In southern Alberta (Canada), experiments were undertaken at two Fescue Prairie sites (University of Alberta Ranch, Kinsella, and the Agriculture Canada Range Research Substation, Stavely) and on a Mixed Prairie (Stipa-Bouteloua) grassland (at the Agriculture Canada Research Substation, Manyberries) to determine the effects of removing mulch and standing litter (simulating grazing) during the dormant season on forage production.
Experiment 1 At Stavely and Manyberries, plots (2 x 2 m, in 8 rows x 10 columns) were laid out in areas ungrazed for about 30 years. Two rows were selected each year (1977-1979): plots in one row were controls; plots in the other had mulch and litter removed by raking in early spring. Plant response was measured as dry weight herbage yield (separated into forbs, grass, and mulch/litter) estimated by harvesting l m² quadrats per plot in late September.
Experiment 2 At Stavely, the effect of removing standing dead litter from rough fescue Festuca hallii was assessed. Treatments comprised clipping 10 plants (at 5 or 15 cm), or no clipping (control). Plants were clipped in early spring (1982); and in a second trial, clipped in autumn (1982) or spring (1983). Response was assessed in late summer (following the growing season).
Experiment 3 At Kinsella in areas ungrazed for 30 years and unmown for 8 years, treatments (in 2 x 2m plots) were applied: removing mulch and standing litter (harvested with a mower in late April 1979, 1980 and 1981), removing and replacing it, and a control. Treatment effects (tiller height and number, herbage yield) were measured in August 1981 within a 0.5 m² quadrat per plot.
Experiment 1 Litter and mulch yielded an average of 805 g/m² (Stavely, Fescue Prairie) and 57 g/ m² at Manyberries (Mixed Prairie) in the first year. Herbage yields decreased as mulch and litter removal frequency increased in the Mixed Prairie (yield as a proportion of that of controls: year 1: 72%; year 3: 43%) but remained the same in the Fescue Prairie (year 1: 77%; year 3: 76%).
Experiment 2 Standing litter removal resulted in shorter but more fescue tillers (similar for both seasons of removal: 222-284 spring; 232-246 autumn) than the control (168).
Experiment 3 Clipping and litter removal resulted in a small increase in herbage yield. A significant increase was obtained when litter was replaced. The proportion of rough fescue decreased from 82% in the control to 70% on clipped plots; total weight remained the same.
These results suggest that dormant season grazing would not be detrimental to forage yield in Fescue Prairie and that it might in fact enhance plant vigor (i.e. stimulate grass tillering). In Mixed Prairie, however, it might decrease yields as a result of removing standing dead litter.