Submitted to: Annual Forest and Wildlife Research Review
Publication Type: Abstract Only
Publication Acceptance Date: 12/20/2003
Publication Date: 1/15/2004
Citation: Knowles, R., Biesboer, D., Pastor, J., Russelle, M.P., Snyder, J. 2004. Peltigera, a genus of nitrogen-fixing, terricolous lichens: its contribution of nitrogen to forest soils of northern minnesota [abstract]. 3rd Annual Forest and Wildlife Research Review. Paper No. 26.
Technical Abstract: Nitrogen-fixing, terricolous lichens of the genus Peltigera (Willd.) occur in northern forests around the globe. Peltigera and other lichens leak nutrients and carbon upon rehydration. Our objectives were (i) to estimate the potential contribution of leached nitrogen by Peltigera lichens to the forests of northeastern Minnesota, and (ii) to determine whether soil N availability varies with distance from thalli of Peltigera. Throughfall and rain-induced leachate was collected in situ for 49 days under species of N2-fixing Peltigera and non-N2-fixing lichens from contrasting habitats in Lake County, Minnesota. Peltigera thalli produced an enrichment of 0.39 ± 0.06 mg N/L in leachate. The N concentration of leachate from the non-N2-fixing lichens did not differ significantly from that of throughfall. We estimated the total N leached by bipartite Peltigera lichens to be 2.3 micrograms N/cm2 of thallus/yr (from May through September) in this region. Upper surface area of all thalli of bipartite species of Peltigera in 104 forested sites totaled 8.3 km2. From the estimates of leaching and surface area of Peltigera, we calculated a potential contribution of 193 kg N leached/yr to the forests of northeastern Minnesota. In addition to exogenous, atmospheric N contributed by decaying thalli of Peltigera, this N leached from healthy tissue is likely vital over time to counter losses of N from volatilization, leaching, and denitrification. We found a potential zone of influence, or thallosphere, of up to 150 cm from bipartite thalli of Peltigera based on 1) season-long exposure of ion-exchange resin bags buried along 150 cm transects that radiated up- and downslope from thalli of Peltigera in the contrasting sites; 2) soil samples incubated in the lab for 74 wk and extracted for inorganic N; and 3) total N in soil near (10 cm) and distant (120 cm) from thalli of Peltigera in eight forest types across the Laurentian Mixed Forest province in Minnesota. These studies demonstrated an association of thalli of Peltigera with significantly increased soil N availability, potentially mineralizable N, and %N (p-values < 0.05).