| 1. |
- Olsson, Bengt, et al.
(författare)
-
A decision support model for individual tree stump harvesting options based on criteria for economic return and environmental protection
- 2017
-
Ingår i: Scandinavian Journal of Forest Research. - : Taylor & Francis Group. - 0282-7581 .- 1651-1891. ; 32, s. 246-259
-
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.
|
|
| 2. |
|
|
| 3. |
- Coucheney, Elsa, et al.
(författare)
-
Long-term fertilization of a boreal Norway spruce forest increases the temperature sensitivity of soil organic carbon mineralization
- 2013
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3, s. 5177-5188
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal ecosystems store one-third of global soil organic carbon (SOC) and are particularly sensitive to climate warming and higher nutrient inputs. Thus, a better description of how forest managements such as nutrient fertilization impact soil carbon (C) and its temperature sensitivity is needed to better predict feedbacks between C cycling and climate. The temperature sensitivity of in situ soil C respiration was investigated in a boreal forest, which has received long-term nutrient fertilization (22 years), and compared with the temperature sensitivity of C mineralization measured in the laboratory. We found that the fertilization treatment increased both the response of soil in situ CO2 effluxes to a warming treatment and the temperature sensitivity of C mineralization measured in the laboratory (Q10). These results suggested that soil C may be more sensitive to an increase in temperature in long-term fertilized in comparison with nutrient poor boreal ecosystems. Furthermore, the fertilization treatment modified the SOC content and the microbial community composition, but we found no direct relationship between either SOC or microbial changes and the temperature sensitivity of C mineralization. However, the relation between the soil C:N ratio and the fungal/bacterial ratio was changed in the combined warmed and fertilized treatment compared with the other treatments, which suggest that strong interaction mechanisms may occur between nutrient input and warming in boreal soils. Further research is needed to unravel into more details in how far soil organic matter and microbial community composition changes are responsible for the change in the temperature sensitivity of soil C under increasing mineral N inputs. Such research would help to take into account the effect of fertilization managements on soil C storage in C cycling numerical models.
|
|
| 4. |
|
|
| 5. |
- Fröberg, Mats, et al.
(författare)
-
Long-term effects of experimental fertilization and soil warming on dissolved organic matter leaching from a spruce forest in Northern Sweden
- 2013
-
Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 200-201, s. 172-179
-
Tidskriftsartikel (refereegranskat)abstract
- Nitrogen deposition and increasing temperature are two of the major large-scale changes projected for coming decades and the effect of this change on dissolved organic matter is largely unknown. We have utilized a long-term fertilization and soil warming experiment in Northern Sweden to study the effects of increased nutrient levels and increased temperature on DOC transport under the O horizon. The site is N limited and mean annual temperature 2. °C. Experimental fertilization with ammonium nitrate and a physiological mixture of other macro- and micro-nutrients has been going on for 22. years and soil warming, 5. °C above ambient soil temperature for 14. years, prior to the study. Experimental plots have been irrigated to avoid drying and we also studied the effect of this long-term irrigation on DOC by establishing control plots receiving no irrigation.DOC concentrations and fluxes under the O horizon were approximately 50% higher in fertilized plots than in non-fertilized control plots. We did not find any statistically significant effect of soil warming. There was a statistically significant effect of long-term irrigation on DOC with higher DOC concentration and fluxes in irrigated plots than in plots without irrigation. There were no major effects on DOC quality measured by specific UV absorbance. Fertilization approximately doubled soil organic matter stocks in the O horizon, whereas there were no such effects of warming or irrigation on soil organic matter amounts. There was no statistically significant treatment effect on DOC collected from the B horizon. We hypothesize that the positive effect of fertilization on DOC is related to increased soil C stocks.
|
|
| 6. |
- Grelle, Achim, et al.
(författare)
-
Carbon balance of a forest ecosystem after stump harvest
- 2012
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 762-773
-
Tidskriftsartikel (refereegranskat)abstract
- Stump harvest in forests can cause both reductions of CO2 emissions through a decrease of decomposable substrate (direct effect) and emission increases as a consequence of deep and extensive soil disturbance (indirect effect). Here, the effects of stump harvest on net ecosystem CO2 exchange (NEE) in a former Norway spruce stand in mid Sweden are presented. CO2 exchange was continuously followed by eddy-covariance measurements during the first years after harvest. Differences in NEE from stump harvested and mounded (reference) plots were determined by soil-surface respiration measurements. Respiration from decaying stumps was estimated by a decomposition model. Fluxes indicated a direct effect (decreased efflux) during the first year after harvest that corresponded to the absence of decomposing stumps. During the following years, this emission reduction was increasingly counteracted by an indirect effect (increased efflux) of similar magnitude. This means that the expected emissions caused by extra soil disturbance occur with a certain delay and seem to increase with time. By these emissions, the substitution efficiency of stumps as bioenergy resource is reduced. Furthermore, at a time scale of centuries, instant combustion of stumps leads to a larger contribution to global warming than slow decomposition, because the stump carbon is available earlier in form of greenhouse gas. This is estimated by the time integral of emissions. Thus, despite the surprisingly low initial emissions, the overall substitution efficiency and climate benefits of stump harvest are likely to be small. The long-term consequences of stump harvest for the carbon budget are, however, still uncertain.
|
|
| 7. |
- Grelle, Achim, et al.
(författare)
-
From source to sink : recovery of the carbon balance in young forests
- 2023
-
Ingår i: Agricultural and Forest Meteorology. - : Elsevier. - 0168-1923 .- 1873-2240. ; 330
-
Tidskriftsartikel (refereegranskat)abstract
- We analyzed ecosystem carbon fluxes from eddy-covariance measurements in five young forests in southernSweden where the previous stand had been harvested by clear-cutting or wind-felled: three stands with Norwayspruce (Picea abies (L.) Karst.), one with Scots pine (Pinus sylvestris) and one with Larch (Larix x eurolepis A.Henry). One of the spruce stands had the stumps harvested, one was fertilized and one without any specialtreatments. These stands returned from positive (sources) to negative (sinks) annual carbon fluxes 8–13 yearsafter disturbance, depending on site productivity and management. This corresponds to approximately 15% ofthe rotation periods at these sites. Extrapolation in combination with chronosequence data suggests thatconventionally regenerated stands reach a neutral carbon balance after approximately 30% of the rotationperiod. The lowest carbon emissions and shortest recovery time was observed in a stand where the stumps of thetrees, in addition to the stems and logging residues, were removed after harvest. This stand not only returned to acarbon sink within this time period but the total carbon gains since disturbance also equaled the total losses afteronly 11 years. These results stress that production stands in southern Sweden are carbon sources during arelatively small part of the rotation period, and that this part can be considerably shortened by measures thatincrease productivity or reduce the amount of woody debris left after disturbance.
|
|
| 8. |
- Hyvönen, Riitta, et al.
