FHK:Fuji Hokuroku Flux Observation Site


General site detail (Updated 31 July 2025)
 Site name
 Fuji Hokuroku Flux Observation Site
 AsiaFlux site code
 FHK
 Location Fujiyoshida City, Yamanashi Pref, Japan
 Position 35º 26' 36.8"N, 138º 45' 53.0"E 
 (revised Jan. 8, 2025)
 Elevation 1050-1150 m above sea level
 Slope 3-4 deg
 Terrain type
 Flat
 Area 150 ha
 Fetch -
 Climate Cfa:Temperate - mild with no dry season, 
 hot summer
 Mean annual air temperature
 8.9 deg C (2006-2023, at a height of 2m)
 Mean annual precipitation
 1831 mm (2006-2023)
 Vegetation type
 Deciduous needleleaf forest 
 (Japanese larch afforestation)
 Dominant species (Overstory)
 Japanese larch (Larix Kaempferi Sarg.), evergreen 
 needle-leafed species (Pinus densiflora and Abies
 homolepis), deciduous broad-leafed species (Swida
 controversaQuercus serrataQuercus crispula
 Betula platyphylla var.japonicaPrunus incisa, etc.)
 Dominant species (Understory)
 Ferns (Dryopteris crassirhizomaDryopteris
 expansa), bamboo grass (Sasamorpha borealis), 
 and other herbs.
 Canopy height
 20-26 m
 Age Around 70 years old (Planted around 1950)
 LAI Larch: 2.88 m2m-2 estimated based on the leaf 
 mass abundance (Okano & Arase 2007), and 
 2.4 m2m-2 estimated based on 3D portable laser 
 scanner measurement (Maki et al., 2012),
 Understory: 3.0 m2m-2 (max)
 After thinning, the tree LAI was 2.31 in 2016.
 Disturbance As the first thinning, approximately 36% of the larch trees located more than 20 meters away from the observation tower were cut down in May 2014.
 The second thinning was carried out near the observation tower in March 2015.
 Between 2014 to 2015, approximately 39% of the larch trees were cut down, reducing the forest density from 409 trees per hectare in 2013 to 249 trees per hectare in 2015. The harvested timber and above-ground residues were removed from the site. 
 Soil type
 Coarse volcanic ash (Urakawa et al., 2015)

Observations
Eddy Covariance method (CO2)
 System Open- and closed-path systems (CO2 flux, latent heat flux)
 Wind speed 
 Three-dimensional sonic anemometer-thermometers:
 DA-600-3TV, Probe TR-61C, SONIC CORP. 
                                      (Jan.1, 2006-  May 9, 2011);
 DA-650-3TV, Probe TR-61C, SONIC CORP. 
                                      (May 9, 2011- Nov.22, 2011);
 DA-600-3TV, Probe TR-61C, SONIC CORP. 
                                      (Nov.22, 2011- Apr.18, 2012);
 DA-700-3TV, Probe TR-61A, SONIC CORP. 
                                      (Apr.18, 2012- Apr.11 2016);
 CSAT3, Campbell Scientific (Apr. 14, 2014-)
 Air temperature
 Platinum resistance thermometer and capacitive hygrometer : HMP45A, Vaisala (Jan. 2006 - May 9, 2011); HPM155A, Vaisala (May 9, 2011 - ) coupled with aspirated radiation shield, CPR-AS-21, Climatec, Japan.
 Water vapor
 Open-path CO2/H2O analyzers, LI-7500, LI-COR 
  (Jan.1, 2006); LI-7000, LI-COR (Jan. 1, 2012-Apr. 11, 2016)
 Closed-path CO2/H2O analyzers, LI-6262, LI-COR 
  (Jan.1, 2006- Apr.11, 2016)
 Platinum resistance thermometer and capacitive hygrometer : HMP45A, Vaisala (Jan. 2006-May 9, 2011); HMP155A, Vaisala (May 9, 2011- ) coupled with aspirated radiation shield, CPR-AS-21, Climatec, Japan
 CO2 Open-path CO2/H2O analyzer, LI-7500, LI-COR (Jan.1, 
 2006- ), 
 Closed-path CO2/H2O analyzer, LI-6262, LI-COR (Jan.1, 
 2006- Apr.11, 2016); LI-7000, LI-COR (Apr. 19, 2012- )
 Measurement height
 35 m
 Sampling frequency
 10 Hz
 Averaging time
 30 min
 Data logger
 DR-M3, TEAC, Japan (Jan.2006-March 2012);
 CR-23X, Campbell Scientific, USA (Jan.2006 - April 2008);  
 CR-3000, Campbell Scientific, USA (May 2008-)
 Data storage
 Magneto-Optical Disk (TEAC); Data-logger CR-3000, Campbell Scientific, USA
 Original data
 Raw data

