Cones of invasive pines are significant firebrands in Patagonia

Abstract

Pine invasions in South America commonly modify fire regimes by changing habitat fuel characteristics, but studies have often overlooked cones as a fuel component. In South America, cones are a novel and unique fuel type, especially those from serotinous pines. Despite their significant contribution, their role as canopy fuels and firebrands has not been reported in invaded areas. This study addresses this gap by evaluating the role of Pinaceae cones as firebrands through field observations from wildland firefighters from Andean Patagonia, Argentina. We also characterized the canopy cone load of the serotinous Pinus radiata in both invasion and plantation contexts. Of the surveyed firefighters, 93.55% reported that cones, especially those of P. ponderosa, act as firebrands and effectively spread fire. The fuel load of serotinous cones in P. radiata invasion was 9.57 kg m−2, nearly seven times higher than in plantations due to higher pine density. Given this, pine invasion could spread fires more readily than plantations due to their higher cone load, increasing the likelihood of fire propagation to surrounding areas. This newly identified ecological role of cones in the introduced range of pines emphasizes the need to consider cones in fire behavior models and invasion management to mitigate the impact of fire spread.