Effects of Season of Burning on the Microenvironment of Fescue Prairie in Central Saskatchewan

Abstract

The microenvironmental effects of spring, summer and autumn burns were investigated for a small area of fescue prairie in Saskatchewan over two growing seasons. Maximum fire temperature in all burns exceeded 300°C at a height of 5-10 cm in the canopy. At a depth of 1 cm in the soil, temperature increased to 40°C during the summer burn, but was unaffected by burns at other seasons. Spring-burned grasses recovered to the same height as the unburned control plot by the end of the first summer. Grass height was similar in all plots by the end of the second growing season, but aboveground biomass in all burned plots was about half that of the control. Graminoid leaf area index at the end of the second growing season ranged from 0.65 in the control plot to 0.27 in the autumn burn. Surface albedos dropped to about 0.03 immediately after burning and took about 3 months to return to the pre-burn values near 0.20. By mid-June of the second year, albedos were similar in all plots. Soil temperatures at 50 cm depth in the burned plots were higher than in the control during the first summer and lower during the winter. The greatest winter snowpack (73 mm water equivalent) accumulated in the control, compared to 48, 35 and 25 mm in the spring, summer and autumn burned plots, respectively. In the first growing season the greatest demand for water occurred in the spring plot followed by the summer, control and autumn plots. In the second season water demand did not differ significantly among plots, reflecting the similarities in plant cover. The microenvironmental effects of a single burning episode in fescue prairie disappear rather quickly, so that there is little long-term impact on the vegetation.

Temporal changes in species composition in Fescue Prairie: relationships with burning history, time of burning, and environmental conditions

“…Recurring fire presumably shifts the plant community composition to species that are adapted to changes in the microenvironment. Soil water content is reduced and plant water stress increases Romo et al 1993;Grilz and Romo 1994), particularly after autumn burning, because less snow accumulates on burned sites and sites are warmer in the summer Romo et al 1993; Grilz and Romo 1994;Sinton Gerling et al 1995;Archibold et al 2003). Soil temperatures on burned sites are also colder in the winter (Archibold et al 2003).…”

“…Portions of Kernen Prairie were grazed or hayed periodically until 1967 (Pylypec 1986). Several studies on the effects of burning have been conducted at Kernen Prairie since 1986 (see Pylypec 1991;Redmann 1991;Redmann et al 1993;Romo et al 1993;Romo 1994, 1995;Archibold et al 1998Archibold et al , 2003Pylypec and Romo 2003).…”

Long-term effects of burning Festuca and Stipa-Agropyron grasslands

“…This 130-ha remnant grassland has been relatively undisturbed since the 1930s except for periodic mowing on portions of it until 1976 (Pylypec 1986). Since 1986 various parts of the prairie have been burned by prescribed fires, and the impacts of these fires on the vegetation have been described in Redmann et al (1993), Romo et al (1993), Romo (1994, 1995), Archibold et al (1998) and Ripley and Archibold (1999 Pylypec (1986). Climate in this area has been described by Walter andLieth (1960-1967) (Coupland and Brayshaw 1953) and also of Northern Mixed Prairie (Coupland 1950), and were adjacent to similar controls where no fire has been recorded for the past eight decades.…”

Rough fescue (Festuca campestris Rydb.) response to heat injury

“…Average temperatures ranging from 102 to 388°C have been reported for fires in the Great Plains (Stinson and Wright 1969), the Aspen Parkland (Bailey and Anderson 1980;Archibold et al 1998), and other grassland systems (Bentley and Fenner 1958;Britton and Wright 1971). Greater fire temperatures in grasslands have been associated with increased fuel biomass (Stinson and Wright 1969;Bailey and Anderson 1980;McDaniel et al 1997;Archibold et al 1998;Morgan 1999), provided the fuel is readily available and combustible.…”

“…Greater fire temperatures in grasslands have been associated with increased fuel biomass (Stinson and Wright 1969;Bailey and Anderson 1980;McDaniel et al 1997;Archibold et al 1998;Morgan 1999), provided the fuel is readily available and combustible.…”