Towards Healthy Soils by 2050: Linking NBS Implementation with Soil–Plant Indicators

Nature-Based Solutions (NBS), such as urban green infrastructure, agroforestry, and wetland restoration, are increasingly recognized as effective strategies for restoring soil health and enhancing ecosystem resilience, particularly in the context of climate change and land degradation. However, the scientific and operational integration of soil health monitoring within NBS implementation remains limited, despite its critical role in assessing long-term effectiveness. The forthcoming EU Soil Monitoring and Resilience Directive, which mandates harmonized soil monitoring systems and robust indicators across Member States, underscores the urgency of addressing these gaps.

Drawing on case studies and insights from European initiatives and research activities within the LIFE and Next Generation EU projects under the National Recovery and Resilience Plan, we focus on designing, applying, and monitoring NBS in both urban and natural areas, with restoration actions targeting degraded soils and ecosystems.

In line with the Directive’s requirement for harmonized monitoring systems, we propose a soil–plant indicator framework integrating physical, chemical, and biological dimensions: (i) enzyme activities and ecological stoichiometry to quantify functional microbial biodiversity loss; (ii) stable isotopes of C and N to quantify soil carbon loss; (iii) soil biodiversity metrics (taxonomic and diversity of microbiomes) to quantify biodiversity loss; and (iv) plant functional traits as proxies for soil–plant interactions. These indicators could be introduced as new descriptos in the Annex I during the Directive revision.

By bridging NBS implementation with soil health assessment, this work highlights research opportunities to support the Directive’s objectives and advance evidence-based strategies for achieving healthy soils by 2050. Collaborative efforts among scientists, policymakers, and stakeholders are essential to overcome methodological bottlenecks and promote resilient, biodiversity-friendly solutions at multiple scales.