Meteorology
 Observation items
  Levels/ Depth
 Instrument 
 Global solar radiation
 (incoming)
 32 m,
 30 m
 Pyranometer (32m): MS-402F, Eko, Japan (Jan. 2006 - Apr. 15, 2015); CMP6, Kipp&Zonen, Netherland (Apr. 15, 2015 -),
 Radiometer (30m): MR-50, Eko, Japan (Jan. 2006 to Nov. 16, 2015); NR01, Hukseflux, Netherland (Nov. 16, 2015 -)
 Transmitted solar radiation 
 (below canopy incoming)
 2 m (5 points),
 2 m (2 points)
 Pyranometer (5 points): MS-601, Eko, Japan (Jan. 2006 - Apr. 15, 2015); CMP6, Kipp&Zonen, Netherland (Apr. 15, 2015 -)
 Radiometer: MR-50, Eko, Japan (Jan. 2006 - Apr. 12, 2018; Jan. 2006 - Apr. 10, 2017); NR01, Hukseflux, Netherland (Apr. 12, 2018 - ; Apr. 10, 2017 -)
 Global solar radiation  
 (outgoing)
 30 m
 Radiometer: MR-50, Eko (Jan. 2006 - Nov. 16, 2015); NR01, Hukseflux, Netherland (Nov. 16, 2015 -)
 Transmitted solar radiation 
 (below canopy outgoing)
 2 m (2 points)
 Radiometer: MR-50, Eko (Jan. 2006 - Apr. 12, 2018; Jan. 2006 - Apr. 10, 2017); NR01, Hukseflux, Netherland (Apr. 12, 2018 -; Apr. 10, 2017 -)
 Long-wave radiation
 (incoming) 
 30 m
 Radiometer: MR-50, Eko (Jan. 2006 - Nov. 16, 2015); NR01, Hukseflux, Netherland (Nov. 16, 2015 -)
 Transmitted long-wave 
 radiation (below canopy 
 incoming)
 2 m (2 points)
 Radiometer: MR-50, Eko (Jan. 2006 - Apr. 12, 2018; Jan. 2006 - Apr. 10, 2017); NR01, Hukseflux, Netherland (Apr. 12, 2018 - ; Apr. 10, 2017 -) 
 Long-wave radiation 
 (outgoing)
 30 m
 Radiometer: MR-50, Eko (Jan. 2006 - Nov. 16, 2015); NR01, Hukseflux, Netherland (Nov. 16, 2015 -)
 Transmitted long-wave
 radiation (below canopy  
 outgoing)
 2 m (2 points)
 Radiometer: MR-50, Eko (Jan. 2006 - Apr. 12, 2018; Jan. 2006 - Apr. 10, 2017); NR01, Hukseflux, Netherland (Apr. 12, 2018 - ; Apr. 10, 2017 -)
 Net radiation
 30 m Radiometer: MR-50, Eko (Jan. 2006-Nov. 16, 2015); NR01, Hukseflux, Netherland (Nov. 16, 2015-)
 2 m (2 points) Radiometer: MR-50, Eko (Jan. 2006- Apr. 12, 2018; Jan. 2006- Apr. 10, 2017); NR01, Hukseflux, Netherland (Apr. 12, 2018-; Apr. 10, 2017-) 
 PPFD (incoming)
 32 m
 Quantum sensor: LI-190S, LI-COR (Jan. 2006 - Apr. 16, 2015); LI-190S, LI-COR encased in a weather-proof external housing with a glass dome (Apr. 16, 2015 -) (Akitsu et al., 2020);  ML-020P, Eko, Japan (Jan. 2006 - Apr. 15, 2013); SQ-110, Apogee, USA (Apr. 15, 2013 -)
 Transmitted PAR 
 (below canopy incoming)
 2 m (5 points) Quantum sensor: LI-190S, LI-COR (Jan. 2006 - Mar. 2007); ML-020P, Eko (Mar. 2007 - Apr. 15, 2013); SQ-110, Apogee, USA (Apr. 15, 2013 -)
 Reflected PAR (outgoing)
 30 m Quantum sensor: LI-190S, LI-COR (Jan. 2006-Mar. 2007); ML-020P, Eko (Mar. 2007-Apr. 15, 2013); SQ-110, Apogee, USA (Apr. 15, 2013-); LI-190S, LI-COR encased in a weather-proof external housing with a glass home (Apr. 12, 2018-) (Akitsu et al., 2020)
 Reflected PAR 
 (below canopy outgoing)
