Effects of Stocking Rate on a Rough Fescue Grassland Vegetation

Abstract

their construction, to a stable range condition, took from 14 years in the lightly grazed field to more than the length of the study in the A study was conducted to examine the effects of 4 stocking rates on the vegetation in a Rough Fescue Grassland vegetation in southwestern Alberta. Stocking at a light rate (1.2 AUM/ha) for 32 very heavily grazed field. The duration required for recovery was years did not affect range condition. However, a modest increase in stocking rate (1.6 AUM/ha) led to a marked decline in range related to the original range condition of the exclosures. condition. This was associated with a change in the composition of rough fescue from 38 to 21% of basal area. Rough fescue (FestzCQ ScQbreflQ) was nearly eliminated with a stocking rate of 2.4 AUM/ha. Rough fescue was repiaced by Parry oat grass (DQnthoni~ parryi) which increased from 24% at 1.2 AUM/ha to 48% at 2.4 AUM/ha. However, stocking at 4.8 AUM/ha resulted in severe deterioration of the grassland. This required annual adjustment of the stocking rate to avoid animal losses. The recommended stocking rate for good condition range in the area is 1.6 AUM/ha. Recovery of the vegetation within the exclosures, from the time of setting stocking rates. The stocking rate, expressed in this paper as animal unit months per hectare (AUM/ ha), defines the relative quantity of forage that will be harvested during the grazing period in a given year. The effect of increasing the stocking rate is to increase the proportion of forage utilized, which may lead to changes in species composition of grasslands (Ellison 1960). The species that increase because of an increased stocking rate are often subdominants in the plant community and are potentially less productive than the dominant species (Looman 1969). The purpose of this study was to examine the changes that occur in species composition of a Rough Fescue Grassland as a result of stocking with cattle at different rates. The work described is part of a final assessment of the study which was reported earlier (Johnston 1961, Peake and Johnston 1965). The Rough Fescue Grasslands (Festuca scabrella)t in western Canada are managed primarily for grazing by cattle. They are found on highly productive soils, but cultural practices are limited by steep terrain. Consequently, management of grassland vegetation is through management of grazing by cattle. This is normally accomplished using a continuous grazing system where the cattle are turned onto the range in spring and removed in autumn. The most critical management decision made, with this system, is in ing in elevation from 1,280 to 1,420 met&above sea level (Fig. i). Average precipitation at the substation, over a 30-year period from April to August, was 35 I mm. Average precipitation from April to Site Description August at 2 similar areas within 65 km (Pincher Creek and Pekisko) was 353 mm while the annual precipitation averaged 614 The study area was at the Agriculture Canada Research Substamm over the same 30-year period. Annual precipitation data a...

Effects of heavy grazing pressure on the random amplified polymorphic DNA marker diversity of mountain rough fescue (Festuca campestris Rydb.) in south western Alberta

“…Presently, it is used for grazing livestock, but the species is extremely sensitive to summer defoliation, which will reduce its vigor and cause it to decline in the plant community. Mountain rough fescue was reduced from about 40% of basal area to about 1% after 32 yr of heavy grazing pressure, with most changes occurring within 6 yr (Willms et al 1985). This was caused by fewer and smaller plants (Willms, unpublished data) and suggests that grazing-sensitive plants were eliminated.…”

Cutting frequency and cutting height effects on forage quality of rough fescue and Parry oat grass

“…Even light grazing reduces the proportion of rough fescue and increases Parry oat grass (Looman 1969). As a result, Parry oat grass is often the dominant forage species on grazed range (Moss 1955 (Willms et al 1985). …”

Weathering losses of forage species on the fescue grassland in southwestern Alberta

“…Rough fescue is displaced by Parry oat grass (Danthonia parryi Scribn.) and other associated species on more xeric sites and with heavy grazing pressure (Willms et al 1985). However, rough fescue tolerates grazing while dormant, and appears to be a suitable species for winter grazing since it is a tufted, "hard" grass with a large stature that maintains its quality better than other forage species in this community .…”