Scotts Bluff National Monument - Fire Regime

Scotts Bluff National Monument by National Parks Service

We know that the prairies of North America, and specifically the grasslands of the Great Plains, were maintained by fire. These fires were caused by both natural events, such as lightning, and Native Americans. Native Americans ignited fires to create better grazing for the large prairie ungulates, such as bison, and therefore improve their own hunting success. However as Euro-American settlement moved west into the prairies these natural fire regimes were altered. When the natural fire regimes were altered then the vegetative species composition of the prairies also changed.

Euro-American people considered fire to be destructive and suppressed fires as much as possible. The result has been dramatically longer fire return intervals (fewer fires over time), out-of-season fires (spring vs. fall), with the resulting invasion of woody and non-native vegetation species. What was the natural fire regime for the greater Scotts Bluff area? This very question was researched in 1993. Reviews of published literature and historical records of an area from the confluence of the North and South Platte Rivers, north to the Black Hills, and south to the Kansas border were conducted. A review was also made of the fire records of the Monument, which were first begun in 1935.

This intensive study revealed that fires were much more common on the prairie that in the pine forests of the west. In areas where the prairies were level to gently rolling, the natural fire return interval was as frequent as every five years. In more rugged prairies with broken topography, such as areas with steep ravines and rocky outcrops or badlands, the fire return intervals were as high as fifteen to thirty years. Also fires generally were uncommon during the wettest periods of the year, spring and early summer. Natural fires burned usually in the late summer and early fall, when the dominant cool season grasses were cured and dry.

With Euro-American settlement fires were suppressed. Occasionally fires were used to manage prairie, These fires were usually ignited in the spring or early summer, normally the wettest times of the year. This would allow the fires to burn with less intensity and be easier to control than the naturally occurring late summer and early fall fires. The Euro-American settlement of the North American prairies led to a complete alteration of the natural fire regime. Reduced fire occurrence, fires ignited in the spring, and fires of low intensity have all contributed to the alteration of prairie vegetation. Today the Monument has an active prescribed fire program. All wildfires are suppressed, but prescribed fires are ignited to manage the vegetation. Depending on the area to be treated with fire and the prescribed fire plan's goals, fire may be used in the spring or late summer/early fall. Generally spring burning is used to control exotic grasses, such as downy and smooth brome or reduce hazardous fuels. Late summer and early fall fires are used to mimic what would be naturally occurring fires and maintain the natural prairie vegetation.