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

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 suitabilityLand capability Carbon sequestration capacity Climate regulation Soil structure Soil fertility Water holding capacity Infiltration capacity Water use efficiency Soil biological health 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

Soil N, pH, CEC Texture Bulk density Water Holding Capacity Land use 15 land use types Climate Winter Temperature Summer temperature Annual Rainfall Site Elevation Slope CarboSOIL

CarboSOIL model diagram SOIL ORGANIC CARBON 0-25, 25-50, cm OUTPUTS Incorporation of residues MineralisationAereation Nutrient availability Biological activity Accumulation / lossRespiration SOIL PROCESSES CLIMATE TJJAPPT LAND USE LULC SITE ELEVSLOPSERODRAI SOIL FCAPSANDCLAYPHWANITROCEXCBULK INPUT FACTORS TDJF Source: Muñoz-Rojas, 2012 CarboSOIL: a land evaluation tool for soil C assessment

CarboSOIL structure Variables CarboSOIL 25CarboSOIL 50CarboSOIL 75 Coef Intercept Climate PRPT TDJF TJJA Site ELEV SLOP DRAI ad--- df ex SERO ne--- se re ge Soil NITRO PHWA CEXC SAND CLAY BULK FCAP Variables CarboSOIL 25CarboSOIL 50CarboSOIL 75 Coef Intercep t Land use LULC ot--- nr pr vn fr ol cm af bf cf mf gr sc wd sm y = a+ b 1 x 1 +b 2 x 2 +b 3 x b n x n 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 6 th 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 NAMECODEUNITSOURCE AND REFERENCE Dependent variable Soil Organic CSOCCMg/ha University of Sassari Francaviglia et al. (2012;2014) ClimateTotal precipitationPRPTmm CRA elaborations from baseline data and GCMs Winter TemperatureTDJF oCoC Summer TemperatureTJJA oCoC SiteElevationELEVm University of Sassari SlopeSLOP% DrainageDRAI- Field surveys and lab analyses Francaviglia et al. (2012;2014) Soil ErosionSERO- SoilNitrogenNITROg/100g pHPHWA- Cation Exchange Capacity CEXCmeq/100g SandSANDg/100g ClayCLAYg/100g Bulk densityBULKg/cc Field capacityFCAPg/100g Land useLand use/land coverLULC- Field surveys Input data Model 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 (2020) (2050) (2080) IPCC Models A2 (high population growth, slow economic and energetic development) B2 (more emphasis on sustainability and efficient technologies Input data Model test and validation Scenario analysis CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input data Model test and validation Model application Assessment of the model performance and comparison between measured and simulated values where O i and S i are observed and simulated SOC at i th 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 data Model test and validation Model application 0-25 cm measured SD= cm measured SD= cm measured SD=11.09 Regression coefficients are significant at p<0.001 and R 2 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 data Model test and validation Model application 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 cm section, and the smaller in the cm soil section. CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input data Model test and validation Model application A SOC decrease is instead expected in the 2050 and 2080 scenarios in the cm soil section, more marked in the vineyards in comparison with the other land uses. CarboSOIL application in agro-silvo-pastoral Mediterranean management systems

Input data Model test and validation Model application Oppositely, SOC increases are still expected in the 0-25 cm section and to a more extent in the 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 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 Thank you!