Climate Sensitivity of Soil Organic Carbon and Nutrient Stocks under Different Land Uses in Europe

Abstract

Soil organic carbon (SOC) and nutrient stocks play a key role in climate change mitigation by influencing biogeochemical cycles, plant productivity, and greenhouse gas emissions; however, their responses to the future projected warming scenarios remain uncertain. The aim of this study was to estimate the SOC and nutrient stocks under different land uses across the European Union (EU) and the United Kingdom (UK) in 2018 and to predict these stocks under the different warming scenarios (RCP2.6, RCP4.5, and RCP8.5) to identify the best land uses that can steadily maintain and improve SOC and nutrient stocks. A random forest model (R2 = 0.66) was employed to estimate soil bulk density. To predict the stocks for 2050 and 2070 under the different RCPs, mean annual temperature (MAT), total precipitation (TP), sand content, and land use types were used as the predictor variables. The results revealed that SOC and nitrogen (N) stocks increased under RCP2.6, while they significantly decreased under RCP8.5, particularly in croplands. In contrast, phosphorus (P) and potassium (K) stocks increased with rising temperatures across all land uses. Grasslands and shrublands appeared to be more resistant compared with croplands and woodlands, as SOC and N stocks did not show any notable changes with warming. Woodland ecosystems, especially pine-dominated woodland, exhibited an increase in these stocks, while spruce-dominated woodland showed a significant decline in SOC and N stocks with increasing temperature. These findings reveal the most climate-resistant and effective land management strategies to improve SOC and nutrient stocks and provide a roadmap for policymakers by recommending the cultivation of root crops, vegetables, and flowers in agricultural lands, and the planting of pine and broadleaved species in woodland to optimize SOC and nutrient stocks under future climate scenarios.