(författare)
-
Carbon and nitrogen pools and mineralization rates in boreal forest soil after stump harvesting
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 377, s. 61-70
-
Tidskriftsartikel (refereegranskat)abstract
- The use of forest-derived biomass has steadily increased in Finland and Sweden during the past decades leading to more intensive forest management practices in the region, such as whole-tree harvesting, both above- and belowground. Stump harvesting results in a direct removal of stump and coarse-root carbon (C) from the stand and can cause extensive soil disturbance, which has been suggested to increase C mineralization. In this study, the effects of stump harvesting on soil C and nitrogen (N) mineralization, and soil surface disturbance were studied in two different clear-felled Norway spruce (Picea abies) sites in Central Finland. The treatments were whole-tree harvesting (WTH, removal of stems and logging residues), and WTH and stump harvesting (WTH + S). Both sites, Honkola (2 stands) and Haukilahti (6 stands) were mounded. In both treatments, soil samples were taken from different soil layers down to a total depth of 20 cm in the mineral soil from (i) mounds, (ii) undisturbed soil and (iii) pits. The sampling was performed 11-12 years after treatments. Soil C and N mineralization rates were determined in laboratory incubation experiments. In addition, total C and N pools (g m(2)) were estimated for each disturbance class and soil layer. Soil C and N pools had a tendency to be lower following stump harvesting, but no statistically significant treatment effect was detected. Stump harvesting increased soil mixing as indicated by a significant decrease in C concentration in the mound disturbance class. There was no significant effect of stump harvesting on soil C mineralization rates. A combination of mineralization rates and soil pool data showed that field C mineralization (g CO2-C m(-2) yr(-1)) did not significantly differ between stands where stumps were removed or were retained. Further, stump harvesting did not seem to have any stimulating effect on soil CO2 efflux 11-12 years after treatment. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 9. |
- Håkansson, Charlotta, 1971-, et al.
(författare)
-
Effects of fertilization on soil CH4 and N2O fluxes in young Norway spruce stands
- 2021
-
Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 499
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change mitigation strategies have increased the demand for wood products, resulting in an urgent needto increase wood production. One approach is to fertilize forest land, but this can influence greenhouse gas (GHG) fluxes within the ecosystem. The aim of this study was to examine the effects of forest N fertilization onsoil CH4 and N2O fluxes in young Norway spruce (Picea abies (L.) Karst.) stands in southern Sweden. The gasfluxes were measured using flow-through non-steady-state dark chambers. In the first, long-term, experiment,half of the stand was fertilized twice (once in 2014 and once in 2016) with 150 kg ha-1 of N, and gas fluxmeasurements were taken throughout 2014–2017. In the second, dose, experiment, 0, 150, 300, or 450 kg ha-1 of N was added to the stand in April 2016, and gas flux measurements were taken during April-December 2016.The dose experiment showed that the sink strength of CH4 decreased with increasing amounts of N; the long-termexperiment indicated that repeated fertilization decreased the CH4 sink strength over time. Additionally, thelong-term experiment indicated that, while significantly higher N2O emissions were recorded in the fertilizationyears, this was not detected in subsequent years, suggesting the effect to be short-lived. In the dose experiment,fertilization tended to increase the N2O emissions relative to the amount of fertilizer. However, despite thesignificant effects of fertilization on these GHGs, the summed fluxes were a fraction of the net uptake of C at thesites, as recorded in another study. These findings suggest that fertilizing forest land with commercial NP or NPKfertilizers corresponding to 150 kg ha-1 of N, the level used in operational forestry in Sweden today, can beconducted without changing CH4 and N2O fluxes to any great extent.
|
|
| 10. |
- Håkansson, Charlotta, 1971-
(författare)
-
Greenhouse Gas Fluxes and Carbon Sequestration in Young Norway Spruce Stands : The Effects of Fertilization
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The enormous challenge of climate change is discussed and debated today because of its major impact on life on Earth. The forests have an important role to play as the plants absorb carbon dioxide (CO2) from the atmosphere through their photosynthesis and the growing tree retain carbon (C). Hence, the larger the growth the greater the carbon storage and climate benefit. The demand for wood and wood products is increasing as well as the ongoing debate about forest management. Therefore, alternative management methods to increase wood production is of interest and the effects these methods could have on climate change mitigation. In this context this Thesis deals with the effect of fertilization on carbon balance and growth in young forest as well as flows of the greenhouse gases, CO2, methane (CH4), and nitrous oxide (N2O) from forest land. In addition, it deals also with the reliability and comparability of different measurement methods which are compared with respect to the carbon balance.The studies have been carried out in a young mixed stand of Norway spruce (Picea abies (L.) Karst) and birch (Betula pendula and B.pubescens) on a storm-felled (Gudrun 2005) area in southern Sweden, Kronoberg county. Part of the area was fertilized with 150 kg N ha-1 everysecond year from 2014 and forward, while the other part was kept unfertilized. In the unfertilized part a dose experiment was set up where 0,150, 300, and 450 kg N ha-1 were added to investigate the impact of the different fertilizer levels on forest floor greenhouse gas fluxes. Chamber measurements of forest floor fluxes, eddy-flux measurements of stand net-fluxes and tree measurements of height, diameter and birch leaf biomass were conducted in different, occasionally overlapping, periods in the years 2013-2021.The results show that even if the flows of CO2 from the forest floor increase initially after a first standard fertilization, the effect decreases quickly. The net fluxes show that the stands become carbon sinks already eight years after the storm with a net uptake of about 18 ton CO2 ha-1 yr-1 of. The forest floor fluxes of CH4 and N2O also show a short-term effect of fertilization, however the levels are very low compared to CO2. The fertilization induced increase of total tree biomass growth increased with time. The results show that 12 and 15 years after regeneration, the fertilization compared to the control has increased the tree growth by 3.4 and 6.3 m3 ha-1 yr-1 and carbon storage by 4.7 and 8.7 ton C ha-1 yr-1 respectively.Comparison of measurement results of the Eddy-flux technique's netflows and chamber measurements of soil respiration together with tree growth shows the importance of calibrating the measurement methods when the results are later to be used in modeling future climate scenarios.
|
|
| 11. |
- Jordan, Sabine, et al.
