Korean Journal of Agricultural and Forest Meteorology (한국농림기상학회지)

Korean Society of Agricultural and Forest Meteorology (한국농림기상학회)
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The Dynamics of CO2 Budget in Gwangneung Deciduous Old-growth Forest: Lessons from the 15 years of Monitoring

광릉 낙엽활엽수 노령림의 CO2 수지 역학: 15년 관측으로부터의 교훈

  • Yang, Hyunyoung (Interdisciplinary Program in Agricultural & Forest Meteorology, Seoul National University) ;
  • Kang, Minseok (National Center for AgroMeteorology) ;
  • Kim, Joon (Interdisciplinary Program in Agricultural & Forest Meteorology, Seoul National University) ;
  • Ryu, Daun (Interdisciplinary Program in Agricultural & Forest Meteorology, Seoul National University) ;
  • Kim, Su-Jin (Forest Ecology Division, National Institute of Forest Science) ;
  • Chun, Jung-Hwa (Forest ICT Research Center, National Institute of Forest Science) ;
  • Lim, Jong-Hwan (Forest Ecology Division, National Institute of Forest Science) ;
  • Park, Chan Woo (Forest Ecology Division, National Institute of Forest Science) ;
  • Yun, Soon Jin (Forest Ecology Division, National Institute of Forest Science)
  • 양현영 (서울대학교 협동과정 농림기상학전공) ;
  • 강민석 (국가농림기상센터) ;
  • 김준 (서울대학교 협동과정 농림기상학전공) ;
  • 류다운 (서울대학교 협동과정 농림기상학전공) ;
  • 김수진 (국립산림과학원 산림생태연구과) ;
  • 천정화 (국립산림과학원 산림ICT연구센터) ;
  • 임종환 (국립산림과학원 산림생태연구과) ;
  • 박찬우 (국립산림과학원 산림생태연구과) ;
  • 윤순진 (국립산림과학원 산림생태연구과)
  • Received : 2021.12.01
  • Accepted : 2021.12.28
  • Published : 2021.12.30
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Abstract

After large-scale reforestation in the 1960s and 1970s, forests in Korea have gradually been aging. Net ecosystem CO2 exchange of old-growth forests is theoretically near zero; however, it can be a CO2 sink or source depending on the intervention of disturbance or management. In this study, we report the CO2 budget dynamics of the Gwangneung deciduous old-growth forest (GDK) in Korea and examined the following two questions: (1) is the preserved GDK indeed CO2 neutral as theoretically known? and (2) can we explain the dynamics of CO2 budget by the common mechanisms reported in the literature? To answer, we analyzed the 15-year long CO2 flux data measured by eddy covariance technique along with other biometeorological data at the KoFlux GDK site from 2006 to 2020. The results showed that (1) GDK switched back-and-forth between sink and source of CO2 but averaged to be a week CO2 source (and turning to a moderate CO2 source for the recent five years) and (2) the interannual variability of solar radiation, growing season length, and leaf area index showed a positive correlation with that of gross primary production (GPP) (R2=0.32~0.45); whereas the interannual variability of both air and surface temperature was not significantly correlated with that of ecosystem respiration (RE). Furthermore, the machine learning-based model trained using the dataset of early monitoring period (first 10 years) failed to reproduce the observed interannual variations of GPP and RE for the recent five years. Biomass data analysis suggests that carbon emissions from coarse woody debris may have contributed partly to the conversion to a moderate CO2 source. To properly understand and interpret the long-term CO2 budget dynamics of GDK, new framework of analysis and modeling based on complex systems science is needed. Also, it is important to maintain the flux monitoring and data quality along with the monitoring of coarse woody debris and disturbances.

