Journal of Climate Change Research 2017, Vol. 8, No. 4, pp. 385 391 DOI: http://dx.doi.org/10.15531/ksccr.2017.8.4.385 국가산림자원조사자료를활용한강원도산림내낙엽층의탄소저장량및변화량추정 이선정 * 김래현 ** 손영모 * 임종수 * * 국립산림과학원산림산업연구과, ** 국립산림과학원연구기획과 Estimating Litter Carbon Stock and Change on Forest in Gangwon Province from the National Forestry Inventory Data Lee, Sun Jeoung *, Kim, Raehyun **, Son, Yeong Mo * and Yim, Jong Su * * Division of Forest Industry Research, National Institute of Forest Science, Seoul 02455, Korea ** Division of Research Planning and Coordination, National Institute of Forest Science, Seoul 02455, Korea ABSTRACT This study was conducted to estimate litter carbon stock change from the National Forest Inventory (NFI) data for national greenhouse gas inventory report. Litter carbon stocks were calculated from the NFI dataset in NFI5 (2008) and NFI6 (2013) in Gangwon province. Total carbon stock change of litter was 0.68±0.71 t C/ha from NFI5 (2008) to NFI6 (2013), however, there was no significant difference between the both dataset at 2008 and 2013 year. Litter carbon stock of coniferous stands was higher than deciduous stands in NFI5 (2008) and NFI6 (2013) (P<0.05). This study was limited to pilot study, so we will assess litter carbon stock using more complete data from NFI systems. It can be used as data sources for national greenhouse gas inventory report on forest sector. Key words: Carbon Stock Change, Litter, Forest Sector, LULUCF, National Forest Inventory, National Greenhouse Gas Inventory 1. 서론 2015년에파리협정이체결되면서기후변화협약에참여하는모든당사국들은전지구적온실가스감축을위하여국가별역량과다양한상황및공통의그러나차별화된책임을고려하는상향식의국가기여방안 (Nationally Determined Contributions; NDC) 방식을채택하였다. 이에따라 2020년이후부터모든당사국은온실가스감축목표를이행할책임을지게되었고, 연간국가온실가스배출량을측정가능하고제3자에의해검증이가능하도록보고해야한다 (IPCC, 2006). 기후변화협약에서낙엽층은토지이용, 토지이용변화및산림 (Land Use, Land-Use Change and Forestry; LULUCF) 의다섯가지탄소저장고중하나이다 (IPCC, 2006). 낙엽층은전체산림생태계탄소저장량의약 5% 를차지하고있고 (Pan et al., 2011), 국가 온실가스인벤토리보고와국가온실가스인벤토리감축목표설정에있어중요한요인이될수있다 (Domke et al., 2016). 대부분의부속서 I 국가들은산림부문국가온실가스인벤토리보고를위하여국가산림자원조사 (National Forest Inventory; NFI) 체계를개편하여 NFI에서수집된자료를활용하고있다 (Federal Environment Agency, 2015; Swedish Environmental Protection Agency, 2015; Statistics Finland, 2015). 특히독일과스웨덴은국가산림자원조사와토양조사자료에서수집된자료를산림부문온실가스인벤토리보고를위한기초자료로활용하고있다 (Federal Environment Agency, 2015; Swedish Environmental Protection Agency, 2015). 핀란드의경우, 토양및유기물의탄소저장량산정에 Yasso 모델을활용하고있으며, 모형의입력값으로국가산림자원조사에서수집된낙엽층자료를활용하고있다 (Statistics Finland, 2015). Corresponding author: yimjs@korea.kr Received October 19, 2017 / Revised November 1, 2017 1st, November 29, 2017 2nd / Accepted December 11, 2017