(författare)
-
Ecosystem respiration, methane and nitrous oxide fluxes from ecotopes in a rewetted extracted peatland in Sweden
- 2016
-
Ingår i: Mires and Peat. - 1819-754X. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- Ecosystem respiration (carbon dioxide; CO2), methane (CH4) and nitrous oxide (N2O) fluxes to the atmosphere were determined using an opaque closed chamber method within various ecotopes (vegetation covered, bare peat and open water) in a rewetted extracted peatland and within an adjacent open poor fen in Sweden. Ecotopes had a significant impact on CO2 and CH4 fluxes to the atmosphere. Ecosystem respiration and CH4 emissions from the bare peat site, the constructed shallow lake and the open poor fen were low but were much higher from ecotopes with Eriophorum vaginatum tussocks and Eriophorum angustifolium. A combination of vascular plant cover and high soil temperatures enhanced ecosystem respiration, while a combination of vascular plant cover, high water table levels and high soil temperatures enhanced CH4 emissions. N2O emissions contributed little to total greenhouse gas (GHG) fluxes from the soil-plant-water systems to the atmosphere. However, the overall climate impact of CH4 emissions from the study area did not exceed the impact of soil and plant respiration. With regard to management of extracted peatlands, the construction of a nutrient-poor shallow lake showed great potential for lowering GHG fluxes to the atmosphere.
|
|
| 12. |
- Jordan, Sabine, et al.
(författare)
-
Greenhouse gas emissions from two rewetted peatlands in Sweden
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two rewetted, former cut-over peatlands were investigated for their greenhouse gas (GHG) emissions. The closed-chamber method was used. In the rich Västkärr fen, CO2-fluxes decreased along the moisture gradient from vegetated soil to open water. CH4 emissions varied with season: highest in the open water with a decreasing trend towards the vegetated soil (June 2009). N2O emissions were observed occasionally: highest in the driest parts with a decreasing trend towards the open water (October 2008). In the poor Porla wetland CO2 and CH4-fluxes followed a seasonal gradient at all sites, from low fluxes in spring over high emissions in summer to low output in autumn. The bare peat emitted no CH4 whereas the wet Eriophorum vaginatum tussocks released the highest amounts during summer.
|
|
| 13. |
- Jordan, Sabine, et al.
(författare)
-
Methane and Nitrous Oxide Emission Fluxes Along Water Level Gradients in Littoral Zones of Constructed Surface Water Bodies in a Rewetted Extracted Peatland in Sweden
- 2020
-
Ingår i: Soil systems. - : MDPI AG. - 2571-8789. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Rewetted extracted peatlands are sensitive ecosystems and they can act as greenhouse gas (GHG) sinks or sources due to changes in hydrology, vegetation, and weather conditions. However, studies on GHG emissions from extracted peatlands after rewetting are limited. Methane (CH4) and nitrous oxide (N2O) emission fluxes were determined using the opaque closed chamber method along water level gradients from littoral zones to the open water body of constructed shallow lakes with different vegetation zones in a nutrient-rich rewetted extracted peatland in Sweden. Vegetation communities and their position relative to water level, together with short-term water level fluctuations, such as inundation events and seasonal droughts, and temperature had a significant impact on CH4 emissions fluxes. During "normal" and "dry" conditions and high soil temperatures, CH4 emissions were highest from Carex spp.-Typha latifolia L. communities. During inundation events with water levels > 30 cm, sites with flooded Graminoids-Scirpus spp.-Carex spp. emitted most CH4. Methane emissions from the water body of the constructed shallow lakes were low during all water level conditions and over the temperature ranges observed. Nitrous oxide emissions contributed little to the emission fluxes from the soil-plant-water systems to the atmosphere, and they were only detectable from the sites with Graminoids. In terms of management, the construction of shallow lakes showed great potential for lowering GHG emission fluxes from nutrient rich peatlands after peat extraction, even though the vegetated shore emitted some N2O and CH4.
|
|
| 14. |
|
|
| 15. |
- Jurevics, Arnis, et al.
(författare)
-
Slash and stump harvest have no general impact on soil and tree biomass C pools after 32-39 years
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 371, s. 33-41
-
Tidskriftsartikel (refereegranskat)abstract
- The energy from forest biomass is central in achieving climate mitigation goals in the European Union (EU). The carbon (C) balance and climate mitigation benefits of this strategy are, however, questioned; particularly, when stumps and slash are also removed during harvest. Stump and slash harvest result in nutrient loss, which might cause reduced growth and thereby decrease C sequestration of the next generation of trees. In addition, the removal of the slowly decomposing biomass may lead to a depletion of the soil C pool. In the case of stump harvest, these negative effects may be partly compensated for by increased nutrient availability due to a stimulated mineralization and reduced competition from under story vegetation as a result of the soil disturbance caused by the stump harvest.Here we analyze the effect of different harvest intensities on total, soil (humus and mineral down to 10 cm), and tree biomass C pools based on data from eight field experimental sites across Sweden regenerated with Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) Karst.) 32-39 years after clear-cut with (i) stem-only harvest; (ii) stem and stump harvest; (iii) stem and slash harvest; and (iv) stem, stump and slash harvest. Due to a lack of replicates at the site level we focused our analyses on general treatment effects across all sites and on species level effects (n = 4). The main hypotheses were that across all sites (i) the total C pool is generally unaffected by stump harvest, (ii) whereas the total C pool generally decreases after slash harvest. We also hypothesized that (iii) the total C pool of spruce stands is more negatively affected by slash harvest in comparison to pine stands.Despite considerable variation, there was no significant general effect of harvest treatments on the total, soil or tree biomass C pools across all sites, thus hypothesis (i) was confirmed, whereas hypothesis (ii) was rejected. As compared to the total C pool following stem-only harvest the average total C pool was reduced following the two treatments which included slash harvest in spruce stands, whereas the C pool was unaffected or increased in pine stands, indicating a species-specific effect. However, these differences were not statistically different and hypothesis (iii) was therefore also rejected. Based on the results presented here we conclude that stump and/or slash harvest have no general medium-term effects on the total forest C pool. However, given the limitations of the experimental design in this study and the general lack of studies investigating stump and slash harvest effects on the C balance, we call for more studies with focus on long-term field experiments that are replicated at the site level to be able to reveal potential site- and species-specific responses to slash and stump harvest. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 16. |
- Jönsson, Mari, et al.
(författare)
-
A spatially explicit decision support system for assessment of tree stump harvest using biodiversity and economic criteria
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:21
-
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.
|
|
| 17. |
|
|
| 18. |
- Lim, Hyungwoo, et al.