  2 m (3 points)
 Quantum sensor: LI-190S, LI-COR (Jan.2006-Mar.2007);  ML-020P, Eko (Mar.2007-Apr. 15, 2013); SQ-110, Apogee, USA (Apr. 15, 2013-) 
 Wind direction
 35 m Three-dimensional sonic 
 anemometer-thermometers: DA-600-3TV, Probe TR-61C, SONIC CORP. (Jan.1, 2006-
 May 9, 2011); DA-650, Probe  
 TR-61C, SONIC CORP. (May 9, 2011- Nov.22, 2011);
 DA-600-3TV, Probe TR-61C,  SONIC CORP. (Nov. 22, 2011
 -Apr. 18, 2012); DA-700-3TV, Probe 
 TR-61A, SONIC CORP. (Apr.18, 2012-Apr.11, 2016); CSAT3, Campbell Scientific, USA (Apr. 14, 2014-)
 32, 27, 22, 16,
 10, 4.5, 2 m 
 Sonic anemometer: MA-130A, Eko, 
 Japan (Jan.2006-Mar.2007); 
 PGWS-100-3, GILL (Apr.2007-)
 Wind speed
 35 m Three-dimensional sonic 
 anemometer-thermometers: DA-600-3TV, Probe TR-61C, SONIC CORP. (Jan.1, 2006-
 May 9, 2011); DA-650, Probe 
 TR-61C, SONIC CORP. (May 9, 2011 - Nov. 22, 2011); DA-600-3TV, Probe TR-61C, SONIC CORP. (Nov.22,2011
 - Apr.18, 2012); DA-700-3TV, Probe 
 TR-61A, SONIC CORP. (Apr.18, 2012 - Apr.11, 2016); CSAT3, Campbell Scientific, USA (Apr. 14, 2014-)
 32, 27, 22, 16,
 10, 4.5, 2 m
 Sonic anemometer: MA-130A, Eko, 
 Japan (Jan. 2006 - Mar. 2007); 
 PGWS-100-3, GILL (Apr. 2007-)
 Air temperature
 32, 27, 22, 16,10,
 4.5, 2, 1, 0.5 m
 Platinum resistance thermometer and capacitive hygrometer: HMP-45D, Vaisala (Jan. 2006 - Apr. 12, 2011); HMP155, Vaisala (Apr. 12, 2011-) coupled with aspirated radiation shield, CPR-AS-21, Climatec, Japan
 Relative humidity 32, 27, 22, 16, 
 10, 4.5, 2, 1, 
 0.5 m
 Platinum resistance thermometer and capacitive hygrometer: HMP-45D, Vaisala (Jan. 2006 - Apr. 12, 2011); HMP155, Vaisala (Apr. 12, 2011-) coupled with a fan-aspirated radiation shield, CPR-AS-21, Climatec, Japan
 Soil temperature
 0, 0.02,
 0.05 m (3 points),
 0.15, 0.3, 0.6 m
 Platinum resistance thermometer: 
 C-PTWP, Climatec, Japan
 Ground heat flux
 0.02 m (3 points)
 Heat flux plate: PHF-01, REBS
 Soil water content 
 0 m (3 points), 
 0.1, 0.2 m (2 points)
 TDR sensor: CS616, Campbell
 Barometric pressure
 1.5 m Barometer: PTB210, Vaisala
 Precipitation 32 m Tipping-bucket rain gauge with heater : CYG-52202, R. M. Young
 Snow depth 2 m Sonic ranging sensor:SR50,Campbell
 Spectral radiation(incoming)
 Global, direct/diffuse, 
 transmitted
 32, 2 m Spectroradiometer: MS-700, Eko, 
 Japan with shadow band (32 m; 
 PRB-100, PREDE, Japan)
 Spectral radiation reflected,
 transmitted (outgoing)
 30 m Spectroradiometer: MS-700, Eko, 
 Japan (Jan. 2006 - Apr. 15, 2014); MS-700 with automated masking device to exclude contaminated reflection (Apr. 15, 2014- (Ide et al., 2016))
 Spectral radiation reflected, 
 transmitted (outgoing,below canopy)
 2 m Spectroradiometer: MS-700, Eko, Japan (Jan. 2006 -)
 COconcentration
 35, 32, 27, 22, 
 16,10, 4.5, 2, 1,  
 0.5  m
 Closed-path CO2/H2O analyzer: 
 LI-6262, LI-COR (Mar.2006-Jul.2010)

