202 years of changes in Mediterranean fire regime in Pinus nigra forest, Corsica
Résumé
Wildfires are critical socio-ecological features in the Mediterranean basin. In a context of global changes (climate, land use), we questioned whether the wildfire regime was altered in the mountains of Corsica, France. Using tree- ring analysis of fire-scarred trees, we tested for changes in frequency, seasonality, and area. We hypothesized that the fire regime changed during the middle-20th century due to human activities, as observed elsewhere in the Mediterranean. We sampled fire-scarred trees, geolocated for mapping fire areas, in a forest of black pine (Pinus nigra laricio). The oldest fire was in 1684 but the fire chronology with adequate sample depth for analysis covered 202 years [1820–1921]. Between 1820–2012, 15 fires were recorded, 8 of which scarred at least 25% of the sampled trees. The mean fire interval was 14 years, corresponding to a high fire frequency with 4 major fires per century. Most fires occurred between 1931–1970. On average, about 50% of trees were scarred by fires before 1931, but this percentage decreased thereafter. The exception was the 2000 fire that impacted 100% of living trees. Mapping showed spatially heterogenous fire areas. These results match other Mediterranean studies showing longer fire intervals since the late-20th century, and wildfires generally occurred during the period of late-earlywood or latewood formation, i.e., summer or early autumn, which is the season of contemporary fires. Although fires were recurrent for more than 200 years with no change in the fire season, the regime changed twice in frequency. These changes likely result from a combination of land use and warmer summer conditions. While pines survived most past fires of low intensity through the last large fire in the 1970’s, the severe fire of 2000, following ca 30 years of fire suppression, killed large patches of mature trees. Such chronology provides rational arguments for black pine ecosystem management, notably to consider seeking to recover the sustainable fire regime of the 19th century, for instance by using prescribed fires to manage surface fuel.
Origine | Fichiers produits par l'(les) auteur(s) |
---|