386 이선정 김래현 손영모 임종수 우리나라도산림부문국가온실가스인벤토리보고시국가산림자원조사자료를활용하고있으나, 토양, 고사목, 낙엽층의탄소저장량및온실가스흡수량은시계열활동자료및배출계수등의부재로산정하지못하고있다 (GIR, 2016). 최근우리나라의국가산림자원조사체계는 1992년리우환경개발회의 (UNCED) 이후지속가능한개발의원칙에따라지속가능한산림경영기반연구의필요성이대두됨에따라 2006년부터개편되었다 (KFRI, 2015). 개편된제5차국가산림자원조사 (2006 2010) 는계통적추출법에의해집락표본점및부표본점을전국에배치하고, 매년 20% 씩총 5년에걸쳐임분현황, 임목, 벌근및고사목, 낙엽층, 산림식생조사및토양특성조사등이조사되었고, 제6차국가산림자원조사 (2011 2015) 가완료되면서시계열자료가확보되었다 (KFS, 2016a). 국내낙엽층탄소저장량연구는특정임분의낙엽층탄소저장량연구 (Ju et al., 2015; Lee et al., 2013; Won et al., 2016) 와간벌에따른낙엽층탄소저장량의변화연구 (Kim. 2008; Ko et al., 2014; Yang et al., 2011) 등이진행되었다. 그러나기존연구는시계열적일관성및대표성등의한계로우리나라탄소변화량을추정하기에는어려움이존재한다. 따라서전국단위로시계열자료를확보할수있는제5차및제6차국가산림자원조사에서수집된낙엽층의건중량, 탄소농도등의자료를활용하여강원도산림내낙엽층의탄소저장량및변화량을산정하고, 국가온실가스인벤토리의적용가능성을검토하고자한다. 운경우부적합사유를감안하여조사구개수가변경될수있 다 (KFRI, 2008; KFS, 2012). 토양조사는제 5 차국가산림자원 조사이후 10 년주기로진행되기때문에시계열자료를확보 Fig. 1. Sampling points of NFI5 (2008) and NFI6 (2013) in Gangwon provinces. 2. 재료및방법 2.1 연구자료 본연구는우리나라전체산림면적의약 22% 를차지하는강원도산림을대상으로하였다 (KFS, 2016b). 강원도의전체면적은 2015년을기준으로 1,683천 ha이며, 산림은 1,372천 ha 로강원도전체면적의약 82% 가산림으로구성되어있다. 강원도산림면적은침엽수림이 31.8%, 활엽수림 38.4%, 그리고혼효림이 27.2% 를차지하고있으며, 전체산림면적의 57% 가 V 영급으로이루어져있다 (KFS, 2016b). 강원도낙엽층의탄소저장량및변화량을산정하기위해제5차 (2008) 및 6차 (2013) 국가산림자원조사자료를활용하였다 (Fig. 1). 국가산림자원조사의고정표본점은집락표본점으로총 4개의부표본점으로구성되어있다 (Fig. 2). 총 4개의부표본점 (S1, S2, S3, S4) 중중심표본점 (S1) 내에서 3개의조사구를설치하고, 그중 2개의지점을선택하여낙엽층과토양의시료가채취되는데현장의시료채취가불가피하게어려 Cluster plot design Fig. 2. Sampling and plot designs for the National Forest Inventory (KFRI, 2010). Journal of Climate Change Research 2017, Vol. 8, No. 4
국가산림자원조사자료를활용한강원도산림내낙엽층의탄소저장량및변화량추정 387 할수없다. 따라서제5차및 6차국가산림자원조사의중심표본점 (S1) 에서취득한 1 2개지점에서채취된낙엽층에대한탄소저장량만산정하였고 (Fig. 1), 낙엽층탄소저장량산정에활용한고정표본점의개수는 2008년에 40개 ( 침엽수림 : 6개, 활엽수림 : 23개, 혼효림 : 11개 ) 이고, 2013년도에 40개 ( 침엽수림 : 7개, 활엽수림 : 25개, 혼효림 : 8개 ) 이었으며, 낙엽층의탄소변화량을추정하기위한동일고정표본점의개수는총 38 개였다 (Table 1). 2.2 낙엽층의탄소저장량및변화량산정국가산림자원조사에서낙엽층은분해정도에따라서 L층과 FH층으로구분한다. L층은분해되지않은낙엽층이며, FH층은식물조직이분해된부식층을의미한다. 강원도산림내낙엽층의탄소저장량을산정하기위하여국가산림자원조사의 S1 표본점에서상단부로부터 L층과 FH층의모든낙엽과낙지 ( 직경 6 cm 미만 ) 를채취하였다 (Fig. 2). 시료를채취한후 80 건조기에서 24시간건조하였으며, 건중량 (dry weight) 을칭량후시료를곱게갈아원소분석기로탄소농도 (carbon content) 를측정하였다 (KFRI, 2008; KFS, 2012). 낙엽층의탄소저장량은건중량에탄소농도를곱하여산정하였으며 (Eq. 1), 탄소저장량의변화량은 2006 IPCC 가이드라인에따라산정하였다 (IPCC, 2006; KFRI, 2010). Carbon stock(t C/ha) = Dry weight (t/ha) Carbon content (C%) 100 (Eq. 1) 2.3 통계분석동일고정표본점에서발생하는탄소저장량변화량차이의유의성을검정하기위하여쌍체 t-검정 (paired t-test) 을활용하여분석하였으며, 임상별낙엽층의탄소저장량의차이는다중선형회귀모형 (General liner model) 을활용하여분산분석을수행하였다. 