Site Description and Study Design

Study sites are located on harvested cutblocks planted with spruce and pine in Weyerhaeuser Forest Management Agreement areas (FMAs). Grazing was completed during the summer (June-September) in 2023 and 2024 with a herd density of 1100-1200 sheep. Cutblocks were chosen based on suitability for grazing, with criteria including accessibility, low slash coverage, and reasonably level topography.

Five research blocks were randomly selected the Saddle Hills FMA (2023 and 2024) and three in the Pembina Timberlands FMA (2024). Saddle Hills sites were planted with white spruce and Pembina Timberlands with lodgepole pine. In each research block, three locations were randomly selected for paired grazed and fenced (control) plots (Fig 1, 2).

The key response variables in this study are competing vegetation biomass (fresh and dry weights), competition index (percent cover and height of competing vegetation groups, seedling height), and crop tree condition. Predictor variables are the treatment, grazed or ungrazed (control), but response variables will also be analyzed by location to evaluate if results are consistent despite different grazing contractors being used at each site.