Study of methodological approaches for biodiversity monitoring in Nature-based Solutions (NBS) interventions, using Soil and Water Bioengineering (SWBE) techniques in the Mediterranean region.

In the context of the current climate crisis, the intensification of extreme meteoro-logical events necessitates a shift in hydrogeological risk-mitigation strategies, promoting a transition toward Nature-Based Solutions (NBS). Among these, Soil and Water Bioengineer-ing (SWBE) represent a bioinspired solution for slope stabilisation, as it combines geotech-nical safety with the restoration of ecological functionality. However, the scientific valida-tion of such techniques is often caught up in disciplinary fragmentation and by the lack of long-term monitoring protocols capable of assessing both the evolution of slope stability and the success of environmental recovery. This study aims to address this gap through the development and application of an integrated, multidisciplinary monitoring approach. The research focuses on shallow landslides in the Northwest Tuscany (Pomezzana case study, 1996 flood events), comparing sites restored using SWBE techniques and naturally evolved landslides. Subsequently, the core of the research focused on a dual-phase long-term monitoring campaign, focusing on both slope stability and ecological recovery. The first phase involved a comparative stability analysis between a landslide restored with SWBE techniques and an adjacent landslide left to natural evolution. Data acquired from the multi-approach protocol were incorporated into slope-stability modelling to quantify the temporal evolution of the Factor of Safety. The results demonstrate that, in the SWBE restored site, the physiological degradation of wooden structural elements is effectively compensated by the progressive in-crease in soil-root reinforcement. This dynamic equilibrium ensures that the Factor of Safe-ty remains stable over time, contrasting with the fluctuations observed in the natural evolu-tion scenario. Parallel to the mechanical assessment, the second phase expanded to a comprehen-sive multi-taxon monitoring of biodiversity. This investigation evaluated the effectiveness of ecological restoration by analysing three key biological factors: vegetation composition, soil macrofauna communities, and soil microorganisms. Through the analysis of alpha-diversity indices, the study assessed the capacity of SWBE interventions to reactivate eco-system functions and support complex biological communities comparable to those found in natural succession. As a significant added value to the ecological investigation, the research presents preliminary insights from an ongoing advanced analysis of beta-diversity. Utilising shotgun metagenomic sequencing of the soil microbiome combined with phytosociological surveys, this current work aims to explore the functional co-occurrence networks between plant communities and microorganisms, seeking to unveil the deeper ecological dynamics activated by Soil and Water Bioengineering techniques. In conclusion, the dissertation confirms that Soil and Water Bioengineering struc-tures are not static infrastructures but dynamic and resilient systems. The results provide new operational guidelines for design, species monitoring, and maintenance, offering an es-sential knowledge base for planning sustainable interventions that integrate technical safety with biodiversity restoration.