THE ECOLOGICAL QUESTION:

How does plant biodiversity in a grassland savannah community affect ecosystem productivity?

ECOLOGICAL CONTENT:

grassland, biodiversity, biomass, productivity, sampling effect hypothesis, quadrat sampling

WHAT STUDENTS DO:

Students make Microsoft Excel graphs to examine the effect of biodiversity on productivity for seven years of data. This leads students to hypothesize the possible reasons for this effect, including sampling effects and niche differences among species, and to examine the challenges and implications of extrapolating these experimental data to biodiversity loss in general. Students discuss their hypotheses, analysis, interpretation, and conclusion orally and/or in writing.

SKILLS:

Using a computer spreadsheet to make simple graphs; writing, hypothesizing, thinking critically, analyzing, interpreting, and drawing conclusions.

ASSESSABLE OUTCOMES:

Graphs from spreadsheet data; written or oral analyses, interpretations, conclusions, and hypotheses.

SOURCE:

Cedar Creek Natural History Area Long-Term Ecological Research (LTER) archive data 1996 – 2002 (http://www.cedarcreek.umn.edu/research/exper/e120/)

AUTHORS:

Joe Fargione^1* and David Tilman²

1 - Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN 55108, farg0001@umn.edu

2 - Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN 55108, tilman@umn.edu

* corresponding author

ACKNOWLEDGMENTS:

This lab is largely based on the paper Tilman et al. 2001. We gratefully acknowledge Peter Reich, Jean Knops, David Wedin, Troy Meilke, and Clarence Lehman. These co-authors of the Tilman et al. 2001 paper all contributed to the ideas and data presented in this lab. The numerous interns that work at Cedar Creek maintain the experiment and collected the data that made this lab possible. The critiques and responses section of the lab was inspired by the real criticisms of other scientists, notably Michael Huston.

CITATION:

Fargione, J., and D. Tilman. July 2004, posting date.
Effects of Plant Biodiversity on Ecosystem Productivity within a Savannah Grassland Community, Teaching Issues and Experiments in Ecology, Vol. 2: Issues: Data Set #1 [online].
http://tiee.ecoed.net/vol/v2/issues/data_sets/cedar_creek/abstract.html