IMPACT OF CLIMATE CHANGE ON CANOPY CO2 AND H2O H EXCHANGE OF A TROPICAL RAINFOREST IN PENINSULAR MALAYSIA, PASOH

Transcription

1 IMPACT OF CLIMATE CHANGE ON CANOPY CO2 AND H2O H EXCHANGE OF A TROPICAL RAINFOREST IN PENINSULAR MALAYSIA, PASOH Yoshiko Kosugi (Kyoto Univ.) Satoru Takanashi (FFPRI) Makoto Tani (Kyoto Univ.) Shinjiro Ohkubo (Kyoto Univ.) Naoko Matsuo (Mie Univ.) Masayuki Itoh (Kyoto Univ.) Shoji Noguchi (FFPRI) Abdul Rahim Nik (FRIM)

2 INTRODUCTION Flux Tower Sites in Southeast Asia Monthly rainfall (mm month -1 ) Moderate dry Pasoh and wet periods (189mm) 24 (16mm) 2 (1649mm) PasohDua average (184mm) Pasoh Month 1 Most rainfall occur in the evening 4 amount (mm/year) Occasion (time/year) Occasion Amount (mm) Annual rain fall : 18mm Border of Tropical rainforest Objective : Evaluation of the impact of climate change on evapotranspiration and canopy CO2 exchange Time of Day

3 METHOD Pasoh Tower Equipments SR+PAR Vaisala Ta &RH LI7Box Thermocouple CREddy &CR1 Backup CR1-Ptower CR1Spectro MS7control m Solar24V Box B Solar24V Box A 4m Solar 12V control Tower Flux Observation now 3m 2m 1m m 1 m CR1 CO2profile Lightning conductor and network a lightning rod at tower top sheet line from tower top to the ground and their network under the ground to induce the electricity Commercial electricity lines 1V line to the 3m corridor from the House. Solar Panels and their systems Main Solar 24V system (6 big panels, lines to and from the House, 2 control boxes at tower top) Old 12V Solar system (2 panels, lines to and from House, one control box at tower top) CR1-12V (a panel, line to CR1-Ptower battery) Spectrometer-12V 2 panels, line to CR1Specrto, 2 batteries) Data Loggers and Boxes 4 data loggers and 7 boxes at the top of tower 2 data loggers at the House Earth lines from data loggers to the ground Equipments (line to the tower top loggers) CREddy SAT, LI7 Probe and Box CR1-Ptower Ta & RH Vaisala (3m, 4m, 4m, 3m, 2m) Pair, Wind (3m, 4m) and wind direction(3m) Rainfall gauge SR (3m, upper & lower), LR (3m, upper & lower) PAR (3m, upper & lower) SR & PAR (3m, 2m, 2m, 1m) Thermocouple (4-3, 3m, 4m, 3m, 2m, 1m, m, 1m) CR1-Pbackup SR(3m, upper & lower), LR(3m, upper & lower), PARdiffusive (3m), PAR (backup), Wind(3m) CO2-Vaisala (3m, 3m) CR1-Spectro MS-7 Spectrometers (3m, upper & lower) Phenology auto cameras Equipments (line to the House loggers) CR1-Phouse Ta & RH Vaisala (1m, m, 1m) SR & PAR (1m, m), SR (1m, upper & lower), PAR (1m, upper & lower) Soiltemp (A2cm, 1cm, B2cm, C2cm) G (A1cm, B1cm, C1cm), TDR(1), Tensiometer (14) CO2-Vaisala(1m, 1m) CR1-CO2pro CO2 sampling tube and filter (3m, 4m, 4m, 3m, 2m, 1m, m, 2m, 1m,.2m) CR1 Phouse Seasonal/interannual variations in evapotranspiration and CO2 exchange at Pasoh, with the change in environmental conditions? Tsoil ４ G ( ３ Temsiomete r 14 TDR 1)

4 Rain, Soil water A Rainfall (mm month -1 ) Temperature (degc) :1896mm 24: 16mm 2:1649mm 26: 29mm 27: 2111mm 28: 223mm 29: 141mm Rain VSWC.1 23/1 24/1 2/1 26/1 27/1 28/1 29/1 21/1 Temperature, VPD B S d or R n -G-S (MJ m -2 day -1 ) /1 24/1 2/1 26/1 27/1 28/1 29/1 21/1 Solaer2 Radiation, Available Energy C RESULTS : Meteorology Dry Wet&Sunny Wet&Cloudy δe, Average T soil2cm S Available Energy, R n -G-S T a, Average T a, Maximum Rainfall:1,41-2,23mm, Micrometeorology change with rainfall pattern 23/1 24/1 2/1 26/1 27/1 28/1 29/1 21/ VSWC (m 3 m -3 ) 29: 141mm Driest Year with ENSO δe (hpa)

5 RESULTS : Evapotranspiration Excessive Energy partitioned more to H 1 A 1 H, le (MJ m -2 day -1 ) H, le(mj m -2 day -1 ) C R n -G-S (MJ m- -2 day -1 ) H le le (MJ m -2 day -1 ) δe (hpa) le H R n -G-S 23/1 24/1 2/1 26/1 27/1 28/1 29/1 21/1 B le Stomatal closure regulates Evapotranspiration at high VPD R n -G-S (MJ m -2 day -1 )

