Browsing by Subject "carbon"

The purpose of this study was to examine the integrated climatic impacts of forestry and the use fibre-based packaging materials. The responsible use of forest resources plays an integral role in mitigating climate change. Forests offer three generic mitigation strategies; conservation, sequestration and substitution. By conserving carbon reservoirs, increasing the carbon sequestration in the forest or substituting fossil fuel intensive materials and energy, it is possible to lower the amount of carbon in the atmosphere through the use of forest resources. The Finnish forest industry consumed some 78 million m3 of wood in 2009, while total of 2.4 million tons of different packaging materials were consumed that same year in Finland. Nearly half of the domestically consumed packaging materials were wood-based. Globally the world packaging material market is valued worth annually some €400 billion, of which the fibre-based packaging materials account for 40 %. The methodology and the theoretical framework of this study are based on a stand-level, steady-state analysis of forestry and wood yields. The forest stand data used for this study were obtained from Metla, and consisted of 14 forest stands located in Southern and Central Finland. The forest growth and wood yields were first optimized with the help of Stand Management Assistant software, and then simulated in Motti for forest carbon pools. The basic idea was to examine the climatic impacts of fibre-based packaging material production and consumption through different forest management and end-use scenarios. Economically optimal forest management practices were chosen as the baseline (1) for the study. In the alternative scenarios, the amount of fibre-based packaging material on the market decreased from the baseline. The reduced pulpwood demand (RPD) scenario (2) follows economically optimal management practices under reduced pulpwood price conditions, while the sawlog scenario (3) also changed the product mix from packaging to sawnwood products. The energy scenario (4) examines the impacts of pulpwood demand shift from packaging to energy use. The final scenario follows the silvicultural guidelines developed by the Forestry Development Centre Tapio (5). The baseline forest and forest product carbon pools and the avoided emissions from wood use were compared to those under alternative forest management regimes and end-use scenarios. The comparison of the climatic impacts between scenarios gave an insight into the sustainability of fibre-based packaging materials, and the impacts of decreased material supply and substitution. The results show that the use of wood for fibre-based packaging purposes is favorable, when considering climate change mitigation aspects of forestry and wood use. Fibre-based packaging materials efficiently displace fossil carbon emissions by substituting more energy intensive materials, and they delay biogenic carbon re-emissions to the atmosphere for several months up to years. The RPD and the sawlog scenarios both fared well in the scenario comparison. These scenarios produced relatively more sawnwood, which can displace high amounts of emissions and has high carbon storing potential due to the long lifecycle. The results indicate the possibility that win-win scenarios exist by shifting production from pulpwood to sawlogs; on some of the stands in the RPD and sawlog scenarios, both carbon pools and avoided emissions increased from the baseline simultaneously. On the opposite, the shift from packaging material to energy use caused the carbon pools and the avoided emissions to diminish from the baseline. Hence the use of virgin fibres for energy purposes, rather than forest industry feedstock biomass, should be critically judged if optional to each other. Managing the stands according to the silvicultural guidelines developed by the Forestry Development Centre Tapio provided the least climatic benefits, showing considerably lower carbon pools and avoided emissions. This seems interesting and worth noting, as the guidelines are the current basis for the forest management practices in Finland.

In the carbon cycle carbon is sequestrated from the atmosphere through photosynthesis in vegetation, returned into soils as litter and released into atmosphere in decomposition as carbon dioxide. In the boreal zone a large proportion of the organic carbon is bound into soil. The aim of this study was to find out how the amount of soil organic carbon (SOC) has changed in Finnish forests in last 20 years by comparing results of empirical measurements from two projects (1986-1995 and 2006). The purpose of the study was also to analyze how well the field measurements of SOC collected in two consecutive periods of time are suitable for characterization of changes in the SOC stock. The effect of soil structure, vegetation type and climatic factors on possible SOC changes were also studied. The average size of SOC stock (organic layer + mineral layer 0-40cm) in Finnish forests is 5.65 kg C m-2. About one third of SOC is in the organic layer (2.10 kg C m-2) and the rest of it is in the mineral soil (3.56 kg C m-2 ). Higher amount of SOC stock in the organic layer has been determined on plots with thicker organic layer, poor drainage and the presence of peat mosses. Higher amount of SOC in the mineral layer has been measured on plots which have a more southerly location, lower stoniness and high proportion of fine textures. Coefficients of determination in General Linear Models were between 23-61%. The average annual change of SOC (organic layer + mineral layer 0-40 cm) is +33.9 g C m-2a-1. Change in the organic layer has been +11.4 g C m-2a-1 and in the mineral soil +22.5 g C m-2a-1. The accumulation of organic carbon into the organic layer is positively correlated with the thickness of the organic layer, the southern location, pine dominance in tree layer and the age of the trees, while in the mineral soil higher carbon accumulation occurs in less stony soils and in more southern locations. Coefficients of determination in General Linear Models describing the change in SOC were low, between 11-14%. The largest positive or negative changes in SOC are in plots where the depth of the organic layer measured in two successive measurements was very different. Also, the differences in the measurements of SOC were large if the plots were drained, divided to two different sections or plots were excessively moist. Climate change and higher temperature will probably affect soil carbon sequestration positively, forecasted by using the results of the south-north gradient in which more carbon was accumulated into the soils of southern Finland. Soil monitoring research should be developed by using precise sampling methods and establishing permanent instructions for field work in order to avoid additional sources of error and to minimize variation.