1960-70년대 대규모 산림녹화 이후에 한국의 산림은 점차 노령화되고 있다. 노령림의 순 CO2 교환은 이론적으로 중립에 가깝지만, 교란이나 관리에 의해 CO2 흡원 또는 발원이 될 수 있다. 본 연구는 한국의 광릉 낙엽활엽수 노령림(GDK)의 CO2 수지 역학을 이해함으로써, 다음 두 가지 질문에 답하고자 하였다: (1) 보전되고 있는 GDK는 과연 이론적으로 알려져 있는 CO2 중립인가? (2) 관측된 CO2 수지의 경년 변동이 문헌에 보고된 조절 인자들과의 선형적인 인과관계로 설명이 가능한가? 이에 답하기 위해, 본 연구는 KoFlux GDK 관측지에서 에디 공분산 기술로 2006년부터 2020년까지 15년 동안 관측된 CO2 플럭스 자료와 생기상학적 자료를 분석하였다. 연구 결과, (1) GDK는 15년 자료를 평균해서 보면 약한 CO2 발원이며, 관측기간 동안 흡원과 발원 사이를 오갔으나 최근 5년 동안 CO2 발원으로서의 강도가 증가하고 있다. (2) 전천일사, 생장기간, 엽면적지수의 경년 변동은 총 일차생산량(Gross Primary Production, GPP)의 경년변동과 양의 상관관계(R2=0.32~0.45)가 있는 반면, 기온과 지표면 온도의 경년 변동은 생태계 호흡(Ecosystem Respiration, RE)의 경년 변동과 유의한 상관관계가 없었다. 또한, 관측기간 초반(첫 10년)의 CO2 플럭스와 기상요인 및 생물학적 요인으로 학습시킨 기계학습은 관측기간 후반(최근 5년)의 GPP와 RE의 경년 변동을 제대로 모사해내지 못했다. 단, 고사목에서 배출된 탄소 추정량이 CO2 발원으로의 전환에 일부 기여했을 것으로 추정된다. GDK의 장기 CO2 수지 역학에 대해 올바로 이해하고 해석하기 위해서는, 분석과 모델링을 위한 복잡계과학 기반의 새로운 프레임워크가 필요하다. 더불어, 플럭스 모니터링 및 자료 품질 유지와 함께 고사목과 교란을 지속적으로 모니터링하는 것이 중요함을 다시 한 번 확인하였다.

Keywords

Acknowledgement

본 연구는 국립산림과학원의 2021년도 주요 산림생태계 플럭스 타워 관측망 유지보수 및 자료품질 관리 사업과, 서울대학교 아시아연구소의 2021년도 아시아연구기반구축 사업의 지원을 받아 수행되었습니다. 연속적인 자료 수집과 관측소 관리에 헌신해 주신 모든 KoFlux 구성원분들께 감사드립니다. 중요한 지적과 제안을 해주신 심사위원들께 감사드립니다.

References

  1. Baldocchi, D., H. Chu, and M. Reichstein, 2018: Inter-annual variability of net and gross ecosystem carbon fluxes: A review. Agricultural and Forest Meteorology 249, 520-533. https://doi.org/10.1016/j.agrformet.2017.05.015
  2. Besnard, S., N. Carvalhais, M. A. Arain, A. Black, S. de Bruin, N. Buchmann, A. Cescatti, J. Chen, J. G. P. W. Clevers, A. R. Desai, C. M. Gough, K. Havrankova, M. Herold, L. Hortnagl, M. Jung, A. Knohl, B. Kruijt, L. Krupkova, B. E. Law, A. Lindroth, A. Noormets, O. Roupsard, R. Steinbrecher, A. Varlagin, C. Vincke, and M. Reichstein, 2018: Quantifying the effect of forest age in annual net forest carbon balance. Environmental Research Letters 13(12), 124018. https://doi.org/10.1088/1748-9326/aaeaeb
  3. Burba, G. G., D. K. McDermitt, A. Grelle, D. J. Anderson, and L. Xu, 2008: Addressing the influence of instrument surface heat exchange on the measurements of CO2 flux from open-path gas analyzers. Global Change Biology 14(8), 1854-1876. https://doi.org/10.1111/j.1365-2486.2008.01606.x
  4. Cho, S., M. Kang, K. Ichii, J. Kim, J.-H. Lim, J.-H. Chun, C.-W. Park, H. S. Kim, S.-W. Choi, S.-H. Lee, Y. M. Indrawati, and Jongho Kim, 2021a: Evaluation of forest carbon uptake in South Korea using the national flux tower network, remote sensing, and data-driven technology. Agricultural and Forest Meteorology 311, 108653. https://doi.org/10.1016/j.agrformet.2021.108653
  5. Cho, Y.-C., H.-B. Lee, H.-G. Kim, D.-H. Lee, and H.-C. Kim, 2020: Annual report on Gwangneung forest and Experimental forests 2019. Korea National Arboretum.
