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The Data
The Data
Our raw data was sourced from the Applied Conservation Ecology (ACE) Lab. The dataset contained percent cover values for various plant species and other cover types spread out among the four different treatments and their associated plot type. Species abundance (percent cover) and presence were utilized to determine the species richness of each sample as well as some diversity metrics. Vegetative species were also classed into the plant communities of graminoids, forbs, or browse based on prior research (Hecker et al., 2020) and classifications from the Alberta Biodiversity Monitoring Institute (ABMI). The simplified data table (Table 1) is representative of our data as a whole. Treatment and Plot Type are considered the categorical predictor variables. Cover types, Richness and Plant Communities are considered the observed response variables.
Table 1. Simplified data table displaying ten rows of variables. The rows are represented by unique site ID's and represent possible Treatment and Plot Type combinations. Only a partial section of the 48 plants species and 7 other cover types are displayed. Additionally only one of three for both the plant community types and richness metrics is displayed.
Exploring The Data
Exploring The Data
Figure 8 explores how individual species are distributed across the four treatments. This figure allowed us to examine how species may be affected by the bison but perhaps most importantly it drove us to look at communities instead of individual species. This is because the original figure was saturated with all the species and very difficult to interpret so the graph had to be curated to only include species relevant to our research objectives. From that point it became clear that the focus should be on plant communities. In order for this figure to have been made the data had to transformed from wide to long format.
Figure 8. Boxplot of select speccies across treatment types. This boxplot displays only species thought to be relevant to bison foraging or succession dynamics questions. Species names are composed of the first four letters of the genus and the first 3 letters of the specific epithet except in the case of Aw which represents trembling aspen (Populus tremuloides).
Although communities were more relevant to this study, how species varied by plot type was also explored in order to confirm that communities were more important to look at (Figure 9).
Figure 10. Boxplot of select species across plot types in the loafing treatment type. This boxplot displays only species thought to be relevant to bison foraging or succession dynamics questions. Species names are composed of the first four letters of the genus and the first 3 letters of the specific epithet except in the case of Aw which represents trembling aspen (Populus tremuloides).
Next, the diversity metrics of species richness and the Shannon and Simpson diversity indices were also examined via graphical representation as seen in Figure 11. The original data was then used to calculate the diversity indices. This was accomplished by using a specific package that calculated these metrics as Hill values which essentially allows for comparison between the values by turning the raw output of the diversity indices into effective species values (Tan et al., 2022). Subsequently, the data had to converted from wide into long format to put In order for this these values to only capture the plant species columns, the non-species cover type such as bare or water were cleaned from the data.
Figure 11. Species richness distribution between treatments.
Subsequently, the distribution of cover types among treatments was also examined (Figure 12). Here the switch of focus from species to plant communities can be seen . Bare is also included despite not being a plant community as the absence of a community is also pertinent to the question at hand. As for the other 3 categories, all woody plants, trees and shrubs were grouped into the browse category, the graminoid category represented all grasses and plants with grass like morphology, and lastly the forbs category is all the other flowering plant species that are not graminoids. Figure 12 also demonstrated that this data is not normally distributed so a transformation was required. This transformation can be seen in Figure 13 where a constant had to be added in order to avoid zeroes.
Figure 12. Distribution of cover types amongst treatment types.
Figure 13. Transformed distribution of cover types amongst treatment types. The alteration to the data was done via a log10 transformation with a log adjusted x-axis.
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