Enrichment-planting with pines alters fuel amount and structure in endangered Araucaria araucana forests in northwestern Patagonia, Argentina

The introduction of non-native tree species for large-scale afforestation may alter the fire regime of native ecosystems by modifying fuel proprieties. We quantified changes in fuel abundance and structure resulting from the establishment of commercial Pinus spp. plantations in Araucaria araucana ecosystems in northwestern Patagonia, Argentina. Specifically, we assessed the amount, distribution, and condition (live/dead) of surface and standing fine fuel in A. araucana stands with mature pine plantations (i.e. > 20 cm dbh) and in stands dominated only by A. araucana (control). Our study shows that both types of stands are prone to wildfires, but pine plantations have fuel characteristics that imply greater flammability due to higher fuel load and vertical continuity in the understory and in the overstory canopy. In the absence of fuel mitigation practices, A. araucana stands with plantations exhibit greater flammability than the control A. araucana stands, potentially promoting the occurrence and spread of fires of greater severity. This study contributes to understanding the effects of enrichment planting of pines, and possibly pine invasions, on A. araucaria ecosystem flammability and their potential consequences on fire behavior.

Automated summary

The introduction of non-native tree species for large-scale afforestation may alter the fire regime of native ecosystems. This study in the Araucaria araucana ecosystems in Patagonia, Argentina confirms that the establishment of commercial Pinus spp. plantations increases flammability due to higher fuel load and vertical continuity. These pine plantations are more prone to wildfires and can potentially promote the occurrence and spread of fires of greater severity.