  6. Cho, Y., H. Kim, S. Jung, H. Sim, D. Lee, J. Kim, J. Cho, K. Bae, J. Kim, and T. Kim, 2021b: Annual report on Gwangneung Forest and experimental forests 2020. Korea National Arboretum.
  7. Cho, Y. C., B. Y. Goo, J. G. Shin, S. S. kIM, K. W. Park, S. H. Oh, and Y. M. Lee, 2012: Changing environment and biodiversity in Gwangneung forest. Korea National Arboretum.
  8. Choung, Y., J. Lee, S. Cho, and J. Noh, 2020: Review on the succession process of Pinus densiflora forests in South Korea: progressive and disturbance-driven succession. Journal of Ecology and Environment 44(1), 16. https://doi.org/10.1186/s41610-020-0150-3
  9. Chun, J. H., J. H. Lim, and D. K. Lee, 2007: Biomass Estimation of Gwangneung Catchment Area with Landsat ETM+ Image. Journal of Korean Society of Forest Science 96(5), 591-607.
  10. Clusener-Godt, M., 2020: A message from the Secretary of UNESCO's Man and the Biosphere (MAB)Programme, Miguel Clusener-Godt, on the COVID-19 crisis. UNESCO.
  11. Coursolle, C., H. A. Margolis, M. A. Giasson, P. Y. Bernier, B. D. Amiro, M. A. Arain, A. G. Barr, T. A. Black, M. L. Goulden, J. H. McCaughey, J. M. Chen, A. L. Dunn, R. F. Grant, and P. M. Lafleur, 2012: Influence of stand age on the magnitude and seasonality of carbon fluxes in Canadian forests. Agricultural and Forest Meteorology 165, 136-148. https://doi.org/10.1016/j.agrformet.2012.06.011
  12. Curtis, P. S., and C. M. Gough, 2018: Forest aging, disturbance and the carbon cycle. 219(4), 1188-1193. https://doi.org/10.1111/nph.15227
  13. Froelich, N., H. Croft, J. M. Chen, A. Gonsamo, and R. M. Staebler, 2015: Trends of carbon fluxes and climate over a mixed temperate-boreal transition forest in southern Ontario, Canada. Agricultural and Forest Meteorology 211-212(15), 72-84. https://doi.org/10.1016/j.agrformet.2015.05.009
  14. Gao, S., T. Zhou, X. Zhao, D. Wu, Z. Li, H. Wu, L. Du, and H. Luo, 2016: Age and climate contribution to observed forest carbon sinks in East Asia. Environmental Research Letters 11(3), 034021. https://doi.org/10.1088/1748-9326/11/3/034021
  15. Gough, C. M., P. S. Curtis, B. S. Hardiman, C. M. Scheuermann, and B. Bond-Lamberty, 2016: Disturbance, complexity, and succession of net ecosystem production in North America's temperate deciduous forests. Ecosphere 7(6), e01375. https://doi.org/10.1002/ecs2.1375
  16. Goulden, M. L., A. M. S. McMillan, G. C. Winston, A. V. Rocha, K. L. Manies, J. W. Harden, and B. P. Bond-Lamberty, 2011: Patterns of NPP, GPP, respiration, and NEP during boreal forest succession. Global Change Biology 17(2), 855-871. https://doi.org/10.1111/j.1365-2486.2010.02274.x
  17. Guan, D.-X., J.-B. Wu, X.-S. Zhao, S.-J. Han, G.-R. Yu, X.-M. Sun, and C.-J. Jin, 2006: CO2 fluxes over an old, temperate mixed forest in northeastern China. Agricultural and Forest Meteorology 137(3), 138-149. https://doi.org/10.1016/j.agrformet.2006.02.003
  18. Gundersen, P., E. E. Thybring, T. Nord-Larsen, L. Vesterdal, K. J. Nadelhoffer, and V. K. Johannsen, 2021: Old-growth forest carbon sinks overestimated. Nature 591(7851), E21-E23. https://doi.org/10.1038/s41586-021-03266-z
