Summer Maximum Temperature and the Abundance of Collema
A negative correlation existed between summer maximum temperature (mean daily maximum temperature during June) and subsequent abundance of the lichen Collema, which dominates the biological soil crust in many semi-arid western ecosystems. Even after 2 cooler years, the lichen had not recovered from the warm period of 1997 to 2003. Credit: J. Belnap, S.L. Phillips, and T.T. Troxler, U.S. Geological Survey.