Improvement of accuracy and completeness on assessment of forest carbon stocks and CO₂removals in Korean national GHG inventory

다국어 초록 (Multilingual Abstract)

The United Nations Framework Convention on Climate Change (UNFCCC) officially ratified efforts to stabilize the concentration of greenhouse gases (GHGs) in the atmosphere is needed, and as the Paris Agreement (PA) has been adopted in 2015, all parties have submitted nationally determined contributions (NDCs). Korea plans to use forests to contribute to national GHG reduction targets, and it is necessary to establish national GHG inventory reporting system for transparently measuring, reporting, and verifying the achievements of GHG reductions in domestic forests. GHG removals within Korean forests are estimated solely as an absorption by living biomass due to activity data issues of soil and dead organic matter. To improve the matter, this study aims to improve emission factor and activity data for GHG inventory report and apply them to evaluate forest carbon stocks and CO2 removals and potential GHG reduction in Korea.
In the first study, forest carbon stocks and CO2 removals were calculated according to the Intergovernmental Panel on Climate Change (IPCC) methodology. The results show that country-specific emissions factor coverage was 1.2 times higher than annual average CO2 removals based on IPCC defaults (41,761 Gg CO2 per year) from 2010 to 2015. The developed country-specific emission factors were applied to estimate the carbon stocks of soil and dead organic matter (litter and deadwood). Although annual CO2 removal was reduced from loss of carbon in soil and dead organic matter, GHG inventory reporting was improved through enhancing complement reporting due to estimation of all carbon pools. To improve the accuracy of current inventory systems, national forest inventory (NFI) data were used to estimate the annual CO2 removal of each species, and the result showed that 60,648 Gg CO2 per year is absorbed annually, with the uncertainty of 16%, which is among the lowest uncertainty values achieved with different methodology approaches.
The second study was conducted to enhance the time-series consistency of activity data according to change in the NFI survey system. The survey system revised after the 5th NFI survey encountered a problem with regard to the time-series consistency of the growing stocks due to the rapid increase of annual growing stock changes in 2007 and 2010, which is the most important activity data. To compensate for the growing stocks, which is the activity data, the overlap method presented in IPCC guidelines was applied, and the overlap ratio and calibration factor were obtained from the growing stocks in NFI survey data and yield table. The result showed that time-series consistency was ensured, and the total growing stocks have increased approximately 1.2 times than that in official statistics.
In the third study, a land-use change matrix was constructed for the improvement of the LULUCF inventory. The land-use change matrix from 1990 to 2015 was constructed by using domestic data and documents available from previous studies. Carbon stocks were calculated using the country-specific factors and the default values of IPCC. The construction of the land-use change matrix, which has not been constructed in the past, enabled the estimation of soil and dead organic matter, and annual CO2 removal of the forest sector was estimated to be 48,410 Gg CO2 per year in 2015. Carbon stocks and CO2 removals were estimated by separating forests that are forests remaining forests and land converted to forests. This can be expected to improve the completeness of national GHG inventory reporting.
Finally, this study assessed the potential carbon reduction for GHG mitigation of domestic forests through carbon sink activities that could contribute to national reduction targets. Based on the results of the 24th Conference of the Parties (COP), the LULUCF carbon accounting system in the PA adopted the existing methods and guidance established under the convention, and annual CO2 emissions and removals are calculated by considering forest-related activities. According to the forest management carbon accounting rules, the forest management reference levels ranged from 0 to 47,070 Gg CO2, based on the results presented in Chapter 3. The forest management ratio was calculated using a domestic forest management information system including the area in forest management, and 56% of the forest management ratio (including protected forests) was calculated. As of 2015, when the forest management reference level using the gross–net with narrow approaches is applied, the overall amount of reduction of Korean forests can contribute to the NDC target that was estimated to be 18,769 Gg CO2, meaning that they can contribute 49% to the target reduction amounts from forests and internationally transferred mitigation outcomes of 38.3 Mt CO2.

목차 (Table of Contents)

• Chapter 1. General introduction 13
• 1.1. Backgrounds 13
• 1.1.1. Role of forests on United Nations Framework Convention on Climate Change (UNFCCC) 13
• 1.1.2. Greenhouse gas inventory systems of Annex I countries 14
• 1.1.3. Greenhouse gas inventory systems in Korean forests 16
• 1.2. Research objective 17
• 1.3. Outline of study 18
• 1.4. References 19
• Chapter 2. Estimating forest carbon stocks for national greenhouse gas inventory 24
• 2.1. Introduction 24
• 2.2. Materials and Methods 27
• 2.2.1. Estimation of emission factor for deadwood carbon stocks 27
• 2.2.2. Estimating forest carbon stocks and CO2 removals 27
• 2.3. Results 32
• 2.3.1. Estimation of emission factors in deadwood 32
• 2.3.2. Estimation of forest area and growing stocks 33
• 2.3.3. Estimation of carbon stocks and their changes 35
• 2.4. Discussions 38
• 2.5. Conclusions 42
• 2.6. References 43
• Chapter 3. Recalculation of forest growing stocks for national greenhouse gas inventory 47
• 3.1. Introduction 47
• 3.2. Materials and Methods 50
• 3.2.1. Growth rate for calculating official statistics 50
• 3.2.2. Estimation of the growing stocks using the national forest inventory 52
• 3.2.3. Calibration factor estimation by overlap method 53
• 3.2.4. Calibration using yield table 53
• 3.3. Results and discussions 54
• 3.3.1. Estimation of calibration factors by overlap method 54
• 3.3.2. Calibration using yield table 55
• 3.3.3. Recalculation of historical growing stocks 57
• 3.4. Conclusions 60
• 3.5. References 61
• Chapter 4. Application of the improved forest carbon inventory for UNFCCC reporting 63
• 4.1. Introduction 63
• 4.2. Materials and Methods 65
• 4.2.1. Land-use change matrix 65
• 4.2.2. Estimation of carbon stock in forest 66
• 4.3. Results and discussion 71
• 4.3.1. Land-use change matrix 71
• 4.3.2. Estimation of annual CO2 removals and emissions in forest 75
• 4.4. Conclusions 78
• 4.5. References 79
• Chapter 5. Assessment of potential carbon reduction in forests for Nationally Determined Contribution 83
• 5.1. Introduction 83
• 5.2. Materials and Methods 85
• 5.2.1. Afforestation/reforestation 85
• 5.2.2. Deforestation 85
• 5.2.3. Forest management 86
• 5.3. Results and discussions 89
• 5.3.1. Accounting for the afforestation, reforestation and deforestation activities 89
• 5.3.2. Accounting for forest management activities 90
• 5.3.3. Potential carbon reduction 101
• 5.3.4. Suggestions for further study 102
• 5.4. Conclusions 104
• 5.5. References 105
• Chapter 6. Overall conclusions 109
• 6.1. Conclusions 109
• 6.2. Suggestions for policy 113
• 6.3. Implication for GHG inventory compiler 114
• 6.4. References 116
• Appendix A. 117
• Appendix B. 130
• Acknowledgments 135