Cladonia alpestris

The Alkali-soluble Polysaccharides of the Lichen Cladonia alpestris (Reindeer Moss), G. O. Aspinall, E. L. Hirst, and (Mrs.) Margaret Warburton, J. Chem. Soc., 651... 

Fig. 15.4. Titration data from Tuominen (1967) for Cladonia alpestris, depicted as a function of pH versus concentration of added titrant. The closed circles represent forward titration data, while open circles stand for reversed titration data points. The upper curve is a calculated titration curve in pure water. The shaded area denotes the extent of pH buffering capacity exhibited by the lichen, relative to a non-buffering solution of pure water.

Tuominen, Y. (1967). Studies of the strontium uptake of the Cladonia alpestris thallus. Annales BotaniciFennici, 4, 1-28. 

Jaakkola et al (1967) and Jaakkola (1969) reported results very similar to those of Lounamaa (1965) with respect to Fe. They detected a higher content of inactive iron in the dead basal parts of reindeer lichens than in the living tops, i.e. about two to three times that of the top parts. In the case of Cladonia alpestris, the thallus of which changes gradually to an organic decomposed substratum, these high amounts of inactive iron apparently arise from the substratum. In addition to this, according to Jaakkola, the fallout iron Fe seemed to move relatively rapidly from the top part toward the base of the thallus. This movement seems to be unidirectional, because no comments on possible back diffusion exists. This kind of information on the mobility of metal nuclides within a lichen thallus is rare in the present literature. 

Kreuzer and Schauer (1971) reported a smaller difference in the Cs content between the upper and lower parts of Cladonia sylvatica and Cladonia rangiferina than for Cladonia alpestris. This is probably due to the different textures of the upper parts and different relations between the algae and fungal cells within the lichens. The factors affecting the distribution of - Cs and Sr in lichen thalli are discussed later in the subsection on translocation. 

The passive phase of the cation uptake of lichens seems to be some kind of cation-exchange process. This idea is supported by experiments describing the inactive Sr and Cs binding of Cladonia alpestris and Ramalina reticulata, respectively. 

The results of the experiments on the inactive Sr binding of Cladonia alpestris (Touminen, 1967) can be summarized as follows. When the living tops of the thalli were immersed in a dilute solution of Sr, the equilibrium between the thallus and the solution was rapidly established in a few minutes and remained stationary for several hours. The effect of temperature on the... 

Handley and Overstreet (1968) found Sr to be more effective than Cain competitive experiments. This observation is also supported by the separation factors of Cladonia alpestris (Tuominen, 1967) Sr/Ca = 1.5 compared, for example, with Cs/K = 1.0. Further, the values Sr/K = 4.0 and Sr/Cs = 3.0 of C. alpestris show the preference of divalent cations to monovalent ones. One possibility to explain these preference relations can be based on the differences in the radii of the hydrated ions and the three-dimensional structure of the binding site. For example, the Sr ion as a smaller one compared with Ca could fit closer to the site, the structure of which has possibly been solved by Sterling. 

Hanson et al. (1967) performed similar experiments on the effect of seasonal snow cover on the distribution of fallout radionuclides in Cladonia alpestris and the movement of artificially applied radionuclides within the thalli. Strontium-90 concentrations increased during summer months when the lichens were exposed to atmospheric fallout deposition, stabilized at... 

The most interesting feature of all these experiments is that the Sr ions applied to lichens were more mobile than the Cs ions similarly applied, because the diffusion experiments described by Tuominen (1968, 1971) display exactly the reverse order of the mobilities, i.e., Cs seems to move rather freely within the thallus of Cladonia alpestris compared with Sr, which displays rather strong interaction with the binding sites of the thallus. The important difference between these experiments is that the previous ones were performed in free-air using living thalli, whereas the later diffusion experiments were carried out in the closed test tubes in the laboratory with dead thalli. We can try to explain the discrepancy as follows. 

Tuominen, Y. (1968). Studies on the translocation of ceasium and strontium ions in the thallus of Cladonia alpestris. Ann. Bot. Fenn. 5, 102. 

A metal-complexing action may be involved in the accumulation by lichens of radioactive cations such as "Sr. Subbotina and Timofeev-Resovkii (1961) reported high accumulation coefficient values for crustose lichens suspended in aqueous solutions of the radioactive isotopes of several metals. Schulert (1962) suggested that a chelation mechanism was involved in the accumulation of Sr by lichens and Tuominen (1967) showed that the uptake of Sr by Cladonia alpestris was a physicochemical process and was not metabolically controlled. 

The effect of the water content of a thallus on net photosynthesis has been noted earlier. Ried (1960b) showed that for Umbilicaria cylindrica the optimum rate was at 65% saturation but this was reduced by half when the thalli were fully saturated. He found, however, that in more loosely organized thalli, i.e., those without lower cortices (Peltigera) or with cyphellae(5ncra), photosynthesis was most rapid at 90% saturation with only a small decline above this level. He felt the decline was due to the difficulty of gas exchange in fully saturated leathery thalli such as Umbilicaria. However, the findings of Kershaw and Rouse (1971) with Cladonia alpestris, which has a hollow tubular thallus, casts doubt on this. 

Kershaw, K. A., and Rouse, W. R. (1971). Studies on lichen-dominated systems. I. The water relations of Cladonia alpestris in spruce-lichen woodland in northern Ontario. Can. J. Bot. 49, 1389-1400. 

Fig. 11. Heat tolerance of Cladonia alpestris from various areas in Europe. The tolerance is indicated by the rate of COg evolution (% of controls) 24 hours after a heat treatmel t for 30 minutes at different temperatures. (A) Bayerischer Wald (Germany) (B) Stockholmer Scharenhof (Sweden), (C) Rhon (Germany), (D) Jamtland (Sweden). (From Lange, 1953.)...

Nifontova (1967) investigated the influence of heat on the metabolism of Cladonia alpestris and C. arnaurocraea by measuring the COg fixation rate 20 minutes after the treatment. After heating up to 200°C for 4.5 hours, the dry thalli did not completely lose their ability to fix C0.2 but their fixation... 

Cladonia alpestris 37.1 nCi/kg dry weight Nephroma arcticum 61.0 nCi/kg dry weight Cladonia silvatica 46.4 nCi/kg dry weight... 

Hanson, 1958 Kalb, 1970), and Usneafasciata 3,nd Himantormialugubris on the South Shetland Islands (Lindsay, 1971). Cladonia alpestris, C. impexa, and Other Cladinas prefer the opposite type of habitat (Ahti, 1961). Many of these relationships between lichens and the substrate are considered in detail by Brodo (Chapter 12). 

Fig. 1. Relative growth rate (RG R) of young Cladonia alpestris specimens in Finland plotted against mean daily rainfall and the linear regression line. (From Karenlampi, 1971.)...

Karenlampi, L. (1970). Morphological analysis of the growth and productivity of the lichen Cladonia alpestris. Rep. Kevo Subarctic Res. Sta. 7, 9-15. 

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