1. Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 USA
2. Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA 91125 USA
3. School of Integrative Plant Science, Soil and Crop Sciences Section Cornell University Ithaca NY 14853 USA
4. Biology Department Occidental College Los Angeles CA 90041 USA
5. Forest and Rangeland Stewardship Colorado State University Fort Collins CO 80523 USA
6. Department of Global Ecology Carnegie Institution for Science Stanford CA 94305 USA
7. Heinz Walz GmbH Eichenring 6 Effeltrich 91090 Germany