| 1. |
- Erhagen, Björn, et al.
(författare)
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Temperature sensitivity of heterotrophic soil CO2 production increases with increasing carbon substrate uptake rate
- 2015
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 80, s. 45-52
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Tidskriftsartikel (refereegranskat)abstract
- Temperature profoundly affects saprotrophic respiration rates, and carbon quality theory predicts that the rates' temperature Sensitivity should increase as the quality of the carbon source declines. However, reported relationships between saprotrophic respiration responses to temperature and carbon quality vary widely. Some of this variability may arise from confounding effects related to both substrate quality and substrate availability. The importance of these variables, as well as substrate diffusion and uptake rates, for the temperature sensitivity of saprotrophic respiration has been validated theoretically, but not empirically demonstrated. Thus, we tested effects of varying substrate uptake rates on the temperature sensitivity of organic carbon degradation. For this purpose we created a model system using the organic layer (O-horizon), of a boreal forest soil, specifically to test effects of varying monomer uptake and release rates. The addition of both monomers and polymers generally increased the temperature sensitivity of saprotrophic respiration. In response to added monomers, there was a linear increase in the temperature sensitivity of both substrate-induced respiration and the specific growth rate with increasing rate of substrate uptake as indicated by the CO2 production at 14 degrees C. Both of these responses diverge from those predicted by the carbon quality theory, but they provide the first empirical evidence consistent with model predictions demonstrating increased temperature sensitivity with increased uptake rate of carbon monomers over the cell membrane. These results may explain why organic material of higher carbon quality induces higher temperature responses than lower carbon quality compounds, without contradicting carbon quality theory.
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| 2. |
- Sundqvist, Maja K., et al.
(författare)
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Contrasting nitrogen and phosphorus dynamics across an elevational gradient for subarctic tundra heath and meadow vegetation
- 2014
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Ingår i: Plant and Soil. - : Springer Netherlands. - 0032-079X .- 1573-5036. ; 383:1-2, s. 387-399
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Tidskriftsartikel (refereegranskat)abstract
- This study explores soil nutrient cycling processes and microbial properties for two contrasting vegetation types along an elevational gradient in subarctic tundra to improve our understanding of how temperature influences nutrient availability in an ecosystem predicted to be sensitive to global warming. We measured total amino acid (Amino-N), mineral nitrogen (N) and phosphorus (P) concentrations, in situ net N and P mineralization, net Amino-N consumption, and microbial biomass C, N and P in both heath and meadow soils across an elevational gradient near Abisko, Sweden. For the meadow, NH4 (+) concentrations and net N mineralization were highest at high elevations and microbial properties showed variable responses; these variables were largely unresponsive to elevation for the heath. Amino-N concentrations sometimes showed a tendency to increase with elevation and net Amino-N consumption was often unresponsive to elevation. Overall, PO4-P concentrations decreased with elevation and net P immobilization mostly occurred at lower elevations; these effects were strongest for the heath. Our results reveal that elevation-associated changes in temperature can have contrasting effects on the cycling of N and P in subarctic soils, and that the strength and direction of these effects depend strongly on dominant vegetation type.
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| 3. |
- Andersson, Jon, et al.
(författare)
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Wood-Inhabiting Beetles in Low Stumps, High Stumps and Logs on Boreal Clear-Cuts: Implications for Dead Wood Management
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The increasing demand for biofuels from logging residues require serious attention on the importance of dead wood substrates on clear-cuts for the many forestry-intolerant saproxylic (wood-inhabiting) species. In particular, the emerging harvest of low stumps motivates further study of these substrates. On ten clear-cuts we compared the species richness, abundance and species composition of saproxylic beetles hatching from four to nine year old low stumps, high stumps and logs of Norway spruce. By using emergence traps we collected a total of 2,670 saproxylic beetles among 195 species during the summers of 2006, 2007 and 2009. We found that the species assemblages differed significantly between high stumps and logs all three years. The species assemblages of low stumps, on the other hand, were intermediate to those found in logs and high stumps. There were also significant difference in species richness between the three examined years, and we found significant effect of substrate type on richness of predators and fungivores. As shown in previous studies of low stumps on clear-cuts they can sustain large numbers of different saproxylic beetles, including red-listed species. Our study does, in addition to this fact, highlight a possible problem in creating just one type of substrate as a tool for conservation in forestry. Species assemblages in high stumps did not differ significantly from those found in low stumps. Instead logs, which constitute a scarcer substrate type on clear-cuts, provided habitat for a more distinct assemblage of saproxylic species than high stumps. It can therefore be questioned whether high stumps are an optimal tool for nature conservation in clear-cutting forestry. Our results also indicate that low stumps constitute an equally important substrate as high stumps and logs, and we therefore suggest that stump harvesting is done after carefully evaluating measures to provide habitat for saproxylic organisms.