  19. Hong, J.-K., H.-J. Kwon, J.-H. Lim, Y.-H. Byun, J.-H. Lee, and J. Kim, 2009: Standardization of KoFlux eddy-covariance data processing. Korean Journal of Agricultural and Forest Meteorology 11(1), 19-26. https://doi.org/10.5532/KJAFM.2009.11.1.019
  20. Hong, J., and J. Kim, 2011: Impact of the Asian monsoon climate on ecosystem carbon and water exchanges: a wavelet analysis and its ecosystem modeling implications. Global Change Biology 17(5), 1900-1916. https://doi.org/10.1111/j.1365-2486.2010.02337.x
  21. Huete, A., K. Didan, T. Miura, E. P. Rodriguez, X. Gao, and L. G. Ferreira, 2002: Overview of the radiometric and biophysical performance of the MODIS vegetation indices. Remote Sensing of Environment 83(1), 195-213. https://doi.org/10.1016/S0034-4257(02)00096-2
  22. Kang, M.-S., H.-J. Kwon, J.-H. Lim, and J. Kim, 2009: Understory evapotranspiration measured by eddy-covariance in Gwangneung deciduous and coniferous forests. Korean Journal of Agricultural Forest and Meteorology 11(4), 233-246. https://doi.org/10.5532/KJAFM.2009.11.4.233
  23. Kang, M., K. Ichii, J. Kim, Y. M. Indrawati, J. Park, M. Moon, J.-H. Lim, and J.-H. Chun, 2019a: New Gap-Filling Strategies for Long-Period Flux Data Gaps Using a Data-Driven Approach. Atmosphere 10(10), 568. https://doi.org/10.3390/atmos10100568
  24. Kang, M., J. Kim, S.-H. Lee, J. Kim, J.-H. Chun, and S. Cho, 2018: Changes and improvements of the standardized eddy covariance data processing in KoFlux. Korean Journal of Agricultural Forest and Meteorology 20(1), 5-17. https://doi.org/10.5532/KJAFM.2018.20.1.5
  25. Kang, M., J. Kim, H. Yang, J.-H. Lim, J.-H. Chun, and M. Moon, 2019b: On securing continuity of long-term observational eddy flux data: Field intercomparison between open-and enclosed-path gas analyzers. Korean Journal of Agricultural Forest and Meteorology 21(3), 135-145. https://doi.org/10.5532/KJAFM.2019.21.3.135
  26. Kang, M., B. L. Ruddell, C. Cho, J. Chun, and J. Kim, 2017: Identifying CO2 advection on a hill slope using information flow. Agricultural and Forest Meteorology 232, 265-278. https://doi.org/10.1016/j.agrformet.2016.08.003
  27. KFS (Korea Forest Service), 2018: The 2nd Comprehensive Plan for Improving Carbon Sinks (2018-2022).
  28. KFS (Korea Forest Service), 2019a: Firest Geospatial Information Service.
  29. KFS (Korea Forest Service), 2019b: National Forest Culture Resource: Anmyeondo Pine Forest.
  30. Kim, J., D. Lee, J. Hong, S. Kang, S.-J. Kim, S.-K. Moon, J.-H. Lim, Y. Son, J. Lee, S. Kim, N. Woo, K. Kim, B. Lee, B.-L. Lee, and S. Kim, 2006: HydroKorea and CarboKorea: cross-scale studies of ecohydrology and biogeochemistry in a heterogeneous and complex forest catchment of Korea. Ecological Research 21(6), 881-889. https://doi.org/10.1007/s11284-006-0055-3
  31. Kim, S. J., J. Kim, and K. Kim, 2010: Organic carbon efflux from a deciduous forest catchment in Korea. Biogeosciences 7(4), 1323-1334. https://doi.org/10.5194/bg-7-1323-2010
  32. Kitamura, K., Y. Nakai, S. Suzuki, Y. Ohtani, K. Yamanoi, and T. Sakamoto, 2012: Interannual variability of net ecosystem production for a broadleaf deciduous forest in Sapporo, northern Japan. Journal of Forest Research 17(3), 323-332. https://doi.org/10.1007/s10310-012-0335-4