Agricultural systems hold great potential in contributing greenhouse gas mitigation measures globally. Crop diversification, perennial vegetative cover and soil conservational measures are highlighted in order to develop agricultural production in a sustainable way. Increasing climate related public concern has created a demand for sustainable materials for manufacturing industries. Nettle (Urtica dioica) has been proven to hold economic and ecological advantages and great commercial potential. Nettle is a perennial low input crop with multiple end uses within harvest offering an attractive crop for farmers. The crop has been historically used in industrial scale however, current nettle production in agricultural scale is marginal despite its positive characteristics. Research on nettle’s commercial potential has been conducted in various industries. Lack of farmers has left results idle and commercial potential unachieved. This study uses basic management accounting practices in order to find the break-even points and profitability of the production in Finnish conventional farming framework. The production information is gathered from various international projects and is used in order to assess the profitability of nettle production and expand the assessment to evaluate production’s environmental benefits. For a comparison, similar assessment is performed for a conventional crop rotation consisting an oilseed crop, wheat and grass. In the chosen 4-year setting, the nettle production proves more expensive majorly due to first year’s economically non-viable production. Nettle’s low input use during the yield years and predictable long term yield output is likely to reduce unit costs over time. Nettle’s production cost of dry biomass is 0,29 euros per kilogram and break-even price after subsidies is 0,16 euros for a kilogram, similar to wheat. Nettle’s low input use and relatively large, annual 8000kg fresh yields indicate the production could turn profitable with comparably low prices. Environmentally, after the first year nettle creates an annual 1,3 ton carbon sink despite conventional fertilizer use and machinery work done of field.

Boreal forests are an important storage of carbon (C), representing over one-third of terrestrial C stocks. The continuity of C storage in boreal forests and forest soils is critical to mitigate climate change. Climate change will likely increase the fire season length and the frequency of forest fires in Finland, of which surface fires are the dominant type. Fire affects C dynamics by modifying biotic (SOM, vegetation, microbial activity) and abiotic (soil temperature, moisture, chemistry) components of the forest ecosystem. These fire-induced effects will depend on the intensity of the fire (duration, flame temperature) and the site characteristics, ultimately resulting in either the persistence of, or in a net C loss, which has implications on both a local and global scale. There is a lack of existing research regarding the short-term impacts of surface forest fires and comparisons between different fire intensities. Subsequently, this thesis describes an experimental burn conducted in an even-aged Pinus sylvestris forest in southern Finland and the short- term post-fire impacts on soil biogeochemical processes (June-October 2020). The aims of this study were: (1) to study the effects of low- (200-300 oC) and high- (500-600 oC) intensity surface fires on soil temperature, moisture and soil surface CO2 fluxes straight after fire and through four months after experimental fire; (2) to study the effects of low- and high-intensity surface fires on plant (above and below ground) biomass immediately and four months after fire; (3) to identify the most important factors driving soil CO2 effluxes shortly after the fire. Eight sample plots (225 m2 each) were used, divided between high and low biomass loads to achieve high- and low-intensity fires. Continuous soil temperature and moisture measurements, vegetation inventories, soil sampling (0-30 cm), and soil CO2 efflux measurements were obtained using portable chambers. The results of this study showed that some soil physical and chemical properties were significantly altered due to the experimental surface fire (vegetation, temperature, moisture, root biomass, C, N (nitrogen), C/N), whereas some remained unchanged (pH, humus thickness). Soil moisture was the only variable, which increased as a result of higher fire intensity. Fires at both intensities resulted in the mortality of ground vegetation whilst trees did not experience mortality by the end of the monitoring period. Soil CO2 fluxes decreased in burned areas compared to unburned plots over time, but this change was not significantly different between burning intensities. Future research should investigate the mechanisms of C and N translocation through the soil profile following the addition of water, the relationship between post-fire soil temperature and soil CO2 efflux, how burning different biomass components changes the composition of ash, and how larger differences in burning intensities affect soil properties and soil CO2 effluxes. If trees experience mortality after the time period encompassed by this study, the site could become a potential C source; further monitoring of the study site could account for delayed indirect impacts such as these.