agriculture. Simulation was used to assess the effect of switching conventional diesel tractors to multiple lighter autonomous battery-electric tractors on a Swedish grain farm. An autonomous diesel tractor was also considered. An LCA was made to assess environmental impacts, and the annual cost was calculated. The electric scenario had a 65% lower climate impact than its diesel counterpart and had a reduced the annual cost by lowering operator, fuel and maintenance cost. In total, the cost was lowered by 31% from the conventional scenario. In both the environmental impact and cost, fuel played an important role.
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| 5. |
- Lagnelöv, Oscar, et al.
(författare)
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Impact of lowered vehicle weight of electric autonomous tractors in a systems perspective
- 2023
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Ingår i: Smart agricultural technology. - : Elsevier BV. - 2772-3755. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Modern agriculture rely on heavy machinery that has increased risk of detrimental soil compaction of arable fields. This can lead to negative effects such as reduced yields, reduced field trafficability and increased fuel use. Electric, autonomous tractors makes it possible to replace one heavy machine with several lighter without increased labour costs. In this study, the economic and environmental effects of reduced soil compaction for smaller autonomous tractors were assessed and compared to a scenario with conventional tractors. A discrete event simulation of a Swedish 200 ha grain farm with clay soil was used for the calculations. The electric, autonomous system had lower soil compaction impacts as well as other benefits, and reduced cost in total from 385 to 258 euro ha-1 and the climate impact from 270 to 77 kg CO2eq ha-1 compared to the conventional scenario. Soil compaction constituted 20% of the cost and 26% of the climate impact for the conventional scenario. It was concluded that soil compaction was impactful in machinery studies, especially on heavier soil like clay, and should not be omitted. Soil compaction avoidance alone was not impactful enough to warrant a change to electric, autonomous tractors but it reinforced already existing trends and further improved the cost and environmental benefits.
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| 6. |
- Lagnelöv, Oscar, et al.
(författare)
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Life Cycle Assessment of Autonomous Electric Field Tractors in Swedish Agriculture
- 2021
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- There is an increased interest for battery electric vehicles in multiple sectors, including agriculture. The potential for lowered environmental impact is one of the key factors, but there exists a knowledge gap between the environmental impact of on-road vehicles and agricultural work machinery. In this study, a life cycle assessment was performed on two smaller, self-driving battery electric tractors, and the results were compared to those of a conventional tractor for eleven midpoint characterisation factors, three damage categories and one weighted single score. The results showed that compared to the conventional tractor, the battery electric tractor had a higher impact in all categories during the production phase, with battery production being a majority contributor. However, over the entire life cycle, it had a lower impact in the weighted single score (-72%) and all three damage categories; human health (-74%), ecosystem impact (-47%) and resource scarcity (-67%). The global warming potential over the life cycle of the battery electric tractor was 102 kg CO(2)eq.ha(-1) y(-1) compared to 293 kg CO(2)eq.ha(-1) y(-1) for the conventional system. For the global warming potential category, the use phase was the most influential and the fuel used was the single most important factor.
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| 7. |
- Lagnelöv, Oscar, et al.
(författare)
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Performance comparison of charging systems for autonomous electric field tractors using dynamic simulation
- 2020
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 194, s. 121-137
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Tidskriftsartikel (refereegranskat)abstract
- A model simulating an autonomous battery electric vehicle system for agricultural field use was created, assuming a 200-ha conventional cereal farm in Swedish conditions. The different subsystems were verified against sources in the literature, field experiments and general common practice. The model was used to compare two different charging systems (conductive charging and battery exchange) for battery electric tractors to each other. A comparative simulation was made with conventional diesel systems (fully autonomous or manned for 10 h d(-1)). The simulation results indicated that battery exchange was generally a faster system than conductive charging. The results also showed that both electric systems were able to achieve similar active time during spring field operations as a corresponding system of a simulated manned diesel tractor for battery sizes from 50 kWh and charge powers from 50 kW. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of IAgrE.
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| 8. |
- LarsOlle, Anders, et al.
