Effects of a long-term field sulfur dioxide fumigation on Arctic caribou forage lichens

The gross photosynthetic response of Cladonia stellaris (Opiz.) Pouz. & Vezda., Cladonia rangiferina (L.) Wigg., and Cetraria cucullata (Bell.) Ach. to a continuous, long-term, in situ SO 2 fumigation was monitored during the growing season at Anaktuvuk Pass, Alaska. The photo-synthetic capabilities of the test species were either destroyed or significantly reduced depending upon the SO 2 stress gradient over the fumigation plot. Additional sampling of the plot 1 year after termination of the fumigation revealed no significant recovery in photosynthesis, and chlorophyll contents of the test species were significantly less than the controls.