Host tree species mediate corticolous lichen responses to elevated CO and O after 10 years exposure in the Aspen-FACE system.

Lichens contribute significantly to the biodiversity and functioning of many ecosystems. Although lichens are useful air pollution bioindicators and may respond in significant ways to global change, they are studied infrequently under field conditions in chamberless exposure systems. We surveyed corticolous lichens on paper birch (Betula papyrifera) and trembling aspen (Populus tremuloides) after 10 years exposure (1998-2007) to elevated CO (eCO) and O (eO) in the Aspen-FACE experiment in Rhinelander, WI, USA.