Distribution of epiphytic lichens on Quercus pubescens along an altitudinal gradient on the Adriatic side of Central Italy

The distribution of epiphytic lichens on Quercus pubescens on the Adriatic side of Central Italy (Abruzzo) was studied along an altitudinal gradient from O to 1000 m by multivariate techniques. The general response of epiphytic lichens to elevation was similar to that found on the Tyrrhenian side of Italy, with great differences in community structure and the altitude of 500 m as an ecotone. However, suboceanic species, which are widespread on the Tyrrhenian side, were rare and confined to higher elevations, or not present at all in the Adriatic gradient. The use of epiphytic lichens as phytoclimatic indicators is discussed

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

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