Ecological resilience and biodiversity dynamics of an Island forest following a volcanic eruption.

Volcanic eruptions are complex natural disturbances with profound effects on ecosystems; however, detailed studies on their spatio-temporal impacts remain scarce. The Tajogaite eruption on La Palma (Canary Islands) lasted 85 days, from September 19 to December 13, 2021, severely affecting the endemic Canary Islands pine forest through lava flows, widespread tephra fallout, and gases. In this habitat, we conducted a comprehensive biodiversity survey over two years on twelve 30 × 30 m plots along a 7 km transect from the crater southwards. We quantified species richness and abundance of gymnosperms, angiosperms, invertebrates, lizards, birds, and bats, linking biodiversity patterns to tephra thickness and distance from the crater. Pinus canariensis near the crater resprouted a month after the eruption; however, their severe physical damage eventually resulted in their death. From June 2022 onwards, a more pronounced recovery was observed in the pines located more than 400 m from the crater. Woody understory plants survived at farther distances, while herbs and grasses have not yet arrived for recolonisation of the new substrate. The abundance and recovery of invertebrates were closely linked to host plant availability, with increases in Hemiptera, Coleoptera, and Araneae. Lizards were the most affected vertebrates, with slow recovery. Small passerines returned to fragmented habitat, while raptors and corvids remained present throughout the affected region, with populations correlating with food availability. Bats were observed throughout the pine forest, but sparsely. Overall, the study highlights the complex, group-specific dynamics of ecosystem recovery after volcanic disturbance, providing insights into resilience and succession in island ecosystems.