Impacts of rice terrace abandonment on soil ecosystem multifunctionality: Insights into reduced microbial diversity and exacerbated nitrogen limitation

Soil ecosystem multifunctionality (EMF) reflects the ability of soils to perform multiple ecological functions, and enzyme stoichiometry indicates microbial involvement in ecosystem nutrient cycling and energy balance. However, it remains unclear how the prevalence of terrace abandonment drives soil EMF and its relationship with microbial nutrient limitations. Soil samples were taken from rice terraces (RT), as well as from dry land (DLT) and forest land (FLT) formed after abandonment, and soil profiles were excavated to a depth of 0–120 cm. It was found that the soil EMF decreased significantly by 144.84% and 142.03%, respectively, in the DLT and FLT compared to RT. Soil EMF was not significantly different between DLT and FLT, and individual soil ecosystem functions were more similar. Microbial phosphorus limitation was observed in this study area, and the abandonment of RT resulted in a shift in microbial limitation from phosphorus to nitrogen, weakening microbial elemental homeostasis. Further analysis revealed that soil microbial diversity was the primary driver of decreased soil EMF, followed by enzyme stoichiometry. Therefore, soil microbial diversity may serve as a biological indicator of soil EMF quality. Overall, the abandonment of RT reduces soil EMF, but it is more beneficial to improve it by alleviating microbial nutrient limitation and fostering microbial diversity. Additionally, this study also highlights the significant impact of enzyme stoichiometry on soil EMF. More importantly, reducing the prevalence of abandoned terraces in mountainous and hilly areas contributes to sustainable soil resource management and cleaner agricultural production.