Ecological Restoration Process of El Hito Saline Lagoon: Potential Biodiversity Gain in an Agro-Natural Environment

In the global context of biodiversity and ecosystem services loss, the integration of agriculture with ecological restoration is crucial. This study presents the biodiversity value (Bv) index for the first time as a tool for decision-making and securing funding for future restoration projects. The Bv index was used to assess biodiversity values in both restored natural habitats and agricultural areas in the saline lagoon of El Hito, a natural reserve located within an agricultural landscape in central Spain. Additionally, we estimated biodiversity gains from habitat transitions and explored the relationship between biodiversity, soil pH, and salinity. Sustainable agricultural practices, combined with ecological restoration methods, can lead to synergistic actions that reduce the potential detrimental effects of agriculture. Our results show that transitioning from agricultural to natural habitats consistently increases biodiversity. Among agricultural practices, multiannual vegetated fallows had the highest Bv values. Restoration led to a continuous biodiversity improvement, with the exception of the final transition from permanent pastures to Elymus 1410, which showed a slight decline in biodiversity. We also found that higher soil salinity and pH were associated with greater biodiversity values, likely due to historical agricultural practices that favored areas with lower salinity and pH for higher productivity. Salinity and pH act as limiting factors for biodiversity; therefore, agricultural plots with lower salinity and pH, particularly those adjacent to natural habitats, are expected to yield greater biodiversity gains if restored.