A Tool to Assess the Impact of Forest Land Expansion on Greenhouse Gas Sequestration and Emissions

The emergence of carbon trading mechanisms is increasing the need for transparent, reproducible, and policy-relevant tools to quantify carbon stock changes in the forest sector. In this context, this study presents an Excel-based carbon calculation tool developed in accordance with IPCC principles for estimating carbon stock changes within the LULUCF sector. The tool supports scenario-based assessments of land-use change and afforestation planning using readily available spatial and statistical inputs and enables evaluation of the potential impacts of legislative initiatives on carbon sequestration from afforestation of non-forest land, serving as an analytical instrument for policy formulation, legislative decision-making, and scientific analysis of forest cover expansion.To test the applicability of the tool, afforestation scenarios were developed for Jonava municipality (944 km²), Lithuania, using GIS-based identification of suitable areas. Twocontrasting cases were applied: afforestation limited by current land-use regulations and an extended scenario including drainage bund areas. The regulation-aligned case identified 2,862 ha suitable for afforestation, while the extended case increased the afforestable area to 20,189 ha, raising potential forest cover from 41.1% to 62.6%.When processed with the Excel-based IPCC-consistent tool, the extended scenario demonstrated a substantially higher carbon sequestration potential, with up to 14.1 million tons of additional CO₂ equivalent over a 50-year period – approximately six times the annual sequestration estimated under the regulation-aligned scenario. These results demonstrate the tool’s capacity to quantify long-term carbon stock changes under contrasting land-use assumptions, supporting its use for scenario testing, land-use planning, and carbon accounting.