Fluxes of non-CO2 gases
 Gas
 CH4
 Method Hyperbolic relaxed eddy accumulation (HREA) method with 
 a laser-based analyzer (GGA-24r-EP, Los Gatos Research 
 Inc., USA), from Aug. 2011 to Sep. 2012 (Ueyama et al., 
 2013)
 Automated dynamic closed (non-steady-state through-flow) 
 chambers with a laser-based analyzer (GGE-24r-EP), from 
 Oct. 2012 (Ueyama et al., 2015)
 Measurement height
 35, 28, 18, 5, and 0.3m (HREA method), 0m (chambers)
 Data logger
 Laptop PC via serial communication
 Data storage
 -
 
Observation Period and Data Availability
 Measurement Period
 January 2006 to present
 Measurement Frequency
 Continuous
 Data Availability
 2006-2023 in AsiaFlux Database

Contact
 Ryuichi Hirata (hirata.ryuichi [at] nies.go.jp)
 Center for Global Environmental Research (CGER),
 Earth System Division,
 National Institute for  Environmental Studies (NIES)
 16-2 Onogawa, Tsukuba, Ibaraki 305-8506  JAPAN
 Tel : +81-29-850-2202   Fax : +81-29-858-2645
  https://esd.nies.go.jp/en/about/organization/tm/
 Researcher #1 [Flux and micrometeorology] 
 Yoshiyuki Takahashi (yoshiyu [at] nies.go.jp), CGER/NIES
 Researcher #2 [Soil respiration] 
 Naishen Liang (liang [at] nies.go.jp), CGER/NIES
  https://db.cger.nies.go.jp/gem/en/flux/fuji.html
 
