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Organic soils in cropland and grassland are absolutely the largest source of greenhouse gas (GHG) emissions in Latvia contributing to output of 3.1 mill. tons CO2 eq; therefore, it is important, to evaluate different management scenarios and their effect on the GHG emissions. In this study we compared 3 scenarios of management of organic soils used in agriculture: afforestation with birch and retaining of drainage system, afforestation with birch with following rewetting and management these areas as grasslands as a reference scenario. We estimated carbon stock changes in living biomass of trees and forest floor vegetation, litter, dead wood, harvested wood products and soil, substitution effect of forest biofuel, and N2O and CH4 emissions from soil. AGM model is used to create forest growth projections. The average annual GHG emissions from grassland is 7.3 tons CO2 eq ha-1 yr-1. In afforested and drained areas average GHG emissions are 2.6 tons CO2 eq ha-1 yr-1, and in afforested and rewetted areas - 3.8 tons CO2 eq ha-1 yr-1. Afforestation of grassland and maintenance of drainage system during 200 years period reduces GHG emissions by 916 tons CO2 eq ha-1, while the afforestation and rewetting reduces GHG emissions by 670 tons CO2 eq. ha-1. The substitution of fossil fuel has significant role in the climate change mitigation effect. The cost of the emissions' reduction in 2050 reaches 5.8 and 21.3 € ton-1 CO2 eq in drained and rewetted areas, accordingly. [ABSTRACT FROM AUTHOR]

Latvia is one of the largest exporters of pellets in Europe, and at the same time share of biofuel in energy production in Latvia is also one of the largest between the developed countries. Rapid increase of biofuel production and export raises questions about sustainability of forest sector and contribution of the forest biofuel produced in Latvia to the greenhouse gas (GHG) balance in Europe. Sustainability of forest biofuel is broadly discussed issue in Baltic states; particularly, due to continuous increase of production and export of wood pellets. GHG mitigation potential of the forest biofuel is one of the sustainability aspects surrounded by multiple speculations, which has to be addressed by comprehensive comparison of GHG fluxes due to production and use of forest biofuel and substituted fossil fuel. Assessment of the GHG mitigation potential of forest biofuel is complex process requiring multiple activity data and assumptions. Particular complexity of calculation is determined by the need to use harmonized approach for the whole calculation period. The assessment of the climate change mitigation in this study is based on the methods applied in National GHG inventory and literature data on GHG emissions due to production and delivery of substituted fossil fuel and forest biomass including demolition wood. According to the study results substitution effect of the forest biofuel in Latvia continuously increases since 2000, mainly due to export of biofuel, reaching 14323 Gg CO2 eq. in 2020 (by 30% more than the net GHG emissions in Latvia in 2019). Electricity production in pellet factories, in spite of major reduction of GHG emissions in the production process, has minor role in the total substitution effect. [ABSTRACT FROM AUTHOR]