Background & Project Rationale

American bison (Bison bison) once roamed North America in the tens of millions but were brought to the brink of extinction in the late 1800's due to land conversion and overhunting (Cherry et al., 2019). Although the plains bison (Bison bison bison) bore the brunt of this onslaught, their relatives the wood bison (Bison bison athabascae), have also been significantly reduced in their range due to overhunting (Strong and Gates, 2009).  As such, wood bison are listed as a threatened species in Canada with around 5,000-7,000 individuals being left in the wild (COSEWIC, 2013; Environment and Climate Change Canada, 2020). Their decline has affected the habitats they left behind as plains bison were once ecosystem engineers, by significantly modifying their habitat within their vast former range (Nickell et al., 2018). This was accomplished via their grazing patterns, disturbing the soil while migrating, and through wallowing, which all had a regulating effect on plant communities. However, do wood bison also occupy this profound ecosystem role?  To answer this question we examined data collected from the Ronald Lake Herd in 2024.

Contrary to the grasslands occupied by the plains bison, the Ronald Lake wood bison are situated in mostly Jack-pine and deciduous forest environments interspersed with graminoid dominated wetlands and meadows (Rawleigh and Hecker, 2022) The Ronald Lake Herd is a subpopulation of approximately 300 individuals south of Wood Buffalo National Park (Hecker et al, 2024). This subpopulation is genetically unique, and is one of the few disease-free herds of Wood Bison in existence. Of interest, is that during the spring calving season, females will congregate at a series of meadows with several bare areas known as loafs (Hecker et al., 2024) (Figure 2). These loaves, are thought to be a direct result of heavy bison use during their occupancy period with trampling  and wallowing resulting in large patches of bare soil. The comparison of the loaves and their surrounding vegetative community to the adjacent meadows can directly allow us to quantify how heavy bison use, at least for part of the season, is affecting plant community composition and biodiversity. In addition to this, the meadows themselves seem to be unique as the surroundings are composed strictly of aspen dominated boreal forest (Hillman, personal communication, 2024). Resultingly, it is thought that the meadow complex exists primarily as a function of bison presence. To test this, we used the surrounding  forest as a reference state in comparison to the meadow and loaves to see how successional dynamics have been altered by bison use.  It is also important to note that there are loaves in the northern section of the meadows that no longer appear to be used by the bison and therefore have recovering vegetation, hereafter referred to as recovering loafs. This is relevant because it allows us to examine whether the bison are creating better habitat for themselves via the creation of these loafing areas. We can collect vegetation data from these recovering loaves in order to determine if the community composition has shifted towards their preferred forage of graminoids and browsable species as the vegetation recovers from bison foraging. 

The Ronald Lake Herd is important from a conservation and management standpoint due to its unique genetic structure, disease-free status and culture significance to local Indigenous culture that has attracted a large amount of interest from a management standpoint. Additionally, this study serves to contribute to the growing body of scientific knowledge on an understudied herd (Sheppard et al., 2021). 

Research Objectives

1. How are the Ronald Lake Bison herd affecting the biodiversity of the plant community in their habitat, through loafing and grazing activity?

2. How is loafing and grazing activity affecting the successional pathways of the plant communities in the Ronald Lake Bison habitat? Are loafing areas beginning to resemble nearby forest or meadow communities, or something else entirely?

3. Are the Ronald Lake Bison actually improving the foraging opportunities for themselves through loafing and grazing activities?