임상간차이를확인하기위한사후검정은 LSD 검정 (Least significant difference test) 을이용하였다. 3. 결과및고찰 3.1 강원도산림내낙엽층의탄소저장량및변화량 강원도에서제5차 (2008) 및 6차 (2013) 국가산림자원조사로수집된낙엽층의탄소저장량은 Table 1 및 Fig. 3과같다. 강원도낙엽층탄소저장량은시간이지남에따라증가하는경향을보였으며, 통계적으로유의하지는않았지만 5년동안총탄소저장량은 0.68±0.71 t C/ha의탄소가증가한것으로나타났다 (Table 1). 임분성숙에따라탄소저장량이다소증가하 Table 1. Total litter (L+FH) carbon stock and change in NFI5 (2008) and NFI6 (2013) in Gangwon province (mean±standard error) Num. of plot Forest type Age class Crown density t C/ha C (t C/ha) NFI5 NFI6 NFI5 NFI6 NFI5 (%) NFI6 (%) NFI5 NFI6 2285121 D D 51 75 76 100 5.50 3.21 2.29 2365241 D D 51 75 76 100 1.43 4.68 3.25 2684161 D D 0 25 51 75 3.73 3.62 0.11 2724681 D D 51 75 76 100 1.27 1.51 0.24 2724721 C C 51 75 51 75 5.66 4.12 1.54 2724801 C 76 100 5.72 2725001 D D 76 100 76 100 4.92 3.42 1.50 2725161 D D 76 100 76 100 5.87 1.82 4.05 2804881 M C 76 100 76 100 2.11 7.13 5.02 2844201 C C 51 75 51 75 2.85 19.80 16.94 2844521 M M 51 75 76 100 10.43 12.37 1.94 2884761 D D 51 75 76 100 1.32 2.36 1.04 http://www.ekscc.re.kr
388 이선정 김래현 손영모 임종수 Table 1. Continued Num. of plot Forest type Age class Crown density t C/ha C (t C/ha) NFI5 NFI6 NFI5 NFI6 NFI5 (%) NFI6 (%) NFI5 NFI6 2924241 D D 76 100 76 100 5.62 6.41 0.79 2924641 D D 51 75 76 100 4.26 3.17 1.10 2924961 D D 51 75 76 100 1.80 5.00 3.20 2925081 M M 76 100 76 100 1.47 4.40 2.93 2964281 D D 51 75 76 100 4.70 4.03 0.67 2964321 D D 51 75 76 100 1.77 7.56 5.79 3164481 D D 76 100 76 100 2.55 2.41 0.13 3164841 D D 26 50 51 75 4.01 2.25 1.76 3165201 M D 51 75 76 100 5.58 5.50 0.08 3205121 D D 76 100 51 75 1.78 3.32 1.54 3205361 D 76 100 3.28 3205561 M 51 75 3.16 3285041 D D 51 75 76 100 3.28 6.00 2.73 3285241 D D 51 75 76 100 3.29 4.12 0.83 3364601 C C 76 100 76 100 4.44 5.32 0.88 3404441 D D 76 100 76 100 2.65 4.43 1.78 3484921 M M 51 75 76 100 5.59 4.06 1.52 3524121 M M 76 100 76 100 2.07 9.21 7.14 3524161 D D 51 75 76 100 1.14 8.20 7.06 3564401 D D 76 100 76 100 1.93 5.18 3.26 3604361 C C 51 75 76 100 8.02 5.39 2.63 3604561 D 76 100 2.37 3684081 D D 51 75 76 100 4.92 3.44 1.47 3724241 D D 0 25 76 100 5.61 3.11 2.50 3724721 C C 76 100 76 100 6.28 4.03 2.25 3764041 M D 76 100 76 100 19.00 7.49 11.51 3764521 C M 51 75 76 100 9.22 6.06 3.16 3804281 M M 76 100 76 100 4.72 4.34 0.38 3804641 M M 51 75 76 100 7.08 3.49 3.58 3924321 M M 76 100 76 100 4.34 5.94 1.60 C: Coniferous, D: Deciduous, M: Mixed. Mean 4.47±0.51 5.15±0.51 0.68±0.71 Journal of Climate Change Research 2017, Vol. 8, No. 4
