Flammability features of native and non-native woody species from the southernmost ecosystems: a review

Vegetation plays a crucial role in the ignition, propagation, and severity of fire, and understanding the relationship between plants and fire through flammability attributes has become a useful tool that is increasingly used in studies on fire dynamics worldwide. However, in the southern cone of South America, rather few studies have systematically and specifically addressed the flammability of vegetation, and yet fewer have compared native and non-native species. Given the increasing interest in knowing the flammability characteristics of vegetation, this review aims to assess the potential differences in flammability between native and non-native plant species that inhabit the southern cone and to identify the main methodologies and experiments used to analyze vegetation flammability. Twenty-eight species were identified, 18 native to the region and 10 non-native. Additionally, 64 experimental tests were revised to evaluate plant flammability. It was found that Cryptocarya alba, Acacia dealbata, Eucalyptus globulus, and Pinus ponderosa are the species with a high flammability index. By contrast, the species Araucaria araucana, Austrocedrus chilensis, Embothrium coccineum, and Persea lingue showed low flammability. The methodologies used to evaluate vegetation flammability were highly variable, with the use of epiradiators being the most frequent. Our review indicates that the geographic origin of vegetation (native vs. non-native in South America) is not a decisive factor in determining species-level differences in flammability. Other relevant factors that contribute with the degree of plant flammability include fuel moisture, the morphology of the species, and its internal chemical compounds. We highlight the necessity of continuing the study of plant flammability and advance in the standardization of protocols and measurements, using uniform criteria and increasing comparative studies between species, particularly in the southern cone of South America where catastrophic wildfires are increasing.