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

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