WATER RELATIONS AND GROWTH OF BROMUS-INERMIS LEYSS (SMOOTH BROME) FOLLOWING SPRING OR AUTUMN BURNING IN A FESCUE PRAIRIE

Bromus inermis Leyss (smooth brome) is an invasive perennial grass in Fescue Prairie in North America. Prescribed burning is a potential met hod of controlling this exotic, but its responses to burning in this g rassland are not known. This study was conducted to determine the impa cts of a single burn in the autumn or spring on the growth and water r elations of B. inermis in Fescue Prairie in central Saskatchewan. In 1 yr, leaf xylem water potential and stomatal conductance were lower in plants burned in the autumn than the reference and the spring burn. I n another year they were generally similar among the burns and referen ce. Regardless of water stress following burning, tiller densities, st anding crop and the leaf area indices of B. inermis were not significa ntly different among the reference, autumn and spring burns. Because B . inermis is apparently resistant to fire effects and native species a re suppressed by burning, fire may increase B. inermis in Fescue Prair ie. Unlike grasslands dominated by C4 species, a single burn in autumn or spring while plants are dormant is not expected to reduce B. inerm is in the C3-dominated Fescue Prairie.