Discussion

摘要

Correlative studies such as Pollock et al. can not only be valuable in identifying potential factors and processes controlling hydrologic and water quality responses, but are also subject to false correlations. We must remember the admonition that correlation does not imply causation. Pollock et al. found that "... forest harvesting activities is in some way contributing to stream heating other than by exposing the stream surface to direct solar radiation," but key factors known to control stream temperature were not measured. This reduced their ability to attribute mechanisms and test the three hypotheses they proposed. Further, it limited their ability to provide useful solutions to questions about forest management strategies.