Experimental Design

 The study took place at two locations within the East Kootenay region of southern British Columbia (Figure 1). At KCPP a total of eight sites were selected, and at YFN a total of four sites were selected. At both locations a strip/split factorial plot design with four blocks was used with a partially randomized design. At KCPP two distinct herbicide treatments (HerbicideC (Aminopyralid, metsulfuron-methyl at 200 g ai/ha) and HerbicideR (Aminopyralid, metsulfuron-methyl at 200 g/ha ai, 2,4-D at 1.7 L/ha ai)), were combined with a prescribed burning treatment while at YFN three distinct herbicide treatments (HerbicideR, HerbicideP (Indaziflam at 200 g/L ai), and HerbicideR + HerbicideP) were combined with a prescribed burning treatment (Table 1). 

Table 1. Treatments applied at two study sites. A symbol of 'X' indicates the treatment was applied at that site. Herbicide P refers to Indaziflam, Herbicide C refers to Aminopyralid + Metsulfuron-methyl, and HerbicideR refers to Aminopyralid + Metsulfuron-methyl + 2,4-D 

Both HerbicideR and HerbicideC were applied in July, when plants were actively growing, a time when these chemicals are most effective (Corteva, 2021). HerbicideR was applied in July 2023 at KCPP and July 2024 at YFN. HerbicideC was applied in July 2023 at KCPP. HerbicideP was applied in September 2024 at YFN. This herbicide functions by interfering with germination of winter annual seedlings, so was applied in the fall, before these seedlings germinated (Figure 2). In order to capture residual effects of herbicides following initial application, sites are monitored for at least 3 years following herbicide application. There are currently three years of monitoring completed at KCPP, while at YFN one more year is required to assess the residual effects of herbicides.

Each site was split into four blocks. At KCPP, within each block were six plots (Figure 3). At YFN, within each block were eight plots. (Figure 4). Data was collected in four subplots contained within each plot (Figure 5).

Figure 3. Example of site design at Kikomun Creek Provincial Park. Each site has the same layout, however precise placement of treatment varies between sites and was randomly assigned

Figure 4. Example of site design at Yaq̓it ʔa·knuqⱡi’it. Each site has the same layout, however precise placement of treatment varies between sites and was randomly assigned

Figure 5. Setup of subplots located within each plot

Data Collection

Vegetative cover (Foliar cover) of all species was collected within sublots. Cover of grasses and forbs were taken within a 50 x 50 cm frame and cover of shrubs was taken within a 1 x 1 m frame. All covers were determined using foliar cover, with the percentage of ground covered by vegetation estimated within each frame (Figure 5). Data was collected in June of 2023, 2024, and 2025 in KCPP. Data was collected in June 2024 and 2025 at YFN. 

Three years of data was taken at KCPP. Eight sites, each with 24 plots, were surveyed. This created a total of 576 unique sample IDs. At KCPP, sites were one of two types; either PG (pinegrass dominated) or NG (needlegrass dominated). A total of 123 species were recording at KCPP. At Yaq ̓itʔa·knuqⱡi’it two years of data were collected. Four sites, each with 32 plots, were surveyed for a total of 256 unique sample IDs. A total of 49 species were recorded at YFN.

Figure 5. Description of method for determining foliar cover of vegetation, with the cover estimated indicated by the grey shadow. Gaps in foliage are not included in the cover estimation (Government of Alberta, 2009)