Response of 2 Semiarid Grasslands to Cool-Season Prescribed Fire

Abstract

Woody perennials have invaded semiarid grasslands throughout the Southwestern United States. This invasion was coupled with decreased grass cover and increased runoff and soil erosion. Fire, which was a natural force that shaped and maintained the grasslands, is a management tool that may aid in restoring and maintaining grass cover. However, fire also poses the risk of increasing erosion and further soil degradation because protection afforded by vegetation is reduced immediately after the fire. Using a randomized block study design, this study measured vegetation cover, soil potentially mineralizable N, and erosion associated with the first application of prescribed fire on 2 semiarid grasslands. The potential for adverse effects from these fires was great because the fires occurred at the beginning of a drought period. However, the effects of the burn were minor relative to the effects of the drought, which caused the greatest change. Grass cover on the burn plots was nearly equal to grass cover on the controls 1 year after the fire. After 2 growing seasons, grass cover was equal on the control and burn plots. Potentially mineralizable soil N and sediment transport were similar on the control and burned plots during the 2 years following the fire. Thus, prescribed fire for reducing the cover of woody perennials may not increase the risk of site degradation over that caused by drought and weather fluctuations.

Response of the shortgrass steppe plant community to fire

“…Unfortunately, data are too limited concerning soil responses to fire for robust statements to be made about how soil temperature, moisture or nutrients relate to vegetation responses. Several authors noted that climatic and geographic variability had effects at least as great as fire and some interactions between climate or site and fire were reported (Biondini et al, 1989;Dix, 1960;Engle and Bultsma, 1984;White and Loftin, 2000;Whisenant and Uresk, 1989;White et al, 2006).…”

Burning and cultivation effects on greenhouse gas emissions and nutrients in wetland soils from Saskatchewan, Canada

“…High temperature burns causes the greatest volatile losses of nitrogen, while ash from lower intensity fires can contain large amounts of ammonium (DeBano et al 1998). Ash can also stimulate microbial activity, affecting CO 2 production and increase the amount of mineralizable N in the soil (White and Loftin 2000). Sometimes, N 2 O emissions have been reported to be higher from untilled soil than tilled soil (Linn and Doran 1984;MacKenzie et al 1997).…”

Homogenization of the Soil Surface Following Fire in Semiarid Grasslands

“…lternet.edu). Related research on these areas is reported in White and Loftin (2000), White et al (2004), and White et al (2006). All areas had domesticated livestock excluded for 20 yr to 30 yr prior to the fires.…”

“…Microtopographic relief was measured with a removable soil bridge that has 31 bushings spaced at 5-cm intervals (White and Loftin 2000;White et al 2006;Ravi et al 2009). Each bridge site has two pieces of reinforcement bar that are driven into the soil to a depth of about 40 cm and fit into holes on the soil bridge so that the bridge was level when in place.…”

“…Multiple-year measurements of soil microtopographic relief, which used identical methods of Ravi et al (2009), were used to evaluate the effect of both prescribed fires and a wildfire on net soil erosion in two semiarid grasslands (White and Loftin 2000;White et al 2006). Microtopographic relief also is being measured by the same method during an ongoing long-term study of a prescribed fire in an additional semiarid grassland that is located about 3 km from the area used by Ravi et al (2009;.…”