Sideoats Grama Growth Responses to Seasonal Fires and Clipping

Abstract

There is increased interest in the use of summer-season fires to limit woody plant encroachment on southern prairie grasslands, but collateral effects of these fires on grasses are poorly understood. We quantified effects of repeated winter fires, repeated summer fires, simulated grazing (clipping), and their interaction on yields of the C 4 midgrass, sideoats grama (Bouteloua curtipendula) in northern Texas. Monoculture patches of sideoats grama were exposed to 1 of 3 fire treatments: 1) no burn, 2) 2 winter fires in 3 years, or 3) 2 summer fires in 3 years; and to 1 of 2 clip treatments (no clip or clip once each spring). Total yield (live þ standing dead), live yield, percent live tissue, and foliar cover were measured in spring and late-growing season (late-season) over a 7-year period. In unclipped plots, late-season total yield did not fully recover until 2 growing seasons after winter fires and 3 growing seasons after summer fires. By 5 years postfire, total yield was greater in both fire treatments than in the no burn. Live yields recovered more quickly than total yields following summer fires but never exceeded the no burn. Percent live tissue was greater in both fire treatments than in the no burn for up to 2 years postfire. Clipping reduced total and live yields in the no burn and winter-fire treatments but not in the summer-fire treatment. By 5 years postfire, total and live yields were greater in the summer fire þ clip than the no burn þ clip or winter fire þ clip treatments. Results suggest that 1) sideoats grama is tolerant of summer fires but full recovery may require at least 3 years, and 2) in the long-term, summer fire þ clipping may stimulate sideoats grama production more than winter fire þ clipping or clipping alone. ResumenHay creciente interés de usar fuego en verano para limitar la expansió n de plantas leñ osas en los pastizales del sur, pero, los efectos colaterales de estos fuegos sobre los zacates son pobremente entendidos. En el norte de Texas, cuantificamos los efectos de fuegos repetidos en invierno, fuegos repetidos en verano, apacentamiento simulado (cortes) y sus interacciones en el rendimiento de zacate C4 ''Sideoats grama'' (Bouteloua curtipendula). Parches de monocultivo de ''Sideoats grama'' fueron expuestos a 1 de 3 tratamientos de fuego: 1) sin quema, 2) 2 fuegos en invierno en 3 añ os, y 3) 2 fuegos en verano en 3 añ os; y a 1 de 2 tratamientos de corte (sin corte y un corte cada primavera). El rendimiento de biomasa total (viva þ muerta), el rendimiento de biomasa viva, el porcentaje de tejido vivo y la cobertura foliar fueron medidos en primavera y al final de la estació n de crecimiento durante un periodo de 7 añ os. En las parcelas sin corte, el rendimiento de biomasa total a fines de la estació n se recuperó totalmente hasta 2 estaciones de crecimiento después de recibir los fuegos de invierno y hasta 3 estaciones después de recibir los de verano. Cinco añ os después del fuego, el rendimiento de biomasa total fue mayor en ambos tratamientos de fuego que en l...

Prescribed Fire, Grazing, and Herbaceous Plant Production in Shortgrass Steppe

“…Fire and grazing are key drivers of rangeland ecosystem structure and function, but their individual and interactive roles can vary considerably in semiarid versus mesic ecosystems (Oesterheld et al 1999). Effects of fire and its interaction with grazing have been studied extensively in mesic tallgrass and mixed-grass rangelands of the North American Great Plains (Wright and Bailey 1982;Knapp et al 1999;Fuhlendorf and Engle 2004;Vermeire et al 2004;Ansley et al 2006) and in semiarid sagebrush steppe of the intermountain region (Bates et al 2009). However, understanding of fire effects in semiarid areas of the western Great Plains is more limited (Ford 1999).…”

Plant Community and Soil Microbial Carbon and Nitrogen Responses to Fire and Clipping in a Southern Mixed Grassland

“…This increase is primarily because of enhanced growth of C 4 perennial grasses as a result of both increased light availability and the advantage conferred by C 4 grasses' higher N use efficiency following fire-induced volatilization losses of N from the soil surface litter layer (Hulbert 1988;Seastedt and Ramundo 1990;Ojima et al 1994;Blair 1997). In southern Great Plains grasslands, fire in late winter and early spring is a common management tool, with minimal or even short-term (2-3 yr) stimulatory effects on C 4 grass production (Engle and Bidwell 2001;Ansley et al 2006;Ansley and Castellano 2007). These shifts toward greater abundance of C 4 grass species entail a corresponding shift in the C:N stoichiometry of plant litter inputs, with uncertain but potentially significant implications for soil microbial communities (Knops et al 2002).…”

Restoration of C4 grasses with seasonal fires in a C3/C4 grassland invaded by Prosopis glandulosa, a fire‐resistant shrub

“…First, the most pronounced increases in C 4 mid‐grass cover relative to the control occurred several years after the last fire in a particular treatment. This suggests that an effective fire return interval for promoting shifts in herbaceous composition toward C 4 mid‐grass dominance may be at least 3–5 yr (Ansley et al 2006). More frequent fires may slow the ability of this functional group to assert dominance.…”

“…Accordingly, there has been an increased interest in application of late‐summer fires when C 3 grasses are not green and most C 4 grasses have entered a summer‐dormant stage. These fires usually yield greater top‐kill of woody plants than winter fires (Ansley et al 2008), but there is a concern that they may damage important native C 4 grasses (Engle et al 1998; Ansley et al 2006).…”