Effect of burning or clipping Agropyron spicatum in the autumn on the spring foraging behaviour of mule deer and cattle.
Abstract
To estimate the effects of autumn clipping or burning on the foraging behaviour of mule deer (Odocoileus hemionus hemionus) and cattle, trials were set up in 2 plant communities in south-central British Columbia. Communities were predominantly of big sagebrush (Artemesia tridentata) and blue wheatgrass (Agropyron spicatum) or of Douglas fir (Pseudotsuga menziesii) and A. spicatum. A. spicatum was the dominant herbaceous plant in both communities and contributed the greatest proportion to the diet of cattle and a large proportion to the diet of deer. Observations of foraging behaviour were made at different intensities of spring grazing. Deer and cattle preferred the burned treatment to the clipped treatment and both were preferred to the untreated control areas. Deer maintained these relative preferences at all levels of utilization but for cattle the treatment effect was less important and was greatly reduced by the second year. Deer avoided switching to the control area by heavily utilizing plants from treated areas. The weight of each bite of forage from the treated areas decreased relative to the control at higher levels of utilization.<new para>ADDITIONAL ABSTRACT:<new para>Dead stems and leaves of A. spicatum affect the grazing behaviour of deer and cattle by imposing a barrier to new growth. To determine the effects of autumn clipping or burning on the foraging behaviour of deer and cattle, trials were set up in 2 communities and observations made at different intensities of spring grazing. Deer and cattle preferred the burned treatment to the clipped treatment and both were preferred to the control. Deer maintained these relative preferences at all levels of utilization but for cattle the treatment effect was less important and was considerably reduced by the 2nd yr. Deer avoided switching to the control by closely utilizing plants from treated areas. The wt. of each bite of forage from the burned and clipped treatments decreased relative to the control at higher levels of utilization.