  33. KNA (Korea National Arboretum), 2020: Regular Review Report of the Gwangneung Forest Biosphere Reserve.
  34. Kosugi, Y., H. Tanaka, S. Takanashi, N. Matsuo, N. Ohte, S. Shibata, and M. Tani, 2005: Three years of carbon and energy fluxes from Japanese evergreen broad-leaved forest. Agricultural and Forest Meteorology 132(3), 329-343. https://doi.org/10.1016/j.agrformet.2005.08.010
  35. Kwon, H., K. J, J. Hong, and J.-H. Lim, 2010a: Influence of the Asian monsoon on net ecosystem carbon exchange in two major ecosystems in Korea. Biogeosciences 7, 1493-1504. https://doi.org/10.5194/bg-7-1493-2010
  36. Kwon, H., J. Kim, J. Hong, and J. H. Lim, 2010b: Influence of the Asian monsoon on net ecosystem carbon exchange in two major ecosystems in Korea. Biogeosciences 7(5), 1493-1504. https://doi.org/10.5194/bg-7-1493-2010
  37. Law, B. E., O. J. Sun, J. Campbell, S. Van Tuyl, and P. E. Thornton, 2003: Changes in carbon storage and fluxes in a chronosequence of ponderosa pine. Global Change Biology 9(4), 510-524. https://doi.org/10.1046/j.1365-2486.2003.00624.x
  38. Lee, D.-H., J. Kim, S.-J. Kim, S.-K. Moon, J.-S. Lee, J.-H. Lim, Y.-H. Son, S.-K. Kang, S.-H. Kim, and K.-H. Kim, 2007: Lessons from cross-scale studies of water and carbon cycles in the Gwangneung forest catchment in a complex landscape of monsoon Korea. Korean Journal of Agricultural and Forest Meteorology 9(2), 149-160. https://doi.org/10.5532/KJAFM.2007.9.2.149
  39. Lee, H., 2011: The Estimation of Climax Index for Deciduous Tree Species by Ecomorphological Factors. Department of Forest Management, Graduate School, Kangwon National University.
  40. Lee, M.-S., J.-S. Lee, and H. Koizumi, 2008: Temporal variation in CO2 efflux from soil and snow surfaces in a Japanese cedar (Cryptomeria japonica) plantation, central Japan. Ecological Research 23(4), 777-785. https://doi.org/10.1007/s11284-007-0439-z
  41. Lee, M., B. Kwon, S.-g. Kim, T. K. Yoon, Y. Son, and M. J. Yi, 2019: Coarse Woody Debris (CWD) Respiration Rates of Larix kaempferi and Pinus rigida: Effects of Decay Class and Physicochemical Properties of CWD. Journal of Korean Society of Forest Science 108(1), 40-49. https://doi.org/10.14578/JKFS.2019.108.1.40
  42. Lee, Y. G., M. S. Won, S. J. Kim, and H. J. Yoon, 2020: Mid-to-Long term Forest Resource Management Research Direction (2021~2040). National Institue of Forest Science.
  43. Lim, J.-H., J. H. Shin, G. Z. Jin, J. H. Chun, and J. S. Oh, 2003: Forest stand structure, site characteristics and carbon budget of the Kwangneung natural forest in Korea. Korean Journal of Agricultural and Forest Meteorology 5(2), 101-109.
  44. Luyssaert, S., E. D. Schulze, A. Borner, A. Knohl, D. Hessenmoller, B. E. Law, P. Ciais, and J. Grace, 2008: Old-growth forests as global carbon sinks. Nature 455(7210), 213-215. https://doi.org/10.1038/nature07276
  45. Mizoguchi, Y., Y. Ohtani, S. Takanashi, H. Iwata, Y. Yasuda, and Y. Nakai, 2012: Seasonal and interannual variation in net ecosystem production of an evergreen needleleaf forest in Japan. Journal of Forest Research 17(3), 283-295. https://doi.org/10.1007/s10310-011-0307-0
  46. Moon, G. H., and J. S. Yim, 2021: Changes in Carbon Stocks of Coarse Woody Debris in National Forest Inventories: Focus on Gangwon Province. Journal of Korean Society of Forest Science 110(2), 233-243. https://doi.org/10.14578/JKFS.2021.110.2.233
  47. Odum, E. P., 1969: The Strategy of Ecosystem Development. Science 164(3877), 262-270. https://doi.org/10.1126/science.164.3877.262
  48. Ohtani, Y., N. Saigusa, S. Yamamoto, Y. Mizoguchi, T. Watanabe, Y. Yasuda, and S. Murayama, 2005: Characteristics of CO2 fluxes in cool-temperate coniferous and deciduous broadleaf forests in Japan. 6th International Symposium on Plant Responses to Air Pollution 45, 73-80.
