Ecophysiological Adaptations of the Lichen Genera Pseudocyphellaria and Sticta to South Temperate Rainforests

Abstract

Temperate rainforests are a poorly researched habitat with respect to lichen ecophysiology in comparison to desert and polar regions. The evergreen, broadleaf forests provide a dim, moist environment that is relatively stable throughout the year. Lichens are abundant in both quantity and species diversity with the large foliose genera Sticta and Pseudocyphellaria normally being dominant, visually and in terms of biomass. These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1 (imolm" 2 s"', PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity. Photobiont versatility is also a feature of these genera. Photosymbiodemes occur, i.e. a single thallus containing both green algal and cyanobacterial sectors. Because the different sectors have the same fungal partner and grow in the same habitat, it is possible to investigate whether particular physiological traits are photobiont determined. The ability to recover photosynthetic activity in humid air is confined to thalli with green algal photobionts whilst the inability of thalli containing cyanobacterial photobionts to tolerate high light stress may be related to their lack of a protective xanthophyll cycle.

Growth and ecophysiological acclimation of the foliose lichen Lobaria pulmonaria in forests with contrasting light climates

“…4c) suggest that the light climate in the source habitat was in between the young and the old forest climates. Increased DM per area implies (1) higher solar radiation screening due to thicker layers of upper cortex and/or photobiont Green and Lange 1991;Ma´guas and Brugnoli 1996) and (2) increased waterholding capacity (Ma´guas and Brugnoli 1996;Gauslaa and Solhaug 1998) that may lengthen the duration of hydration events. Increased DM gain is related to the lichens' C acquisition, whereas area gain is also presumably determined by N acquisition (Sundberg et al 2001;Dahlman et al 2002) and water status since the expansion of fungal hyphae is regulated by turgor pressure (Wessels 1993).…”

Chlorophyll a fluorescence and CO 2 exchange of Umbilicaria aprina under extreme light stress in the cold

“…The highest F v /F m values, mainly found in lichens from shaded sites, ranged between 0.65 and 0.78 (Demmig- Adams et al 1990a;Green and Lange 1991;Jensen and Feige 1991;Calatayud et al 1996). Untreated specimens of various lichen species also revealed maximal values as low as 0.45±0.65 (Manrique et al 1993, Valladares et al 1995 and values could widely dier within one species.…”

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).…”

“…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). Por lo anterior, contribuyen para que los pára-mos sean fuentes indispensables de agua para áreas metropolitanas como lo es la ciudad de Bogotá (Luteyn, 1999;Crespo et al, 2010;De Brievre & Calle, 2011).…”