Monitoring Natura 2000 habitats to support Opuntia stricta containment on Capraia Island (Tuscan Archipelago, Italy)

Invasive alien species are a major threat to biodiversity, prompting management actions. Here, we present the first two years of monitoring Natura 2000 habitats on Capraia Island (Tuscan Archipelago, Italy), in relation to control measures for the invasive plant Opuntia stricta, within the LIFE TETIDE project (Turning Eradication Targets into Durable Effects). We randomly sampled 25 permanent 100 m2 macroplots in the areas most affected by Opuntia stricta, recording the vegetation macrocategory and cover values of Opuntia stricta and Natura 2000 habitats. Within each macroplot, we surveyed two 4 m2 subplots for compositional analyses. We used Linear Mixed-Effects Models to assess temporal and vegetation effects on Opuntia stricta and habitat cover; multivariate ordination and PERMANOVA to evaluate community composition, with environmental variables linked to the ordination; and Wilcoxon tests to validate habitat classification accuracy using species of the reference physiognomic combination according to the Italian Habitats Interpretation Manual. Our results indicate spatial heterogeneity in Opuntia stricta distribution, with a slight increase in coastal habitats. We recorded an ecological preference for coastal vegetation and low maquis, particularly on habitats 1240 “Vegetated sea cliffs of the Mediterranean coasts with endemic Limonium spp.”, 5320 “Low formations of Euphorbia close to cliffs”, and 5330 “Thermo-Mediterranean and pre-desert scrub”. We recorded a substantial representation of reference species across all habitats, except for 8220 “Siliceous rocky slopes with chasmophytic vegetation”, which requires further investigation. Data collected provide a useful pre-intervention snapshot of Capraia’s habitats, pivotal for the full evaluation of the impacts of the project actions.