How does the precipitation gradient interact with common disturbances to structure prairies?

Abstract

How plant communities are structured, and the relative roles of gradients and disturbances in that structuring, has long been of interest. Here I use plots in replicate tallgrass, mixedgrass, and shortgrass prairies across Northern Oklahoma to address this issue by sampling plant percent cover three years after applying treatments realizing common prairie disturbances of burning, grazing, and soil turnover. I found (1) shortgrass plots had the least amount of aboveground biomass (AGB), with burning and soil turnover plots also having low AGB in the other two prairies, (2) tallgrass plots had the most total cover, with soil turnover plots having the least in the other two prairies, (3) tallgrass plots had the most species, with soil turnover plots having the least in the other two prairies, (4) control plots in mixedgrass had the smallest evenness and plots in shortgrass had the highest, and (5) a high degree of functional similarity in all three prairies. In addition to controlling these different aspects of population and community structure in prairies, results also show that the most severe disturbances can lead to a prairie plant composition and structure more similar to that found in the drier, most western prairie areas.

Keywords:

• bison
• burning
• gopher
• grazing
• soil turnover

Acknowledgements

The author thanks B. Hamilton, B. Northup, C. Milner, R. Gillen, D. Maple, J. Young, N. Wallis, and J. Hall for their assistance in setting up experiments. The author also thanks J. Briggs, B. Northup, and R. Gillen for commenting on a previous draft of the manuscript.