6 RESULTS : Evapotranspiration Cumulative E, Method 1 Cumulative E, Method 2 Cumulative E, Method 3 Cumulative Rainfall 2 A 1 (mm) 1 (mm) 23/1 24/1 2/1 26/1 27/1 28/1 29/1 21/1 1 Rainfall - Evapotranspiration with Method 1 8 B Storage water of -. m soil Annual Evapotranspiration : 13mm (Quite Stable!) -2 23/1 24/1 2/1 26/1 27/1 28/1 29/1 21/1 Water supply from deeper layer under drought Water supply from -cm layer at most periods

7 RESULTS : Evapotranspiration E (mm year -1 ) E, Method 1' E, Method 1 E, Method 2 E, Method 3 ENSO year R n -G-S (MJ m- -2 year -1 ) Rainfall (mm year -1 ) Annual Evapotranspiration : approximately 13 mm dependence with available energy, no dependence with rainfall

8 RESULTS : Nighttime Respiration Night-time Soil Respiration NEE, Rate F c, or (µmol S c m -2 Frequency s -1 ) (µmol m -2 s -1 ) Chamber Soil Respiration A Volmetric soil water content (m 3 m -3 ) u* NEE Coinsided with the soil respiration F c VSWC *m Plot 2ha Plot related with S c soil water content (base on 8-year chamber observations) Nighttime NEE (=RE) versus Soil water content Volumetric soil water content (m 3 m -3 ) Frequency Night-time NEE, F c, or S c (µmol m -2 s -1 ) B Volumetric soil water content (m 3 m -3 ) NEE F c S c NEE linear regression RE estimated from soil + leaf + trunk + CWD respiration RE related with soil water content

9 Daytime canopy CO2 exchange No seasonal/interannual change NEE daytime (µmol m -2 s -1 ) Driest month NEE, 7-year average NEE, Monthly average The number of NEE data points rejected per month because of rain Wet&cloudy Wet&sunny JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC The number of NEE data points rejected per month because of rain

10 Daytime canopy CO2 exchange Radiation did not govern daytime NEE. NEE daytime (µmol m -2 s -1 ) A B C PPFD (µmol m -2 s -1 ) All data Feb2 Dec27 Nov NEE daytime.mean (µmol m -2 s -1 ) S d (MJ m-2 day -1 ) VSWC (m3 m -3 ) Daytime NEE had an circadian rhythms independent of PPFD, and with clear decline in the afternoon. No dependence of daytime-mean NEE on daily solar radiation No dependence of daytime-mean NEE on soil water content These results consist with those of leaf-scale gas exchange measurements at the study site (Takanashi et al, 26; Kosugi et al, 29)

11 Daily/Monthly GPP NEE RE GPP (gc m-2 day -1 ) 1 1 A GPP (gc m-2 day -1 ) 1 1 B No dependence 1 of 1daily 2 GPP 2 on daily solar radiation 3 C S d (MJ m- -2 day -1 ) moderate.2.3 decline.4 of GPP at the dry period VSWC (m 3 m -3 ) GPP 2 RE (gc m -2 month -1 ) NEE Seasonal -4 variation of GPP RE were influenced by VSWC. At the dry period, canopy 23/1 tended 24/1 to absorb 2/1 CO2, caused 26/1 by 27/1 decrease 28/1 of RE larger 29/1 than 21/1 that of GPP.

12 GPP (gc m -2 year -1 ) 36 with 34 solar radiation GPP RE RE (gc m -2 year -1 ) Annual GPP NEE RE No increase of annual GPP Method 1 Method 2 Method 3 GPP:3~36tC ha -1 yr -1 RE:3~36tC ha -1 yr -1 NEE:-2~2tC ha -1 yr -1 GPP/RE increase with VSWC mostly balanced annual NEE NEE (gc m -2 year -1 ) NEE Annual -3 budget influenced lot by the method of gap filling and correction Cross check SRadiation d (MJ with m- -2 year ecological -1 ) and Rainfall ecophysiological Rainfall (mm year -1 ) VSWC data annualmean Soil is Water (m needed. 3 m -3 )

13 Observation Campaign of Ecosystem Respiration 21.2

14 Summary Micrometeorology:had moderate seasonal and interannual variations influenced by rainfall pattern. Evapotranspiration: moderately increased with available energy. Annual balance was stable with approximately 13mm. A little decline at the ENSO dry year. Ecosystem Respiration:increased increased with VSWC. Daitime photosynthesis:did not increase with PPFD. Monthly average was stable during 7 years. GPP NEE RE: GPP did not increase with PPFD, but increased with VSWC. Moderate seasonal and interannual variation of GPP RE NEE were caused by VSWC.

15 Evapotranspiration and CO2 exchange at Pasoh Forest were very stable during these several years. Stable Static In terms of stomatal regulation, photosynthetic ability, and ecosystem respiration, forest acted sensitive to climate change. These reactions compensated each other to produce very stable output as a canopy of Pasoh forest.

16 Prediction for future climate change Decrease of Solar radiation: [ET] decrease [NEE] no change Increase of rainfall: [ET] no change [GPP] increase [RE] increase [NEE] no change or increase(=co2 emit) Decrease of rainfall: [ET] no change or decrease [GPP] decrease [RE] decrease [NEE] no change or decrease(=co2 absorb)