Suppression of an invasive pine by a native shrub following a megafire

Abstract

Seedling density of the Chilean wineberry Aristotelia chilensis negatively correlates with the seedlings’ abundance of an invasive pine Pinus radiata, particularly in post-fire areas. This pattern emerged following a megafire in Chile’s Coastal Maulino Forest, a biodiversity hotspot facing increasing fire threats. This pattern, coupled with a high proportion of plots lacking pine seedlings, suggests that A. chilensis may play a role in limiting P. radiata invasion. The negative relationship was strongest in areas with moderate fire severity, likely reflecting differences in shade tolerance. A. chilensis, a light-demanding species with some degree of shade tolerance, can persist in partially shaded environments. In contrast, P. radiata, a more strictly light-demanding species, struggles to establish under significant shade. In high-severity fires, however, we found no significant relationship between these species, likely due to detrimental effects on both species, including potential microbiome dependence for A. chilensis. As A. chilensis shows successful establishment at low fire severity, enhancing its post-fire recruitment, particularly in moderately burned areas, could be a valuable strategy for mitigating P. radiata invasion and restoring fire-affected Mediterranean ecosystems.