Lichen species

A study of Cladonia cervicornis (Achar.) Flotow from two widely disjunct populations in California, one from coastal Mendocino County and one from the foothills of the Sierra Nevada in Amador County, revealed a difference in the frequency of occurrence of the depside atranorin [245] (see Fig. 2.76) (Hammer and Ahti, 1990). The compound, considered to be a primitive feature of this lichen species, was present in 80% of the... 

Rhodocladonic acid is an anthraquinone that occurs in several lichen species, especially in the family Roccellaceae).20 Little research has been done documenting bioactivity, particularly phytotoxic activity. Similar to emodin, we tested two sets of analogues (Fig. 1.10). Series 1 consisted of a group of compounds with aliphatic R-groups ending in a terminal hydroxyl. Series 2 had a terminal methyl. The R-group substitutions were identical to those of emodin. 

Prillinger H, Kraepelin G, Lopandic K, Schweigkofler W, Molnar O, Weigang F, Dreyftiss MM New species of Fellomyces isolated from epiphytic lichen species. Syst Appl Microbiol 1997 20 572-584. 

Some species of lichens are very sensitive to air pollutants. Consequently, urban environments are often highly impoverished in lichen species. Some ecologists have developed schemes by which the intensity of air pollution can be reliably assayed or monitored using the biological responses of lichens in their communities. Monitoring of air quality using lichens can be based on the health and productivity of these organisms in places variously stressed by toxic pollution. Alternatively, the chemical composition of lichens may be assayed, because their tissues can effectively take up and retain sulfur and metals from the atmosphere. 

The term hyperaccumulators was first used by Brooks et al. [113] to describe the plants that take up and accumulate more than 1000 pmoles As/g dry weight. A report about an arsenic-hyperaccumulating fern species additionally discussed the ph)Poremediation potentials of such plants [114]. Recent investigation has shown that the arsenic compounds in terrestrial and aquatic plants, fimgi, and lichen species are also interesting natural products [115, 116]. 

Data on the occurrence of trace metals in lichen species from different continents have been reported, but this kind of information is scarce for Antarctic species (29, 48, 52-56). 

Table 6.10. Cadmium and Pb contents (+ standard deviation) in lichen species from Antarctica (pg g dry weight)...

In the laboratory, remains of the tree bark and other lichen species where removed from P. sulcata transplants. Then each sample was put in a nylon sieve and rinsed in 18 Mfl water ejected for 30 s, freeze dried and ground in a Teflon (balls and capsule) mill. 

Table 3. Anthropogenic activities biomonitored by different lichen species selected publications in the 1990s...

France. In 1980 the Pb pollution produced by car exhausts on the adjacent motorway (A6) was assessed by means of several lichen species Cladonia portentosa, Cladonia chlorophaea, Lasallia pustulata, Umbilicaria grisea, H. physodes, P. caperata, Ever-nia prunastri, Lecanora conizaeoides and U. hirta. In 1992 these lichens were found to contain less Pb than twelve years previously. The average figure for all measured species in all sites displayed a similar decrease 3.2-3.S times less. The decrease of Pb fallout along the motorway was ascribed to the consumption of unleaded gasoline. 

Lichen species Chemical elements Region/ country(ies) Reference... 

An additional investigation of elemental content of lichens sampled along the shore of glacial lakes around the Indian station Maitii in the Schirmacher Oasis, East Antarctica, was carried out by Kureishy et al. (1993). The name of the lichen species was not presented. This study detected low contents of Cd, Ni, Co and Pb (<0.05 p.g g wet weight) and 14.0 jLg g Cu. 

An additional lichen species, Cladina stellaris, produces large amounts of ethylene upon exposure to Fe salts at pH 3.5 and lesser amounts upon exposure to Cu and Zn... 

As the K efflux from plant tissue demonstrates membrane disintegration in particular, Nifontova et al. (1995) investigated the permeability of lichen membranes as a result of gamma radiation. Thalli of different lichen species were irradiated for this purpose. The membrane permeability in irradiated thalli of Cladonia arbuscula, Cetraria islandica and Hypogymnia physodes increased considerably in comparison with untreated control thalli. The K efflux from H. physodes thalli intensified with an increase of the radiation dose whereas no correlation was obtained for the K efflux and the radiation dose in C. arbuscula and C. islandica. The N content in Peltigera aphtosa appeared, however, to remain stable under acute gamma radiation. 

Lichens may grow on Pb/Zn-rich rocks and associated soils. Purvis and Halls (1996) present a list of 61 terricolous lichen species characteristic of Pb/Zn-rich environments in Britain and Europe. Epilithic crustose lichens were observed also on heaps of mine spoil containing Ee and Pb near old silver mines in Sala, Sweden (Fig. 9). 

Branquinho, C., Brown, D.H., Maguas, C., Catarino, F., 1997a. Lead (Pb) uptake and its effects on membrane integrity and chlorophyll fluorescence in different lichen species. Environ. Exp. Bot. 37, 95-105. 

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