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Gastropods, trees, pH, subsoil and epiphytic lichens
Pelant, Filip ; Svoboda, David (advisor) ; Peksa, Ondřej (referee)
Epiphytic lichens are under considerable grazing pressure due to invertebrate lichenivores, mostly gastropods. Preferences of tree-climbing gastropods affect vertical distribution of lichens, their habitat preferences and whole area of distribution. Higher grazing pressure is expected on sites with basic subsoil and sufficient sources of calcium, where the abundance of gastropods is higher. Most of researches about the topic of grazing pressure were therefore conducted on such sites, although this hypothesis has never been formally tested. Epiphytic communities are also affected by pH and other properties specific to its photophyte. Nevertheless, it is not known, if the same applies for grazing gastropods and how is the grazing pressure affected by tree species. I have addressed these questions in my thesis. I set an 80-days-long field transplantation experiment in the mixed forest of Moravský kras (South Moravia, Czech Republic). Glass fiber meshes with lichen thalli were placed on sixty trunks of three tree species (Carpinus betulus - hornbeam, Abies alba - fir, Fagus sylvatica - common beech) on both calcareous (limestone) and acidic (granodiorite) sites. Abundance and diversity of gastropods were measured. Determined grazing pressure was higher than pressure detected by other authors and was...
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Epiphytic species of the Lecanora subfusca group in the Czech Republic
Malíček, Jiří ; Palice, Zdeněk (advisor) ; Guttová, Anna (referee)
- 4 - ABSTRACT During the revision of epiphytic species of the Lecanora subfusca group in the Czech Republic, nine taxa have been recorded. L. cinereofusca and L. exspersa are reported for the first time from the country. L. circumborealis has been excluded from the list of Czech lichens. L. cinereofusca and L. horiza could be considered as extinct. L. rugosella and L. subrugosa are regarded as extreme morpholocial forms from L. chlarotera and L. argentata. These morphotypes corelate with ecological conditions: substrate (nutrient enriched bark) and habitat (eutrophisation effect). In case of L. subrugosa, this speculation was confirmed by molecular data (ITS rDNA sequences). Several new secondary metabolites have been discovered during the detailed research of chemical lichen compounds. These substances belonging to terpenoids are taxonomically important and very helpful for distinguishing single species. The abundance of L. allophana and L. chlarotera has decreased during last decades. Contrarily, L. pulicaris expanded slightly. The main reasons of changes in distribution are air pollution and acidification of substrates as the impact of acid rains. The rate of substrate acidification has been shown on example of L. pulicaris. In the past, this lichen predominated on acid-barked porophytes. Nowadays, it...
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