Lichen flora of the Czech Republic.

This review of the lichen flora of the Czech Republic deals with the history of the research and highlights the most important summarizing publications. The diversity of the lichen flora is discussed and compared with that recorded in neighbouring countries. The main phytogeographic elements are outlined and illustrated with representative examples. The threat to the lichen flora in the Czech Republic is discussed in terms of the recently published Red List (version 1.1) and several endangered ecological groups of lichens with examples of the most threatened and extinct species are identified. Changes in the lichen flora along with the main causal factors are discussed. Air pollution, in particular sulphur dioxide was the most serious damaging factor in the 20th century. However, there has been a change in the trend in air pollution over the last two decades, with a decrease in sulphur and increase in nitrogen emissions, which has resulted in recolonization by formerly vanishing species of nitrophytic lichens (e.g. Xanthoria parietina) and decrease in the abundance of the toxitolerant acidophytic species Lecanora conizaeoides. Ongoing present changes are very dynamic and not yet fully recognized. Therefore, field surveys are very important and will result in the recording of further species new to the Czech lichen flora.