Article

Evaluating Alternative Explanations in Ecosystem Experiments

Ecosystems (Impact Factor: 3.53). 06/1998; 1(4):335-344. DOI: 10.1007/s100219900025
Source: OAI

ABSTRACT Unreplicated ecosystem experiments can be analyzed by diverse statistical methods. Most of these methods focus on the null
hypothesis that there is no response of a given ecosystem to a manipulation. We suggest that it is often more productive to
compare diverse alternative explanations (models) for the observations. An example is presented using whole-lake experiments.
When a single experimental lake was examined, we could not detect effects of phosphorus (P) input rate, dissolved organic
carbon (DOC), and grazing on chlorophyll. When three experimental lakes with contrasting DOC and food webs were subjected
to the same schedule of P input manipulations, all three impacts and their interactions were measurable. Focus on multiple
alternatives has important implications for design of ecosystem experiments. If a limited number of experimental ecosystems
are available, it may be more informative to manipulate each ecosystem differently to test alternatives, rather than attempt
to replicate the experiment.

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