Ocena zagrożenia bioty porostów Polski [Evaluation of the threat to lichens in Poland

Abstract

The documentation of lichen state in Poland in the form of edition 3 of <em>Red list of extinct and threatened lichens in Poland</em> indicates the continuation of a very high degree of threat to this Poland's important nature heritage. It comprises 55.4% of the lichen biota, which means that at present every second species in Poland has the status of an extinct or to various degree threatened species. The causes of the disappearance of sites and of diminishing of the occurrence ranges of native lichen biota components may be generalized as follows in Poland's scale: (1) Indirect activities - changes in environmental conditions: disturbances of present water relations, pollution of water, air, and soil with various toxicants, eutrophization of less rich habitats, development of building grounds and constructing over them communication facilities, quarries, strip mines, mass tourist movement, etc. (2) Destruction of phytocoenoses without more advanced habitat changes and causing permanent abiotic changes in habitats by clear cutting, forest fragmentation and isolation, transformation of whole plant communities - natural forest communities - into pine, spruce, etc. plantations. (3) Direct destruction of species. The most important effect of transforming the lichen biota is abrupt pauperization of the pool of forest epiphytes and epixylites, which is related to the areas of deciduous forests of the <em>Querco-Fagetea</em> class. As regards forest lichens in the extensive area of Poland, proportionally to various anthropogenic factors, phenomena of simplification, i.e. making the species composition simpler, and degression, i.e. decrease in species number, continue to operate. There appear an urgent need to preserve forest ecosystems, which consists in maintaining specific habitats that arę characteristic for natural forest environments, which may prevent futher decrease in taxonomic and ecological diversity of biocoenoses, including that of lichens.