Historical fire-climate relationships of upper elevation fire regimes in the south-western United States
The authors reconstructed both regional climate teleconnections (ENSO, PDO, and AMO) and historical fire occurrence using tree-ring analysis. Their objectives were to analyze the relationship between moisture variability and regional, individual and phase combinations of, ENSO, PDO, and AMO and then compare this climate variability to fire occurrence in upper elevation forests across the southwest.
Both individual and phase combinations of ENSO, PDO, and AMO were strongly associated with moisture variability. As a consequence, periods of regional drought were strongly related to regional synchrony of fire occurrence in upper elevation forests historically. The authors found that all stand-replacing fire years and 18 of 20 synchronous fire years occurred during periods of regional drought that were 2-4 times as dry as normal conditions. No antecedent drought lags were necessary for fire occurrence due to the fact that fuels in high elevation forests are typically dense enough to burn when sufficiently dry conditions allow for successful ignition and spread. The authors suggest that ENSO strongly and consistently affects regional moisture conditions in the Southwest, thereby fire occurrence, including high severity fire occurrence, but that the effects can be tempered by phases of PDO.
Climate and Fire Linkages
Both individual and phase combinations of ENSO, PDO, and AMO were strongly associated with moisture variability. The authors found that all stand-replacing fire years and 18 of 20 synchronous fire years occurred during periods of regional drought that were 2-4 times as dry as normal conditions. The authors suggest that ENSO strongly and consistently affects regional moisture conditions in the Southwest, thereby fire occurrence, including high severity fire occurrence, but that the effects can be tempered by phases of PDO.
Both individual and phase combinations of ENSO, PDO, and AMO were strongly associated with moisture variability. As a consequence, periods of regional drought were strongly related to regional synchrony of fire occurrence in upper elevation forests historically. The authors found that all stand-replacing fire years and 18 of 20 synchronous fire years occurred during periods of regional drought that were 2-4 times as dry as normal conditions. No antecedent drought lags were necessary for fire occurrence due to the fact that fuels in high elevation forests are typically dense enough to burn when sufficiently dry conditions allow for successful ignition and spread. The authors suggest that ENSO strongly and consistently affects regional moisture conditions in the Southwest, thereby fire occurrence, including high severity fire occurrence, but that the effects can be tempered by phases of PDO.