Dennis Baldocchi, Sara Knox, Cove Sturtevant, Laurie Koteen, Jaclyn Hatala, Joe Verfaillie

Transcription

1 Exploring Methane and Carbon Dioxide Exchange from Agricultural and Wetland Land Use Classes in the Sacramento San Joaquin Peatland Delta in California Dennis Baldocchi, Sara Knox, Cove Sturtevant, Laurie Koteen, Jaclyn Hatala, Joe Verfaillie Department of Environmental Science, Policy and Management University of California, Berkeley Royal Society Seminar, Chicheley Hall, UK, December, 2013

2 The Delta is a Vulnerable Peatland Ecosystem via Drainage and Severe Land Subsidence

3 Delta Peatland is Subsiding! Landscape is Vulnerable to Flooding by Levee Failure; Its Collapse would Shut Down California s Water Conveyance System

4 New Plans to Abate or Reverse Subsidence with Carbon Farming: Restored Tule Wetlands and Rice on Twitchell and Sherman Islands What are the: Cost/Benefits?; Unintended Consequences?

5 160 What Are the Trade Offs? Annual Methane Emission Scales with Net Primary Productivity of Wetlands, Natural and Managed In Wetlands, Large Carbon Uptake is Associated with Large Methane Losses 140 Fluxes, Sources and Sinks of Methane Air, O2 Xylem Transport 120 CH 4 Air-Water Exchange Ebullition F CH4 (gc m -2 y -1 ) Oxidation: Methanotropic Bacteria CO 2 Water Anoxic Sediments Anaerobic Methanogenic Archaea Coefficients: b[0] b[1] r ² NEP (gc m -2 y -1 )

6 Methane Fluxes Travel by Multiple Routes: Need Eddy Covariance Measurements to Assess Fluxes Across a Spectrum of Time and Space Scales, without Sampling Artifacts Air Fluxes, Sources and Sinks of Methane Xylem Transport Air-Water Exchange Ebullition CO 2 Water O xidation: Methanotropic Bacteria Anoxic Sediments Methanogenic Bacteria

7 There Has Been A Revolution in Stable, Precise, Accurate and Low Power Fast Response Methane Sensors

8 Eddy Covariance Flux Method F wc ' ' New Generation of Open Path, Low Power, Laser Spectrometers allow us to Measure Methane Fluxes Continuously and where Methane is Being Produced, in Remote Wetlands

9 Big Ideas/Concepts to Explore What are the Seasonal and Annual Sums of Methane Emission? How do they Vary with Weather/Climate, Plant Traits and Depth/Temperature/Chemistry of the Water? What are the Links between Photosynthesis and Methane Emissions, on short and long time scales? How Do Methane Fluxes Change with Time since Disturbance? How to Minimize Methane Fluxes with Ecological Restoration of Wetlands? How to Manage Rice to Minimize Methane Emissions?

10 Outline Experiences with Open and Closed Path Methane Sensor performance Experiences with Eddy Covariance Flux Measurements of Methane and CO 2 under Natural (tidal wetland), Disturbed (pasture, rice and corn), and Reclaimed (restored wetlands) conditions Demonstrate the Use of Multiple Flux Towers, Flux Footprint Modeling and Remote Sensing to Quantify Spatial Variation in Fluxes in a Wetland Mosaic

11 Delta Field Sites DDB Birth Place Father s Birth Place DDB Childhood Home

12 Six Contrasting Study Sites Drained Peatland Pasture, BAU Alfalfa, BAU Corn, BAU Newly Restored, Wetland 15+ Year Old, Restored Wetland Seasonally Flooded, Rice, Agricultural Option

13 Pilot Study: C Flux Measurements on Natural Tidal Wetland

14 SCIENCE, RESULTS and DISCUSSION

15 CoSpectra Open Vs Closed Path Methane Sensors Detto et al AgForMet

16 Density Corrections Open Vs Closed Path Methane Sensors Detto et al AgFormet

17 Open vs Closed Path Methane Sensor Flux Measurements Detto et al AgForMet

18 Natural Tidal Wetland Newly Restored Wetland

19 Wetland Vs Drained Peatland Pasture Sherman Island, D , Tidal Wetland: gc m -2 d -1 Drained Pasture: gc m -2 d -1 2 F co2 ( mol m -2 s -1 ) Time Hours Flooding Inhibits Nocturnal Respiration and Daytime Photosynthesis, Compared to the Drained Peatland.

20 Methane from a Tidal vs Non Tidal and Restored Wetland Day F CH4 (nmol m -2 s -1 ) Tidal Wetland, 2010 Restored Wetland (t 0 = 2010), Hour

21 Old Wetland, Pilot Project, USGS Newly Restored Wetland Rice

22 Mean Diurnal Pattern of CH 4 Exchange, Summer 2012 Days 200 to 250, Older Wetland (1997) Newly Restored Wetland (Fall, 2010) Rice Old Wetland is a Huge Methane Source F CH4 (nmol m -2 s -1 ) Convection at Night in the Water Layer Promotes Methane Transport Methane Emissions Increase with Age and Density of the Wetland Hour

23 Mean Diurnal Pattern of CO 2 Exchange, Summer 2012 F CO2 mol m -2 s rice newly restored wetland older wetland corn alfalfa hour Corn photosynthesis enhances respiration Drainage (corn) & Disturbance by Restoration Promote Dark Respiration Flooding of Rice and the Older Wetland Suppresses Dark Respiration Photosynthesis of C 4 Corn out paces C 3 Photosynthesis of Rice and Wetlands Ranking of Carbon Sequestration Potential, peak summertime: Wetland > Rice > Corn

