Research article Characterizing historical and modern fire regimes in Michigan (USA): A landscape ecosystem approach

We studied the relationships of landscape ecosystems to historical and contemporary fire regimes across 4.3 mil-lion hectares in northern lower Michigan USA. Changes in fire regimes were documented by comparing his-torical fire rotations in different landscape ecosystems to those occurring between 1985 and 2000. Previously published data and a synthesis of the literature were used to identify six forest-replacement fire regime categories with fire rotations ranging from very short 100 years to very long 1,000 years. We derived spatially-explicit estimates of the susceptibility of landscape ecosystems to fire disturbance using Landtype Association maps as initial units of investigation. Each Landtype Association polygon was assigned to a fire regime category based on associations of ecological factors known to influence fire regimes. Spatial statistics were used to inter-polate fire points recorded by the General Land Office. Historical fire rotations were determined by calculating the area burned for each category of fire regime and dividing this area by fifteen years to estimate area burned per annum. Modern fire rotations were estimated using data on fire location and size obtained from federal and state agencies. Landtype Associations networked into fire regime categories exhibited differences in both histori-cal and modern fire rotations. Historical rotations varied by 23-fold across all fire rotation categories, and mod