Application of CarboSOIL model to predict the effects of climate change on soil organic carbon stocks in agro-silvo-pastoral

Mediterranean management systems

Miriam Muñoz-Rojas , Luca Doro, Luigi Ledda, and Rosa Francaviglia

MED_SoilResearch Group

CarboSOIL, a new component of the Agroecological Decision Support System MicroLEIS

MicroLEIS DSS

Land degradation risk

Land suitability

Land capability

Carbon sequestration

capacity

CarboSOIL: a land evaluation tool for soil C assessment

MicroLEIS DSS

Land degradation risk

Land suitability

Land capability

Carbon sequestration capacity

Climate regulation

Soil structure

Soil fertility

Water holding capacity

Infiltration capacity

Water use efficiency

Soil biological health

CarboSOIL: a land evaluation tool for soil C assessment

CarboSOIL: a land evaluation tool for soil C assessment

SoilN, pH, CEC

TextureBulk density

Water Holding Capacity

Land use15 land use types

ClimateWinter Temperature

Summer temperatureAnnual Rainfall

SiteElevation

Slope

CarboSOIL

CarboSOIL model diagram

SOIL ORGANIC CARBON0-25, 25-50, 50-75 cmO

UTP

UT

S

Incorporation of residuesMineralisation Aereation Nutrient

availabilityBiological

activity

Accumulation / loss Respiration

SOIL

PR

OCE

SSE

S

CLIMATE

TJJA PPT

LAND USE

LULC

SITE

ELEV SLOP SERO DRAI

SOIL

FCAP SAND CLAY PHWA NITROCEXC BULKINPU

T FA

CTO

RS

TDJF

Source: Muñoz-Rojas, 2012

CarboSOIL: a land evaluation tool for soil C assessment

CarboSOIL structure Variables CarboSOIL 25 CarboSOIL 50 CarboSOIL 75

Coef Coef CoefIntercept 774.69 1085.65 1150.92

ClimatePRPT 0.003 0.000 0.000TDJF 1.430 0.615 0.637TJJA -0.930 -0.687 0.067

SiteELEV 0.000 0.003 0.001SLOP 0.004 0.005 0.001DRAI

ad - - -df -2.078 -1.502 -0.210ex 1.887 -2.391 -4.076SERO

ne - - -se -0.997 -0.883 -0.403re -0.159 0.449 -0.466ge -0.333 1.216 -0.879

SoilNITRO 1.934 26.309 6.063PHWA 0.837 0.072 1.039CEXC -0.009 0.000 0.029SAND 0.803 1.056 1.161CLAY -1.192 -1.597 -1.687BULK -493.990 -686.455 -746.993FCAP 0.018 -0.068 0.002

Variables CarboSOIL 25 CarboSOIL 50 CarboSOIL 75

Coef Coef CoefIntercept 774.69 1085.65 1150.92

Land useLULC

ot - - -nr 1.169 -0.527 -0.469pr -1.483 0.858 -0.580vn -0.210 -3.229 -1.816fr -1.009 -0.525 1.068ol 1.481 -0.232 -0.313cm -0.371 -1.068 -2.222af -0.051 -1.627 -0.063bf -0.335 -2.405 0.029cf 0.284 -1.367 0.697mf 6.329 -1.377 0.982gr 1.511 0.409 -0.526sc 1.358 -0.635 -2.021wd 1.396 -3.398 1.334sm -2.465 -3.064 -3.576

y = a+ b1x1+b2x2+b3x3+ ---+bnxn

y= SOC ; a= Intercept; b= variables; x= coefficients

CarboSOIL: a land evaluation tool for soil C assessment

Study area

Mean altitude -285 m

Climate- warm temperate with dry and hot summer.• Mean annual rainfall of 623

mm (range 367–811)• Mean annual temperature

15.0°C (13.8–16.4)

Soil type - Haplic Endoleptic Cambisols, Dystric (WRB)

Potential native vegetation - Cork oak forest (Quercus suber L.), converted to managed land with pastures and vineyards in recent years

North-eastern Sardinia (Italy) 40°46’N, 9°10’E

Land use transformation

Study area

Six land uses with different levels of cropping intensification were compared:

Tilled vineyards (TV)

No-tilled grassed vineyards (GV)

Hay crop (HC): oats, Italian ryegrass and annual clovers or vetch for 5 years and intercropped by spontaneous herbaceous vegetation in the 6th year

Pasture (PA): 5 years of spontaneous herbaceous vegetation, and 1 year of intercropping with oats, Italian ryegrass and annual clovers or vetch cultivated as a hay crop

Cork oak forest (CO)

Semi-natural systems (SN): natural re-vegetation of former vineyards (scrublands, Mediterranean maquis and Helichrysum meadows)

Land use transformation

From left to right clockwise: no-tilled grassed vineyard (GV), grazed hay crop under oats land

cover (HC), semi-natural systems with scrubs and Mediterranean maquis (SN), grazed pasture with spontaneous vegetation (PA).

Study area

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input data• Climate (actual and

future)• Site• Soil• Land use

Model test and validation• Measured values vs.

