Seasonal and Inter-Annual Variability in Net Ecosystem CO2 Exchange at Six Forest Flux Sites in Japan

Y. Ohtani*1, Y. Yasuda*1, Y. Mizoguchi*1, T. Watanabe*1, Y. Nakai*2, K. Kitamura*2, S. Suzuki *1, K. Yamanoi*2, T. Saito*3, T. Morisawa*3, Y. Kominami*4, T. Miyama*4,

Y. Goto*4, T. Shimizu*5 and K. Tamai*5

*1 Forestry and Forest Products Research Institute (FFPRI);*2 Hokkaido Research Center, FFPRI; *3 Tohoku Research Center, FFPRI;

*4 Kansai Research Center, FFPRI; *5 Kyushu Research Center, FFPRI, Japan

LU-209 / ICDC7 Land Use and the Terrestrial Carbon Cycle / September 28, 2005

Contents:• Sites, Measurements and Data Processing• Seasonal Changes in Observed Net Ecosystem Production (NEP) and Meteorological Factors• Inter-Annual Variation in NEP• Concluding Remarks

Observation Sites

Sapporo

Kawagoe

Fujiyoshida

Yamashiro

Kahoku

AppiJAPAN

Fig.1 Site Map of FFPRI FluxNet

Sapporo

Kawagoe

Fujiyoshida

Yamashiro

Kahoku

AppiJAPAN

Sapporo

Kawagoe

Fujiyoshida

Yamashiro

Kahoku

AppiJAPAN

Fig.1 Site Map of FFPRI FluxNet

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Deciduous forestConiferous forestMixed forest

Measurement

CO2 Flux: SAT: DA-600-3T / KAIJO (20cm span) IRGA: Li-6262 / Li-Cor (closed-path) Low-pass filter (24Hz cut off) 5~10Hz Sampling, Recorded in MO Tubing: 30~50m (6mm, teflon) Air sampling rate: Approx. 10Lmin-1

Water vapor removedCO2 Storage Change: IRGA: Li-6262 / Li-Cor 5 Levels below SAT

CO2 flux measurement system using closed-path gas analyzer

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Data Processing

Calculation of Fc: Eddy covariance method (every 30 min) Lateral wind and vapor effects (Kimal et al, 1968) ; Wind rotation (McMillen,1988) ; WPL correction (Webb et al, 1980) Compensation of CO2 delay ; Correction of CO2 flux dumping NEE = Fc + ScQuality Control: Visual inspection for raw data QC for raw data (Vickers & Mahrt, 1997) u* selection for Fc

Parameterization for Gap-Filling: Semi-empirical parameterization (30 min) Nighttime Re: Exponential to Ta or Ts Re = a Q10 (Ta/10)

Daytime: Ag = NEP + Re

APAR)/(

APAR

max

max

Ag

AgAg

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Observed NEP and Estimated Ag and Re

Observed NEP and estimated gross assimilation (Ag) and ecosystem respiration (Re). Ag and Re are calculated by the parameterization used for gap-filling at every 30 minutes. Daily sums are plotted.

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

NEP and Meteorological Factors

Observed NEP (2002) indicated with air temperature, short wave radiation and precipitation (averaged over 5 days).

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)SAPPORO

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)JAN MAR MAY JUL SEP NOV

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)APPI

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)

JAN MAR MAY JUL SEP NOV

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)KAWAGOE

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)

JAN MAR MAY JUL SEP NOV

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)FUJIYOSHIDA

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)

JAN MAR MAY JUL SEP NOV

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)YAMASHIRO

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)

JAN MAR MAY JUL SEP NOV

0

20

Ta ( C

)

0

20

Sd

(M

Jm

-2d

-1)KAHOKU

Ta

Sd

0

5

10

NE

P (

gC

m-2

d-1

)

0

200

P (

mm

)

JAN MAR MAY JUL SEP NOV

Soil: andosol

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Monthly NEP and Its Inter-Annual variations

Observed monthly NEP for 4 years indicated with air temperature, short wave radiation and precipitation.

-10

0

10

20

30

Ta ( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

SAPPORO

Ta Sd 2000 2001 2002 2003

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 2000 2001 2002 2003

-10

0

10

20

30

Ta ( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

APPI

Ta Sd 2001 2002 2003

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 2001 2002 2003

-10

0

10

20

30

Ta ( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

KAWAGOE

Ta Sd 1999 2000 2001 2002

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 1999 2000 2001 2002

-10

0

10

20

30

Ta ( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

FUJIYOSHIDA

Ta Sd 2000 2001 2002 2003

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 2000 2001 2002 2003

-10

0

10

20

30Ta

( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

KAHOKU

Ta Sd 2000 2001 2002

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 2000 2001 2002

-10

0

10

20

30

Ta ( c

)

-10

0

10

20

30

Sd

(M

Jm

-2d

-1)

YAMASHIRO

Ta Sd 2000 2001 2002 2003

0

100

200

NE

P (

gC

m-2

mo

nth

-1)

0

200

400

600

P (

mm

mo

nth

-1)

JAN MAR MAY JUL SEP NOV

P NEP 2000 2001 2002 2003

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

(deg C) (MJ m- 2d- 1) (gCm- 2y- 1) (deg C) (MJ m- 2d- 1) (gCm- 2y- 1)Ta Sd NEP Ta Sd NEP

SAPPORO 2000 7.2 12.2 344 FUJ IYOSHIDA 2000 9.6 14.6 3592001 6.6 13.0 449 2001 9.3 14.5 3762002 7.2 12.6 480 2002 9.7 14.1 4592003 7.1 13.0 502 2003 9.3 12.9 318

APPI 2001 5.5 13.1 436 YAMASHIRO 2000 14.8 11.7 3012002 6.0 12.5 378 2001 14.6 11.8 3432003 5.9 12.6 657 2002 14.9 12.1 338

KAWAGOE 1999 15.3 13.8 264 2003 14.5 11.1 2762000 15.2 13.6 287 KAHOKU 2000 15.1 13.8 3952001 14.9 13.5 245 2001 15.2 13.7 5002002 15.2 13.2 325 2002 15.4 13.7 387

Annual NEP and Its Inter-Annual variations

Annual NEP, annual mean air temperature and annual mean of daily short wave radiation. Red and blue background colors indicate the maximum and minimum NEP among the years.

30 35

Our results ranged: N

EE

(gC

m-2 y

-1)

Deciduous (NEE)

Coniferous (NEE)

Mixed (NEE)

Ronald (1998)

Added to Ronald (1998)Latitude (North)

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Observed Annual NEE to Latitude

LU-209 / Seasonal and Inter-Annual Variability of NEP in Japan / Y.Ohtani et al.

Concluding RemarksTower flux measurement of CO2 was conducted in six forest sites in Japan.In the seasonal change, the maximum NEP was about 1.5 ~ 2 times larger in the deciduous sites, although the growing period was about 2 ~ 2.5 times longer in coniferous sites. The monthly NEP in the coniferous sites had inter-annual variation throughout the season, but the variation was only appeared from April to October in the deciduous sites.In the coniferous forests, the balance of assimilation and respiration induced by seasonal changes in solar radiation and air temperature seemed to be an important factor.In the deciduous broadleaved forest, solar radiation and the duration of the growing season are important factors with regards to annual NEP. The annual NEP had no clear relationships to annual mean Ta and Sd.NEP was obtained in six forest sites from 33 °to 43 °N, ranged from 250 to 650 gCm-2y-1 .