Observations cont.
Soil respiration
 Measurement method
 Automated dynamic closed chamber 
 method (flow-through, non-steady-state design using IRGA and Integrated Cavity Output Spectroscopy 
 (CH4/CO2))
 References for method
 Teramoto M., Liang N., Takahashi Y., 
 Zeng J., Saigusa N., Ide R., Zhao X., 
 2019: Enhanced understory carbon flux components and robustness of net 
 CO2 exchange after thinning in a larch 
 forest in central Japan. Agricultural and
 Forest Meteorology, 274, 106-117.
 Teramoto M., Liang N., Zeng J., 
 Saigusa N., Takahashi Y., 2017: Long-
 term chamber measurements reveal 
 strong impacts of soil temperature on 
 seasonal and inter-annual variation in 
 understory CO2 fluxes in a Japanese 
 larch (Larix kaempferi Sarg.) forest. 
 Agricultural and Forest Meteorology
 247, 194-206.
 Measuring system
 A 24-channel automated chamber 
 system (home-made by the 
 investigator)
 IRGA
 Integrated Cavity Output
 Spectroscopy
 Li-820 (LI-COR), UGGA (LGR)
 Flow control
 High-precision flow transducer (FSM-V,  CKD) and manual flow regulator
 Chamber type
 Clear PVC chamber
 Chamber size
 90cm in length × 90cm in width × 
 50cm in height (8 chambers for soil 
 respiration and 8 chambers for 
 heterotrophic respiration), and 90cm in 
 length × 90cm in width × 100cm in 
 height (8 chambers for net understory 
 CO2 exchange).
 Number of chambers
 24
 Measuring intervals
 The mesurement period, during which 
 the chamber lids were closed, was 
 2.5min for each chamber with data 
 recorded at 10-s intervals using 
 CR1000 datalogger (Campbell 
 Scientific Inc.) from 2006 to 2009. 
 The measurement period was 5.0min 
 from 2010 on.
 Is the ground covered by snow
 in winter (how about the 
 measurement on winter?)
 Missing soil CO2 efflux data (gaps) 
 during snow covered period were 
 estimated based on Lloyd and Taylor 
 equation for each chamber.
 Original data
 Raw data
 Air temperature collection
 Air temperature inside each chamber 
 was measured using the home-made 
 T-Type thermocouple.
 Soil temperature collection
 Soil temperature at the depth of 5-cm 
 inside each chamber was measured 
 using the home-made T-Type 
 thermocouple.
 Air pressure collection
 Air pressure was measured using 
 PX2760 (Omega Engineering)
 Understory PPFD collection
 6 sensors (SQ225; Apogee 
 Instruments Inc.) at the height of 1m 
 around plant chambers
 Soil moisture collection
 6 CS616 (Campbell Scientific Inc.) 
 were used for monitoring soil moisture 
 at the depth of 10cm in 6 randomly 
 selected chambers (two chambers for 
 each treatment).

Other
 Photosynthesis Occasionally 
 Ecological Investigation
 Tree heights (every 5 years), stand density (annual), diameter (annual),  biomass, LAI
 Phenology Continuous (photos)

Calibration Information
 Open-path analyzers were calibrated approximately every two months  with standard CO2 gases and a dew point generator (LI610, LI-COR).

 The gain of CO2 of the closed-path analyzers was checked once a day
 flowing two standard CO2 gases of 320 ppmv and 420 ppmv that were 
 automatically controlled using a programmable data logger (CR23X 
 during 2006-mid-2007 and CR3000 after that, both were made by  
 Campbell Scientific, Logan, UT, USA.)







Infrastructure
 Tower (35m), Electrical power (AC), Internet communications is 
 available.



Research Fund
 Global Environmental Monitoring funded by National Institute for Environmental Studies
 Global Environmental Research Coordination System from Ministry of the Environment of Japan (NOU0751, NOU1251, NOU2254) 
 Global Environment Research Fund from Ministry of the Environment of Japan (B-3)
 Environment Research and Technology Development Fund from Ministry of the Environment of Japan (2-1705, 2-2006)

Publication

 Okano T., Arase T. 2007: Biomass measurement of larch forest in Fuji Hokuroku Flux Research Site, Annual Report of Global Environment Monitoring H19, Center for Global Environmental Research, National Institute for Environmental Studies. (in Japanese)

 

 Arase T. 2012: Estimation of Seasonal Changes in the Biomass of Forest Floor Vegetation in a Larch Forest at the Northern Foot of Mt. Fuji, Japan. Journal of Environmental Information Science, 40-5, 23-30.

 

 Maki M., Takahashi A., Okano T., OgumaH. 2012: Development of the method to estimate light environment on forest floor using 3D portable laser scanner and radiative transfer model. Journal of The Remote Sensing Society of Japan, 32-2, 77-87.

 

 Ueyama M., Takai Y., Takahashi Y., Ide R., Hamotani K., Kosugi Y., Takahashi K., Saigusa N. 2013: High-precision measurements of the methane flux over a larch forest based on a hyperbolic relaxed eddy accumulation method using a laser spectrometer. Agricultural and Forest Meteorology, 178,183-193.

