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- Pendrill, Florence, 1983
(författare)
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Felling Forests from Afar: Quantifying Deforestation Driven by Agricultural Expansion and International Trade
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deforestation is a major source of human-caused greenhouse gas emissions and the largest threat to terrestrial biodiversity. Most forest loss is due to the expansion of agricultural land use increasingly driven by international demand for food, fuel and fibre. However, there is still limited understanding of the extent to which different agricultural commodities are contributing to deforestation. It has therefore also been difficult to evaluate the role of international trade in driving deforestation. This dissertation aims at quantifying the agricultural drivers of tropical deforestation (Papers I and II) and the associated carbon emissions (Paper III). It further assesses the role of international trade, by following the agricultural commodities with embodied deforestation through international supply chains using trade models (Papers II and III). The results show that a few commodity types, primarily cattle meat and oilseed products, account for a large part of tropical deforestation. Much (26–39%) of the embodied deforestation and concomitant emissions were found to be associated with international demand (from products and services). Looking closer at the countries that import embodied deforestation, Paper II finds that many countries that are increasing their forest cover at home, import products associated with deforestation elsewhere, thereby offsetting about a third of their forest gains. Paper III finds that imports of embodied deforestation emissions for many developed countries are similar in size to their national agricultural emissions amounting, e.g., for the EU, to around 15% of the carbon footprint of an average diet. Put together, the results add to the evidence that combating deforestation can benefit from complementing domestic policies with measures that target international demand. The results also indicate that tackling deforestation and its associated impacts at the global level is probably even more challenging than at the national level, although international trade can also provide efficiency gains by optimising land use globally.
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| 3. |
- Monteith, Albert, 1990
(författare)
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Radar Measurements of Temporal Variation in a Boreal Forest
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Synthetic aperture radar (SAR) on a satellite platform is a suitable technique for all-weather global monitoring of forest parameters such as biomass. This is important for increasing the accuracy of the global terrestrial carbon flux, the largest uncertainty in our current understanding of the Earth’s carbon cycle. In recent decades there has been increasing interest in relating SAR observables from current and future spaceborne SAR missions to forest parameters. Ideally, these SAR observables are only dependent on the forest parameters of interest, but they are also affected by temporal variations in the forest due to weather, diurnal and seasonal changes. These effects are not properly accounted for in current forest parameter estimation models using SAR data due to shortcomings in our understanding of these effects.To fill this knowledge gap, a tower-based radar has been developed for measuring temporal variation of radar signatures in a boreal forest site in southern Sweden. The instrument allows monitoring of radar signatures from the forest site over timescales ranging from less than a second to years. The experiment consists of a 50-m high tower equipped with 30 antennas, allowing fully-polarimetric tomographic imaging at microwave frequencies of P-band (420 - 450 MHz), L-band (1240 - 1375 MHz) and C-band (5250 - 5570 MHz). Results from an on-site weather station assists in interpretation of the radar results. The work in this thesis involves the design and implementation of the experimental setup and analysis of the first results. The results have provided new information about variations in forest radar backscatter during freeze-thaw cycles at P- and L-band, causing drops in backscatter of 4 to 10 dB. An effect where strong winds cause a drop in co-polarised backscatter at P-band has been directly observed for the first time. Finally, the tomographic capabilities of the instrument were demonstrated. Tomographic imaging quality was shown to be better than for measurement protocols used by previous tower-based radars when acquired while the trees were moving due to wind.The results of this experiment are important for understanding and modelling temporal variations in radar measurements over boreal forests such that these unwanted variations can be compensated for in forest parameter estimation algorithms using SAR data.
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| 4. |
- Albjär, Göran
(författare)
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Sandgrunnorna in Lule Archipelago : Recent Transformation of a Glaciofluvial Deposit in an Environment of Land Uplift
- 1985
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In an area of rapid land uplift the geomorphological evolution of the glaciofluvial island of Sandgrunnorna, 25 km SE Luleå, in the Bothnian Bay, is discussed from old maps, air photographs and field studies. The island were marked on a map for the first time in 1790, but the highest parts can be estimated to have reached the sea surface about 100 years earlier. The areal growth has been reconstructed by map and air photograph studies. A model of the geomorphological evolution based on the interaction between bottom morphology, land uplift and waves is presented.
