Fire Impact on Diversity and Forest Structure of Castanea sativa Mill. Stands in Managed and Oldfield Areas of Tenerife (Canary Islands, Spain)

Wildfires are integral to many forest ecosystems, yet their ecological effects are often influenced by historical land use and management. In this study, we assess the short-term impacts of fire and management on Castanea sativa Mill. stands in the fayal-brezal zone of northern Tenerife (Canary Islands), where traditional agroforestry systems have been widely abandoned. We established 12 transects across four stands: managed-burned, managed-unburned, oldfield-burned, and oldfield-unburned. We analyzed forest structure, understory species richness and composition, and soil nutrient content one year after a large wildfire. Forest structure has primarily been determined by management history, with oldfield plots showing greater tree density, basal area, and basal sprouting. Fire has had a limited effect on tree mortality, affecting ~10% of individuals on average. Understory species richness was significantly higher in managed plots, particularly those affected by fire, suggesting a positive interaction between disturbance and management. Species composition differed significantly among treatments, with Indicator Species Analysis identifying distinct taxa associated with each condition. Fire in oldfield plots led to increased compositional similarity with managed stands, indicating fire’s potential homogenizing effect. Principal Component Analysis of soil nutrients did not reveal clear treatment-related patterns, which was probably due to microenvironmental variability and the short post-fire interval. Overall, our results highlight the dominant role of land-use legacy in structuring these forests, with fire acting as a secondary but influential driver, revealing significant changes in species composition as well as in species richness. These findings have direct relevance for conservation and restoration strategies as well as for maintenance in these stands of Castanea sativa. They should also encourage managers of these protected areas, where land abandonment and fire are increasingly shaping forest dynamics.