 

 Mochizuki T., Tani A., Takahashi Y.,Saigusa N., Ueyama M. 2014: Long-term measurement of terpenoid flux above a Larix kaempferi forest using a relaxed eddy accumulation method. Atmospheric Environment 83, 53-61.

 

 Ueyama M., Takanashi S., Takahashi Y.2014 Inferring methane fluxes at a larch forest using Lagrangian, Eulerian, and hybrid inverse models. Journal of Geophysical Research: Biogeosciences, 119 (10), 2018-2031.

 

 Urakawa R., Ohte N., Shibata H., Tateno R., Hishi T., Fukushima K., Inagaki Y., Hirai K., Oda T., Oyanagi N., Nakata M., Toda H., Kenta T., Fukuzawa K., Watanabe T., Tokuchi N., Nakaji T., Saigusa N., Yamao Y., Nakanishi A., Enoki T., Ugawa S., Hayakawa A., Kotani A., Kuroiwa M., Isobe K. 2015: Biogeochemical nitrogen properties of forest soils in the Japanese archipelago. Ecological Research,30(1), 1-2.

 

 Akitsu K. T., Nakaji T., Kobayashi H.,Okano T., Honda Y., Bayarsaikhan U., Terigele, Hayashi M., Hiura T., Ide R.,Igarashi S., Kajiwara K., Kumikawa S., Matsuoka Y. Nakano T., Nakano T., OkudaA., Sato T., Tachiiri K., Takahashi Y., Uchida J., Nasahara N. K. 2020: Large-scale ecological field data for satellite validation in deciduous forests and grasslands. Ecological Research, 35(6), 1009-1028.

 

 Ueyama M., Takeuchi R., Takahashi Y.,Ide R., Ataka M., Kosugi Y., Takahashi K., Saigusa N. 2015: Methane uptake in a temperate forest soil using continuous closed-chamber measurements. Agricultural and Forest Meteorology, 213, 1-9. 

 

 Takahashi Y., Saigusa N., Hirata R., IdeR., Fujinuma Y., Okano T., Asarse T., 2015: Characteristics of temporal variations in ecosystem CO2 exchange in a temperate deciduous needle-leaf forest in the foothills of a high mountain. Journal of Agricultural Meteorology, 71(4), 302-317.

 

 Mochizuki T., Miyazaki Y., Ono K., Wada R., Takahashi Y., Saigusa N., Kawamura K., Tani A. 2015: Emissions of biogenic volatile organic compounds and subsequent formation of secondary organic aerosols in a Larix kaempferi forest.Atmospheric Chemistry and Physics,15, 1-13.

 

 Urakawa R., Ohte N., Shibata H., Isobe K., Tateno R., Oda T., Hishi T., Fukushima K., Inagaki Y., Hirai K., Oyanagi N., Nakata M., Toda H., Kenta T., Kuroiwa M., Watanabe T., Fukuzawa K., TokuchiN., Ugawa S., Enoki T., Nakanishi A., Saigusa N., Yamao Y., Kotani A. 2016: Factors contributing to soil nitrogen mineralization and nitrification rates of forest soils in the Japanese archipelago. Forest Ecology and Management, 361, 382-396.

 

 Ide R., Hirose Y., Oguma H., Saigusa N.2016: Development of a masking device to exclude contaminated reflection during tower-based measurements of spectral reflectance from a vegetation canopy. Agricultural and Forest Meteorology, 223, 141-150.

 

 Teramoto M., Liang N., Zeng J., Saigusa N., Takahashi Y., 2017: Long-term chamber measurements reveal strong impacts of soil temperature on seasonal and inter-annual variation in understory COfluxes in a Japanese larch (Larix kaempferi Sarg.) forest. Agricultural and Forest Meteorology, 247, 194-206.

 

 Teramoto M., Liang N., Takahashi Y.,Zeng J., Saigusa N., Ide R., Xin Zhao 2019: Enhanced understory carbon flux components and robustness of net CO2 exchange after thinning in a larch forest in central Japan. Agricultural and Forest Meteorology, 274, 106-117.


 Please refer below webpage.

 http://db.cger.nies.go.jp/gem/moni-e/warm/flux/pub.html