Nitrogen Fixing Lichens in Forests of the Southern Appalachian Mountains of North Carolina

Abstract

The abundance and species diversity of nitrogen fixing lichens were determined for several forests of the southern Appalachian Mountains of western North Carolina. Gray beech forests of wet, high-elevation beech gaps were auspicious locations for these lichens. The bark of Aesculus octandra Marshal was the optimum habitat, particularly for the dominants Lobaria quercizans Michx. and Lobaria pulmonaria (L.) Hoffm. Lichen biomass in this gray beech forest commonly ranged from 7 to 9 kg ha-' but was higher where Aesculus octandra was abundant. Lichens were less abundant in oak forests and cove forests, and none was found on conifers. The annual contribution of ammonia nitrogen by lichens was roughly estimated to be 0.8 kg ha-' for the gray beech forest in beech gaps. The southern Appalachian Mountains are known for their scenic beauty, abundant rainfall and vegetation which is rich in community types and species diversity. Meteorological records taken along the southern limits of the Blue Ridge escarpment and the adjoining mountain ranges indicate that annual precipitation commonly approaches or exceeds 200 cm yr-1. In the gorges along the Blue Ridge escarpment values exceeding 250 cm yr-1 occur with regularity (Cooper, 1963). Warm moist air from the south rises, as it moves from the flat Piedmont of Georgia and South Carolina, cools and loses this moisture as it proceeds into these mountainous areas. The combination of high rainfall and great diversity in habitats found in these old and geologically stable mountains has led to considerable complexity in the types of climax forests found there (Whittaker, 1956). Representatives of the northern boreal forests are found at high elevations, cove hardwood forests are common in many of the mesophytic locations, a variety of oak forests occupy the majority of the landscape and several other forest types are interspersed within these communities. From previous publications on the nitrogen fixing lichens it appears that there is an association between the abundance of these lichens and the moisture available to the lichen. In the arctic, where these lichens have been implicated as important contributors of reduced nitrogen (Kallio & Kallio, 1975; Schell & Alexander, 1973; Crittenden, 1975), moisture is not a limiting factor. In an investigation of the Colombian montane rain forest Forman (1975) estimated that the biomass of these lichens was 5.7 kg ha-1 and that the annual rates of nitrogen fixation were in the range of 1.5 to 8 kg N ha-1. In the tall Douglas fir forest of Oregon Denison (1973) reported a nitrogen fixing lichen biomass of 390 to 500 kg ha-'. Precipitation in the tropical rain forest is considered to be between 200 to 300 cm yr-' (Forman, 1975) and in the tall Douglas fir forest is greater than 200 cm yr-' (Zobel et al., 1976). These two forested areas, however, vary in the annual distribution of that

Do lichens domesticate photobionts like farmers domesticate crops? Evidence from a previously unrecognized lineage of filamentous cyanobacteria

“…While cultures are needed to establish the exact morphological variation in Rhizonema , we have to assume that, other than lichenization, differences between Rhizonema and Scytonema are to be found at the level of microanatomy and physiology, rather than morphology, a situation not uncommon in prokaryotes. This problem has important implications for ecosystem research because a large proportion of nitrogen‐fixing cyanobacteria previously believed to occur both lichenized and free‐living (Forman, 1975; Becker, 1980; Green et al, 1980; Fritz‐Sheridan, 1988; Antoine, 2004; Cornelissen et al, 2007) appear to be restricted to lichen symbioses.…”

15N2 FIXATION AND MOLYBDENUM ENHANCEMENT OF ACETYLENE REDUCTION BY LOBARIA SPP.

“…Hitch and Millbank (1975) report Ngase activity measured in the laboratory for L. scrobiculata, a non-cephalodiate species, collected in Scotland, at 290 nmol C2H4 g-^ hr^ at 25 °C. L. pulmonaria collected in North Carolina produced 963 nmol C2H4 g-i h'^ at 20 °C in the laboratory (Kelly and Becker, 1975) and 12330 nmol C2H4 g-^ h-^ at 16 to 18 °C in the field (Becker, 1980). These latter rates are much higher than the mean rates (L. pulmonaria 278 and L. oregana 350 nmol C2H4 g"^ h'^) reported by Denison (1979) for a large number of samples collected in the Cascades and measured in the field over a temperature range of 0 to 15 °C (September 1976to May 1978.…”

Ecogeografía del género Sticta (Ascomycota liquenizados: Lobariaceae) en Colombia

“…Considerando la intensidad lumínica, se puede reconocer que las especies con cianobacterias como fotobionte primario son frecuentes en todos los lugares, desde sombreados a expuestos, probablemente por la capacidad de absorber agua líquida que poseen las cianobacterias, además de la fijación de nitrógeno (Kelly & Becker, 1975;Becker, 1980;Green et al, 1980Green et al, , 1985Guzmán et al, 1990;Green & Lange, 1991;Beckett, 1995;Zotz et al, 1998;Antoine, 2004;Benner et al, 2007). También podría deberse a las diferentes adaptaciones cromáticas de las cianobacterias en la utilización de numerosos pigmentos, entre ellos los ficobilínicos, que les permiten absorber energía lumínica hasta a bajas intensidades de luz (Grossman, Schaefer, Chiang & Collier, 1993;Kehoe, 2010).…”

“…Especies de Sticta predominan en las zonas paramunas y bosques subandinos y andinos, donde cubren ramas y troncos de árboles y arbustos en grandes cantidades. Por asociarse en su mayoría con fotobiontes cianobacteriales, estos líquenes contribuyen a la fijación de nitrógeno atmosférico y sirven como fertilizantes naturales (Kelly & Becker, 1975;Becker, 1980;Green, Horstmann, Bonnett, Wilkins & Silvester, 1980;Green & Lange, 1991;Antoine, 2004;Benner, Conroy, Lunch, Toyoda & Vitousek, 2007). Además, por su capacidad de retener grandes cantidades de agua, permiten balancear los efectos de la precipitación y generan un microclima húmedo sobre la vegetación terrestre aún tiempo después que la precipitación haya terminado (Green, Snelgar & Wilkins, 1985;Guzmán, Quilhot & Galloway, 1990;Green & Lange, 1991;Beckett, 1995;Zotz, Büdel, Meyer, Zellner & Lange, 1998).…”