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Title Sink or source?
Publication Date
Degree Level doctoral
University/Publisher Swedish University of Agricultural Sciences
Abstract Soil organic carbon (SOC) is the largest terrestrial carbon pool and small changes in this pool may affect the global carbon balance, especially atmospheric concentration of CO2. Within the context of climate policy, the quantification of these changes is important, as pool changes may affect a country's national greenhouse gas budget. The aim of this thesis was to assess and analyze uncertainty related to the up-scaling of modelled SOC stocks and change estimates to regional or national scale. Two process-based models Q and Yasso07, were used to estimate SOC stocks and changes at different regional scales in Swedish coniferous forests. The parameter uncertainty of the Q model was assessed and established with the Generalized Likelihood Uncertainty Estimation (GLUE) method through the Swedish Forest Soil Inventory (SFSI) data at county scale. The calibration resulted in a set of parameters that were used for further modeling at regional scale. The Q and Yasso07 models were used to assess the impact of different uncertainties in the SOC stocks and changes. The most important uncertainty source in the model estimates was litter production. Increased harvest residue extraction was analyzed with the Q model to study the effects on SOC accumulation. SOC accumulation decreased with increased harvest residue extraction, although there was temporal and geographical variation. However, increased emissions from changes in the SOC pool resulted in a net decrease in CO2 emissions due to the substitution of coal combustion with biofuels. The coherence of scales between large-scale inventory data and process-based simulation models was explored. Inventory data became more uncertain when going from national to regional scale, due to the smaller sample, whereas, model estimates became more uncertain when applied to larger areas, due to increased uncertainty in parameter determination at larger scales resulting from varying conditions. The magnitudes of the uncertainties for model and inventory estimates of SOC were comparable, but the origins of uncertainties differed and could not be compared. Both models and inventories can be used to estimate the carbon sink of Swedish forest soils at national level, but if the changes are small, a few ‰ yr-1 in the SOC pool, the uncertainty may prevent a definite answer, if there is a change in the SOC pool.
Subjects/Keywords coniferous forests; forest soils; carbon; soil organic matter; forest litter; carbon dioxide; climatic change; simulation models; statistical uncertainty; forest inventories; sweden; SOC; GLUE; Swedish Forest Soil Inventory; models; uncertainty; GHG reporting; sensitivity analysis; coniferous forests
Language en
Country of Publication se
Record ID oai:pub.epsilon.slu.se:8695
Repository slu
Date Retrieved
Date Indexed 2017-05-01

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…effect of forest management needs to be considered when estimating the climate benefits of biofuels. The measurement of soil carbon in forest soil inventories is normally associated with high cost and large spatial variability (Muukkonen et al., 2009…

…associated with the estimation of SOC stock changes through inventories and process-based models at both regional and national scale. The studies are based on processbased models applied at different scales and driven by input data from forest inventories

…compare the first and the second inventories, which is the reason why data from the first inventory was not used in these studies. 25 Figure 3. A schematic figure of the Swedish Forest soil Inventory (SFSI) at different scales. The complete 10…

…Change and Forestry Markov Chain Monte Carlo Model Efficiency National Forest Inventory Probability Density Functions Root Mean Squared Error Swedish Meteorological and Hydrological Institute Swedish Forest Soil Inventory Swedish National Forest Inventory…

…x28;Goodale et al., 2002; Raich & Schlesinger, 1992). In the global carbon cycle, the soil C pool is both larger than the atmospheric (twice as large) and the terrestrial pools (2 to 3 times larger). Boreal forest soils (…

…and slow decomposition due to climatic conditions (Raich & Schlesinger, 1992). The SOC stock in Swedish forest soils is estimated at around 80 ton C ha-1 (SLU, 2012b; Stendahl et al., 2010; Olsson et al., 2009; gren et al., 2007)…

…Kyoto protocol, Annex I countries are obliged to report changes in forest SOC pools, unless they can prove the soils are not a source of CO2 to the atmosphere (UNFCCC, 2006). There are many ways of assessing SOC change (Smith, 2004; IPCC…

…2003), including repeated measurements in soil inventories (Bellamy et al., 2005), 11 CO2 flux measurements (Baldocchi et al., 2001), empirical/statistical models (Martin et al., 2011) with remote sensing, and…