Respiratory Activity of Some Lichen Species–Representatives of Antarctic Flora

Resumo

Data on the respiratory activity of 12 species of Antarctic lichens are presented. It is found that the respiration of foliose lichens is more intensive than the respiration of fruticose lichens. The O₂ uptake rate correlates positively with the nitrogen content in the biomass of thalli and depends on temperature. The thalli O₂ uptake rate increased 2.2–2.4 times with a temperature increase from 5 to 15°C. The reaction of respiration upon a further rise in temperature is species-specific. The decrease in the temperature coefficient of respiration (Q₁₀) with a temperature increase to 35°C is most pronounced in the endemic species Usnea aurantiaco-atra, which is well-adapted to Antarctic conditions. The calculations show that, in summer, lichens are able to lose an amount of substrate equivalent to 0.8–1.4% of the thallus dry biomass in respiration daily. The total respiration cost of the lichen maintenance under snow during the winter can reach of 30–35% from their biomass. These results extend our knowledge on Antarctic lichens, and prediction their response to climatic change.