Woody encroachment mediates the effects of management abandonment on plant species diversity across agroforestry systems in southern Europe

• Abandonment of agroforestry practices is increasing in southern Europe • Woody encroachment expands after abandonment across contrasting agroforestry systems • In silvopastoral and chestnut systems encroachment hinders plant species richness • Recently treated sites after abandonment rapidly boost plant species richness • Maritime pine woodlands show weak diversity responses to conservation state The abandonment of traditional agroforestry practices in southern Europe may entail serious consequences for plant biodiversity and wildfire risk. In this study, we evaluated how plant species diversity responds to management history across contrasting agroforestry systems in southern Europe, with particular emphasis on the role of woody encroachment as a key underlying process. We focused on silvopastoral systems used for livestock grazing, chestnut orchards managed for fruit production and maritime pine woodlands managed for resin extraction. Within each agroforestry system, sampling sites represented three management conditions: (i) actively managed systems currently under traditional use, (ii) long-term abandoned systems (>20 years), and (iii) recently restored systems where management had been reintroduced (<1 year). Woody encroachment increased significantly in long-term abandoned systems and emerged as a key driver of plant species diversity patterns. Higher woody species cover and height were associated with increased woody species richness but with marked reductions in herbaceous and total plant species richness across systems. In silvopastoral systems, plant species richness, particularly of herbaceous species, declined sharply under long-term abandonment, with recently restored sites showing intermediate values. In chestnut orchards, responses of plant species richness to management history were weaker than in silvopastoral systems but remained statistically significant. In contrast, species richness in maritime pine woodlands was insensitive to management condition. Overall, our results highlight the context-dependent role of woody encroachment in shaping responses to the abandonment of agroforestry systems and subsequent restoration, suggesting that the reintroduction of low-intensity management can help maintain plant species diversity in structurally open systems.