(författare)
-
Boreal forest biomass accumulation is not increased by two decades of soil warming
- 2019
-
Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 9, s. 49-52
-
Tidskriftsartikel (refereegranskat)abstract
- Increased soil organic matter decomposition with increasing temperature has been hypothesized to enhance soil nitrogen availability, consequently stimulating forest biomass production and offsetting decomposition-induced soil carbon losses(1-5). This projection, however, is based on evidence gathered from short-term studies (<= 10 years)(2,3,5). The key question for carbon sequestration is whether such responses are transient or persist over long forest rotation periods. Here we report on biomass production in a typical nitrogen-limited boreal Picea abies forest, exposed to 18 years of soil warming manipulation (+ 5 degrees C) at a plot scale (100 m(2)). We show that two decades of soil warming elicited only short-duration growth responses, thus not significantly increasing aboveground biomass accumulation. Furthermore, in combination with published work from this forest, our results suggest that increased decomposition is slight and ephemeral, and increased fine root production and turnover in deeper soil may be greater than increased decomposition, netting slightly more biomass, perhaps conserving the soil carbon stock. Thus, this long-term study does not support the notion that the projected increase in soil temperatures will cause either an increased carbon loss with decomposition or a compensatory growth increase from nitrogen mineralization.
|
|
| 19. |
- Lindroth, Anders, et al.
(författare)
-
Hur påverkas lustgas- och metanavgivning av stubbskörd?
- 2017
-
Ingår i: Stubbskörd - hur påverkas klimat och miljö?. - 9789157694546 - 9789157694553 ; , s. 39-41
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I fyra försök var utsläppen av de kraftfulla växthusgaserna lustgas och metan ungefär på samma nivå från stubbskördade ytor som från ytor där stubbarna var kvar. Inte heller markberedning gav några signifikanta effekter. De här studierna är de första i världen på det här området, och resultaten måste därför tolkas med viss försiktighet.
|
|
| 20. |
- Lindroth, Anders, et al.
(författare)
-
Stump harvesting can affect the emissions of methane and nitrous oxide
- 2017
-
Ingår i: Stump Harvesting : Impact on Climate and Environment - Impact on Climate and Environment. ; , s. 38-42
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The emissions of the greenhouse gases methane and nitrous oxide wereconsistently low in relation to carbon dioxide emissions at four experimental sites.Stump harvesting did not seem to affect the emissions of methane and nitrousoxide. Soil moisture was a major factor for methane emissions – independent ofsoil treatments. These studies are the first ones in the world and should beinterpreted with care until further data have been obtained.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Lundin, Lars, et al.
(författare)
-
Effekter vid restaurering av avslutade torvtäkter genom återvätning; undersökningar vid Porla, Toftmossen och Västkärr
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Torvmarker täcker stora arealer i Sverige och utvinning vid torvtäkter är en etablerad verksamhet. Efter avslutad täkt erfordras efterbehandling till nytt nyttjande av täktområdet. Detta kan vara till jordbruksmark, skogsproduktion, våtmark m.fl. användningsområden. Just omföringen av avslutad täkt undersöktes i detta projekt inriktat på restaurering av täktområdet genom återvätning till våtmark och i förlängningen till ny myr. Undersökningarna inriktades på hydrologi, mark, vattenkemi, vegetation och växthusgaser. Projektet startade i slutfasen av täktverksamheten med bestämningar av mark- och vattenförhållanden före återvätning och följde sedan tillstånd och processer i tillskapad våtmark. Undersökningarna genomfördes i etapper med ökat fokus på växthusgaser de senare sju åren. Vattenförhållandena ändrades från det dikade tillståndets vattennivåer några decimeter under markytan till ett ytvatten med flerstädes 0.5 - 1.5 m djup. De grunda sjöarna hade tämligen hög vattenomsättning och merdeles goda syrgasförhållanden, som endast under kortare stagnationsperioder under senvinter och sensommar visade syrgasfria förhållanden i bottenvattnet. Förhållandena påverkade bottenfaunan som varierat men med tidig etablering av stort antal individer och biomassa men som minskade något under senare år. Artantalet visade dock en tendens att öka med tiden. Vegetation saknades nästan helt när täkternas avslutades med endast en bar torvyta, som återstod. Begynnande växtkolonisation startade redan första året men det tog 2-3 år för att nå större täckning. Vegetationsetableringen var snabbare i Västkärrs näringsrikare miljö men efter ett antal år föreföll arterna att bli tämligen triviala och en långsam igenväxning vidtog. Särskilt expanderade vassruggar ute i det öppna vattnet. På den fattigare miljön vid Porlan etablerades vegetationen långsammare men efter en femårsperiod var vegetationen nästan heltäckande även om vatten och bar torv fanns främst mellan vegetationstuvorna. Främst var det tuv- och ängs-/kärrull som startade etableringen även om bl.a. starr, sileshår och vitag också förekom. Björnmossan noterades tidigt upp och efter sju år kunde spontan vitmossetablering noteras och täckningen har fortsatt att expandera. Markförhållandena påverkades av kvarlämnad torv och den fastare kärrtorven i bottenskikten var mer stabil än ytligare kvarlämnad vitmosstorv. Vid Västkärr med en plan torvmark ovan en postglacial lera kunde torvutvinningen nå jämn och relativt tunt torvlager vid täktavslut. Detta substrat blev också en tämligen stabil botten i våtmarkstillståndet. Porlanområdet med torv på en ojämn moränbotten kom också att ha kvarlämnad torv med olika kvalité och den ytliga vitmosstorven kom att svälla och delvis lyfta och bilda flyttorv med låg bärighet. Kemiskt ändrades inte torvsubstratet i större omfattning med stabilt pH, kol- och fosforhalt medan kväveinnehållet ökade något med större inslag av ammonium. CN-kvoten blev något lägre i den fattigare Porlan. Hydrologin i våtmarksområdet speglades av vattennivån i våtmarkerna, grundvattennivåer i den närmaste omgivningen och avrinningen från områdena. Ytvattennivåen finns relaterad ovan. Grundvattenförhållandena i omlandet påverkades av höjd vattennivå i våtmarken men ändringen på större avstånd (50-100 m) var liten, möjligen någon decimeter. På kortare avstånd från våtmarkskanten var ändringen större och det noterades 0.2-0.3 m högre nivå på 30-5 0 m avstånd. Avrinningen speglas i vattenbalansen, som visade lägre avrinning och högre avdunstning från våtmarksområdena. För den mer stabila perioden 7-13 år efter återvätning visar kontrollområdet en avrinning i medeltal per år om 246 mm och avdunstningen 492 mm. Motsvarande värden för våtmarken Porla A1 var 197 mm respektive 540 mm. Höga vattenföringar vid kraftiga regn och snösmältning visade lägre toppar från våtmarken jämfört med kontrollen. Låga flöden vid torrperioder verkade bli lägre och perioder utan flöde längre än förhållandena under pågående täkt. Vattenkemi var olika vid de tre undersökningsområdena där Porlan utgjorde en näringsfattig miljö med pH strax över 5 medan Toftmossen hade ett pH på ungefär 6 och Västkärr det rikaste med pH mellan 6 och 7. Även näringsämnen som oorganiskt kväve, baskatjoner och fosfor speglade denna bild. Ändringar efter återvätning kunde endast bestämmas för Porlan och Västkärr. Vattnets pH var tämligen oförändrat vid Porlan medan det inledningsvis blev lägre vid Västkärr för att med tiden öka till högre värden än före återvätningen. Flertalet ämnen visade lägre koncentrationer i våtmarkerna jämfört med i täkttillstånd men fosforhalterna ökade. Även transporter av flertalet ämnen var lägre efter återvätning. Växthusgasemissioner från öppet vatten visade generellt låga värden för de tre växthusgaserna koldioxid, metan och lustgas. Från växter på mark i strandzonen förekom dock höga flöden av CH4, vilket var betydlig högre än den som uppmätts på den orörda myren. Det blev tydligt att våtmarksväxterna är en förutsättning för betydande metanemissioner. Även höga emissioner av CO2 uppmättes från dessa växter, men de nya kontinuerliga mätningarna från det automatiska mätsystemet visade att en mycket stor andel av CO2-emissionerna hade tagits upp genom fotosyntes under dagarna. Om detta kan generaliseras för alla ekotoper med vegetation, tillsammans med att N2O-emissionerna generellt var låga eller obefintliga för de tre undersökta lokalerna, pekade resultaten på att det var CH4, som dominerade nettoflödet av växthusgasemissioner från torvtäkter som restaurerats genom återvätning. Allmänt kan sägas att det är ett möjligt och bra alternativ att efterbehandla avslutade torvtäkter till våtmark till fördel för landskapsdiversitet och biologisk variation. Betydelsen ur ett växthusgasperspektiv kan vara mer dubiöst och erfordrar ytterligare studier. På sikt kommer dock torvbildningen att ackumulera kol.