Predicted values

Scenario analysis• Actual scenario• Climate change

scenarios

Input data: variables description and sources

VARIABLE TYPE VARIABLE NAME CODE UNIT SOURCE AND REFERENCE

Dependent variable

Soil Organic C SOCC Mg/ha University of SassariFrancaviglia et al. (2012;2014)

Climate Total precipitation PRPT mmCRA elaborations from baseline data

and GCMsWinter Temperature TDJF oC

Summer Temperature TJJA oCSite Elevation ELEV m

University of SassariSlope SLOP %Drainage DRAI -

Field surveys and lab analysesFrancaviglia et al. (2012;2014)

Soil Erosion SERO -Soil Nitrogen NITRO g/100g

pH PHWA -Cation Exchange Capacity

CEXC meq/100g

Sand SAND g/100gClay CLAY g/100gBulk density BULK g/ccField capacity FCAP g/100g

Land use Land use/land cover LULC - Field surveys

Input dataModel test

and validation

Scenario analysis

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input data: climate change scenarios

Global Climate Models

• GISS (Goddard Institute of Space Studies, USA)

• HadCM3 (Met Office, Hadley Centre, UK)

Climate Change Horizons

• 2010-2039 (2020)

• 2040-2069 (2050)

• 2070-2099 (2080)

IPCC Models

• A2 (high population growth, slow economic and energetic development)

• B2 (more emphasis on sustainability and efficient technologies

Input dataModel test

and validation

Scenario analysis

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input dataModel test

and validation

Model applicationAssessment of the model performance

and comparison between measured and simulated values

n

iii SO

nRMSE

1

2)(1

n

1i

2i

n

1i

2ii

)OO(

)OS(1EF

where Oi and Si are observed and simulated SOC at ith value, Ō is the mean of the observed data and n is the number of the paired values. The lowest possible value of RMSE is zero, indicating that there is no difference between simulated and observed data.

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

EF compares simulations and observations on an average level, and can range from - to 1, with the best performance at EF=1.

Input dataModel test

and validation

Model application

y = 0.777x + 5.4985R² = 0.9774; RMSE = 8.42; EF = 0.63

0

20

40

60

80

100

0 20 40 60 80 100

pred

icte

d SO

C (M

g/ha

)

measured SOC (Mg/ha)

y = 0.8215x + 3.7392R² = 0.9902; RMSE = 5.07; EF = 0.98

0

20

40

60

80

100

0 20 40 60 80 100

pred

icte

d SO

C (M

g/ha

)

measured SOC (Mg/ha)

y = 0.9702x + 1.4942R² = 0.7621; RMSE = 5.88; EF = 0.93

0

20

40

60

80

100

0 20 40 60 80 100

pred

icte

d SO

C (M

g/ha

)

measured SOC (Mg/ha)

0-25 cm measured SD=14.12

25-50 cm measured SD=19.53

50-75 cm measured SD=11.09

Regression coefficients are significant at p<0.001 and R2 are high, the standard deviation of the measured values is higher than RMSE, and EF is very close to the optimum value.

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input dataModel test

and validation

Model application

0.0%

1.0%

2.0%

3.0%

4.0%

TV GV HC PA CO SN

GISS 2020 A250-75

25-50

0-25

0.0%1.0%2.0%3.0%4.0%5.0%

TV GV HC PA CO SN

GISS 2020 B250-75

25-50

0-25

0.0%

1.0%

2.0%

3.0%

TV GV HC PA CO SN

Hadley 2020 A250-75

25-50

0-25

-1.0%

0.0%

1.0%

2.0%

3.0%

TV GV HC PA CO SN

Hadley 2020 B2 50-75

25-50

0-25

CarboSOIL model predicted an overall increase of SOC stocks in the 2020 climate scenarios in all the soil sections, with the higher increases in the 50-75 cm section, and the smaller in the 25-50 cm soil section.

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input dataModel test

and validation

Model application

A SOC decrease is instead expected in the 2050 and 2080 scenarios in the 25-50 cm soil section, more marked in the vineyards in comparison with the other land uses.

-1.0%

0.0%

1.0%

2.0%

3.0%

4.0%

TV GV HC PA CO SN

GISS 2050 A250-75

25-50

0-25

-2.0%

-1.0%

0.0%

1.0%

2.0%

3.0%

TV GV HC PA CO SN

GISS 2050 B250-75

25-50

0-25

-2.0%

0.0%

2.0%

4.0%

6.0%

TV GV HC PA CO SN

Hadley 2050 A250-75

25-50

0-25

-2.0%

0.0%

2.0%

4.0%

6.0%

TV GV HC PA CO SN

Hadley 2050 B250-75

25-50

0-25

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input dataModel test

and validation

Model application

-4.0%-2.0%0.0%2.0%4.0%6.0%8.0%

TV GV HC PA CO SN

GISS 2080 A250-75

25-50

0-25

-2.0%

0.0%

2.0%

4.0%

6.0%

TV GV HC PA CO SN

GISS 2080 B250-75

25-50

0-25

-5.0%

0.0%

5.0%

10.0%

TV GV HC PA CO SN

Hadley 2080 A250-75

25-50

0-25

-2.0%

0.0%

2.0%

4.0%

6.0%

TV GV HC PA CO SN

Hadley 2080 B250-75

25-50

0-25

Oppositely, SOC increases are still expected in the 0-25 cm section and to a more extent in the 50-75 cm section, particularly evident in the vineyards.

CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

• The model CarboSOIL has proved its ability to predict SOC stocks at different soil depths under different climate change scenarios.

• Climate change will have a negative impact on SOC stocks in the soil section 25-50 cm, in particular in a long term (2050 and 2080).

• Important decreases of SOC stocks were found in vineyards.

• The methodology developed in this research might be easily applied to other Mediterranean areas with available data on climate, site, soil and land use.

Conclusions

Miriam Muñoz-Rojas , Luca Doro, Luigi Ledda, and Rosa Francaviglia

MED_SoilResearch Group

Thank you!