| 1. |
- Klapwijk, Maartje, et al.
(författare)
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Capturing complexity : Forests, decision-making and climate change mitigation action
- 2018
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Ingår i: Global Environmental Change. - : Elsevier. - 0959-3780 .- 1872-9495. ; 52, s. 238-247
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Tidskriftsartikel (refereegranskat)abstract
- Managed forests can play an important role in climate change mitigation due to their capacity to sequester carbon. However, it has proven difficult to harness their full potential for climate change mitigation. Managed forests are often referred to as socio-ecological systems as the human dimension is an integral part of the system. When attempting to change systems that are influenced by factors such as collective knowledge, social organization, understanding of the situation and values represented in society, initial intentions often shift due to the complexity of political, social and scientific interactions. Currently, the scientific literature is dispersed over the different factors related to the socio-ecological system. To examine the level of dispersion and to obtain a holistic view, we review climate change mitigation in the context of Swedish forest research. We introduce a heuristic framework to understand decision-making connected to climate change mitigation. We apply our framework to two themes which span different dimensions in the socio-ecological system: carbon accounting and bioenergy. A key finding in the literature was the perception that current uncertainties regarding the reliability of different methods of carbon accounting inhibits international agreement on the use of forests for climate change mitigation. This feeds into a strategic obstacle affecting the willingness of individual countries to implement forest-related carbon emission reduction policies. Decisions on the utilization of forests for bioenergy are impeded by a lack of knowledge regarding the resultant biophysical and social consequences. This interacts negatively with the development of institutional incentives regarding the production of bioenergy using forest products. Normative disagreement about acceptable forest use further affects these scientific discussions and therefore is an over-arching influence on decision-making. With our framework, we capture this complexity and make obstacles to decision-making more transparent to enable their more effective resolution. We have identified the main research areas concerned with the use of managed forest in climate change mitigation and the obstacles that are connected to decision making.
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| 2. |
- Forsmark, Benjamin, et al.
(författare)
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Anthropogenic nitrogen enrichment increased the efficiency of belowground biomass production in a boreal forest
- 2021
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic nitrogen (N) enrichment in boreal forests has been shown to enhance aboveground net primary production and downregulate soil respiration, but it is not well understood if these effects are driven by reduced belowground C allocation or shifts between biomass production and respiration in fine-roots and ectomycorrhizal fungi (EMF). We utilized an experiment in a Pinus sylvestris (L.) forest simulating anthropogenic N enrichment with additions of low (3, 6, and 12 kg N ha−1 yr−1) and high (50 kg N ha−1 yr−1 × 12 yr) doses of N (n = 6) and measured the production of needles, fine-roots, and EMF mycelium during the 12th and 13th year of the experiment. We created a biomass production efficiency index by relating the biomass production rate to root-associated respiration, including both root and EMF respiration. The high N treatment enhanced the production of both needles and fine-roots, with a relatively larger increase in fine-roots, and strongly increased fine-root biomass production efficiency but had no effect on the fungal biomass in fine-roots or the production of EMF mycelium. The low N treatments had no effect on any of the measured variables. These results show that high levels of N enrichment drive shifts in the use of C allocated below ground, with less C going towards metabolic functions that result in rapid C emissions, and more C going towards the production of new tissues.
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| 3. |
- Hedwall, Per-Ola, et al.
(författare)
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Nitrogen-retention capacity in a fertilized forest after clear-cutting - the effect of forest-floor vegetation
- 2015
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 45, s. 130-134
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Tidskriftsartikel (refereegranskat)abstract
- Forest fertilization with nitrogen (N) has several benefits to society such as increased wood production and carbon sequestration. There are, however, concerns about N leakage, particularly following clear-cutting. The forest-floor vegetation may increase the N retention of forest ecosystems; however, very few studies have quantified the amount of vegetation required. We studied the relationship between vegetation cover and risk of N leakage, estimated by the amounts of ammonium-N and nitrate-N retained on ion-exchange capsules in the soil, during 4 years following the clear-cutting and harvesting of logging residues in a previously fertilized forest in southern Sweden. Previous fertilization increased the amount of nitrate-N captured on the capsules, whereas the amount of ammonium-N decreased. The vascular vegetation cover increased from almost zero to approximately 25% independent of fertilization. The amount of ammonium-N and nitrate-N retained on the capsules was already reduced by 50%-75% at 20% vegetation cover, and by 30%-40% cover, it approached zero, independent of the number of years since clear-cutting. The vegetation may impede tree-seedling establishment, implying a trade-off between seedling growth and N-retention capacity. However, our results indicate that maximum N retention may be achieved at a relatively low vegetation cover, which could be accomplished with less intrusive scarification methods than currently used.