|
|
| 24. |
|
|
| 25. |
- Lundin, Lars, et al.
(författare)
-
Impacts of rewetting on peat, hydrology and water chemical composition over 15 years in two finished peat extraction areas in Sweden
- 2017
-
Ingår i: Wetlands Ecology and Management. - : Springer Science and Business Media LLC. - 0923-4861 .- 1572-9834. ; 24, s. 405-419
-
Tidskriftsartikel (refereegranskat)abstract
- Restoration of wetlands is a high priority world-wide. Peat extraction areas can be restored by rewetting, however affecting the environment. It could be expected to turn the drained peat-cutover area from a source to a sink of most elements. This study examined effects of such rewetting on peat, hydrology and water chemistry over 15 years at two sites in Sweden; the nutrient-poor Porla peatland and the nutrient-rich Vastkarr peatland. Rewetting caused minor changes to peat chemistry, but at the Vastkarr site ammonium concentrations increased in superficial peat layers while nitrate decreased. In terms of hydrology, rewetting of the Porla site decreased annual runoff and both high and low discharges. Water pH at the Porla site stayed fairly stable, but at the Vastkarr site pH, after an initial 4 years dip, gradually increased to higher values than before rewetting. Water colour and organic matter content were fairly stable, but slightly lower values were found after 15 years than in initial 4-5 years. The concentrations of base cations and of inorganic N were lower after rewetting, while total P was higher. However, these impacts could change from an initial phase as the wetlands in the long-term perspective develop into mires.
|
|
| 26. |
- Lundin, Lars, et al.
(författare)
-
Prospects for new mire wetland restoration in Sweden following termination of peatland excavation.
- 2015
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The site-specific state and use of mires and peatla nds constrains possible restoration options. There is a long and widespread tradition in northern Europe of using mires for agriculture, forestry and peat harvesting. While drainage is often a prerequisite for use, it changes the mire status from a natural to an impacted state. Mire status determines conservat ion value but even slightly affected mires could be of great interest for preservation. This could lead to conflicts between protection and utilization. However, peatlands influenced by drainage activitie s may be the ones available for utilization but are anyhow considered for protection. At least 0.5 Mha of Swedish peatlands have been drained in unsuccessful attempts to improve forest production. Some of these drained areas might be suitable for peat excavation. Added to this is c. 15.000 ha in o ngoing or terminated peat excavation. After cessation of peat extraction, the excavated area mu st be restored to a hydrologically functioning wetland which could eventually form a new mire. Two such areas were investigated in SW Sweden both before rewetting and for almost 15 years afterwards. Ecological characteristics of the sites differed considerably, being reflected in the remaining peat conditions, established hydrology an d water chemistry. Vegetation and surface soil conditions changed with new spontaneous Sphagnum co lonisation. Changes in hydrology and hydrochemistry after rewetting relate to altered re dox conditions influencing especially pH, sulphur, nitrogen and phosphorus. The return of anaerobic co nditions in the sediments reduced peat decomposition. Peat site properties such as vegetat ion and chemical conditions affected greenhouse gas emissions. Both CO2 and CH4 emissions varied by site type but with an overall increase in CH4. The project was funded by the Swedish Energy Agency and the Swedish Peat Research Foundation.
|
|
| 27. |
|
|
| 28. |
- Lundin, Lars, et al.
(författare)
-
Restoration of water quality and biology in two rewetted cut-over peatlands
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Restoration of wetlands is of high priority in Europe. After-use of peat excavation areas, including rewetting, is one such measure and has been investigated at two sites in Sweden. Water quality changed after rewetting with fairly stable or higher pH and concentrations of base cations. Nutrient concentrations were initially high but decreased after a number of years. Oxygen contents in water were similar to ordinary small lakes, also with occasional depletion in bottom layers at stagnation periods. The colonization of vegetation was rapid at Västkärr site but slower at Porla site, also with start of Sphagnum colonization. The bottom fauna consisted of high numbers of species and individuals the very first years after rewetting. After a few years the bottom fauna decreased to lower levels but is now slowly rising.
|
|
| 29. |
- Lundin, Lars, et al.
