The University of Arizona

Defoliation impacts on Festuca campestris (Rydb.) plants exposed to wildfire.

A.D. Bogen, E.W. Bork, W.D. Willms


Wildfires commonly occur in the Fescue Prairie of Alberta, but little information exists to provide a basis for making grazing recommendations after burning. A wildfire in April 1999 provided an opportunity to study the effect of season and intensity of post-burn defoliation on foothills rough fescue (F. campestris Rydb.) in southwestern Alberta. A 3 (date of defoliation) x 2 (defoliation intensity) factorial experiment with 10 replicates (plants) was established in both a burned and a non-burned grassland and analyzed as a nested design. Plants were defoliated once during active vegetative growth (17 May), inflorescence development (2 July), or dormancy (30 September), at either 5 or 15-cm clipped stubble heights in the first growing season after fire. Burning increased tiller numbers by 54% compared to non-burned plants but reduced plant ANPP by 51% in the second growing season. While a single defoliation of burned plants, particularly early in the year, had little effect on growth, delaying defoliation into July decreased tillers 1 year later. Increasing defoliation intensity had the greatest impact on non-burned plants, reducing plant height (15%) as well as tiller (21%) and plant (32%) ANPP in the second year. May defoliation reduced etiolated growth 1 year later regardless of burn treatment. A single grazing event after wildfire does not necessarily appear to detrimentally affect rough fescue; however, the low herbage available immediately after fire may not justify the increased risk to the plant with subsequent grazing.



seasonal development;flowering;grazing management;Festuca altaica;primary productivity;harvest date;Festuca campestris;fire ecology;Alberta;tillering;precipitation;biomass;range management;defoliation

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