The relationship between ENSO state and wildfire extent in the Cape Floristic Region of South Africa
Steven Myburgh, Karen J. Esler, Heath Beckett, R. Arthur Chapman, Guy F. MidgleyBackground
Predictive understanding of how major climatic teleconnections influence fire regimes in Mediterranean-type ecosystems remains limited, despite emerging evidence of regional teleconnection effects on fire activity.
Aims
To test for associations between El Niño–Southern Oscillation (ENSO) state and wildfire extent in two montane protected-area complexes (one semi-arid, the other more mesic) in the Cape Floristic Region (CFR).
Methods
Using historical climate and fire records, we related monthly mean area burnt to the Oceanic Niño Index (ONI), used to classify ENSO phase and intensity, including by season and fire-size class, and applied complementary frequentist and Bayesian models to test for relationships between ONI and area burnt.
Key results
Frequentist models showed significant positive relationships between ONI anomaly magnitude and monthly area burnt for both negative (La Niña-associated) and positive (El Niño-associated) anomalies in the Hottentots–Holland complex, whereas Bayesian models strongly supported the La Niña-associated relationship. Across both complexes, large and very large fire classes generally contributed more to monthly mean area burnt at more extreme ONI values.
Conclusions
Both statistical approaches supported a positive association between increasing magnitude of negative ONI anomalies and wildfire extent.
Implications
These findings support heightened wildfire vigilance and preparedness during intense ENSO phases in the more mesic southern CFR.