Estimation of carbon budget change in South and North Korea by land cover change : using VISIT model and land cover map

다국어 초록 (Multilingual Abstract)

In order to manage and reduce carbon dioxide emission, it is necessary to quantify carbon emission caused by human and carbon uptake from terrestrial ecosystem. In this study, the ecosystem model (Vegetation Integrated Simulator for Trace gases, VISIT) was used to elucidate the variation in carbon budget due to land cover change by quantifying the carbon budget of North and South Korea. The key findings are as follows.
(1) Carbon budget of North and South Korea was quantified for the past 30 years. Net ecosystem production (NEP) was estimated as 10.72 ± 5.18 Tg C yr-1(0.83 Mg C ha-1yr-1) in the 1980s, 3.00 ± 7.96 Tg C yr-1 (0.23 Mg C ha-1 yr-1)in the 1990s, and -0.46 ± 5.13 Tg C yr-1(-0.04 Mg C ha-1 yr-1) in the 2000s, which showed that North Korea was changed to a carbon source from sink. In South Korea, NEP was 10.55 ± 1.09 Tg C yr-1(1.09 Mg C ha-1 yr-1) in the 1980s, 10.47 ± 7.28 Tg C yr-1 (1.09 Mg C ha-1 yr-1) in the 1990s, and 6.32 ± 5.02 Tg C yr-1(0.66 Mg C ha-1 yr-1) in the 2000s showing a gradual decrease of carbon uptake.
(2) As a result of the estimate of carbon budget by land cover change, in North Korea, carbon uptake declined by approximately 0.52 Tg C yr-1 (0.04 Mg C ha-1 yr-1) in the 1990s due to the decrease in forest area while carbon emission increased by 0.36 Tg C yr-1 (0.03 Mg C ha-1 yr-1) in the 2000s due to the increase of cropland. In South Korea, carbon uptake in the 1990s decreased by about 0.24 Tg C yr-1 (0.02 Mg C ha-1 yr-1) due to the increase of urban area while it increased by 0.04 Tg C yr-1 (0.01 Mg C ha-1 yr-1)due to the increase in the forest area.
(3) In order to estimate carbon budget of the Korean peninsula more exactly, tree growth rate was considered for revising the model-estimated carbon budget. As a result, when considering the tree growth rate of 6% in South Korea, the carbon uptake was estimated at about 1.11 Mg C ha-1 yr-1 in the 1990s and about 0.69 Mg C ha-1 yr-1 in the 2000s. In North Korea, when considering the tree growth rate of 3%, the carbon uptake in the 1990s was estimated at about 0.25 Mg C ha-1 yr-1 and emission in the 2000s was about 0.03 Mg C ha-1 yr-1.
As shown above, this study conducted the spatiotemporal analysis of carbon budget in each period and quantified carbon budget change by land cover change. Moreover, this result was revised using the tree growth rate. These results suggested the importance of land cover management in the terrestrial ecosystem for ensuring national carbon balance.

목차 (Table of Contents)

• Table of Contents
• Chapter1. Introduction 1
• Chapter2. Material and methods 11
• 2.1 Study area 11
• 2.2 The VISIT model 14
• 2.2.1 Mechanism of the VISIT model 15
• 2.2.2 Input data preparation 20
• 2.2.3 Model validation 23
• 2.3 Carbon budget in South and North Korea 25
• 2.3.1 Carbon budget in the past 30 years 27
• 2.3.2 Carbon budget change by land cover change 28
• 2.3.3 Significance test of carbon budget change through t-test 29
• 2.3.4 Correction of forest carbon stock 30
• Chapter3. Results 32
• 3.1 Results of validation 32
• 3.1.1 Comparison of GPP and NPP 32
• 3.1.2 Validation using observation data 35
• 3.2 Land cover change in South and North Korea 39
• 3.3 Result of carbon budget in South and North Korea 43
• 3.3.1 Result of carbon budget 43
• 3.3.2 Result of carbon budget change by land cover change 46
• 3.3.3 Result of significance t-test 50
• 3.4 Spatial distribution of the carbon budget change 53
• 3.5 Correction of forest carbon stock 61
• 3.5.1 Forest growing stock estimated by the model 61
• 3.5.2 Changes of the annual forest growing stock in South Korea 63
• 3.5.3 Changes of the annual forest growing stock in North Korea 66
• Chapter4. Discussion 71
• 4.1 Comparison of carbon budget change 71
• 4.2 Limitation in our framework and subsequent researches 73
• Chapter5. Conclusions 79
• Reference 81