4.3: Data Dive- Bison Impacts In Prairies

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Page ID: 70812

Melissa Ha and Rachel Schleiger
Yuba College & Butte College via ASCCC Open Educational Resources Initiative

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Overview

In many grassland ecosystems the activities of large grazers, like bison, play a key role in shaping grassland habitat structure and diversity. A 2017 study sought to investigate how bison in tall-grass prairies affect local plant competition. Specifically, they wanted to know if bison have a positive impact on herbaceous forbs (non-woody flower species). To investigate this, they observed plant communities in tall-grass prairies in the presence and absence of bison. The two graphs below display some of the results in this study:

Average percent cover for species groups in the tall-grass prairies with and without bison. — Figure \(\PageIndex{2a}\): Average percent cover (aka what percent of an area a species took up) for grasses, forbs, shrubs, and bare ground in tall-grass prairies with and without bison. Graph by Rachel Schleiger (CC-BY-NC) modified from data in Elson A and Hartnett D, 2017.

Richness in the tall-grass praririe with and without bison. — Figure \(\PageIndex{b}\): Average diversity of non-grasses in tall-grass prairies with and without bison. Graph by Rachel Schleiger (CC-BY-NC) modified from data in Elson A and Hartnett D, 2017.

Questions

What kind of graphs are these?
Does the presence of bison increase diversity? How do you know this? Which graph(s) support this?
How does the presence of bison affect the percent cover of bare ground, grasses, forbs, and shrubs?
Based on the authors objectives/predictions described above, do the results of these graphs support them? Why/why not?
How can we use the results of this graph to inform conservation projects for tallgrass prairies in the future?
What does the results of this graph make you curious about?

Raw Data From Above Graph(s)

Table \(\PageIndex{2a}\): Raw data for average percent covers (aka what percent of an area a species took up) for grasses, forbs, shrubs, and bare ground in tall-grass prairies with and without bison. Graph by Rachel Schleiger (CC-BY-NC) modified from data in Elson A and Hartnett D, 2017.

Status	Average Percent Cover With Bison	Average Percent Cover With No Bison
Bare Ground	27	3
Grass	80	98
Forb	81	63
Shrub	7	6

Table \(\PageIndex{b}\): Raw data for average diversity of non-grasses in tall-grass prairies with and without bison. Graph by Rachel Schleiger (CC-BY-NC) modified from data in Elson A and Hartnett D, 2017.

Average Diversity (Non-Grasses) With Bison	Average Diversity (Non-Grasses) With No Bison
24	13

Attributions

Rachel Schleiger (CC-BY-NC)