Plant production after defoliation of native, Northern Mixed Prairie on hummocky terrain in Saskatchewan

Abstract

Resting plants after grazing is central to sustaining potential plant production. Growth of graminoids and forbs was determined for 3 yr after a single defoliation to 7.5 cm in May, June, July, August, September, October, November, or April on five different landform elements in the Northern Mixed Prairie. Green standing crop and cumulative green standing crop of forbs, graminoids, and their total varied with months of defoliation, landform elements, and years after defoliation. Green standing crop and cumulative green standing crop of forbs, graminoids, and their total was less than the control (P ≤ 0.05) on at least one of five landform elements until the second year after defoliation. This pattern of growth suggests the need to defer grazing for at least 1 yr after use to allow plants to regain their production potential. Plants defoliated early in the growing season recovered their production sooner or at the same time as those defoliated later in the growing season or when dormant. Generalizations that spring or early summer defoliation of native range reduces production and late summer or dormant season grazing has no effect on production warrants reconsideration where adequate rest is provided following a short period of grazing.Key words: Landform, landscape, primary production, rangeland, regrowth, standing crop

Above-ground net primary production of plains rough fescue [Festuca hallii (Vasey) Piper] after a single defoliation on five landform elements

“…Competition with neighboring plants may also have factored into reduced ANPP of plains rough fescue in the first year after defoliation (Mueggler 1975;Archer and Detling 1984). Forbs (Pantel et al 2010), northern wheatgrass, and western porcupine grass (Pantel et al 2011) all recovered their ANPP faster than plains rough fescue, which in turn may confer a competitive advantage and more effective exploitation of resources aboveand below-ground. The possibility that the competitive ability of plains rough fescue diminishes after defoliation is probable.…”