Vegetation Responses to Prescribed Burning of Grazed Shortgrass Steppe

Authors: Augustine, David; MILCHUNAS, DANIEL - COLORADO STATE UNIVERSITY

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2008
Publication Date: 1/28/2009
Citation: Augustine, D.J., Milchunas, D.G. 2009. Vegetation responses to prescribed burning of grazed shortgrass steppe. Rangeland Ecology and Management 62(1):89-97.

Interpretive Summary: Over the past century, fire has been widely suppressed in the western Great Plains, in part due to potential negative effects on forage production for livestock. More recently, interest in the use of prescribed fire in shortgrass steppe has increased due to potential applications for wildlife management, control of unpalatable plant species and restoration of historic disturbance regimes. We studied the effects of low-intensity, prescribed burns conducted during late winter on plant growth on the Pawnee National Grassland in northeastern Colorado. Late-winter burns conducted in moderately grazed sites under a wide range of precipitation conditions during 1997 – 2001 did not negatively affect forage production either in the first or second post-burn growing season. Burning followed by a severe drought in 2002 reduced plant growth in the second post-burn growing season of 2003. Burns temporarily suppressed the abundance of broom snakeweed and prickly pear cactus, and enhanced the amount of nitrogen (N) in blue grama early in the first post-burn growing season. These findings suggest that except following severe drought, prescribed burns conducted during late winter in grazed shortgrass steppe for objectives unrelated to livestock production can also have neutral or positive effects on livestock.

Technical Abstract: Over the past century, fire has been widely suppressed in the western Great Plains, in part due to potential negative effects on forage production for livestock. More recently, interest in the use of prescribed fire in shortgrass steppe has increased due to potential applications for wildlife management, control of unpalatable plant species and restoration of historic disturbance regimes. We studied the effects of low-intensity, prescribed burns conducted during late winter (March) on herbaceous production, forage nitrogen content, and plant species composition of shortgrass steppe on the Pawnee National Grassland in northeastern Colorado. Late-winter (March) burns conducted in moderately grazed sites under a wide range of precipitation conditions during 1997 – 2001 did not negatively affect forage production either in the first or second post-burn growing season. Burning followed by a severe drought in 2002 reduced production by 19% in the second post-burn growing season of 2003. Burns temporarily suppressed the abundance of broom snakeweed (Gutierrezia sarothrae) and prickly pear cactus (Opuntia polyacantha), and enhanced forage nitrogen content during May and June of the first post-burn growing season. These findings suggest that except following severe drought, prescribed burns conducted during late winter in grazed shortgrass steppe for objectives unrelated to livestock production can also have neutral or positive effects on livestock.