(författare)
-
Wetland management after termination of peat extraction and effects on the environment
- 2011
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Peatlands are used for activities such as agriculture, forestry and peat harvesting. The use is often dependent on drainage to regulate the water conditions. In peat excavation plans, after-use is strictly regulated. Restoration of wetlands is highlighted. In industrial use of peatlands, considerable changes in site conditions exist as the very old peat bottom layers are exposed to land surface conditions. In Sweden, rewetting of two such areas started more than ten years ago. Investigations were carried out before and after rewetting using the comparison and calibration period technique. Ecological characteristics of wetlands differ considerably and are reflected in the remaining peat conditions, established hydrology and water chemistry. These characteristics are the driving force for vegetation development, water quality, limnic life and biogeochemistry. Vegetation and surface soil conditions have changed with time and are balanced with new spontaneous Sphagnum colonisation. Changes in hydrochemistry after rewetting relate to altered redox conditions influencing especially pH, sulphur, nitrogen and phosphorus. The return of anaerobic conditions in the sediments have reduced peat decomposition, initiated sedimentation and denitrification and influenced element turnover. Peat site properties such as vegetation and chemical conditions affect the greenhouse gas emissions. Both CO2 and CH4 emissions varied with site type. However, while the bare drained peat did not emit much CH4, the tussocks on drained peat showed higher values. This suggests that the plants can (i) emit CH4, (ii) promote the transport of CH4 from the soil to the atmosphere and/or (iii) promote the formation of CH4 in the soil
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
- Mjöfors, Kristina, et al.
(författare)
-
Impact of site-preparation on soil-surface CO2 fluxes and litter decomposition in a clear-cut in Sweden
- 2015
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 49
-
Tidskriftsartikel (refereegranskat)abstract
- Boreal forest soil contains significant amounts of organic carbon. Soil disturbance, caused for example by site preparation or stump extraction, may increase decomposition and thus lead to higher CO2 emissions, contributing to global warming. The aim of this study was to quantify responses of soil-surface CO2 fluxes (R-s) and litter (needle and root) decomposition rates following various kinds of soil disturbance commonly caused by mechanical site preparation and stump harvest. For this purpose four treatments were applied in a clear-cut site in central Sweden: i) removal of the humus layer and top 2 cm of mineral soil, ii) placement of a humus layer and 2 cm of mineral soil upside down on top of undisturbed soil, forming a double humus layer buried under mineral soil, iii) heavy mixing of the humus layer and mineral soil, and iv) no disturbance (control). Rs measurements were acquired with a portable respiration system during two growing seasons. To assess the treatments' effects on litter decomposition rates, needles or coarse roots (empty set = 6 mm) were incubated in litterbags at positions they would be located after the treatments (buried, or on top of the soil). The results indicate that site preparation-simulating treatments have no effect or may significantly reduce, rather than increase, CO2 emissions during the following two years. They also show that buried litter decomposes more rapidly than litter on the surface, but in other respects the treatments have little effect on litter decomposition rates.
|
|
| 33. |
- Mjöfors, Kristina, et al.
(författare)
-
Indications that site preparation increases forest ecosystem carbon stocks in the long term
- 2017
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 32:8, s. 717-725
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical site preparation (MSP) causes a mixing disturbance of the soil, which may increase decomposition of soil organic matter and subsequent carbon (C) dioxide emissions to the atmosphere. MSP also promotes the establishment and growth of tree seedlings, and hence ecosystem C fixation. However, there are uncertainties regarding the net effects of MSP on C stocks at the ecosystem scale. To assess decennial effects of MSP on ecosystem C stocks, C stocks in soil, ground vegetation and trees at three experimental forest sites with Pinus contorta, Pinus sylvestris and Picea abies in Sweden were sampled and measured for ca. 25 years in a control and after three MSP treatments: disc trenching, mounding and ploughing. After 25 years, all of the MSP treatments resulted in larger ecosystem C stocks than the control treatment due to positive effects on the tree biomass C stock. The tree C stock was highest after ploughing, intermediate after mounding or disc trenching and lowest in untreated control plots at all experimental sites. The MSP treatments did not affect the soil C stocks down to 30cm. We recommend mounding or disc trenching to promote C sequestration as they disturb sites’ ecological, aesthetic and recreation values less than ploughing.
|
|
| 34. |
- Mjöfors, Kristina, et al.
(författare)
-
Stubbskörd och markens koldioxidbalans
- 2017
-
Ingår i: Stubbskörd - hur påverkas klimat och miljö?. - 9789157694546 - 9789157694553 ; , s. 35-37
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Markstörningar, som stubbskörd och markberedning, leder initialt till minskad koldioxidavgång från marken, visar en serie nya försök. Det är tvärtemot vad man tidigare har antagit. Efter det första året ligger avgången på ungefär samma nivå för störd mark som för ostörd.
|
|
| 35. |
- Mjöfors, Kristina, et al.
(författare)
-
Stump harvesting and the soil/atmosphere exchange of CO2
- 2017
-
Ingår i: Stump Harvesting : Impacts on Climate and Environment - Impacts on Climate and Environment. ; , s. 33-37
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Soil disturbance from stump extraction and site preparation will initially lead to a reduction in carbon dioxide emissions from the soil. This is one result achieved from a series of new experiments established throughout Sweden and is contrasting to what was previously assumed. After one year however, this initial reduction had disappeared and emissions were around the same level for bothdisturbed and undisturbed soil.
|
|
| 36. |
- Nilsson, Torbjörn, et al.
(författare)
-
Runoff changes after rewetting of a cutover peatland in Sweden. : Extended abstract No 310.
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Continuous discharge measurements were made in outlets from a rewetted cutover peatland (14 ha) and a nearby self-restoring hand-cut mire (22 ha) during nine years. Mainly cotton grass was slowly but successively established over the peatland. Large areas of open water also existed in the rewetted area. The discharge measurements showed that annual runoff from the rewetted cutover peatland were lower compared to runoff from the self-restoring hand-cut mire. This difference could be explained with higher frequency of low flows and lower peak flows from the rewetted cutover peatland. The low annual runoff from the rewetted cutover peatland was probably caused by water storage in the created wetlands and an increased evapotranspiration. The number of peak flows and their magnitudes were lower from the rewetted cutover peatland compared to the self-restoring hand-cut mire.
|
|
| 37. |
|
|
| 38. |
- Rychel, Katrin, et al.