(författare)
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A multi-criteria decision support model for optimal stump harvesting
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A multi-criteria decision support model for optimal stump harvesting Sweden was developed. The model quantifies the effect of harvesting each individual stump over a harvesting object in four criteria's: - Biodiversity (Biodiversity value index) - Economy (SEK) - Greenhouse gas emissions (CO2) - Soil and water (Soil and water preservation index) The four criteria's are sometimes in conflict to each other, and uses values that are not directly comparable. The intended use for this model is to contribute with the objective evaluation of all four criteria's in the decision in what stumps to harvest and what stumps to leave in the harvesting object. The model uses individual stump data (e.g. position, tree species and stump biomass) and harvesting object GIS data (roads, elevation map, soil map, terrain map). Primary data on individual stumps comes from the logging system in the stem harvesters: GPS and operator classification. Such data are routinely collected in harvesters. Official map data for the harvesting object are available from the Swedish mapping, cadastral and land registration authority (Lantmäteriet). This includes the topographic map and elevation maps data in 2 m resolution. Also, GIS data are collected in the inspections before harvesting the stems. The biodiversity sub-model considers different types of wood-dependent organisms (lichens, mosses, insects and fungi) in terms of their habitat requirements, vulnerability, sun exposure preferences, locality, etc. A panel of external experts has drawn up a grading scale of stump values for the different taxonomic groups. The proximity to key habitats and exposure to sunlight are derived from a spatial model. In the economic sub-model the potential net return from each stump is calculated based on estimated revenue from harvested stump biomass and the costs of stump harvesting and transport (based on cost functions and GIS calculations of transport distances). An energy and climate sub-model incorporates greenhouse gas (GHG) emissions from forest operations and the effect of advancing GHG emissions when stump biomass is incinerated instead of being left to decompose. Soil and water issues are handled within a sub-model estimating the consequences for long-term soil fertility (nutrient cycling and soil compaction) and water (leaching of plant nutrients and mercury, and particle transport due to soil damage by heavy machinery). Each criteria is evaluated in totally four sub-models. To be able to compare the resulting value from each of the criteria, a harvesting index from 0 to 1 is calculated for each stump. The value 0 represents ‘Not at all suitable for harvest’ and 1 ‘Highly suitable for harvest’. Through this, a stump of high biodiversity value is assigned a low harvesting index in the biodiversity sub-model and a large, easily accessible stump is assigned a high harvesting index in the economic sub-model. When calculating the total net index, the harvesting index from each criteria has to be weighed together using one coefficient for each criteria. The weighing coefficient for each criteria is chosen according to the preferences of the decision maker. The tool offers the end-user possibilities to prioritise and plan for cost-effective stump harvesting, while minimising negative environmental impacts.
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| 9. |
- Nilsson, Daniel, et al.
(författare)
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Dynamic modelling of cut-and-store systems for year-round deliveries of short rotation coppice willow
- 2017
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 159, s. 70-88
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Tidskriftsartikel (refereegranskat)abstract
- Short rotation coppice willow (SRCW) is a high-yielding energy crop that can be used to produce solid, liquid or gaseous biofuels. The crop is harvested during the winter, when the leaves have dropped. For economic reasons, however, most fuel processing plants require continuous year-round delivery of raw material. Thus, SRCW should be harvested as stems or in larger pieces in order to be storable, and not chipped directly at harvest for immediate use in large-scale heating plants, which is common practice at present. The aim of the project within which this study was conducted is to find cost-effective whole-stem harvesting and handling systems for year-round deliveries of natural-dried SRCW. A discrete event simulation model for such systems was developed in this study, taking weather, soil trafficability, geographical conditions, natural drying of the material and storage losses into account. The model was applied to a fictitious processing plant in Uppsala, Sweden. Machine performance and costs for a system with one stem harvester and up to three infield shuttles, together with one chipper truck for chipping and transport, were investigated. The simulations showed that field trafficability had a crucial impact on total quantity harvested. The total cost was 40 t(-1) dry matter. Yield of SRCW and harvest productivity were important factors regarding costs. The model can be used to design cost-effective harvesting and handling systems for year-round deliveries of SRCW. (C) 2017 IAgrE. Published by Elsevier Ltd. All rights reserved.
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| 10. |
- Ahmadi Moghaddam, Elham, et al.
