Plant biomass carbon inputs, Plant biomass carbon inputs, losses, and storage in relosses, and storage in re--

established marshes in the established marshes in the SacramentoSacramento--San Joaquin DeltaSan Joaquin Delta

By Robin L. MillerBy Robin L. Miller

Location of Location of SacramentoSacramento--San Joaquin San Joaquin Delta in Delta in California California and depth of and depth of subsidencesubsidence

Demonstration Demonstration Project Project

19971997--presentpresentTwo 3 haTwo 3 ha wetlandswetlandsContinuously floodedContinuously floodedNonNon--tidal systemtidal systemWater managementWater management

West Pond25 cm deep

East Pond55 cm deep

Measurements includeLand-surface elevation change and sediment accretion:

Plant biomass productionDecomposition of organic matterGaseous CO2 and CH4 fluxesEnvironmental Factors (i.e. pH, temperature, dissolved oxygen, etc)

Change in elevation over time by wetland environment

-100

0

100

200

300

400

500

600

11-Mar-97 24-Jul-98 6-Dec-99 19-Apr-01 1-Sep-02 14-Jan-04 28-May-05 10-Oct-06 22-Feb-08 6-Jul-09

mm

25 cm deep wetland

55 cm deepwetland- marsh

55 cm deepsubmerged andfloating

mid season standing live biomass

0

500

1000

1500

2000

2500

3000

1998 1999 2000 2001 2002 2004 2006 2007 2008

year

dry

wt (

g/m

2)

shoots, 25 cm deep

roots, 25cm deep

shoots, 55cm deep

roots, 55cm deep

Scirpus litter in 55 cm deep water

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800 900days of decomposition

prop

ortio

n le

ft

1997

1999

2000

2003

Decomposition Decomposition rates slowed over rates slowed over time.time.Early Early decomposition decomposition was slower in the was slower in the 25 cm deep 25 cm deep wetland.wetland.Later Later decomposition decomposition was slower in the was slower in the 55 cm deep 55 cm deep wetland.wetland.

DDI: November 1997 - February 2000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800 900

days of decomposition

perc

ent r

emai

ning

Scirpus 55cm

Typha 55cm

Scirpus 25cm

Typha 25cm

DDIV: February 2003 - August 2005

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800 900 1000days

ash

free

per

cent

left

Typha 55 cm deep

Scirpus 55 cm deep

Typha 25 cm deep

Scirpus 25 cm deep

DDV: Location of decomposition DDV: Location of decomposition bags in the 55 cm deep wetlandbags in the 55 cm deep wetland

Slide 1outflow

inflowinflow

DDV: Scirpus decomposition by location and vegetation

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800 900 1000days of decomposition

perc

ent r

emai

ning

inlet submergent

mid submergent

inlet marsh

mid marsh

25 cm marsh

Average water temperatures in marsh and submergent vegetation (4/30/06-5/2/06)

10

12

14

16

18

20

22

24

26

0 20 40 60 80 100 120 140 160

degr

ees

C

emergent marsh surface

submergent vegetation surface

emergent marsh midpt (-18 cm)

submergent vegetation midpt (-30cm)

water temperature in emergent marsh by location (April 30 - May 2, 2006)

12

13

14

15

16

17

18

19

20

21

0 20 40 60 80 100 120 140 160

degr

ees

C

inlet marsh surfacemid marsh surfaceinlet marsh mid depth (-18)mid marsh mid depth (-18)

Spatial variability in Spatial variability in wetland environmentswetland environments

Submergent Vegetation Emergent Marsh Edge Emergent Marsh Interior

Water residence time Shortest Mid Longest

Water Temperature Warmest Cooler Coolest

pH Highest Lower Lowest

Dissolved Oxygen Highest Lower Lowest

NO3 (river source) Available Absent/Available Absent

SO4 (river source) Available Available Depleted/Absent

H2S Absent Elevated/Absent Absent/Increased

Fe (sediment source) Low Low/Increased Elevated

Decomposition rate Fastest Slowed Slowest

Correlations among wetland Correlations among wetland environmental factors (p<0.0001)environmental factors (p<0.0001)

