Acknowledgements
The authors are thankful to Bjorn Karlsson from the Biotron Laboratory
at the University of Wisconsin for technical service and support in the
greenhouse, Jesse Nippert at Kansas State University and Ben Harlow at
Washington State University for University for help with elemental
analyses, and Jeff Merriam and Jan Hislop at the USDA Northern Research
Station for technical support with the inorganic ion analysis. The
authors declare that the research was conducted in the absence of any
commercial or financial relationships that could be construed as a
potential conflict of interest.