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Title: PELTIGERA, A GENUS OF NITROGEN-FIXING, TERRICOLOUS LICHENS: ITS NITROGEN CONTRIBUTION TO THE FORESTS OF NORTHERN MINNESOTA

Author
item KNOWLES, REBECCA - UNIV OF MINNESOTA
item BIESBOER, DAVID - UNIV OF MINNESOTA
item RUSSELLE, MICHAEL
item SNYDER, JOHN - NATIONAL PARK SERVICE

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2003
Publication Date: 10/8/2003
Citation: Knowles, R.D., Biesboer, D.D., Russelle, M.P., Snyder, J.S. 2003. Peltigera, a genus of nitrogen-fixing, terricolous lichens: its nitrogen contribution to the forests of northern minnesota [abstract]. 13th Annual Conference and Workshops, Minnesota GIS/LIS Consortium. p. 67.

Interpretive Summary:

Technical Abstract: Our objective was to estimate the potential contribution of leached N by Peltigera lichens to the forests of northeastern Minnesota. We collected species of N2-fixing Peltigera and non-N2-fixing lichens from contrasting habitats. Throughfall and rain-induced leachate from these lichens was then collected in situ for 49 days. Analysis of total dissolved N (nitrate-N + nitrite-N + total Kjeldahl N) showed an enrichment of 0.39 ± 0.06 mg N/L of leachate from the Peltigera thalli. The nitrogen concentration of leachate from the non-N2-fixing lichens did not differ significantly from throughfall. We estimated the total N leached by bipartite Peltigera lichens from May through September in this region to be 2.3 µg N/cm2 of thallus. To estimate the abundance of Peltigera lichens, we used GIS technology to select sites to survey. From a set of random coordinates that span northeastern Minnesota, we selected sites according to accessibility, land ownership, and land cover. We then surveyed 104 forested sites and sketched all thalli of bipartite species of Peltigera. Dominant species of plants were recorded for site classification according to the Ecological Land Classification Program and the Upper Midwest Gap Analysis Program. The sketches were digitized and surface areas of the thalli were calculated. We found patterns of Peltigera occurrence in seven forested communities. The total surface area of Peltigera thalli was then estimated from measurements of lichen cover and the areal extent of each community. From estimates of Peltigera surface area, N contribution/cm2 thallus, and annual rainfall, we have calculated a contribution of leached N of 193 kg/yr. This input of atmospheric N is vital over time to counter the N lost from these northern forests due to volatilization, leaching, or denitrification.