Measuring the Effect of Selective Logging on Forest-Atmosphere Exchange Scott Miller, Mike Goulden, Humberto da Rocha, Helber Freitas, Mary Menton, Adelaine Michela Silva e Figueira, Cleilim Albert Dias de Sousa How is forest-atmosphere exchange effected by selective logging? Measurements/Data Summary Logging Effect on CO2 exchange (preliminary) Annual CO2 Budget (year prior to logging) Whats next... Km 83 Tower Site SITEIS LOGGEDSITEIS LOGGED July 1999July 2000Sept 2001 Select site Infrastructure Installed Ground-Based Measures begin Tower measure begins Tower and ground- based measurements for full year before cut to establish baseline Additional equipment, second tower, automated soil chambers installed after cut Tower and ground-based measurements continue after cut to quantify effects of logging on CO 2 and Energy exchange Tower Wind direction Tower Measurements METEOROLOGY PAR (up/down)LiCor Quantum Sensors SolarKipp & Zonen Net RadiationREBS Q*7 RainTipping Bucket PROFILES Wind (6 hts) Cup, 2D Sonic Anemometers Temperature (6 hts) Campbell 107 CO 2 /H 2 O (12 hts)LI-7000 (Closed Path) FLUXES Momentum/Heat Campbell CSAT3 1)CO 2 /H 2 O LI-7500 (Open Path) 2)CO 2 /H 2 O LI-7000 (Closed Path) Sonic anemometer is looking East, the most common wind direction Tower Top Instruments Air Inlet for Closed Path IRGA Open Path IRGA Elevator to raise and lower eddy flux sensors. Elevator IRGAS Calibration Equipment Data Computer Power Distribution System Control DATA MANAGEMENT PC BOSS TOWER PROFILE SOILPIT EDDY FIELD LBA Santarem PC UCI/ USPed Weekly Bi-weekly: CDs SEDEXed RED: Averaged DataGREEN: Raw Data Weekly Site Visit Carbon Budget Ideally, the forest atmosphere coupling is 1-dimensional, such that the Net Ecosystem Exchange (NEE) of CO2 is given by: S= dC dt FcFc NEE = F c + S F c - turbulent CO2 flux S - rate of change of CO2 in the air-column. CO 2 rich CO 2 depleted Eddy Covariance Directly measures exchange (flux) of CO 2 between forest and atmosphere. Averaging interval is of order 1 hour. F c = Fc = co2 flux w = vertical wind component c = co2 density CO 2 Storage The rate of change of CO 2 beneath the eddy flux sensors is measured via the mean profile of CO 2. Averaging interval is of order 1 hour. S z = c d S z = rate of storage beneath z c = co2 density d dt =0 =z Analysis Requirements I. LOGGING RESPONSE: PRECISION Eddy covariance well established. Analysis Requirements I. LOGGING RESPONSE: PRECISION Eddy covariance well established. II. ANNUAL SUM: ACCURACY Eddy covariance subject to debate I. LOGGING IMPACT Forest-atmosphere exchange monitored continuously during logging. Hypothesis: Short-Term Response to Logging Baseline Hypothesis: Short-Term Response to Logging 1. Immediate reduction in photosynthesis. Baseline Hypothesis: Short-Term Response to Logging 2. Lagged increase in respiration. 1. Immediate reduction in photosynthesis. Baseline Pre- and Post Logging Preliminary data do not support hypotheses of decreased photosynthesis or increased respiration at this stage of the logging. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. Why is logging not apparent in these data? Tower Wind direction General: The cut is not yet completed - may be sampling a mix of logged/intact forest. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. The fluxes shown are preliminary without known important corrections. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. The fluxes shown are preliminary without known important corrections. Daytime Uptake: The understory is dense and possibly makes good use of newly available PAR. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. The fluxes shown are preliminary without known important corrections. Daytime Uptake: The understory is dense and possibly makes good use of newly available PAR. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. The fluxes shown are preliminary without known important corrections. Daytime Uptake: The understory is dense and possibly makes good use of newly available PAR. Pereira et al (2001) showed only 10% reduction in LAI in selectively logged areas - our site had ~2/3 the volume of wood extracted, and possibly even less reduction in LAI. Why is logging not apparent in these data? General: The cut is not yet completed - may be sampling a mix of logged/intact forest. The fluxes shown are preliminary without known important corrections. Daytime Uptake: The understory is dense and possibly makes good use of newly available PAR. Pereira et al (2001) showed only 10% reduction in LAI in selectively logged areas - our site had ~2/3 the volume of wood extracted, and possibly even less reduction in LAI. Respiration: Chamber data indicate that dry season respiration is water limited. Expect to see enhanced respiration in the wet season. Why is logging not apparent in these data? Soil respiration (presumably decomposition) strongly affected by rain (presumably litter moisture) Heavy rains interrupt 2001 dry season Autochamber measurements of soil respiration Large measured carbon uptake of TC/ha/yr! 1 YEAR II. Annual Carbon Budget Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Methodological Biases Trees > 55 cm DBH inventoried 1984 and again in Difference between inventories indicates forest growth. Also have dendrometers for short term wood increment Tree biomass105 tC ha Tree biomass106 tC ha -1 Net wood increment tC ha -1 Probable Delta soil C tC ha -1 (Sue Trumbore) Annual C balance tC ha -1 Ground Based Inventories Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Methodological Biases Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Methodological Biases Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... Sub Canopy Micrometeorology Above canopy wind easterly, night and day Night-time low level (1.3 m) wind not aligned with above canopy wind. Elevator Soundings Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... Gap Micrometeorology Second tower located in a gap Original Tower Second Tower Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... u * Correction Assumption: NEE is independent of u * u * threshold Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... u * Correction A dramatic effect! Open/Closed Path IRGAs Different instruments giving different answers. Why do measurements indicate a large carbon sink? Sink is real - e.g. recent disturbance/regeneration Micrometeorological Biases Below Canopy Dynamics Below canopy 2D sonics added July 2001 Direct horizontal advection measurements (Fitz planned) Elevator Soundings (27 so far...) Gap Dynamics (2nd tower) Methodological Biases Open vs. closed path IRGAs Is a u* correction warranted? Other data processing issues... Range of Different Instruments/Data Treatments Conclusions High quality data set - original plus targeted additional measurements. Logging Effect on CO2 exchange is not obvious. Annual CO2 Budget is sensitive. Data analysis to continue on many fronts. Additional Thanks: Fernando Alves Leo, Roberto Cardoso, Antonio Oviedo, Marcy Litvak, Dan Hodkinson, Lisa Zweede and Bethany Reed, IBAMA, NASA and INPE.