Although the characteristics of indirect effects are fairly readily established in a controlled laboratory experiment involving a very limited number (typically <5) of interacting components, in the natural environment the complexity of interactions renders their characterization, in particular in practical terms as regards the outcome for any specific ecosystem, rather extremely challenging. Using the inverse of 100 community matrices (elements of such an inverse matrix specify how the change in density of a particular species affects the density of the other species, with species pairs determined by the element's position in the matrix) obtained by randomly changing the species-specific parameters, Yodzis has shown that a large number of predictions for overall interactions between separate species were directionally undetermined, that is, positive in some cases and negative in others. Owing to such an uncertainty, some theoreticians have even questioned whether credible predictions of the overall outcome of indirect interactions could be made at all. As a consequence, there are numerous cases where the application of seemingly appropriate environmental management methods, and in particular biomanipulation, resulted in failure.
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