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| 4. |
- Maaroufi, Nadia, et al.
(författare)
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Nutrient optimization of tree growth alters structure and function of boreal soil food webs
- 2018
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Ingår i: Forest Ecology and Management. - Amsterdam : Elsevier. - 0378-1127 .- 1872-7042. ; 428, s. 46-56
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Tidskriftsartikel (refereegranskat)abstract
- Nutrient optimization has been proposed as a way to increase boreal forest production, and involves chronic additions of liquid fertilizer with amounts of micro- and macro-nutrients adjusted annually to match tree nutritional requirements. We used a short-term (maintained since 2007) and a long-term (maintained since 1987) fertilization experiment in northern Sweden, in order to understand nutrient optimization effects on soil microbiota and mesofauna, and to explore the relationships between plant litter and microbial elemental stoichiometry. Soil microbes, soil fauna, and aboveground litter were collected from the control plots, and short- and long-term nutrient optimization plots. Correlation analyses revealed no relationships between microbial biomass and litter nutrient ratios. Litter C:N, C:P and N:P ratios declined in response to both optimization treatments; while only microbial C:P ratios declined in response to long-term nutrient optimization. Further, we found that both short- and long-term optimization treatments decreased total microbial, fungal, and bacterial PLFA biomass and shifted the microbial community structure towards a lower fungi:bacterial ratio. In contrast, abundances of most fungal- and bacterial-feeding soil biota were little affected by the nutrient optimization treatments. However, abundance of hemi-edaphic Collembola declined in response to the long-term nutrient optimization treatment. The relative abundances (%) of fungal-feeding and plant-feeding nematodes, respectively, declined and increased in response to both short-term and long-term treatments; bacterial-feeding nematodes increased relative to fungal feeders. Overall, our results demonstrate that long-term nutrient optimization aiming to increase forest production decreases litter C:N, C:P and N:P ratios, microbial C:P ratios and fungal biomass, whereas higher trophic levels are less affected. © 2018 Elsevier B.V.
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| 5. |
- Nordin, Annika, et al.
(författare)
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Inactivation of Ascaris Eggs in Source-Separated Urine and Feces by Ammonia at Ambient Temperatures
- 2009
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 75, s. 662-667
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable management of toilet waste must prevent disease transmission but allow reuse of plant nutrients. Inactivation of uterus-derived Ascaris suum eggs was studied in relation to ammonia in source-separated urine without additives and in human feces to which urea had been added, in order to evaluate ammonia-based sanitation for production of safe fertilizers from human excreta. Urine was used concentrated or diluted 1:1 and 1:3 with tap water at 4, 14, 24, and 34 degrees C. Fecal material, with and without ash, was treated with 1% or 2% (wt/wt) urea at 24 and 34 C. At 34 degrees C eggs were inactivated in less than 10 days in urine and in amended feces. At 24 degrees C only feces with 2% (wt/wt) urea or 1% (wt/wt) urea at high pH (10) inactivated all eggs within 1 month, and no inactivation was observed after 75 days in urine diluted 1: 3 (18 +/- 11 mM NH(3)). At temperatures of >= 24 degrees C, NH(3) proved to be an efficient sanitizing agent in urine and feces at concentrations of >= 60 mM. Treating fecal material at 34 degrees C can give a 6-log(10) egg inactivation within 1 month, whereas at 24 degrees C 6 months of treatment is necessary for the same level of egg inactivation. At temperatures of 14 degrees C and below, inactivation rates were low, with viable eggs after 6 months even in concentrated urine.
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| 6. |
- Nordin, Annika, et al.
(författare)
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Pathogen and indicator inactivation in source-separated human urine heated by the sun
- 2013
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Ingår i: Journal of Water, Sanitation and Hygiene for Development. - : IWA Publishing. - 2043-9083 .- 2408-9362. ; 3, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- Source-separation of urine enables energy-efficient recycling of large quantities of high quality plant nutrients from the wastewater system to food production. To manage the risk of diseases transmission the urine should be sanitised, which is commonly done by storage. The sanitisation of urine at three ambient exposures, resulting in fluctuating storage temperatures, was studied in 10 L plastic jerry cans in Kampala, Uganda. Follow-up studies using similar temperature cycles were performed under laboratory conditions. Daily mean mid-point temperature in jerry cans in full sun, adjacent to a wall and indoors was 24, 24 and 22 degrees C (amplitude 7.5, 4.7 and 1.2 degrees C), respectively. In urine stored at full sun (total ammonia nitrogen 4 +/- 1.5 g L-1, pH 9) Escherichia coli, Salmonella and Enterococcus spp. (initially 10(5)-10(6) cfu mL(-1)) were not detected (<10(1) cfu mL(-1)) after 11 h, 14 h and 50 d, respectively. No viable Ascaris suum eggs were found after 40 d. The t(90) for enterobacteria phage MS2, coliphage Phi X 174 and Salmonella typhimurium phage 28B in sun-exposed cans was 8.2, 37 and 55 d respectively. Fluctuating temperatures in combination with ammonia gave faster inactivation of bacteria and Ascaris suum eggs than the same constant mean temperature.