  49. Ohtsuka, T., 2003: The origin of pine forest on ken-marubi lava flow on the lower slopes of Mt. Fuji. Veg Sci 20, 43-54.
  50. Park, C. W., J. H. Chun, J. H. Lim, S. H. Kim, C. Y. Park, H. M. Yang, J. H. Seoung, J. H. Oh, and ... 2018: A Research on the Establishment of Foundation for Forest Long-term Ecologial Information and Big data (2014-2018). National Institute of Forest Science.
  51. Park, H., B. H. Jeong, K. D. Kim, J. H. Shin, H. Han, S. M. Lee, J. Y. Jang, R. H. Yu, J. H. Park, J. H. Kim, and Y. H. Kim, 2020: 2020 Forestry Prospect. National Institute of Forest Science.
  52. Peres, L. F., and C. C. DaCamara, 2005: Emissivity maps to retrieve land-surface temperature from MSG/SEVIRI. IEEE Transactions on Geoscience and Remote Sensing 43(8), 1834-1844. https://doi.org/10.1109/TGRS.2005.851172
  53. Pilegaard, K., A. Ibrom, M. S. Courtney, P. Hummelshoj, and N. O. Jensen, 2011: Increasing net CO2 uptake by a Danish beech forest during the period from 1996 to 2009. Agricultural and Forest Meteorology 151(7), 934-946. https://doi.org/10.1016/j.agrformet.2011.02.013
  54. Pregitzer, K. S., and E. S. Euskirchen, 2004: Carbon cycling and storage in world forests: biome patterns related to forest age. Global Change Biology 10(12), 2052-2077. https://doi.org/10.1111/j.1365-2486.2004.00866.x
  55. Saigusa, N., S. Yamamoto, S. Murayama, and H. Kondo, 2005: Inter-annual variability of carbon budget components in an AsiaFlux forest site estimated by long-term flux measurements. Agricultural and Forest Meteorology 134(1), 4-16. https://doi.org/10.1016/j.agrformet.2005.08.016
  56. Saigusa, N., S. Yamamoto, S. Murayama, H. Kondo, and N. Nishimura, 2002: Gross primary production and net ecosystem exchange of a cool-temperate deciduous forest estimated by the eddy covariance method. Agricultural and Forest Meteorology 112(3-4), 203-215. https://doi.org/10.1016/S0168-1923(02)00082-5
  57. Saitoh, T. M., I. Tamagawa, H. Muraoka, N.-Y. M. Lee, Y. Yashiro, and H. Koizumi, 2010: Carbon dioxide exchange in a cool-temperate evergreen coniferous forest over complex topography in Japan during two years with contrasting climates. Journal of Plant Research 123(4), 473-483. https://doi.org/10.1007/s10265-009-0308-7
  58. Shih-Chieh, C., M. S. Taku, H. Shibata, and N. S. Satoshi, 2021: Recent advances in the understanding of ecosystem processes at eddy covariance CO2 flux sites in East Asian forest ecosystems: a review. Journal of Agricultural Meteorology 77(1), 52-65. https://doi.org/10.2480/agrmet.D-20-00018
  59. Son, S. W., S. J. Jeong, J. H. Kim, J. M. Jeong, J. H. Kim, S. Y. Kim, C. H. Lee, H. T. Sin, Y. S. Lim, S. D. Kim, A. R. Mun, D. H. Lee, Y. H. Ham, D. S. Kim, J. S. Sin, M. H. Lee, S. H. Lee, S. G. Lim, N. H. Kim, Y. G. Kim, and S. H. Sin, 2019: Climate change and plant phenology in Korean forests: records of the past 10 years. Korea Naitonal Arboretum, 118-119.
  60. Son, Y. M., R. H. Kim, K. H. Lee, J. G. Pyo, S. W. Kim, J. S. Hwang, S. J. Lee, and H. Park, 2014: Carbon Emission Factors and Biomass Allometric Equations by Species in Korea. National Institute of Forest Science.
  61. Thakuri, B. M., M. Kang, Y. Zhang, J. Chun, and J. Kim, 2016: Seasonal and Inter-annual Variability of Water Use Efficiency of an Abies holophylla Plantation in Korea National Arboretum. Korean Journal of Agricultural and Forest Meteorology 18(4), 1229-5671.
  62. Utsugi, H., 2004: The above ground biomass components of boreal deciduous forest in Northern Japan (I) : the above ground biomass estimation and vertical distribution of foliage area. Trans Meet Hokkaido Br Jpn For Soc 52, 99-101.
