Resilience of European larch (Larix decidua Mill.) forests to wildfires in the western Alps

• Published in: New forests 2017-09, Vol.48 (5), p.663-683
• Main Authors: Moris, Jose V., Vacchiano, Giorgio, Ravetto Enri, Simone, Lonati, Michele, Motta, Renzo, Ascoli, Davide
• Format: Article
• Language: English
• Subjects: Abundance; Biomedical and Life Sciences; Canopies; Combustion; Dominant species; Forest & brush fires; Forestry; Forests; Grazing; Grazing intensity; Ground cover; Larix decidua; Life Sciences; Mountains; Recruitment; Regeneration; Resilience; Snags; Topography; Wildfires
• ISSN: 0169-4286; 1573-5095
• DOI: 10.1007/s11056-017-9591-7

European larch is a dominant species in the subalpine belt of the western Alps. Despite recent increases in wildfire activity in this region, fire ecology of European larch is poorly understood compared to other larch species around the world. This study aims to assess whether European larch forests are resilient to fires, and to find out the factors that drive such resilience. We assessed the recovery of larch forests along a gradient of fire severity (low, moderate, high) based on the abundance and dominance of post-fire larch regeneration. We established 200 plots distributed among burned larch forests in nine wildfires that occurred between 1973 and 2007 in the western Alps. We included variables regarding topography, climate, fire severity, fire legacies, ground cover, grazing intensity, and time since fire. To evaluate potential drivers of larch recruitment, we applied generalized linear mixed models (GLMM) and random forests (RF). Larch regeneration was much more abundant and dominant in the moderate- and high-severity fire classes than in the low-severity class. More than half of the plots in the moderate- and high-severity classes were classified as resilient, i.e., post-fire larch regeneration was enough to recover a larch stand. GLMM and RF produced complementary results: fire severity and legacies, such as snags, canopy cover and distance to seed source, were crucial factors explaining post-fire larch recruitment. This study shows that fire has a positive effect on larch regeneration, and we conclude that European larch forests are highly resilient to mixed-severity fires in the western Alps.