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| 7. |
- Bosiö, Julia
(författare)
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A green future with thawing permafrost mires? : a study of climate-vegetation interactions in European subarctic peatlands
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Climate projections indicate that Arctic and sub-Arctic regions are facing a significant change in climate during the 21st century. With warmer temperatures precipitation is also expected to increase, and in particular winter precipitation. These changes are likely to have large impacts on the Arctic and subarctic environment, and extensive research has focused on ecosystem-climate interactions in Arctic and sub-Arctic environments, but still the environmental response to such changes is not fully understood. This thesis presents the work and outcomes of my research on climate-vegetation interactions in permafrost (ground that remains frozen for two or more consecutive years) mires in subarctic Fennoscandia. In this region permafrost mires demarks the outer border of lowland permafrost existence, where a combination of climatological and environmental conditions allows for the ground to remain frozen year round, making the permafrost particularly sensitive to changes. By combining field observations of vegetation patterns in permafrost mires throughout the study region with spatial data of the present (2008) and projected future climate in subarctic Fennoscandia the future vegetational patterns of these permafrost mires were modeled. Further, the impact of increased snow cover on plant photosynthesis in these environments was assessed through field experiments on a subarctic permafrost mire, where the snow cover was manipulated during seven winters using snow fences. The results suggest that a rapid transition from dry heath tundra vegetation to moist tussock tundra vegetation is to be expected in these permafrost mires with the warmer climate and increased precipitation projected for the studied region. The snow manipulation experiments suggest that even a moderate increase in snow cover thickness increases plant photosynthesis on the long term. This increase in photosynthesis is attributed to the observed shift in plant species composition where moist tussock vegetation is likely to be favored by increased soil moisture, soil temperature and nutrient availability. However, the increased carbon uptake through higher photosynthesis rates is may be completely offset by increased methane emissions from increased wetness in the thawing peatlands.
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| 8. |
- Engstrom, Kerstin
(författare)
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Drivers of global land use change : are increasing demands for food and bioenergy offset by technological change and yield increase?
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Globally, the food and energy demands of the growing global population are rising and require increased agricultural production. Additionally, climate change will have adverse effects on agricultural productivity. Technological change can contribute to closing yield gaps and reducing post-harvest losses, but needs to be facilitated through investments and education. Considering the multiple drivers of the land system and their complex interactions, it is one of the great challenges of the 21st century to find solutions for how to sustainably increase food and bioenergy production. This requires understanding of land use change, its drivers and their multiple interactions. Here, a parsimonious land use model (PLUM) is developed and a review of global scenarios of environmental change is carried out to address the question of how drivers of environmental change, including lifestyle-related dietary changes, bioenergy production, and technological change, will affect future land use. The results of the model development and evaluation suggest that a parsimonious approach can contribute to understanding and exploring solutions to the challenge outlined above. The model can reproduce agricultural land use at the global and regional scale and at the same time the approach is explicit about uncertainties in model input parameters and the quantification of uncertainty ranges for each model output. The exploration of the uncertainty range of the model parameters showed that global cereal land is strongly affected by changes in cereal yields in developing countries. The increasing demand for food, represented by cereals, milk and meat, had in the past 20 years only very little influence on expanding agricultural land. The results of the review of bioenergy representation in global scenario studies show that assumptions related to technological change, such as yield increase and efficiency of bioenergy production, are essential for the projected land use for bioenergy in the future. The projected land use for bioenergy in the reviewed scenarios spans 0.2-10% of total global area in 2100, which can be considered a wide range, given that current cropland is about 12% of global land area. Further, the research suggests that high primary energy requirements, mitigation strategies, or a combination of these driving forces, will in any case stimulate an increased bioenergy production in the future.