국가산림자원조사자료를활용한강원도산림내낙엽층의탄소저장량및변화량추정 389 Fig. 3. Litter (L+FH) carbon stock on Forest type in NFI5 (2008) and NFI6 (2013) in Gangwon province. Values with different indicated significant differences among three forest types on each NFI data at P<0.05. Horizontal bar indicates on standard error (NFI5: coniferous n=6, deciduous n=23, mixed n=11, NFI6: coniferous n= 7, deciduous n=25, mixed=8). 였는데, 이는성숙한임분에서잔뿌리및목질부의수피등이 증가하여낙엽층의탄소량이증가된다는연구결과 (Schulp et al., 2008) 와유사한경향을나타내고있다. 반면, 터키의구주 소나무를대상으로토양탄소저장량을 200 년간모의한자료에 의하면임령이증가함에따라낙엽층 (O 층 ) 의탄소저장량은 감소하지만, 일정임령을기준으로서서히증가하는연구결과 (Lee et al., 2016) 와는차이를나타내고있다. 본연구에서는 통계적으로유의하지않지만낙엽층의탄소저장량이시간에 따라증가하는경향인것은임분성숙과관련이있을것으로 판단된다. 실제로제 5 차 (2008) 및 6 차 (2013) 국가산림자원조 사고정표본점의수관밀도및영급분포변화정보를분석한결 과, 제 6 차국가산림자원조사자료의약 88% 가 76 100% 수 관밀도와 4 영급이상의임분으로변화된것을확인할수있 었다 (Table 2). 낙엽층의탄소저장량은조사지점및모형의구조에따라 변이가매우크고, 영향을미치는요인들도수종, 낙엽층두께, 경사, 모재, 산림경영활동등으로다양하다 (Ko et al. 2014, Gruneberg et al., 2014; Schulp et al., 2008). 국가산림자원조사에서조사되는간벌등시업이력자료를활용해시업에따른낙엽층의탄소저장량변화를분석하려하였으나, 전체 80 개표본점중 7개표본점에서만숲가꾸기및조림등이이루어진것으로나타나정확한원인분석을수행하기어려웠다. 정확한탄소저장량변화의원인을구명하기위해서는표본점내기초정보및변화에대한지속적인모니터링과이력관리가필요한것으로판단된다. 강원도의낙엽층탄소저장량은임상별로차이가있는것으로나타났다. 제5차및 6차국가산림자원조사에서임상별낙엽층탄소저장량은침엽수림, 혼효림, 그리고활엽수림순으로나타났다 (Fig. 3). 제5차 (2008) 및 6차 (2013) 국가산림자원조사에서모두침엽수림에해당하는표본점의낙엽층탄소저장량 (NFI5: 6.08±0.95 t C/ha, NFI6: 7.36±2.11 t C/ha) 이활엽수림 (NFI5: 3.33±0.34 t C/ha, NFI6: 4.19±0.37 t C/ha) 의탄소저장량보다높게나타났으며, 통계적으로유의한차이를보였다 (Fig. 3, P<0.05). 이전연구에서도이와동일한연구결과가보고된바있으며 (KFS and Kopfi, 2013; Schulp et al. 2008), 일반적으로침엽수림의낙엽층은활엽수림의낙엽층보다분해하기어려운물질도구성되어있기때문이다 (Berg, 2000). 또한침엽수림의토양은활엽수림의토양보다 ph가낮아토양내미생물의활동이감소하여부식층보다건전한잎으로구성된낙엽이더많이존재한결과로판단된다 (Thuille and Schulze, 2006). 따라서침엽수림의낙엽층탄소저장량은활엽수림보다많으며, 높은탄소고정효과를가진다고할수있다. 그러나그외탄소저장고인바이오매스와토양의경우단위면적당탄소저장량및배출계수등은활엽수림에서침엽수림보다높은것으로알려져있기때문에 (KFS and Kopfi, 2013; GIR, 2016), 향후산림의전체탄소저장고에대한탄소저장량평가연구가필요한것으로판단된다. 3.2 산림부문국가온실가스인벤토리보고의적용가능성검토국가온실가스인벤토리의산정수준은 Tier 1 3 로구분하 Table 2. Frequency table of crown density and age class in NFI5 (2008) and NFI6 (2013) on Gangwon province Crown density Age class 50 51 75% 76 100% Total Total NFI5 3 21 16 40 23 17 0 40 NFI6 0 5 35 40 5 27 8 40 http://www.ekscc.re.kr
