Land Degradation-Based Approach for Assessing the Performance of the Natura 2000 Network in Mainland Spain

Human impact on natural ecosystems is unsustainable and has led to a significant loss of biodiversity, highlighting the importance of protected area networks such as the European Union’s Natura 2000 (N2000). This study assesses the effectiveness of Special Areas of Conservation (SACs) in mainland Spain, using a Normalised Relative Severity Index (SER) computed from land condition states of ecological maturity (2010–2020). A total of 596 SACs were analysed, comparing their SER index with that of unprotected areas. Biophysical characteristics such as elevation, tree cover density, and human impact were used for explanatory purposes. At the national level, SACs exhibit a significantly higher median SER index than unprotected areas, indicating a better overall land condition status within N2000. However, regional variations were observed, with some Autonomous Communities in the Atlantic showing better land conditions outside N2000, which is attributed to vigorous vegetation growth in marginal areas. Differences in the SER index between inside and outside N2000 are proportional to the isolation degree of SACs. The study demonstrates that N2000 positively contributes to land conservation in mainland Spain. Nevertheless, it emphasizes the need to consider regional specificities and manage non-protected areas for more effective long-term conservation, especially in the Mediterranean region.