Three Examples of Surface Fire Histories Along Elevational Transects

The pine-dominated woodlands and forests of the Sky Islands typically sustained surface burns about once per decade until the turn of the 19th to the 20th centuries, when livestock grazing and organized fire suppression effectively ended this centuries-long pattern. Fire scar chronologies from 31 sites in 10 mountain ranges illustrate this history. By combining elevational transects of fire scar chronologies in three of the mountain ranges it is possible to visualize the temporal changes in widespread fire occurrence. Combining all 31 chronologies for the region, it is evident that there was a high degree of synchrony in fire occurrence that must have been related to broad-scale climate variations. Comparisons of synchronous fire years with a regional tree-ring reconstruction of precipitation confirm the importance of wet/dry seasonal and interannual climate patterns in promoting widspread burning.