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| 4. |
- Carvalho, Ricardo, 1985-, et al.
(författare)
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Household Bioenergy Transitions with Alternative Biomass Feedstocks and Technologies: An Integrated System to Mitigate Environmental Risks in Western Kenya
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In Kenya, over 50% of the total primary energy consumption is from traditional solid-fuel cooking, being this a major cause of deforestation and household air pollution (HAP). Western Kenya has an agricultural biofuel feedstock of over 1.9 million Mt, which could be processed to supply cookstoves with crop-residue pellets and improved wood fallows. The sociotechnical viability of two novel bioenergy value chains were analysed using the Long-Range Energy Alternatives Planning system. Three scenarios of transition to efficient cookstoves and decentralized biofuel and electricity production systems were tested. In the “Optimal scenario”, the current feedstock in the Kisumu and Siaya counties could satisfy over 80% of the cooking energy demand by 2030. Here, the net greenhouse gas emissions from charcoal production and HAP could be reduced by 87% to 12.6 thousand Mt CO2e. Further work should integrate socioeconomic indicators reflecting additional local/regional stakeholders´ collaboration channels (cost-effective) to support the bioenergy transitions.
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| 5. |
- Downing, Andrea S., et al.
(författare)
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Unlocking the unsustainable rice-wheat system of Indian Punjab : Assessing alternatives to crop-residue burning from a systems perspective
- 2022
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Ingår i: Ecological Economics. - : Elsevier BV. - 0921-8009 .- 1873-6106. ; 195
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Tidskriftsartikel (refereegranskat)abstract
- Crop residue burning in Indian Punjab emits particulate matter with detrimental impacts on health, climate and that threaten agricultural production. Though legal and technological barriers to residue burning exist – and alternatives considered more profitable to farmers – residue burning continues. We review black carbon (BC) emissions from residue burning in Punjab, analyse social-ecological processes driving residue burning, and rice and wheat value-chains. Our aims are to a) understand system feedbacks driving agricultural practices in Punjab; b) identify systemic effects of alternatives to residue burning and c) identify companies and financial actors investing in agricultural production in Punjab. We find feedbacks locking the system into crop residue burning. The Government of India has greatest financial leverage and risk in the current system. Corporate stakeholders have little financial incentive to enact change, but sufficient stakes in the value chains to influence change. Agricultural policy changes are necessary to reduce harmful impacts of current practices, but insufficient to bringing about sustainability. Transformative changes will require crop diversification, circular business models and green financing. Intermediating financial institutions setting sustainability conditions on loans could leverage these changes. Sustainability requires the systems perspective we provide, to reconnect production with demand and with supporting environmental conditions.
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| 6. |
- Edvardsson, Johannes, et al.
(författare)
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Old wood in a new light : an online dendrochronological database
- 2023
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Ingår i: International Journal of Wood Culture. - : Brill Academic Publishers. - 2772-3194 .- 2772-3186. ; 3:1-3, s. 442-463
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Tidskriftsartikel (refereegranskat)abstract
- The Old Wood in a New Light database project focuses on the digitization and accessibility of the results of dendrochronological samples analyzed and archived at four Swedish university-based tree-ring laboratories at Lund University, Stockholm University, University of Gothenburg, and the Swedish University of Agricultural Sciences. Collaboration with the Environmental Archaeology Laboratory and Humlab at Umeå University enables long-term open access to data, raw data, and metadata. In this project, we (1) systematically undertake large-scale entry and open access publication of results from wood samples scientifically analyzed and archived by Swedish laboratories and the associated metadata, into the Strategic Environmental Archaeology Database (SEAD; www.sead.se) research data infrastructure, and (2) actively promote the database as a resource for new and ongoing interdisciplinary research initiatives. Including dendrochronological data in SEAD infrastructure allows interdisciplinary studies that combine major scientific and societal questions. Building on a pilot study of construction timber from southern Sweden and adaptation of SEAD digitization workflows, more than 70 000 samples archived at the four dendrochronological laboratories are now being handled in the project. The broad coverage of research networks, stakeholder interaction, and strategic support from the cultural heritage community is guaranteed owing to the ongoing collaboration between laboratories and an established international and multidisciplinary reference group.
