1997 Elemental analysis of Boundary Waters Canoe Area lichens of the Superior National Forest: Final report

Abstract

In the final report of the first study of the lichens and air quality in the Boundary Waters Canoe Area (Wetmore, 1987) it was recommended that a restudy of the elemental analysis of lichens be done every five years. A restudy was done in 1992 (Wetmore 1993a) and the present report is on the second restudy done in 1997.

In the present study four species of lichens were collected during August, 1997 at the same localities as the previous studies. The methods used were the same as in the previous studies.

Statistical analyses of data from all three years showed that species differences are highly significant but locality and year differences are of much less significance. The Isabella Lake and the Trap Lake localities have unusually high levels of some elements and that the enriched levels of Cd in Hypogymnia physodes at Basswood Lake, Isabella Lake, and Lake La Croix may be nearing damaging levels for this species.

The recommendation is made that the periodic five-year restudy of elemental analysis be continued. USPS staff should attempt to determine the reasons for the high levels of some elements at Isabella Lake and Trap Lake.