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| 7. |
- Sandström, Camilla, Professor, 1967-, et al.
(författare)
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Policy goals and instruments for achieving a desirable future forest : Experiences from backcasting with stakeholders in Sweden
- 2020
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Ingår i: Forest Policy and Economics. - : Elsevier. - 1389-9341 .- 1872-7050. ; 111
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Tidskriftsartikel (refereegranskat)abstract
- The future of forests is a controversial issue in Sweden and elsewhere. Different stakeholder groups differ in the importance they give to roles they envision forests should have in, for example, the national economy, the protection of biodiversity and sustainable use of ecosystem services, and in mitigating climate change. We used participatory backcasting, a solution-oriented form of scenario analysis, as a method to identify stakeholders' various views as to what constitutes a desirable future forest in Sweden. By involving key stakeholders, we wanted to explore how to broaden the scope of potential solutions to the controversial issue of forest futures by analyzing goals, measures and policy instruments in order to form a bridge between stakeholders' policy objectives, and the instruments and support tools they would like to use to implement those policies. Preferences for particular policy instruments varied considerably among the stakeholder groups. In line with the literature, our study confirms that policy instruments are not mere empty vessels, but represent particular policy ideas, objectives and outlooks, and can show how stakeholders want forests to be governed in the future.
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| 8. |
- Aguetoni Cambui, Camila, et al.
(författare)
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Patterns of Plant Biomass Partitioning Depend on Nitrogen Source
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) availability is a strong determinant of plant biomass partitioning, but the role of different N sources in this process is unknown. Plants inhabiting low productivity ecosystems typically partition a large share of total biomass to belowground structures. In these systems, organic N may often dominate plant available N. With increasing productivity, plant biomass partitioning shifts to aboveground structures, along with a shift in available N to inorganic forms of N. We tested the hypothesis that the form of N taken up by plants is an important determinant of plant biomass partitioning by cultivating Arabidopsis thaliana on different N source mixtures. Plants grown on different N mixtures were similar in size, but those supplied with organic N displayed a significantly greater root fraction. (15)N labelling suggested that, in this case, a larger share of absorbed organic N was retained in roots and split-root experiments suggested this may depend on a direct incorporation of absorbed amino acid N into roots. These results suggest the form of N acquired affects plant biomass partitioning and adds new information on the interaction between N and biomass partitioning in plants.
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| 9. |
- Axelsson, Petter, et al.
(författare)
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Belowground Competition Directs Spatial Patterns of Seedling Growth in Boreal Pine Forests in Fennoscandia
- 2014
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 5, s. 2106-2121
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Tidskriftsartikel (refereegranskat)abstract
- Aboveground competition is often argued to be the main process determining patterns of natural forest regeneration. However, the theory of multiple resource limitation suggests that seedling performance also depends on belowground competition and, thus, that their relative influence is of fundamental importance. Two approaches were used to address the relative importance of above-and below-ground competition on regeneration in a nutrient-poor pine (Pinus sylvestris) boreal forest. Firstly, seedling establishment beneath trees stem-girdled 12 years ago show that a substantial proportion of the seedlings were established within two years after girdling, which corresponds to a time when nutrient uptake by tree roots was severely reduced without disrupting water transport to the tree canopy, which consequently was maintained. The establishment during these two years also corresponds to abundances high enough for normal stand replacement. Secondly, surveys of regeneration within forest gaps showed that surrounding forests depressed seedlings, so that satisfactory growth occurred only more than 5 m from forest edges and that higher solar radiation in south facing edges was not enough to mediate these effects. We conclude that disruption of belowground competitive interactions mediates regeneration and, thus, that belowground competition has a strong limiting influence on seedling establishment in these forests.
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| 10. |
- Bizjak, Tinkara, et al.
(författare)
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Presence and activity of nitrogen-fixing bacteria in Scots pine needles in a boreal forest : a nitrogen-addition experiment
- 2023
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Ingår i: Tree Physiology. - : Oxford University Press. - 0829-318X .- 1758-4469. ; 43:8, s. 1354-1364
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Tidskriftsartikel (refereegranskat)abstract
- Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha-1 year-1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.
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