-0.395negativeTotal

FepH

0.454positive SO4pH

-0.467negativeTotal

FeSO4

0.533positive DONO3

0.755positive DOpH

Co-efficient

Cor-relationBA

pH indicative of relative wetland pH indicative of relative wetland biogeochemistrybiogeochemistry25 cm deep wetland had lower 25 cm deep wetland had lower pH than the 55 cm deep pH than the 55 cm deep wetland, but more sulfate and wetland, but more sulfate and less iron.less iron.Shorter water residence time in Shorter water residence time in shallower wetland influencing shallower wetland influencing biogeochemistry; river water biogeochemistry; river water source of sulfate to wetlands.source of sulfate to wetlands.

pH and methane emissionspH and methane emissionsMarsh CHMarsh CH4 emissions are emissions are positively correlated to pH positively correlated to pH (coefficient = 0.333, only (coefficient = 0.333, only temperature, water depth temperature, water depth and season stronger).and season stronger).Wetland pH correlated to Wetland pH correlated to COCO2:CH:CH4, such that lower , such that lower pH decreases CHpH decreases CH4 loss loss relative to COrelative to CO2 uptake uptake (coefficient = 0.354, only (coefficient = 0.354, only water depth and plant water depth and plant number stronger)number stronger)

plant methane effluxes by location in 25 cm deep wetland

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

25-Mar-01 03-Jul-01 11-Oct-01 19-Jan-02 29-Apr-02 07-Aug-02 15-Nov-02 23-Feb-03 03-Jun-03

g C

H4-

C/m

2/h

inlet marsh

interior marsh

P=0.0003

Gaseous C fluxes in re-established wetlands and drained peat

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

15-Mar-00 01-Oct-00 19-Apr-01 05-Nov-01 24-May-02 10-Dec-02 28-Jun-03 14-Jan-04

gC/m

2/hr

CH4 flux through plantsCO2 uptakeDiffusive CO2 fluxAg field CO2

Greenhouse gas balance of CO2 uptake and CH4 loss in wetlands, where CH4 has 25x the GWP of CO2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

01-Oct-00 19-Apr-01 05-Nov-01 24-May-02 10-Dec-02 28-Jun-03 14-Jan-04

gCO

2-C

/m2/

hr

55 cm deep

25 cm deep

ConclusionsConclusionsReRe--establishing marshes in the Delta can restore conditions for carestablishing marshes in the Delta can restore conditions for carbon bon storage and reverse subsidence.storage and reverse subsidence.The plant community significantly affected the wetland environmeThe plant community significantly affected the wetland environment and nt and accretion rates. accretion rates. Decomposition rates of marsh vegetation slowed over time, and diDecomposition rates of marsh vegetation slowed over time, and differed by ffered by location with the slowest decomposition occurring in the marsh ilocation with the slowest decomposition occurring in the marsh interior, nterior, where water residence time was greatest. where water residence time was greatest. Wetland pH significantly decreased over time, was significantly Wetland pH significantly decreased over time, was significantly related to related to decomposition rates, and was strongly correlated to methane emidecomposition rates, and was strongly correlated to methane emissions ssions and the availability of electron acceptors, including DO, NOand the availability of electron acceptors, including DO, NO33, SO, SO44, and Fe. , and Fe. Methane emissions affect the GHG balance of marshes, but spatialMethane emissions affect the GHG balance of marshes, but spatialvariability suggests hydrologic management potential.variability suggests hydrologic management potential.Measurements of gaseous C fluxes suggest the carbon storage poteMeasurements of gaseous C fluxes suggest the carbon storage potential of ntial of these wetlands can counterbalance the effects of methane losses,these wetlands can counterbalance the effects of methane losses,particularly when stop loss of COparticularly when stop loss of CO22 and Nand N22O* from drained peat is taken into O* from drained peat is taken into account.account.

Thank you!Thank you!

Great thanks to Great thanks to the California the California Department of Department of Water Water Resources for Resources for funding this funding this research.research.Many thanks to Many thanks to the many hands the many hands that have that have helped with this helped with this study.study.