In this activity, students construct qualitative models of an ecosystem and use the models to gain a better understanding of direct and indirect ecological interactions. Qualitative modeling is described for use in two procedures, each with different educational goals and student backgrounds in mind. Part 1 is designed with the non-major or beginning ecology student in mind, and is intended both to improve student understanding of the ecosystem of interest and to provide a framework for the instructor to assess student learning. Part 2 is designed for more advanced students of ecology and involves the use of modeling software (POWERPLAY) to design researchable hypotheses to analyze the dynamics of ecosystem responses to simulated disturbances. Approximately two lab periods are required for either activity. In both cases, students will generate qualitative ecosystem models, undertake some degree of analysis, and provide responses to essay questions. Students will learn new tools and improve their skills at "qualitative reasoning" to understand the dynamics of complex systems, gain insights into their own understanding of the ecosystem they are studying, and use their models to predict possible experimental outcomes or patterns in the ecosystems they are studying. Students will become more cognizant of indirect effects and complexity through analysis of their models.


J. Scott Blackwood

Invasive Plant Research Laboratory, USDA-ARS, 3225 College Ave., Fort Lauderdale, FL 33314, scott.blackwood@gmail.com

Marion Dresner

Portland State University, Center for Science Education, P.O. Box 751, Portland, OR 97207, dresnem@pdx.edu

Hang-Kwang Luh

Oregon State University, Integrated Plant Protection Center, Corvallis, OR 97330, luhh@science.oregonstate.edu


For Part 1, a minimum of two hours of class time are needed (1) to provide instruction on types of ecological relationships and on how to construct qualitative models, (2) to allow students to construct their own models of a local ecosystem, and (3) to allow students to discuss and then write what they know about the ecosystem in a guided exercise. Ideally, a field trip to the local ecosystem that students are studying should be provided before students construct their own models. For Part 2, at least two one-hour class sessions with computer access are required plus time to discuss what they found with another student in an exercise.


Students can conduct literature research and respond to the analytic questions as homework.


For Part 1, one model will be produced by each student, accompanied by student essay responses to questions about their models. For Part 2, computer generated models, sets of researchable hypotheses, and responses to questions about their models will be produced.


Lab and in the field


No background knowledge in modeling is required to begin. Qualitative modeling is ideally used in conjunction with an ecological field experience. This can range from a single short field trip to a long-term field experiment. The following experiments currently published on TIEE are suggested in conjunction with accomplishing Part 2:


Qualitative modeling has been used in SCI 201, 'Natural Science Inquiry,' a sophomore level class for non-science majors at Portland State University, and FW 591 'Essential Models in Ecology,' a graduate and advanced undergraduate level class for majors at Oregon State University.


Qualitative modeling is not dependent upon access to any special environmental conditions and can even be used without computers (Part 1); therefore, it can be used at any institution.


The authors acknowledge Dr. Andrew Moldenke for his feedback. The use of qualitative models in the manner described in this activity was piloted in the Teachers in the Woods program, where teachers participate in field research projects at the H. J. Andrews Experimental Forest. NSF has provided us with funding through the Teachers in the Woods grant (ESIE #0101957) to enable us to begin to work with qualitative modeling in science education. It was used as a means of helping participants explain to participating scientists what they understood about particular ecological concepts as they proceeded with a field experiment. More recently, Dr. Luh's POWERPLAY program was incorporated into the procedure to reflect the synergy of a new inter-site ecology education program, Teaching Ecological Complexity.

POWERPLAY was originally created by Dr. Bruce D'Ambrosio, a professor of computer science at Oregon State University and the President/CTO of CleverSet, Inc., and his students in 2002. This version of POWERPLAY was designed as a stand along desktop application written with Java. The desktop POWERPLAY is available for free from the Ecological Society of America' Ecological Archives (http://esapubs.org/Archive/ecol/E083/022/suppl-1.htm), from the POWERPLAY dowloads page (http://www.ent.orst.edu/loop/download.aspx), or from the TIEE Downloads page for this experiment (downloads.html). Dr. Hang-Kwang Luh, a research assistant professor/senior researcher at OSU, converted the desktop version into a web accessible applet. He also added several new functions for the applet version, such as a dialogue window for the student writing down the note for the species interaction. POWERPLAY is very useful tool for drawing a large community system with many variables and reducing the transcription errors when the signed digraph is converted to a matrix.

The order of authorship is alphabetical - each author contributed equally to this publication.


Blackwood, J. Scott, Marion Dresner, Hang-Kwang Luh. April 2006, posting date. Using Student Generated Qualitative Ecological Models. Teaching Issues and Experiments in Ecology, Vol. 4: Experiment #4 [online]. http://tiee.ecoed.net/vol/v4/experiments/ecological_models/abstract.html

qualitative model of a tri-trophic ecosystem involving grass, hare, and lynx, showing the network of their interactions
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