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Accueil du site → Doctorat → Australie → 2011 → Spatial and temporal patterns of wildfires in semi-arid south-western Australia

University of Western Australia (2011)

Spatial and temporal patterns of wildfires in semi-arid south-western Australia

O’Donnell, Alison Jane

Titre : Spatial and temporal patterns of wildfires in semi-arid south-western Australia

Auteur : O’Donnell, Alison Jane

Université de soutenance : University of Western Australia

Grade : Doctor of Philosophy (PhD) 2011

Résumé
I compared selection ratios, a measure of the influence of vegetation types and fuel ages on fire spread, among fire sizes to determine if the segmented model represented actual shifts in the controls of fire spread. Results Fire intervals in the LJR ranged from 3 to >> 67 years (67 years is the limit of the observation period). Fire intervals in shrublands were typically shorter (Weibull b = 46 years) and more dependent on fuel age than most other vegetation types, while fire intervals in open woodlands were much longer (Weibull b = 405 years) and less dependent on fuel age than in shrub-dominated vegetation types. Areas adjacent to or surrounded by salt lakes burnt less frequently (Weibull b = 319 years) and fire intervals were less dependent on fuel age compared to more exposed areas (e.g., Weibull b < 101 years). Wildfires tended to occur during extremely dry and hot conditions typically associated with El Niño. However, major (>100,000 ha burnt), minor (<25,000 ha burnt), and nonfire years all occurred under different climatic conditions. Minor fire years were not associated with anomalous climatic conditions, while non-fire years occurred during significantly cool and wet conditions. In contrast, major fire years were associated with extreme drought during the fire year, preceded by wet and cool conditions in the previous year. Individual fires in the LJR varied greatly in size, ranging from 181 to >150,000 ha. The FSD was described well by a segmented model with break points at 2,286 ha and 41,020 ha. Fuels <20 years old were important for limiting fire spread regardless of fire size...

Mots Clés : Forest fires—Western Australia—Prevention and control ; Environmental aspects ; Vegetation dynamics ; Geographic information systems ; Dendrochronology ; Cypress ; Fire ecology ; Arid regions

Présentation

Page publiée le 7 novembre 2011, mise à jour le 1er juillet 2017