Mediterranean Climate‐Change Scenarios Threaten Winter Cover‐Crop Establishment and Soil‐Health Indicators

Abstract

Agricultural systems increasingly face challenges posed by climate change, particularly rising temperatures and altered rainfall patterns. This study evaluated how cover crops (CCs) and soil health indicators respond to six plausible climate change scenarios for the Mediterranean region. Three CC species from the most representative families: barley ( Hordeum vulgare L.), vetch ( Vicia sativa L.) and camelina ( Camelina sativa L.), together with its mixture and with bare soil as the control were considered. Temperature was raised by +1.5°C and + 3.0°C above historical averages recorded in the central Iberian Peninsula using controlled growth chambers. Precipitation was adjusted to three plausible future regimes: −20%, −5% and +10% relative to the historical regional average. Key soil parameters, including organic carbon, electrical conductivity, pH, nutrient availability, mycelial length and microbial abundance, together with plant parameters such as above‐ground and root biomass were evaluated at the end of CCs establishment phase. Results revealed that temperature strongly modulated the responses of the studied parameters to the CC type and precipitation levels, with the +3°C scenario amplifying the contrasts among species and precipitation levels across most plant and soil parameters, thereby shaping both crop performance and soil health indicators. Aboveground biomass declined under +3°C warming, particularly in vetch and camelina, whereas barley exhibited greater resilience. In contrast, root biomass increased at +3°C, suggesting a reallocation of resources to the belowground system as a stress‐induced adjustment to elevated temperatures during CC establishment. Increased precipitation enhanced biomass production and nutrient uptake, while water deficit restricted biomass and microbial abundance in soil. Covered soils maintained higher soil organic carbon contents and exhibited reduced salt accumulation compared with the control. Overall, the temperature increases from October to December negatively affected aboveground growth of cover crops and overall soil health indicators. Fungal and bacterial abundances showed average decline markedly of 61% and 49%, respectively, from +1.5°C to +3.0°C, although the magnitude of these declines varied among precipitation treatments. In contrast, archaeal abundance displayed greater thermal resistance. However, the implementation of those cover crops adapted to specific scenarios, such as barley under +3°C conditions, proved effective in mitigating the impact of rising temperatures, thereby enhancing agroecosystem resilience.