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VOLUME 5 TEACHING ISSUES AND EXPERIMENTS IN ECOLOGY
PRACTICE

The effects of bison grazing on plant diversity in a tallgrass prairie (Konza Prairie LTER)

The Flint Hills of Kansas contain the largest tract of remaining tallgrass prairie. Photo by T. M. Woods

Tallgrass prairie is dominated by three main grasses: Andropogon gerardii (big bluestem), Schizachyrium scoparium (little bluestem), and Sorghastrum nutans (Indiangrass). Subdominant grasses and forbs (non-woody, non-grass, flowering plants), though less abundant, contribute to the diversity of the prairie. Photo by T. M. Woods

AUTHOR

Harmony J. Dalgleish 1 and Teresa M. Woods 2

1 - Division of Biology, Kansas State University, Manhattan, KS 66506
Current address: Utah State University, College of Natural Resources, Logan, UT, 84322 (h.dalgleish@usu.edu)

2 - College of Education, Department of Secondary Education, Kansas State University, Manhattan, KS 66506 (twoods@ksu.edu)


THE ECOLOGICAL QUESTION

How does grazing by large ungulates affect plant community diversity?

ECOLOGICAL CONTENT

diversity, herbivory, plant species composition, quantifying diversity, influence of sample size, species accumulation curves, tallgrass prairie ecosystem

WHAT STUDENTS DO

The exercise is aimed at beginning and intermediate-level ecology students and is divided into three parts. Part 1 introduces biodiversity and includes a short, small group discussion activity to introduce the concepts of richness, evenness, and diversity indices. Part 2 contains three computer-based activities that explore three concepts in detail (species richness, the importance of sample size, and diversity indices) using plant species composition data from the Konza Prairie LTER site. After mastering the analytical techniques presented in Part 2, as well as understanding some of the biases of each technique, students will apply their knowledge to compare plant species diversity in two different tallgrass prairie plant communities: one that has been grazed by bison for >10 years and one that has been protected from bison grazing for >20 years. Part 3 challenges students to consider the assumptions of the methods they have learned and how these assumptions may affect their conclusions. Part 3 ends with a brief summary and conclusions about the effects of bison grazing on plant species diversity.

SKILLS

The exercise develops a conceptual understanding of diversity while employing quantitative reasoning skills and data presentation techniques. Specifically, students will practice the following skills: using Microsoft Excel spread sheets, calculating and interpreting diversity indices, presenting data using figures and tables, analyzing results, and critical thinking.

STUDENT-ACTIVE APPROACHES

small group discussion, guided discussion, writing to learn, computer-based projects, calculation

ASSESSABLE OUTCOMES

Students will produce tables and figures to present the results of their data analyses. In addition, students will respond to the questions posed in the exercise. Instructors can decide whether to use the questions for small group discussion, for written analysis to hand in for evaluation, or both.

SOURCE

Konza Prairie Biological Station Long-Term Ecological Research online archives: 2004. http://www.konza.ksu.edu

ACKNOWLEDGMENTS

We would like to thank Dr. Victoria Clegg for the opportunity to develop this exercise in her Principles of College Teaching class at KSU; Dr. Gene Towne for collecting the LTER data; Dr. David Hartnett for the inspiration to develop this exercise and for helpful comments on previous drafts; and Jayne Jonas for helpful comments on previous drafts. In addition, we are indebted to three anonymous reviewers and the TIEE editors for significantly improving this exercise.

CITATION

Harmony J. Dalgleish and Teresa M. Woods. June 2007, posting date. The effects of bison grazing on plant diversity in a tallgrass prairie (Konza Prairie LTER). Teaching Issues and Experiments in Ecology, Vol. 5: Practice #1 [online]. http://tiee.ecoed.net/vol/v5/practice/dalgleish/abstract.html