  63. Wharton, S., and M. Falk, 2016: Climate indices strongly influence old-growth forest carbon exchange. Environmental Research Letters 11(4), 044016. https://doi.org/10.1088/1748-9326/11/4/044016
  64. White, K., J. Pontius, and P. Schaberg, 2014: Remote sensing of spring phenology in northeastern forests: A comparison of methods, field metrics and sources of uncertainty. Remote Sensing of Environment 148, 97-107. https://doi.org/10.1016/j.rse.2014.03.017
  65. Wirth, C., C. Messier, Y. Bergeron, D. Frank, and A. Fankhanel, 2009: Old-Growth Forest Definitions: a Pragmatic View. Old-Growth Forests, C. WirthG. Gleixner and M. Heimann (Eds.), Springer, 11-31.
  66. Yamanoi, K., Y. Mizoguchi, and H. Utsugi, 2015: Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan. Biogeosciences 12(23), 6837-6851. https://doi.org/10.5194/bg-12-6837-2015
  67. Yasuda, Y., T. Saito, D. Hoshino, K. Ono, Y. Ohtani, Y. Mizoguchi, and T. Morisawa, 2012: Carbon balance in a cool-temperate deciduous forest in northern Japan: seasonal and interannual variations, and environmental controls of its annual balance. Journal of Forest Research 17(3), 253-267. https://doi.org/10.1007/s10310-011-0298-x
  68. Yoo, J., D. Lee, J. Hong, and J. Kim, 2009: Principles and applications of multi-level H2O/CO2 profile measurement system. Korean Journal of Agricultural and Forest Meteorology 11(1), 27-38. https://doi.org/10.5532/KJAFM.2009.11.1.027
  69. Yoon, T. K., N. J. Noh, R.-H. Kim, K. W. Seo, S. K. Lee, K. Yi, I. K. Lee, J.-H. Lim, and Y. Son, 2011: Mass dynamics of coarse woody debris in an old-growth deciduous forest of Gwangneung, Korea. Forest Science and Technology 7(4), 145-150. https://doi.org/10.1080/21580103.2011.621388
  70. Yu, G.-R., L.-M. Zhang, X.-M. Sun, Y.-L. Fu, X.-F. Wen, Q.-F. Wang, S.-G. Li, C.-Y. Ren, X. Song, Y.-F. Liu, S.-J. Ham, and J.-H. Yan, 2008a: Environmental controls over carbon exchange of three forest ecosystems in eastern China. Global Change Biology 14(11), 2555-2571. https://doi.org/10.1111/j.1365-2486.2008.01663.x
  71. Yu, G.-R., L.-M. Zhang, X.-M. Sun, Y.-L. Fu, X.-F. Wen, Q.-F. Wang, S.-G. Li, C.-Y. Ren, X. Song, Y.-F. Liu, S.-J. Han, and J.-H. Yan, 2008b: Environmental controls over carbon exchange of three forest ecosystems in eastern China. Global Change Biology 14(11), 2555-2571. https://doi.org/10.1111/j.1365-2486.2008.01663.x
  72. Yu, G.-R., X.-J. Zhu, Y.-L. Fu, H.-L. He, Q.-F. Wang, X.-F. Wen, X.-R. Li, L.-M. Zhang, L. Zhang, W. Su, S.-G. Li, X.-M. Sun, Y.-P. Zhang, J.-H. Zhang, J.-H. Yan, H.-M. Wang, G.-S. Zhou, B.-R. Jia, W.-H. Xiang, Y.-N. Li, L. Zhao, Y.-F. Wang, P.-L. Shi, S.-P. Chen, X.-P. Xin, F.-H. Zhao, Y.-Y. Wang, and C.-L. Tong, 2013: Spatial patterns and climate drivers of carbon fluxes in terrestrial ecosystems of China. Global Change Biology 19(3), 798-810. https://doi.org/10.1111/gcb.12079
  73. Yuan, J., S. Jose, Z. Hu, J. Pang, L. Hou, and S. Zhang, 2018: Biometric and Eddy Covariance Methods for Examining the Carbon Balance of a Larix principis-rupprechtii Forest in the Qinling Mountains, China. Forests 9(2), 67. https://doi.org/10.3390/f9020067