Northern dry mixed prairie responses to summer wildlife and drought

Abstract

In August 1994, wildfire burned 6,500 ha of native Dry Mixed Prairie in southeastern Alberta. The following year, a study was initiated to monitor the recovery of major plant communities. Burning was followed by 3 successive years of drought, reducing total vegetative cover by 10%. Exposed soil increased to a high of 23%, three years after the fire. Litter and grass production were reduced through 1997, with the greatest decline in 1995 when grass production on burned and unburned areas averaged 890 and 1,468 kg ha(-1), respectively. Of the major forage species, Stipa spp. and Koeleria macrantha (Ledeb. J.A. Schultes f.) were affected for a single year and Agropyron spp. 2 years by burning. Both Agropyron and Stipa abundance displayed interactions with topographic position in response to fire. In 1995, Agropyron increased on uplands with burning from 90 to 143 kg ha(-1), but decreased on lowlands from 383 to 238 kg ha(-1), a pattern repeated in 1996. In contrast, Stipa declined at both positions, but only for a single year. Where livestock grazing occurred after the fire, forage removal was greater on burned areas. Drought conditions, in combination with summer wildfire, reduced Dry Mixed Prairie range productivity and ground cover for several years and intensified livestock grazing, highlighting the need for changes in rangeland management under these conditions.