New and interesting species of lichens from xerothermic habitats in NW Poland

This paper presents data on the occurrence of lichens in xerothermic grasslands, representing a great mycological peculiarity of the NW part of Pomerania, Poland. The 12 examined specimens of six species originated from fieldwork carried out in 2011–2014 in the nature reserves Brodogóry, Stary Przylep, Bielinek, Wrzosowiska Cedyńskie, Prof. Adam Wodziczko Nature Reserve in the Wolin National Park, and an old chalk excavation site on Wolin Island. Within the study sites, four lichen species were recorded as a new to Western Pomerania: Agonimia gelatinosa, Collema cristatum, Dermatocarpon luridum, and Leptogium subtile. The other two species, Collema auriforme and C. flaccidum, are rarely observed in the studied region.


Introduction
The great peculiarity of NW Pomerania are a xerothermic grasslands.They develop in specific climatic conditions only, particularly in the areas where high soil and nearsurface air layer temperatures occur periodically.Soils overgrown with xerothermic plants must be reasonably fertile and rich in calcium carbonate.Such conditions create favorable habitats for development of xerothermophilous and calciphilous lichens [1].In Poland, calciphilous lichens usually occur in the mountains and uplands in limestone areas [2,3].In lowlands, this group of lichens is rarely recorded in natural ranges of xerothermic grasslands of the Lower Vistula, Odra, and Warta rivers [4][5][6][7].Xerothermic grasslands of NW Poland are found in morainic areas, characterized by varied relief.The vegetation is not dense, composed mostly of patches of the feather-grass community Potentillo-Stipetum capillatae.Because of its loose structure and specific soil conditions, the community also includes many plants typical of sandy grasslands of the class Koelerio glaucae-Corynephoretea canescentis as well as thermophilous and heliophilous species of the class Festuco-Brometea [8,9] (and also unpublished documentation by Dr Tadeusz Głazek from 1971 "Rezerwat florystyczno-dydaktyczny 'Stary Przylep' ").
Many lichens are adapted to adverse environmental conditions.They may colonize both natural and man-made substrata (such as concrete and bricks), and are often found in anthropogenic habitats, like wooden constructions, mechanically disturbed soils, worked stone surfaces and quarries.Xerothermic lichens in northern Poland are reported with increasing frequency in anthropogenic habitats, such as gravel pits, mine workings or quarries [10][11][12].Such moderate anthropogenic pressure creates new habitats for lichens and may significantly increase their diversity.
This paper presents new localities of lichens that were recorded in xerothermic habitats in NW Poland, developed partly as a result of human activity.DOI: 10.5586/am.1097

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Material and methods
The presented list of records is derived from the material collected during fieldwork in 2011-2014.The study included the following study sites: Brodogóry Nature Reserve (B), Stary Przylep Nature Reserve (SP), Prof. Adam Wodziczko Nature Reserve (AW) in the Wolin National Park, an old chalk (OC) excavation site on Wolin Island, Bielinek Nature Reserve (BI), and Wrzosowiska Cedyńskie Nature Reserve (WC) (Fig. 1).In total, 12 specimens of six species were collected, now deposited in the Lichen Herbarium (SZUB-L) of the Department of Ecology and Environmental Protection at the University of Szczecin.Morphological and anatomical observations were made using standard microscopic techniques, under an inverted fluorescence microscope (Zeiss Axio Observer A1) and a light microscope (Zeiss Axio Scope A1).

Discussion
In the studied localities, xerothermic epigeic lichens were found on calcareous soil, humus, and decaying remains of plants as well as on rock-waste.Calciphilous lichens were not homogeneous with respect to specific habitat requirements.Here, a common factor was only the chemical nature of substratum (calcium carbonate).Other factors differed, e.g., the degree of sun exposure or substratum moisture [72].
In total, six new species of lichenized fungi were observed: one in the Prof. Adam Wodziczko Nature Reserve in the Wolin National Park, five in the old chalk excavation site on Wolin Island, one in the Brodogóry Nature Reserve, one in the Stary Przylep Nature Reserve, two in the Wrzosowiska Cedyńskie Nature Reserve, and two in the Bielinek Nature Reserve (Fig. 1).The species are either new or rare in Western Pomerania.All the collected lichens were found in isolated localities, in small populations.Their thalli were healthy, with well-developed reproductive organs, and did not show any symptoms of decline.Four of the recorded lichens were new to NW Pomerania: Agonimia gelatinosa, Collema cristatum, Dermatocarpon luridum, and Leptogium subtile (Fig. 2).They were found together in the old chalk excavation site located in the buffer zone of the Wolin National Park.
Lichens of xerothermic habitats are usually inconspicuous and rarely observed.They are described chiefly during specialized lichenological explorations.Currently, their distribution in Europe is well-studied.They are recorded in several climatic zones, from the boreal to the Mediterranean zone [73], but most frequently in SE and S parts of Europe with a continental climate.In other parts of the continent, with a more humid climate, isolated patches of steppe vegetation are found on particularly warm and dry sites [74].The patches occupy calcium-rich, steep riverbanks, ravines, or calcareous rocks.In Central Europe, xerothermic lichens are rare or very rare, particularly in the lowlands [75][76][77][78] (Tab.1).The small size of the patches and the increasing eutrophication of adjacent areas are important threats to those populations.The presented records are some of the northernmost localities of xerothermic lichens, which are particularly important for the dynamics of those taxa.
Tab. 1 Other European records of the lichen species reported in this study.