Photosynthetic performance of lichen transplants as early indicator of climatic stress along an altitudinal gradient in the arid Mediterranean area

Abstract

A climatic change was simulated transplanting samples of the lichens Evernia prunastri (L.) Ach. and Pseudevernia furfuracea (L.) Zopf v. furfuracea along a 1,400 m altitudinal gradient in the northern side of the island of Crete (Greece). The working hypothesis was that the photosynthetic performance (i.e. pigment content, chlorophyll degradation and photosynthetic efficiency) of transplanted lichens varies along the altitudinal gradient. The overall effect observed was a general depression of the photosynthetic performance along the gradient. Concentrations of chlorophyll a, chlorophyll b and carotenoids decreased with decreasing elevation and along with the hottest and driest months of the year, with chlorophyll b being the most sensitive parameter to dry conditions. Chlorophyll degradation decreased with increasing elevation. The exposure period was the main factor affecting photosynthetic efficiency, with lower values during summer months. We argued that the water content of lichen thalli is the most important factor determining differences in photosynthesis under the experimental conditions. This allowed to suggest that the lichen photosynthetic performance deserves further investigation as early biological indicator of atmospheric stress induced by dry conditions and, to a greater extent, for the assessment of the desertification risk in the arid Mediterranean environment.

Spatial variation of eco-physiological parameters in the lichen Pseudevernia furfuracea transplanted in an area surrounding a cement plant (S Italy)

“…We consider cluster 4 a Blocal control^with r e g a r d t o t h e p i g m e n t c o n c e n t r a t i o n s a n d phaeophytization quotient. Although the pigment values showed an average reduction of about 15 % compared with the LOA (external control), perhaps as a consequence of both suboptimal temperature for the lichen (Pirintsos et al 2011) and contaminants emitted by anthropogenic sources, they did not differ significantly from the values for thalli in the lichen origin area; hence, these potential negative factors did not have any marked effect on the pigment concentrations. Moreover two thirds of the cluster 4 sites had pigment values higher than the remaining clusters and, as mentioned above, the mean values of chlorophylls, xanthophylls + carotenoids and phaeophytization quotient were significantly different from those of clusters 1, 2 and 3.…”

“…In fact, their mean values in clusters C1, C2 and C3 showed a significant reduction when compared with those of both cluster C4 and the LOA (except OD435/OD415). With the exception of cluster C1, the phaeophytization quotient values do not seem to suggest a strong decline of this parameter in clusters C2 and C3 because lichens located in environments not affected by human pressures show OD435/OD415 values between 1.20 and 1.40 (Frati et al 2011;Pirintsos et al 2011;Bačkor and Loppi 2009). Nevertheless, the values showed a very low coefficient of variation (C2 = 1.714 %, C3 = 0.494 %) and differed significantly from C4 (CV = 2.214 %), meaning a slight but true increase in chlorophyll degradation.…”

Ecophysiological and ultrastructural effects of dust pollution in lichens exposed around a cement plant (SW Slovakia)

“…In the same area, significant correlations were found between the content of Cu, Pb and Zn in the lichen Usnea amblyoclada exposed around the cement mill and the content of hydroperoxy conjugated dienes, suggesting an important oxidative effect caused by these ions (Carreras and Pignata 2002). In addition to dust pollution, microclimatic parameters may influence physiological processes of lichens, in particular during the dry season, when sun irradiance and water availability may heavily affect chlorophyll fluorescence emission and the content of photosynthetic pigments (Paoli et al 2010;Pirintsos et al 2011). Also, the type of deposition can vary according to humidity and precipitation.…”

Indoor and Outdoor Biomonitoring Using Lichens at Urban and Rural Primary Schools

“…Atmospheric conditions may produce changes in photosynthetic processes of lichens since environment determines (1) intensity, quality, and period of light radiation reaching lichen thalli during the day, as well as the exposure period; (2) temperature, which affects lichen optimal metabolism; and (3) water availability in the form of precipitation, humidity, fog, or dew, influencing the degree of thallus hydration (Kershaw, 1985;Pirintsos et al, 2011;Canha et al, 2013a). Further, along with the impact of local environmental pollution as previously described, electrolyte leakage is a measure of lichen cell membrane damage, that is, lichen vitality.…”