(författare)
-
Deep N fertilizer placement mitigated N2O emissions in a Swedish field trial with cereals
- 2020
-
Ingår i: Nutrient cycling in agroecosystems. - : Springer Science and Business Media LLC. - 1385-1314 .- 1573-0867. ; 118, s. 133-148
-
Tidskriftsartikel (refereegranskat)abstract
- Deep fertilizer placement is a proposed strategy to increase crop yield and nitrogen (N) use efficiency while decreasing nitrous oxide (N2O) emissions from soil to atmosphere. Our objective was to test three fertilization depth orientations to compare overall N use efficiency, based on a 2-year field trial on a mineral soil cropped with cereals in Uppsala, Sweden. The field was fertilized with ammonium nitrate at a rate of 120 kg ha(-1)(2016) and 105 kg ha(-1)(2017) and a deep fertilizer placement (DP) at 0.20 m was compared to a shallow placement (SP) at 0.07 m and a mixed-depth placement (MP) where fertilizer was halved between the depths of 0.07 and 0.20 m, and a non-fertilized control (NF). In 2016, compared to SP, MP and DP increased N content in harvested grain by 3.6% and 2.5% respectively, and DP increased grain yield by 11% (P < 0.05). In both years, N2O emissions were similar in DP and NF, whereas SP and MP emissions were similar but generally higher than those in DP and NF. Fertilizer-induced emission factors (EF) for the growing season of 2017 decreased with fertilizer placement depth and were 0.77 +/- 0.07, 0.58 +/- 0.03, and 0.10 +/- 0.02 for SP, MP, and DP, repectively. Although deep N placement benefits are likely dependent on weather conditions and soil type, this strategy has a clear potential for mitigating N2O emissions without adversely affecting yield.
|
|
| 39. |
|
|
| 40. |
- Strömgren, Monika, et al.
(författare)
-
Effects of long-term temperature and nutrient manipulation on Norway spruce fine roots and mycelia production
- 2013
-
Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 366, s. 287-303
-
Tidskriftsartikel (refereegranskat)abstract
- The fine root biomass and necromass were highest in the fertilized plots, following similar trends in the above-ground biomass, whereas the EcM root tip biomass per basal area decreased by 22 % in the fertilized plots compared to the control. Warming increased the fine root biomass, live/dead-ratio and the number of EcM root tips in the mineral soil and tended to increase the production of EcM mycelia. Greater fine root biomass meant more EcM root tips, although the tip frequency was not affected by fertilization or warming. Significantly higher specific root length of EcM root tips indicated an increased need for nutrients in warmed and in unfertilized plots. Better nutrient supply and warmer soil temperature provide a potential to increase the flow of carbon into the soil via increased fine root biomass, but the carbon balance also depends on root turnover.
|
|
| 41. |
- Strömgren, Monika, et al.
(författare)
-
Effects of stump harvest and site preparation on N2O and CH4 emissions from boreal forest soils after clear-cutting
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 371, s. 15-22
-
Tidskriftsartikel (refereegranskat)abstract
- Harvesting stumps after clear-cutting can increase bioenergy supplies and thus reduce needs for fossil fuels, but more knowledge is required about associated changes in greenhouse gas emissions from forest soils to assess the climatic impact of extracting stumps for this purpose. The soil disturbance caused by harvesting stumps may alter soil processes, including N mineralization. N availability is an important determinant of emissions of the potent greenhouse gases N2O and CH4. Effects of stump harvest on these gases are largely unknown. Therefore, they were explored in this study by monitoring differences in N2O and CH4 emissions associated with different types of disturbance during two years following stump harvest and site preparation (as well as their overall effects) at three mesic sites, using the chamber technique. N2O emissions at two of the sites were affected by the type of soil disturbance, but not at the other site. At one site, the N2O emissions were highest from undisturbed soil and mounds and significantly lower from mixed soil, bare mineral soil and wheel ruts. At this site the emission rates were clearly correlated with N availability across the disturbances. At the second site showing significant treatment effects, N2O emissions were higher from the bare mineral soil after site preparation than from other types of disturbed soil. At the third site there were no significant N2O emissions, possibly due to reductions in nitrogen availability caused by the fast establishment of vegetation at that site. The CH4 fluxes included both uptakes and losses, but were generally low following all types of soil disturbances, although they were substantial from wheel ruts and soil pits. In conclusion there were no, or minor, between treatment differences in N2O and CH4 emissions. Furthermore, the radiative forcing potential of these emissions was small compared to mean CO2 emissions from Swedish clear-cuts. Thus, our results indicate that stumps can be harvested without causing elevated emissions of N2O and CH4 on mesic sites. The effects on wetter sites remain to be illuminated. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 42. |
- Strömgren, Monika
(författare)
-
Forest floor CO2 flux measurements with a dark-light chamber
- 2009
-
Ingår i: Biogeosciences Discussions. - 1810-6277 .- 1810-6285. ; 6, s. 9301–9329-
-
Tidskriftsartikel (refereegranskat)abstract
- An automatic closed chamber system for measuring net carbon flux from the forest floor was equipped with both a transparent and an opaque cover. The system was operated in such way that a measurement session with transparent chamber was followed by a session with dark chamber. This made it possible to estimate besides total daytime respiration and nighttime respiration also the gross assimilation of the vegetation enclosed in the chamber. The chamber was used at two locations, Hyytiäla in Finland and Norunda in Sweden. Results were compared to estimation of gross assimilation by extrapolation of nighttime respiration and the difference between daytime and nighttime respiration was analyzed. Estimated gross photosynthesis from the darkening sessions by the chamber resulted in a higher gross photosynthesis then obtained by extrapolation from nighttime respiration for Norunda, but not for Hyytälä. Comparison of obtained gross photosynthesis rates indicated that the forest floor vegetation contributed up to 30% of maximum net ecosystem uptake.
|
|
| 43. |
- Strömgren, Monika
(författare)
-
Klimatet påverkar marken och marken påverkar klimatet – Elever, lärare och forskare i samverkan
- 2009
-
Ingår i: Rapport (Sveriges lantbruksuniversitet, Institutionen för mark och miljö). ; 1, s. 75-84
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Tiden som löper från att något nytt upptäcks inom forskningen till att det kommer i läroböcker eller undervisningen i gymnasieskolan är ganska lång. Detta gäller bland annat aktuella miljöproblem som klimatfrågan. Om elever, lärare och forskare börjar samarbeta kan processen påskyndas. Under åren 2006-2009 har ett samarbete växt fram mellan forskare vid SLU och lärare och elever från Platengymnasiet i Motala. Eleverna har fått använda sig av aktuell forskning och forskningstekniker när det gäller att förstå skogens kolbalans och hur denna balans påverkas av klimatet. Genom detta har de fått en större inblick i forskningen och de osäkerheter som finns. I elevernas projektarbeten har de utvecklat metoder för att undersöka koldioxidflöden i naturliga ekosystem. Dessa metoder har lärarna sedan kunnat använda inom andra kursmoment
|
|
| 44. |
- Strömgren, Monika
(författare)
-
Nitrous oxide emission budgets and land-use-driven hotspots for organic soils in Europe
- 2014
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 11, s. 6595-6612
-
Tidskriftsartikel (refereegranskat)abstract
- Organic soils are a main source of direct emissions of nitrous oxide (N2O), an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time, which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori-identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta-study with a total amount of 659 annual N2O measurements, which was used to derive separate models for different land use types. We applied our models to available, spatially explicit input driver maps to upscale N2O emissions at European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 +/- 1.08 and 0.58 +/- 1.03 gN(2)O-N m(-2) a(-1), respectively. High fluxes from cropland sites were mainly controlled by low soil pH value and deep-drained ground-water tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast, N2O fluxes from natural peatlands were predominantly low (0.07 +/- 0.27 gN(2)O-N m(-2) a(-1)) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 GgN(2)O-N a(-1), which also included fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 GgN(2)O-N a(-1). N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area. Thereby the model demonstrated that the major part (85 %) of the inventory is induced by anthropogenic management, which shows the significant reduction potential by rewetting and extensification of agriculturally used peat soils.
|
|
| 45. |
- Strömgren, Monika, et al.