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| 7. |
- Jansson, K. Ulrika, et al.
(författare)
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Length and classification of natural and created forest edges in boreal landscapes throughout northern Sweden
- 2011
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Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 262:3, s. 461-469
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Tidskriftsartikel (refereegranskat)abstract
- Forest edges have numerous implications for structure and function of forest ecosystems. Previous studies on edge quantity have used broad classifications. However, edge influence is driven by the contrast in vegetation structure between adjoining ecosystems, and thus we need detailed site-specific data to assess the role of edges in forests. We studied the variability of sharp edges in 28 boreal landscapes (4 km × 4 km) across an 830 km gradient throughout northern Sweden. Our objectives were: (1) to compare the length of natural and created edges, (2) to classify edges in detail by edge origin, maintenance and forest attributes, and (3) to examine relationships between length of edge and landscape variables. Data were collected using stereo-interpretation of high spatial resolution colour infrared aerial photographs, in combination with line intersect sampling and plots. The length of edge varied from 12 to 102 m ha−1 among landscapes, with an overall mean of 54 m ha−1. Created edges dominated most landscapes (mean 33 m ha−1) and had greater variability than natural edges (mean 21 m ha−1). Maintained edges (e.g. roads, agricultural land) were more abundant than regenerating edges caused by logging. Thirty percent of total edges adjoined narrow linear features. Seventy percent adjoined wider patches and showed high variability (35 classes). Overall, high-contrast edges towards mature forest dominated, i.e. ones that may experience strong edge influence. The amount of edge increased with percent of landscape affected by disturbance, and decreased with latitude and elevation. This study shows that edges are both abundant and highly variable in boreal forests and that forestry is the main driver behind edge creation. Detailed classification of edges based on site-specific forest and patch attributes may help to estimate edge influence at landscape level, and can guide experimental design for examining the impact of edges on structure and function of forest ecosystems.
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| 8. |
- Josefsson, Torbjörn, et al.
(författare)
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Ancient Bark-peeled Trees in the Bitterroot Mountains, Montana : Legacies of Native Land Use and Implications for Their Protection
- 2012
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Ingår i: Natural areas journal. - Rockford, IL : Natural Areas Association. - 0885-8608 .- 2162-4399. ; 32:1, s. 54-64
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Tidskriftsartikel (refereegranskat)abstract
- Culturally modified trees (CMTs) are trees with scars that reflect human utilization of forested ecosystems. Some CMTs can reveal unique knowledge of native cultures and insight to peoples' subsistence and land use in the past, and are mostly to be found in protected areas since they contain very old trees. In this study, we examine attributes and the spatial and temporal distribution of bark-peeled trees, and present forest structure in two remnant ponderosa pine forests (Pinus ponderosa P. & C. Lawson) in western Montana. We also wanted to use an alternative method of dating CMTs and initiate a broader discussion of threats to such trees and needs for sustaining and protecting them. In total, 343 bark-peelings were recorded on 274 living and dead trees. Our results show that only certain trees were selected for harvest. Nearby trees of similar size and age were not used. The age estimation indicates that the bark-peelings were performed from the mid 1600s until the early 1900s. Today the forest at both study areas is generally low in density and all-aged with very old individual trees. They consist of a mosaic of uneven-aged tree groups and individual trees of various ages. We conclude that the abundance and density of bark-peeled trees at the study areas exceed values reported in most other North American studies (formally protected forests included), that the two areas represent different harvest areas for ponderosa pine inner bark, and that CMTs need to be recognized both as ecologically and culturally valuable features of old ponderosa pine forests.
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| 9. |
- 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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| 10. |
- Lemke, Isgard H., et al.
(författare)
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Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient
- 2015
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Ingår i: Plant Ecology. - : Springer Science and Business Media LLC. - 1385-0237 .- 1573-5052. ; 216:11, s. 1523-1536
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change.
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