Figure 8
From: Multi-Millennial Fire History of the Giant Forest, Sequoia National Park, California, USA
Giant Forest fire history compared with summer Palmer Drought Severity Index (PDSI, Cook et al. 2004) and temperature reconstructions (Graumlich 1993) from tree-ring chronologies. The upper graph (A) shows the 54 largest fire years (25% or more trees scarred each year) superimposed on the annual PDSI time series. Seventy-six percent of these large fire years occurred during dry years. The middle graph (B) shows 25 yr non-overlapping fire frequencies and means of the PDSI series (dashed line). The bottom graph (C) shows 25 yr non-overlapping fire frequencies and means of summer temperature (dashed line). The 25-year binning of the PDSI series (B) shifts the mean of that series to negative (drier) relative to the mean of annual time series (zero, in A).