Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: March 14, 2009
Publication Date: April 1, 2009
Citation: Augustine, D.J., Milchunas, D.G., Derner, J.D. 2009. PNG Prescribed Burn Research Summary. Pawnee National Grassland Range Bulletin 10:1. Technical Abstract: Since 1997, we have been studying the effects of prescribed burns conducted during late winter on shortgrass steppe on the Pawnee National Grassland. During 1997 – 2002, we studied burns on the western (Crow Valley) portion of the Pawnee by comparing plant growth on burns conducted by the Forest Service to adjacent unburned portions of the same allotment at the same topographic position. These late-winter burns conducted in moderately grazed sites under a wide range of precipitation conditions during 1997 – 2001 did not negatively affect plant production either in the first or second post-burn growing season. Burns had a small but significant negative effect on the abundance of broom snakeweed (Gutierrezia sarothrae) and prickly pear cactus (Opuntia polyacantha) during the first post-burn growing season, and enhanced the concentration of crude protein in herbaceous forage during May and June. Burning followed by a severe drought in 2002 reduced plant production by 19% in the second post-burn growing season of 2003. During 2007 - 2008, we conducted more intensive studies of a burn conducted on the eastern side of the Pawnee (South Allotment) in March of 2007. We examined effects of the burn on soil moisture (0 – 10 cm depth), soil N availability (0 – 10 cm depth), herbaceous plant production, and in vitro digestibility of blue grama (Bouteloua gracilis) during the first post-burn growing season. Burning had no detectable effect on soil moisture at any time during the 2007 growing season, but burning did increase the availability of inorganic N in the soil, and increased the digestibility of blue grama collected in late May of 2007. The burn had no effect on herbaceous plant production either in 2007 or 2008. These findings suggest that except during severe drought, prescribed burns conducted during the dormant season in shortgrass steppe can have neutral or positive consequences for livestock.