(författare)
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Gas Hydrates as a Means for Biogas and Biomethane Distribution
- 2021
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Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Biomethane is receiving great attention as a renewable energy gas with lower environmental impacts and diversified sources of production. However, availability of gas infrastructure is an important factor in biomethane development and use. Biomethane can be distributed by the natural gas or local biogas grid. Biomethane can also be road-transported as compressed biomethane (CBG) or liquefied bio-methane (LBG). Biomethane could be distributed via gas hydration technology, where methane molecules are physically trapped within the crystalline structures of frozen host water molecules as gas hydrate compounds. Using life cycle assessment methodology, this study compared the energy performance and climate impact of two gas hydrate scenarios, biogas hydrate and biomethane hydrate, with that of a base case distributing biomethane as CBG. The technical system, from biogas upgrading, hydration, compression and road transport to filling station of biomethane as CBG, was included in the analysis. Results of this study show that distribution of biomethane as gas hydrates had a lower energy performance and higher climate impact than compressed biomethane distribution. The low energy performance was due to high electricity demand in hydrate formation and dissociation processes. The gas hydrate scenarios also had higher climate impacts as a result of high methane losses from hydrate formation and dissociationdissociation and emissions related to energy source use. Biogas upgrading to biomethane also significantly contributed to methane losses and climate impact of the scenarios studied.
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| 11. |
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| 12. |
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| 13. |
- Haby, Lena, et al.
(författare)
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Graderingsmetodik i ogräsförsök
- 2010
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Ingår i: Medd. från Södra jordbruksförsöksdistriktet, Sveriges lantbruksuniversitet. - 0282-180X. ; 2010, s. 9:1-9:2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 14. |
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| 15. |
- Jönsson, Mari, et al.
(författare)
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A spatially explicit decision support system for assessment of tree stump harvest using biodiversity and economic criteria
- 2020
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:21
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Tidskriftsartikel (refereegranskat)abstract
- Stump harvesting is predicted to increase with future increasing demands for renewable energy. This may affect deadwood affiliate biodiversity negatively, given that stumps constitute a large proportion of the deadwood in young managed forests. Spatial decision support for evaluating the integrated effects on biodiversity and production of stump harvesting is needed. We developed a spatially explicit decision support system (called MapStump-DSS), for assessment of tree stump harvesting using biodiversity and economic criteria together with different scenarios for biodiversity conservation and bioenergy market prices. Two novel key aspects of the MAPStump-DSS is that it (1) merges and utilizes georeferenced stump-level data (e.g., tree species and diameter) directly from the harvester with stand data that are increasingly available to forest managers and (2) is flexible toward incorporating both quantitative and qualitative criteria based on emerging knowledge (here biodiversity criteria) or underlying societal drivers and end-user preferences. We tested the MAPStump-DSS on a 45 ha study forest, utilizing harvester data on characteristics and geographical positions for >26,000 stumps. The MAPStump-DSS produced relevant spatially explicit information on the biodiversity and economic values of individual stumps, where amounts of “conflict stumps” (with both high biodiversity and economical value) increased with bioenergy price levels and strengthened biodiversity conservation measures. The MAPStump-DSS can be applied in practice for any forest site, allowing the user to examine the spatial distribution of stumps and to obtain summaries for whole forest stands. Information depicted by the MAPStump-DSS includes amounts, characteristics, biodiversity values and costs of stumps in relation to different scenarios, which also allow the user to explore and optimize biodiversity and economy trade-offs prior to stump harvest.
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| 16. |
- Larsolle, Anders
(författare)
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Measuring and modelling parameters from hyperspectral sensors for site-specific crop protection
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis sought to optimise systems for plant protection in precision agriculture through developing a field method for estimating crop status parameters from hyperspectral sensors, and an empirical model for estimating the required herbicide dose in different parts of the field. The hyperspectral reflectance measurements in the open field took the form of instantaneous spectra recording using an existing method called feature vector based analysis (FVBA), which was applied on disease severity. A new method called iterative normalisation based analysis (INBA) was developed and evaluated on disease severity and plant biomass. The methods revealed two different spectral signatures in both disease severity and plant density data. By concentrating the analysis on a 12% random subset of the hyperspectral field data, the unknown part of the data could be estimated with 94-97% coefficient of determination. The empirical model for site-specific weed control combined a model for weed competition and a dose response model. Comparisons of site-specific and conventional uniform spraying using model simulations showed that site-specific spraying with the uniform recommended dose resulted in 64% herbicide saving. Comparison with a uniform dose with equal weed control effect resulted in 36% herbicide saving. The methods developed in this thesis can be used to improve systems for site-specific plant protection in precision agriculture and to evaluate site-specific plant protection systems in relation to uniform spraying. Overall, this could be beneficial both for farm finances and for the environment.
