do ‘payments for ecosystem services’ promote soil carbon ... · c sink methods total c measured...

C Sink MethodsTotal C measured at the soil analysis lab at Univ.

of Costa RicaActive C via permanganate-oxidizable C (POxC) in the lab

Do PES programs sequester C belowground?

Cumulative Soil Respiration unaffected by PES Land UseSpecific CO2 is lowest in Conservation Forests

C Source Results

Do ‘Payments for Ecosystem Services’ promote soil carbon sequestration in the tropics?Andreas G. Khechfe*1,2, A. Peyton Smith3, Katherine Quiñonez-González3, Malak M. Tfaily4, Jane Fudyma4, Kelly Brumbelow5, Georgianne W. Moore2

*1Undergraduate, Humboldt State University, Dept. of Environmental Science and Management; 2Texas A&M University (TAMU), Ecosystem Science and Management; 3TAMU, Soil and Crop Sciences, 4 University of Arizona, Dept. of Soil, Water and Environmental Science,5TAMU, Civil and Environmental Engineering

Forest Species & Site, not PES, affects Total and Active Soil Carbon

Site, rather than PES, altersmolecular composition of SOM

RationalePayments for ecosystem services (PES) programs support afforestation & forest conservation activities intended to enhance carbon (C) sequestration in tree biomass. Yet, soils hold two-to-three times as much C than trees. With increasing interest in managing land for C sequestration, we ask

Take Home MessageSoils at PES sites appear more efficient at using soil C for respiration than agricultural sites suggesting that there may be more stabilized C at PES sites. Identifying the amount and nature (i.e., stability) of soil C stored may reveal an unidentified sink of C for PES ecosystems.

HypothesesWe hypothesize that the increase in the abundance and diversity of C inputs from forest cover in PES ecosystems will result in greater potential for soil C sequestration.

Experimental ApproachTo determine the C source and sink potential of soils from PES plantations & forests, we measured C source (CO2 burst test) and sink (total organic carbon, active carbon and the molecular composition of soluble C) in PES site & in adjacent agricultural sites (i.e., represents

prior land use) across sites in North-Central Costa Rica.

Funding for this Research Experiences for Undergraduate program is provided by the National Science Foundation’s Division of Earth Sciences (EAR-1659848). Special thanks to Mr. Carlos Porras and FUNDECOR (Fundación para el Desarrollo de la Cordillera Central Volcánica) for their collaboration in this study in the logistics for selecting the PES sites; Don Eugenio Gonzalez- Jimenez and the personnel of the Soltis Center. Thanks also to Kaiya Weatherby, Glen Aguilar, and Melissa Zapata, fellow REU students, for helping with this study.

Costa Rica

PES Sites1. Ecosistemas2. Rio Peje3. Gamboa4. Soltis

Lipids

Lignin Tannins

Condensed Hydrocarbons

Unsa

t. HC

Proteins Amino Sugars

Carbo-hydrates

Hydr

ogen

-to-C

arbo

n Ra

tio

Oxygen-to-Carbon Ratio

-MS

300 400 500 600 700 800 900 m/z0

1

2

3

4

5

7x10Intens.

m/z

Negative-Ion electrospray Ionization FT-ICR MS at 12 TeslaSuwannee River Fulvic Acid (SRFA)10,000 peaks > S/N=7 (200 < m/z < 1000)m/Δm50% > 1000,000 at m/z 500

Ecosistemas Gamboa Hacienda Rio Peje Soltis Center

0

20

40

60

80

100

0

400

800

1200

1600

2000

D. marginata Pasture Grasses H. alchorneoides T. amazonia V. guatemalensis Mixed Species

Agriculture Forest Plantation Conservation Forest

Ecosistemas Gamboa Hacienda Rio Peje Soltis Center

C-C

O2

(!g

g-1so

il)C-

CO2

(!g

g-1so

il C)

Agriculture Plantation Cons. Forest

Ecosistemas Gamboa Rio Peje Soltis

a

b

C Source MethodsCumulative C-CO2 measured via 24 h incubation under constant temperature & moisture. (i.e. CO2burst test)

Direct headspace injection into PP Systems EGM-5

Soils (0-5 cm) were collected in 3 land uses across 4 sites, N = 3 samples per site. Soils were oven dried at 50ºC before analyses

The molecular composition of C via high resolution mass spectrometry, Fourier transform ion cyclotron resonance (FT-ICR MS) from soil-water extracts.

Tota

l C_m

g/kg

POxC

_mg/

kg

0.0e+0

5.0e+4

1.0e+5

1.5e+5

2.0e+5

0

300

600

900

1200

D. marginata Pasture grasses

H. alchorneoides

T. amazona V. guatemalensis

Mixed Species


Total C_mg/kgEcosistemasGamboaRioPejeSoltisEcosistemasGamboaRioPejeSoltis

POxC_mg/kg

Ecosistemas

GamboaRioPejeSoltis

POxC_mg/kgEcosistemasGamboaRioPejeSoltis

Soil

Carb

on (m

g kg

-1)

Activ

e C

(mg

kg-1

)


a

bab ab

ab

ab

a

b

ab ab

abab

Ecosistemas Gamboa Rio Peje Soltis Agriculture Plantation Native Forest

H/C

0.5

1.0

1.5

2.0

2.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2O/C

ClassAminoSugarCarbConHCLigninLipidNoneOtherProteinTanninUnsatHC

Agriculture Plantation Native Forest

N R

ows

4.8%8.3%

9.1%

42.7%

6.5%

5.3%

9.3%

2.4%

11.5% 4.3%7.1%

9.4%

44.7%

6.2%

4.5%

8.3%

2.3%

13.2%4.6%

8.3%

9.2%

39.7%

4.7%

4.3%

10.5%

2.3%

16.3%

ClassAminoSugarCarbConHCLigninLipidOtherProteinTanninUnsatHC



• C composition did not differ between PES and non-PES sites.

Site + Species(Land Use) (p < 0.05)

• PCA shows PES effect differs by site

Ecosistemas Gamboa RioPeje

Prin

2

-5-4-3-2-101234

-6 -5 -4 -3 -2 -1 0 1 2 3 -6 -5 -4 -3 -2 -1 0 1 2 3 -6 -5 -4 -3 -2 -1 0 1 2 3Prin1

Land UseAgricultureNative ForestPlantationAgriculture: (90%)Native Forest: (90%)Plantation: (90%)

Ecosistemas Gamboa Rio Peje

www.noble.org

CO2

www.noble.org www.noble.org www.noble.org

ActiveCarbon

Labile Carbon

SOMTotal Carbon C Sink Results

• There was no effect of PES on cumulative CO2

• Site influenced CO2Gamboa > Rio Peje, Ecosistemas

ab ab

ab

ab

• Carbon use efficiency potentially greater in Cons. Forest.

Van Krevelen diagram used to id compounds

Lignin-like compounds are most abundant

Principal Components Analysis (PCA) of % abundance FT-ICR compounds

do ‘payments for ecosystem services’ promote soil carbon ... · c sink methods total c measured...

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