24 Old Wetland, Favorable Windds F CH4 (mg-c m -2 d -1 ) Day

25 Newly Restored Wetland F CH4 (mg C-CH 4 m -2 d -1 ) Day

26 Carbon Sink Strength of Wetland Increases with Time since Restoration C Fluxes Depend on Percent of Open Water in Fetch Newly Restored Wetland D287, : 21.8 gc m -2 y -1 D : 39.2 gc m -2 y -1 D : 45.9 gc m -2 y -1 F CH4 (mg-c m -2 d -1 ) Day

27 Much Year to Year Variability in Methane Lost by Rice 400 Rice F CH4 (mg C-CH 4 m -2 d -1 ) Day

28 One Year of Methane Flux Measurements Knox, Sturtevant, Koteen, Verfaillie, Hatala, Baldocchi, unpublished

29 Carbon Budget Site ET (mm y 1 ) NEE (g C m 2 y 1 ) GPP (g C m 2 y 1 ) ER (g C m 2 y 1 ) CH 4 (g C m 2 y 1 ) DC (May May ) 719 ( ) 291 ( ) N/A WP (Aug Aug ) 993 ( ) 397 ( ) ( ) MB (Mar Mar ) 1600 ( ) 368 ( ) ( ) SI (Mar Mar ) 676 ( ) 341 ( ) ( ) TI (Mar Mar ) 1036 ( ) 20.9 ( ) ( ) Knox, Sturtevant, Koteen, Verfaillie, Hatala, Baldocchi, unpublished

30 How Well Does Carbon Uptake Modulate Methane Emissions, in General? 600 F CH4 (mg C-CH 4 m -2 d -1 ) Old Restored Wetland, r 2 = New Restored Wetland, r 2 = 0.17 Rice, r 2 = F CO2 (g C m -2 d -1 )

31 Does Photosynthesis Prime Methane Production in Rice? Hatala et al. GRL 2012

32 Hatala et al. GRL 2012 Methane scales with Photosynthesis

33 Low O 2 in Water Promotes High Methane Fluxes older wetland restored wetland rice 300 F CH4 nmole m -2 s DO water, mg/l Daily Averages

34 Windy Region, Open Water is Well Oxygenated White Caps on New Wetland, July, 2011

35 Newly Restored + Older Wetland + Rice F CH4, nmol m -2 s T water O 2 mg/l Shallow Water (< 10 cm) under Rice is Warmer, More Convective and more Oxygenated, Inhibiting Methane Loss compared to non Tidal, Older Wetland with Deeper and Colder Water (~ 35 cm)

36 Spatial Upscaling in Complex Mosaics Wetland Restoration Project, Mayberry Slough

37 Partition Methane Fluxes According to Water and Vegetation Fractions F F f F f CH water water veg veg 4 One Equation and Two Unknowns Deploy a Second Flux Tower over Different Water/Vegetation Fraction And Assess Fraction of Water and Vegetation in Flux Footprint with Remote Sensing and Solve for F water and F veg

38 Anchor and Roving Flux Towers Soccer/Flux Mobile Restored Wetland, Mayberry Ranch on Sherman Island

39 Fluxes Vary by Wind Direction and Tower Location Sturtevant, Hatala, Knox, Koteen, Verfaillie, Baldocchi, unpublished

40 Hatala, 2013, PhD Different Vegetation/Water Footprints Across Landscape

41 80% Perimeter of Vegetation Patches and Veg Fraction Affects Variability and Magnitude in Methane Fluxes Veg New veg Water 80% 80% 40 m 50% 50% 50% Perm Loc 1 Loc 2 Sturtevant, Hatala, Knox, Koteen, Verfaillie, Baldocchi, unpublished

42 Concluding Remarks Methane Emissions at Highly Productive, Restored Wetlands, in California, are Extremely High Methane Emissions from Restored Wetlands Increase with Time Spatial Scaling Depends on Vegetation Fraction and Size of Patches Accurate Flux Footprint Models are Key towards Interpreting Methane Fluxes

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44 Annual Methane Fluxes 10 1 pdf F CH4 (g-c m -2 y -1 )

45 16 Corn: 719 mm Pasture: 676 mm 16 New wetland: 1600 mm Rice: 1036 mm Old wetland: 993 mm Evaporation (mm d 1 ) /12 200/12 300/12 34/13 Day of year (DDD/YY) 0 100/12 200/12 300/12 34/13 134/13 Day of year (DDD/YY)

46 Corn: 291 gc m 2 Pasture: 341 gc m New wetland: 368 gc m 2 Rice: 20.9 gc m 2 Old wetland: 397 gc m CO 2 flux (g C m 2 d 1 ) /12 200/12 300/12 34/13 Day of year (DDD/YY) /12 200/12 300/12 34/13 134/13 Day of year (DDD/YY)

47 16 12 Respiration Corn Pasture Respiration Mayberry Rice West Pond CO 2 flux (g C m 2 d 1 ) Photosynthesis Photosynthesis /12 200/12 300/12 34/13 Day of year (DDD/YY) /12 200/12 300/12 34/13 134/13 Day of year (DDD/YY)

48 Sherman Island Levee, D , F CH4 (nmol m -2 s -1 ) Did Not See a Tidal Signal Study was Short, in Spring Time Hours Tide, m Hour

49 Days 200 to 250, F CO2 mol m -2 s Hours Older Wetland (1997): gc m -2 d -1 Newly Restored Wetland (Fall, 2010): gc m -2 d -1 Rice: gc m -2 d -1 Corn: gc m -2 d -1