Effect of harvest date and frequency on aspen ricegrass (Oryzopsis asperifolia) and cream-coloured vetchling (Lathyrus ochroleucus) in the boreal transition ecoregion of Saskatchewan

Aspen forest communities of Saskatchewan, Canada, support a significant cattle population. The objectives of this study were to determine seasonal forage dry matter (DM) accumulation and evaluate repeated annual defoliation on DM yield (DMY) of aspen ricegrass (Oryzopsis asperifolia) and cream-coloured vetchling (Lathyrus ochroleucus) in the boreal transition ecoregion of east–central Saskatchewan. The experimental design was a randomized completed block with five replicates. Seasonal DMY of aspen ricegrass (p < 0.0001) was lowest in June, intermediate in July, and highest in August to October, with DMY ranging from 2.9–15.3 g m −2 . Cream-coloured vetchling (p < 0.0001) had the highest DMY in July and August (5.5, 4.8 g m −2 ) than other months (1.2–2.3 g m −2 ). Single repeated defoliation, regardless of clipping date, reduced (P = 0.0098) the overall production of aspen ricegrass (Oryzopsis asperifolia) and cream-coloured vetchling (Lathyrus ochroleucus) in this study.