Your graphic about the Klamath was very informative (“What would a healthy Klamath River look like?” December 2021). I would like to point out a misconception regarding the N-15 isotope. The different isotopes of nitrogen do not have any impact on healthy forest growth; all isotopes of nitrogen can be used for growth. The N-15 isotope can be used to determine the amount of nitrogen that comes from marine sources, where it is plentiful, versus land sources where it is not found in high abundance. A forest with increased levels of N-15 indicates the possibility that much of the nitrogen is being transported into the forest from a marine source. This can be a bit confusing, and I would hate to see readers think that they need to increase the amount of N-15 in their diets to have proper growth.
Scott R. Lefler, Ph.D.
School of Molecular Sciences
Arizona State University
Tempe, Arizona
This article appeared in the print edition of the magazine with the headline Letter: N-15 isotopes.
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