Lichens and lichenicolous fungi of the “Wrzosowisko Sowno” nature reserve (NW Poland)

Lichens of the “Wrzosowisko Sowno” nature reserve in the western part of Polish Pomerania were studied in 2006 and 2014. Within the examined area, 90 species of lichens were observed. Eighteen species are included in the red list of threatened lichens in Poland, eight as vulnerable (VU) (Bacidia rubella, Bryoria fuscescens, Buellia disciformis, Calicium viride, Ochrolechia androgyna, Pertusaria pertusa, Pseudoschismatomma rufescens, Ramalina farinacea, R. pollinaria and Tuckermannopsis chlorophylla), seven as near threatened (NT) (Chaenotheca furfuracea, Evernia prunastri, Graphis scripta, Hypogymnia tubulosa, Pertusaria coccodes, Vulpicida pinastri and Zwackhia viridis), two as endangered (EN)( Melanelixia glabra and Pleurostica acetabulum) and one as critically (CR) (Melanohalea exasperata). Porosty rezerwatu „Wrzosowisko Sowno” (NW Polska) Słowa kluczowe porosty, rezerwat, Polska, Pomorze Streszczenie Badania nad biotą porostów rezerwatu „Wrzosowisko Sowno” przeprowadzono w latach 2006–2014. Na badanym obszarze stwierdzono 85 gatunków porostów i 5 grzybów naporostowych. Ponad 52% bioty porostów stanowiły gatunki nadrzewne, wśród których występowały taksony rzadkie i zagrożone w skali całego kraju. Blisko połowę gatunków stanowiły porosty o plesze skorupiastej. Najmniej licznie reprezentowane są epility, co zwiazane jest z brakiem odpowiednich siedlisk dla tej grupy porostów.


Introduction
The floristic reserve "Wrzosowisko Sowno" is located in West Pomerania Province, within Gryfice County, 2 km NW of the town of Płoty. Although the reserve created in 1977 covers 39.3 ha, the peatland covers over 26 ha. It is a transitional mire composed of Sphagnum mats (typical of raised bogs) with Scheuchzeria palustris, but their upper layers in the course of time were partly dried and overgrown by birch woods. Salix thickets and patches of vegetation dominated by mosses and sedges (Janowska et al., 2003(Janowska et al., −2004 have developed at its edges.
The habitat is an Atlantic wet heath specific to the nature of the Baltic coast in the western part of Polish Pomerania, with the characteristic Erica tetralix and Ledum palustre. They are accompanied by other Atlantic species, especially of Sphagnum mosses and boreal species of the family Ericaceae. This study aimed to investigate the species composition of lichens and lichenicolous fungi in the reserve.

Material and methods
The analysis of lichen flora is based on materials collected during field research conducted in the years 2006-2014. The random point method was used, which enabled us to explore the area objectively and evenly. Part of the reserve, especially the innermost portion, was not explored because of difficult access (waterlogged area, thickets).
Easily identifiable species of lichens were recorded in the field, while all the others were collected and identified in the laboratory of the Department of Ecology and Environmental Protection of the University of Szczecin. As a result of the research at 238 sites, 1909 records were collected (herbarium specimens or records in the field) ( Figure 1). Species names follow Fałtynowicz and Kossowska (2016), and Czyżewska and Kukwa (2009).
The list of threatened species, with their threat status, is based on the Polish red list (Cieśliński et al., 2006).
The list of species is ordered alphabetically. Types of substrate are given for each species. Names of lichenicolous fungi are marked with asterisks (*).

Results
In the "Wrzosowisko Sowno" nature reserve, 85 species of lichens and 5 lichenicolous fungi were found.

Epixylic lichens
On decaying or rotting wood, 35 lichen species were found, accounting for 30% of the lichen flora of the study area ( Figure 2). They were mostly frequent and common lichens of the genera Cladonia, Micarea, Placynthiella, and Trapeliopsis. A vast majority of epixylic species were not exclusive to one host species (82%) (Figure 4). In moist patches near the mire, young stumps were usually colonized by crustose lichens, accounting for 40% of the total number of epixylic species (Figure 3). These include Lecanora conizaeoides, Micarea denigrata, Placynthiella uliginosa, and Trapeliopsis flexuosa. On stumps with more strongly decomposed wood, they were succeeded by fruticose lichens, mostly of the genus Cladonia, frequently also Hypocenomyce scalaris and Lepraria sp.

Epigeic lichens
In the "Wrzosowisko Sowno" nature reserve, epigeic lichens accounted for nearly 11% of the total number of species (Figure 2). Most of them were not exclusive but grew at the bases of many tree species (Figure 4). Fruticose lichens prevailed among them ( Figure 5). Epigeic lichens were found at the edges of the mire and of forest glades. They were represented most often by lichens of the genus Cladonia. Species associated with thermophilous sandy pine forests, such as Cladonia arbuscula subsp. mitis, Cladonia uncialis, were less frequent. Only sporadically we recorded Bacidia bagliettoana, Peltigera rufescens, Cladonia rangiferina (partly protected).

Epilithic lichens
This group of lichens was represented exclusively by species found on anthropogenic substrates, such as concrete poles or walls, and accounted for only 7% of the lichen flora of the study area ( Figure 2). The group consists of only 8 species, with crustose thalli, including common calcicolous lichens: Flavoplaca citrina, Calogaya decipiens, Candelariella aurella, Myriolecis albescens, M. dispersa, and Lepraria sp.

Discussion
The species composition of lichens of "Wrzosowisko Sowno" nature reserve is conditioned primarily by specific environmental conditions associated with the presence of the mire. Many species were found at sites that are not accessible to average tourists, so it can be assumed that they are not subject to strong human pressure. The presented results of the research on the biota of the peatland reserve are consistent with data from other small nature reserves in northern Poland (Fałtynowicz, 1996). The dominant species are epiphytic, common or frequent in the western part of Polish Pomerania. Also the lack of epilithic species is characteristic in the nature reserves, which is associated with the absence of suitable substrates.
Nearly 30% of the recorded epiphytic taxa were rare and threatened, reported from 1-2 localities in reserve Their presence in the reserve attests to the high species diversity of the lichen biota of the reserve and it is an important refuge for rare and threatened species.

List of species
For each species, the type of substrate on which it is found and numbers sites are given. Symbols: * = lichenicolous fungus CR = critically endangered, EN = endangered, VU = vulnerable, NT = near threatened; PR = strict or partial protection.