390 이선정 김래현 손영모 임종수 고있으며, Tier 수준이낮을수록국가온실가스인벤토리산정의필수요소인활동자료와배출계수의자료의신뢰성이상대적으로낮다 (IPCC, 2003). IPCC 가이드라인에따르면산림부문의낙엽층의탄소저장량을산정하는경우, Tier 1은낙엽층의탄소저장량의변화가없다고가정하고 0으로보고하는것이며, Tier 2의경우국가자료를활용해축적차이법에의해탄소변화량을산정하는것이며, Tier 3은모델을활용해탄소저장량변화를모의하는것이다 (IPCC, 2003; 2006). 국가산림자원조사자료를활용하여낙엽층의탄소저장량및변화량을추정하는것은 Tier 2에해당하는것이다. 일부국가들도산림의낙엽층탄소저장량및변화량산정시자국의국가산림자원조사를활용하고있다 (Federal Environment Agency, 2015, Statistics Finland, 2015). 국가산림자원조사는고정표본점에서조사가이루어지기때문에시계열적자료확보가가능하며낙엽층의탄소변화량을모의하기에적합하다. 또한국가산림자원조사의자료는토양및고사유기물을모의할수있는 Tier 3을위한모형의기초자료로활용될수있으며, 모형의적합도를높일수있다 (Schulp et al,. 2008). 국가산림자원조사에서수집된낙엽층자료는국가온실가스인벤토리산정에충분히적용될수있는것으로판단되지만, 본연구는강원도를대상으로한시범연구로향후전국단위의탄소저장량산정이이루어진후에국가온실가스인벤토리에적용이가능할것판단된다. 다만, 우리나라전체낙엽층의탄소저장량을산정하기위해서는토지이용변화매트릭스에의한임상별산림면적자료가확보되어야하며, 다양한산림유형에따른낙엽층의탄소순환에대한변화를추적하기위한지속적인모니터링이필요한것으로판단된다. 4. 결론 본연구는시계열로수집된국가산림자원조사자료를활용하여낙엽층의탄소저장량및변화량을산정하고, 국가온실가스인벤토리의적용가능성을검토하기위하여수행되었다. 제5차및제6차국가산림자원조사의 2008년및 2013년도에수집된강원도지역의고정표본점을대상으로낙엽층의탄소저장량변화량을산정한결과, 통계적으로유의하지는않지만 5년동안낙엽층의탄소저장량은 0.68±0.71 t C/ha 증가한것으로나타났다. 또한침엽수림의탄소저장량이활엽수림의탄소저장량보다높은것으로나타났으며, 이전연구와동일한경향인것으로나타났다. 부속서 I 국가들은국가온실가스인벤토리보고시국가의현실상황을잘반영하고, 측정 보고 검증 (MRV) 이가능하도록보고하기위해국가산림자원 조사에의해주기적으로수집되는자료를활용하고있다. 즉, 국가온실가스인벤토리보고에는국가의산림상황을잘반영하여주기적으로정확하게수집된자료를활용하는것이중요하다. 따라서국가온실가스인벤토리보고시낙엽층의탄소변화량을보고하기위한하나의방안으로국가산림자원조사자료의활용을제시할수있을것으로판단된다. 본연구는현재까지국내국가온실가스인벤토리보고서에서보고되지않은낙엽층의탄소저장량산정방안으로국가산림자원조사자료의활용성을검토한시범연구로국가온실가스인벤토리에바로적용하기에는무리가있다. 따라서향후전국단위의표본점을대상으로탄소변화량평가연구를수행한다면국가온실가스인벤토리보고수준 Tier 2에준하는자료로활용될수있을것으로판단된다. 감사의글 본연구는 국립산림과학원일반과제 ( 국가산림자원조사자료의융복합활용기술개발 ) 및 산림청 ( 한국임업진흥원 ) 산림과학기술연구개발사업 ( 신기후체제대응산림분야국가온실가스인벤토리산정체계및탄소계정고도화연구 : 2017-044B10-1719-BB01) 의지원으로수행되었습니다. REFERENCES Berg B. 2000. Litter decomposition and organic matter turnover in northern forest soils. Forest Ecology and Management 133:13-22. Domke GM, Perry CH, Walters BF, Woodall CW, Russell MB, Smith JE. 2016. Estimating litter carbon stocks on forest land in the United States. Science of the Total Environment 557-558:469-478. Federal Environment Agency. 2015. Submission under the united nations framework convention on climate change and the Kyoto Protocol 2015. Federal Environment Agency. Dessau, Germany. GIR (Greenhouse Gas Inventory & Research Center of Korea). 2016. National greenhouse gas inventory report 2016. GIR. Seoul, Korea. (In Korean). Gruneberg E, Ziche D, Wellbrock N. 2014. Organic carbon stocks and sequestration rates of forest soils in Germany. Global Change Biology 20:2644-2662. IPCC. 2003. Good practice guidance for land use, land-use Journal of Climate Change Research 2017, Vol. 8, No. 4
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