Sensitivity of Soil Organic Carbon and Derived Indicators to the SDG 15.1.3 Model in Mediterranean Versus Other European Biogeoclimatic Regions.

The Sustainable Development Goal indicator 15.3.1 is defined as the “proportion of land that is degraded over total land area.” This indicator has been used to characterize degraded land surfaces in the Mediterranean region (Cherif et al., 2023), but its specific sensitivity to soil organic carbon (SOC), a critical component of soil health and land productivity, has not yet been assessed in this biogeoclimatic context considered lower in SOC (Romanya & Rovira, 2011).

This study investigates the relationship between SDG 15.3.1 indicator levels (improving, stable, declining) and SOC contents and derived indicators (e.g. SOC/N, SOC/Clay, SOCstock) using LUCAS topsoil datasets (0–20 cm) across Europe. We compared Mediterranean and non-Mediterranean biogeoclimates to assess the indicator’s responsiveness to soil carbon variations.

Our analysis shows that areas classified as “improving” according to the SDG 15.3.1 indicator correspond to soils with significantly higher SOC and SOC stock values than those classified as “stable” or “declining” in the Mediterranean bioclimate specifically—but not in other European regions. No significant differences were found between the “stable” and “declining” SDG 15.3.1 indicator levels.

These findings suggest that SDG 15.3.1 is particularly sensitive to SOC variations in Mediterranean environments, supporting its use as a reliable indicator of soil degradation in these regions. They also highlight the critical role of SOC as a key parameter for assessing soil degradation, especially under Mediterranean climatic conditions, and reinforce the need for region-specific soil monitoring programs that integrate SOC dynamics with vegetation carbon use efficiency (CUE) for more comprehensive land degradation assessments.

Cherif, I., Kolintziki, E., & Alexandridis, T. K. (2023). Monitoring of Land Degradation in Greece and Tunisia Using Trends . Earth with a Focus on Cereal Croplands. Remote Sensing, 15(1766). https://doi.org/https:// doi.org/10.3390/rs15071766

Le, Q.B., Shiri, Z., & Zucca, C. (2025a). Maps of carbon use efficiency (CUE), inter-annual CUE trends and analyses of relationships between CUE trend and current SDG indicators 15.3.1. Deliverable 7.2. WP7 (Enhanced regional soil condition mapping in the MR including C Stock mapping), SOIL health monitoring and information systems FOR sustainable soil management in the MEDiterranean region (SOILS4MED) project, PRIMA.

Le, Q.B., Zucca, C., & Shiri, Z. (2025b). Functional early warnings of land degradation revealed by carbon-use efficiency across the Mediterranean Eco-Region. Manucript in prepation.

Romanya, J., & Rovira, P. (2011). An appraisal of soil organic C content in Mediterranean agricultural soils. Soil Use and Management, 27, 321–332. https://doi.org/10.1111/j.1475-2743.2011.00346.x