2003 Lichen Studies in St. Croix National Scenic Riverway: Final Report.

Abstract

During 2003 a re-study of the lichens of St. Croix National Scenic Riverway was done. In addition to collections for elemental analysis, new complete lichen collections were made at 15 localities for new species records. There are now 282 lichens found in the park and the new species list should replace the list prepared for the 1991 report. This list includes 20 new species for the park. There are eight species in the park that are on the lists of threatened or endangered lichens for Minnesota or Wisconsin. The number of lichen species increases significantly about eight species per degree of latitude from south to north. The most number of species by county were found in Burnett Co., WI. Lead has decreased significantly overall since the first sampling in 1990, but continues to be higher at Riverside than anywhere else. A local source of lead in this area remains a mystery. Cadmium has not decreased significantly over time, and continues to be elevated at Namekagon Dam. Other lichen species at this locality also have elevated Cd, confirming that there is probably an unknown local source of this element. Unlike the previous two heavy metals, Mn has increased significantly over time, and appears to be very high at Radspur.