An Analytic Approach to Climate Dynamics and Fire Frequency in the Great Plains

Long-term knowledge of fire regimes aids in understanding the past, present, and future changes in Great Plains ecosystems. Dated fire scar histories and fire rate metrics in the Great Plains allow for quantitative analysis of the effects of climate on fire occurrence, frequency, forcing factors, and probability. Up to three centuries of fire scar data combined with modeling results from Great Plains sites show that spatially, fire frequency was greatly affected by annual maximum temperature from north to south, by annual precipitation east to west, by their interactions, and by precipitation thresholds. A fire-climate model, pc 2fm (Physical Chemistry Fire Frequency Model), calibrated with rate metrics (mean fire intervals) derived from fire history data, estimates that in the Great Plains, fire intervals ranged from <4 to > 30 years. A “precipitation threshold” divides the Great Plains into eastern and western fire regime regions along an approximate 60–100 cm north-south annual precipitation isohyet. Future changes in annual wildland fire probability at 1.2 km² are predicted to change from –10% to 70% in the Great Plains. Midlatitude regions of the Great Plains (Wyoming, eastern Colorado, Nebraska, Kansas, and South Dakota) are expected to increase the most in annual fire probability while some areas in Texas will decrease in fire probability due to fuel limitations.