(författare)
-
Nya och gamla fältförsök med stubbskörd
- 2017
-
Ingår i: Stubbskörd - hur påverkas klimat och miljö?. - 9789157694546 ; , s. 26-29
-
Bokkapitel (populärvet., debatt m.m.)abstract
- Merparten av det vi i dag vet om stubbskördens miljöeffekter kommer från fyra stora försöksserier med totalt 33 fältförsök spridda över landet. Till detta kommer fyra enskilda försök. De äldsta försöken är från sent 1970-tal, men merparten är relativt nyetablerade.
|
|
| 46. |
- Strömgren, Monika, et al.
(författare)
-
Skogen och koldioxid. Laborationer om skogens roll i kolets kretslopp
- 2009
-
Annan publikation (populärvet., debatt m.m.)abstract
- Detta häfte innehåller tre laborationer som handlar om skogens roll i kolets kretslopp. Laborationsövningarna är gjorda för att kunna användas direkt med elever i biologi- och miljöundervisning på gymnasienivå. I lärarhandledningen beskrivs metoderna mer noggrant, där finns utrustningslistor och kommentarer. Det här arbetsmaterialet är en produkt av samarbetsprojektet mellan Platengymnasiet i Motala och SLU som har genomförts under åren 2006-2009. Projektet har finansierats av EU genom Socratesprogrammet (Comenius 2.1) och av SLU
|
|
| 47. |
- Strömgren, Monika
(författare)
-
Skogen, växthusgaserna och klimatförändringen – ett samarbetsprojekt mellan elever, lärare och forskare
- 2009
-
Ingår i: Bi-lagan : inspiration och information för lärare i skolan / Nationellt resurscentrum för biologi och bioteknik. - 2000-8139. ; , s. 7-10
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Forskning är nödvändig för att ta fram kunskap om hur ett förändrat klimat kan påverka miljöförhållanden och människors livsvillkor, både i vårt land och i övriga världen. När elever och lärare från Platengymnasiet i Motala möter forskare från Sveriges lantbruksuniversitet, SLU, i ett projekt kring koldioxidbalansen i skogsmark får eleverna både insikt om forskningens villkor och en ökad kunskap om klimatfrågorna
|
|
| 48. |
- Strömgren, Monika, et al.
(författare)
-
Soil-CO2 flux after patch scarification, harrowing and stump harvest in a hemi-boreal forest
- 2012
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 754-761
-
Tidskriftsartikel (refereegranskat)abstract
- Stump harvesting is one way of increasing the amount of bioenergy, but little is known about the consequences of treestump harvesting on the carbon balance in the forest. Therefore, soil-surface CO2 flux (soil respiration, Rs) was determined two years after clear-cutting for common soil disturbances occurring after patch scarification, harrowing and stump harvest in southern Sweden. Rs from intact soil was found to be of the same magnitude as emissions from areas of mixed humus, indicating only small effects of disturbance. Elevated mounds produced lower emissions than in the intact soil during the second year despite larger amounts of organic matter, probably due to low soil moisture. The lowest Rs was found in soil surfaces with exposed mineral soil. The treatment effects on Rs were estimated considering the actual area of different disturbances. During the first year, there was no difference in Rs among the treatments, whereas in the second year the flux was 10% higher after harrowing and stump harvesting than after patch scarification, implying that the effects on CO2 flux after stump harvest were comparable to conventional harrowing. However, it is unclear whether this finding basically applies to regions where decomposition is limited by soil moisture during the summer.
|
|
| 49. |
- Strömgren, Monika, et al.
(författare)
-
Soil CO2 Flux During the First Years After Stump Harvesting in Two Swedish Forests
- 2012
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 46, s. 67-79
-
Tidskriftsartikel (refereegranskat)abstract
- One way of increasing the supply of renewable energy, thereby decreasing the use of fossil fuels, is to extract the stumps that remain after final stem harvesting. However, little is known about the environmental consequences of stump harvesting, and how ecosystem services, such as carbon sequestration, are affected by the practice. In the present paper, the effects on the soil carbon pool during the first months and years after stump harvesting in former Norway spruce stands are presented. The study was performed at two sites in mid- and southern Sweden. At both sites, the soil CO2 flux was measured on several occasions with a portable respiration system, to compare plots on which stump harvesting had occurred, with reference plots. At one of the sites, CO2 exchange was also followed continuously by means of eddy-covariance measurements before and after stump harvesting. Since there was no vegetation at the beginning of the study, almost all emitted CO2 could be assumed to come from heterotrophic sources, and the soil CO2 flux was measured. This study shows that the effect of stump harvesting on CO2 flux or soil decomposition processes is small or absent compared to site preparation such as mounding in a short-term perspective of months and years. The long-term consequences of stump harvesting are, however, still uncertain.
|
|
| 50. |
- Strömgren, Monika, et al.
(författare)
-
Soil-surface CO2 flux during the first 2 years after stump harvesting and site preparation in 14 Swedish forests
- 2017
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 32, s. 213-221
-
Tidskriftsartikel (refereegranskat)abstract
- Stumps are a source of renewable energy (bioenergy) that can mitigate climate change. We aimed to determine whether conclusions from recent studies could be generalized for other sites by monitoring the in situ soil respiration (R-s) by a portable soil-respiration system of 14 clear-cut experimental sites during the first 2 years after stump extraction and site preparation. The sites were established all over Sweden in 2013 and 2014 and were subjected to no disturbance (Control), patch scarification (PatchS), disc trenching (DiscT), and stump harvesting (StumpH). During year 1, R-s from sites treated with PatchS and StumpH were 11% and 13% lower than R-s from Control sites. DiscT-treated sites were apt to produce lower R-s than the Control (-9%, p=.09). In the second year, there were no significant differences in R-s between treatments, as no soil disturbance type occurring after stump harvest and site preparation had higher R-s than untreated, intact soil. Our results suggest that soil disturbances resulting from stump harvest and site preparation do not generally increase R-s and thus, from this perspective, provide support for the use of stumps for bioenergy.
|
|