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| 17. |
- Larsolle, Anders, et al.
(författare)
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Measuring crop status using multivariate analysis of hyperspectral field reflectance with
- 2005
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Ingår i: 5th European Conference on Precision Agriculture. - 9076998698 ; , s. 1008-
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Konferensbidrag (refereegranskat)abstract
- Using spectral reflectance to estimate crop status is a method suitable for developing sensors for site-specific agricultural applications. When developing spectral analysis methods the influence of different crop parameters on the spectral reflectance profile is important to know. The objective of this report was to present and evaluate a multivariate method for objective hyperspectral analysis in the examination of how different parts of the reflectance spectrum are affected by disease severity and above ground plant density. Data from two field experiments was used, fungal disease severity assessments in wheat 1998 and above ground plant density measurements 2003. The analysis method consisted of two steps: normalisation and classification. Using only 12% of the data as training data, the method resulted in the coefficients of determination (R²) of 94.3% for the disease severity data and 96.9% for the plant density data. The presented hyperspectral analysis method could also be used to extract spectral profiles of disease severity and plant density using the experimental data. In general two types of spectral profiles for both data sets were observed (1) a flattening of the green reflectance peak together with a general decrease in reflectance in the near infrared region and (2) a decrease of the shoulder of the near infrared reflectance plateau together with a general increase in the visible region between 550 and 750 nm.
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| 18. |
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| 19. |
- Larsolle, Anders, et al.
(författare)
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Modellbaserat beslutsstöd för stubbskörd [Model based decision support for stump harvest, in Swedish]
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this study a decision support model for tree stump harvest was developed. The model takes into account four criteria: economy, energy and climate, biodiversity, and land and water. The value of each individual tree stump was calculated separately for each criterion. The four criteria values were then weighed together into a final suitability score for stump harvest. The final suitability score decided whether the decision support model recommended harvest of each individual tree stump or not. Data from the harvester collected at final felling was used as input to the decision support model. For each stump the values used in the model was dry mass, stump diameter, tree species and position. In addition, the harvesters log track was used as a basis for localising the terrain roads within the stand. Other geographical data used was elevation data, presence of objects with special value for biodiversity and land/water, such as key biotopes, open water and moist soil. A special study was conducted to estimate the soil stability from a topographical wetness index.The decision support model was evaluated on an existing felling 2010 in Northern Uppland. The area was 45 hectares with about 26 000 stumps. The result of the decision support model showed that general economic parameters had the greatest impact in both sensitivity and scenario analysis. The most important variable was the price for stump biomass at road side. The decision support model results left continuous areas of the stand with all stumps unharvested. The reason for this was the economy criterion's sensitivity to the local amount of stump withdrawal per hectare. Low stump withdrawal gave high harvesting costs. In that economy was the only criterion which motivated stump harvest, the model never suggested harvesting a stump unless surrounding stumps were harvested too.There is potential for developing this decision support model further using updated knowledge and examining the impact of different criteria on the final model result. The decision support model has good opportunities to serve as a comprehensive planning basis in order to ensure sustainable stump harvest.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Olsson, Bengt, et al.
(författare)
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A decision support model for individual tree stump harvesting options based on criteria for economic return and environmental protection
- 2017
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Ingår i: Scandinavian Journal of Forest Research. - : Taylor & Francis Group. - 0282-7581 .- 1651-1891. ; 32, s. 246-259
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Tidskriftsartikel (refereegranskat)abstract
- Based on principles of multi-criteria analysis techniques, a model (MAPStump-E) for decision support on stump harvesting at stand level was developed. The model applies the concept that each stump can be attributed production values (economic) and environmental values (here soil protection and water quality). Individual tree stump information was incorporated directly from the production reports of harvesters and combined with high-resolution Geographical Information System data on topography and soil type to create a production submodel and a soil and water vulnerability submodel (SWM). To test the model, it was applied to a 45-ha study forest in south-central Sweden and the outcome of nine scenarios with varying bioenergy prices and environmental protection levels was examined. Combined analysis of the effects of production and environmental criteria on total dry mass of harvestable stumps at the study site showed that biomass prices had a stronger influence than environmental criteria. Conflict stumps were defined as stumps suitable for harvest based on production criteria, but unsuitable based on soil and water protection criteria. In a ?medium? price scenario, the proportion of conflict stumps at the study site ranged from 6% to 18%, depending on protection level set.
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