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| 9. |
- Eriksson, Bert, 1952-
(författare)
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The zoo-geomorphological impact of fossorial rodents in sub-polar alpine environments
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The geomorphological impact of small fossorial mammals (adapted to digging and living underground), such as rodents can be significant, and both their direct and indirect effects may contribute to landscape formation. This thesis is based on empirical field studies of two burrowing rodent species in sub-polar environments, namely invasive House mice (Mus musculus) on sub-Antarctic Marion Island and Norwegian lemmings (Lemmus lemmus) in sub-Arctic Abisko. The spatial distribution, sediment displacements, impact on vegetation and microclimatic effects of the rodents are documented. Invasive mice and rats, introduced on sub-Antarctic Islands during the 19th century, lack natural enemies and are shown to have a significant direct and indirect geomorphic impact by direct sediment displacement, vegetation removal by burrowing, grazing and trampling and thereby exposing the sediments for rain, wind and frost processes. The geomorphic impacts of lemmings are comparatively more limited as they rely on natural hollows and snow cover for protection and do not burrow to the same extent as other fossorial rodents in cold regions. Lemmings are thus suggested to have little impact on landform integrity, but can affect vegetation composition. A comparison of the findings from this study with published data on seven other rodent species and other physical mass transfer mechanisms in sub-polar and alpine environments suggests that fossorial rodents are a significant and sometimes dominant geomorphic force in sub-polar and alpine environments. The geomorphic work by ground squirrels, ice rats, plateau pikas and zokors is shown to be in the same order of magnitude as solifluction and rock falls. In alpine and periglacial environments these rodents are considered to act as key-stone species and ecosystem engineers through the creation of landforms by dislocation and of soil and other impacts on soil properties, vegetation and ecosystem function
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| 10. |
- Eriksson, Sofia
(författare)
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Cross-scale monitoring, landscape trajectories, and feedback in forest management : Examples from southern and middle boreal ecosystems in Sweden
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To manage for sustainability in a complex and changing world requires understanding of the coupled human-environmental system. The two case studies in this licentiate thesis are linked by what we can learn from past and current management in the form of feedback and how it can be incorporated into practical forest management within the boreal region.Paper I outlines cross-scale monitoring of feedback within three large forest companies in the southern and middle boreal region in Sweden today. Available information as presented in interviews with forest management personnel is compared with 47 indicators linked to ecosystem properties based on a literature review. The indicators are categorized according to five nationally identified deficiencies in the Swedish boreal forest: disturbances, reserved areas, snags and logs, deciduous trees, and old-growth. The results show a separation of recorded data in two largely uncoordinated systems, Ecological Landscape Plans and stand registers. Accumulated statistics are primarily related to the stand scale and production-oriented, there are information gaps regarding different ecosystem structures and spatial distributions, e.g. dead wood and habitat networks.Paper II focuses on the development of landscape structures in a longer time perspective. Historical maps and a forest classification based on satellite data is used to delineate change trajectories in a landscape in Dalarna County over the past 300 years. The trajectories include land cover categories and two selected human drivers of change: management regime and ownership. Links between drivers of change, landscape structure, and feedback to present-day forest cover are analyzed using GIS and extended transition matrixes. The results show that in the studied landscape: forest cover continuity is the dominating landscape feature over time, large dynamics are primarily associated with smaller elements, dominating ownership category shifts over time and spatial redistribution along with large quantitative changes are frequent, ownership changes are reflected in management regimes, and the best predictor of forest composition today is past ownership.The collected information on composition, structure, and function in the “everyday” landscape is limited in current Swedish large-scale boreal forestry. This is most probably not a sufficient basis for maintaining ecosystem heterogeneity and resilience over time. To further promote sustainable forest management, there is a need for tools that incorporate feedback from forest ecosystems into management. By studying local land cover processes in relation to contemporary management based on historical material, properties of the ecosystem feedback can be outlined in a landscape perspective over time. In addition, cross-scale monitoring of dynamics and effects of landscape heterogeneity on management results are limited. Strategies and tools to achieve sustainable boreal forest management need to reflect spatial and temporal dynamics, as well as inherent heterogeneities in landscape mosaics and socioeconomic systems to a larger extent.
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