Lichens from Sisimiut in West Greenland and their Climatic Preferences

Abstract A total of 165 lichen taxa collected from Sisimiut in West Greenland in summer 2017 were reported and categorized toward their climatic preferences. Almost 68% of the 165 lichens are more or less equally distributed in continental and oceanic areas of Greenland. More than 26% of the lichens occur most frequently in oceanic areas and more rarely in continental areas. Almost 5% of the lichens occur most frequently in continental areas and more rarely in oceanic areas. Two lichens are distinctly oceanic. No distinctly continental lichens were found in the present investigation. The results are in good accordance with those obtained from similar investigations in West Greenland. Two different climatic scenarios and their influence upon the lichen communities are discussed.


INTRODUCTION
carried out his extensive floristic and ecological studies on the oceanic and continental vegetation complexes in Southwest Greenland, he included many lichens, which had been identified by the lichenologist M. Skytte Christiansen. The succeeding exploration of the lichen flora of West Greenland during more than 70 years has resulted in a more precise understanding of the distribution of lichens in relation to climatic factors such as the degree of oceanity and continentality. Climatic distribution types have so far been compiled for numerous lichens in selected areas in Southwest Greenland, central West Greenland and Southeast Greenland (K. hansen, 1971;e.s. hansen, 2010, 2012a, b, 2013. Contrary to K. Hansen, who has originally defined the distribution types for macrolichens from Southwest Greenland, in the present study, the author deals with both micro-and macrolichens. Deichmann Branth & GrønlunD (1888) have mentioned some macro-and microlichens from "Holstensborg" (= Sisimiut), but the list is far from complete. The author decided to study the lichen flora more thoroughly and, accordingly, carried out a floristic investigation of the surroundings of Sisimiut in summer 1991 (e.s. hansen, 1998). The present paper aims to stimulate future research on the occurrence and distribution of lichens toward climate change. No doubt, global warming, which now accelerates melting of the Greenland inland ice and glaciers and in some coastal areas formation of virgin landscapes with sand and loess, will give a possibility for colonization of lichens such as soil crust lichens (e.s. hansen, 2001).

Study area
Sisimiut locality (66°06´ N, 53°40´ W) is situated in the north-western part of the peninsula near the outer coast. A broad valley with lakes extends from the town towards the east. The valley is flanked by mountains such as Kaellingehaetten composed of Archaean gneiss (escher & stuart Watt, 1976). The siliceous rocks in the Sisimiut area are comparatively rich in iron, which is reflected by the occurrence of many ferruginous lichens. Climatically and floristically, Sisimiut area is located in the low arctic, oceanic area (Jensen, 1999). The mean temperature of the warmest month (July) is c. 7 to 8°C and of the coldest month (January) c. -15 to 20°C. Annual precipitation is c. 397 mm (e.s. hansen, 1998).

MATERIALS AND METHODS
Lichens were collected from numerous sampling plots in the lowland (< 200 m a. s. l.) near Sisimiut in July 2017. A total of 300 lichen specimens were studied using Zeiss light microscopes and identified by the author. The nomenclature in the list is presented after norDin et al. (2011) with some exceptions. The specimens are deposited at the Botanical Museum of the University of Copenhagen (C). The substrate preference and the main plant communities in which the lichens occur were noted for all collected specimens. The type of distribution toward oceanity or continentality was estimated for all lichens by all available information about their total distribution in Greenland, in particular the distribution maps compiled by thomson (1984,1997) and the information given by E.S. Hansen (1995a).
The following oceanity-continentality indices originally defined by K. Hansen (1971Hansen ( ) with later modifications (e.s. hansen, 2010Hansen ( , 2012aHansen ( , b, 2013 were used: CCO -somewhat continental lichens occurring most frequently in subcontinental and continental areas and more rarely in oceanic areas. CO -lichens with almost equally high frequency in continental and oceanic areas. COO -somewhat oceanic lichens occurring most frequently in oceanic areas and more rarely in continental areas. OO -distinctly oceanic lichens occurring exclusively in oceanic areas.

Annotated list of species
The following list represents 165 lichen taxa. Oceanity-continentality indices are stated for all taxa. "Ap." and "pe." -mean presence of apothecia and perithecia, respectively; "st." means that the specimen is sterile.

DISCUSSION
A total of 111 of the 165 lichens listed above appear to be more or less equally distributed in continental and oceanic areas. This is in fairly good accordance with the many different types of lichen biotopes in the Sisimiut area ranging from seashore rocks to inland rocks and from coastal dwarf shrub heaths to dry inland heaths. In addition, many CO-lichens are characterized by being fairly tolerant and adapted to changing climatic conditions within certain limits. It is in good accordance with the fact that many arctic-alpine lichens extend their distribution to temperate areas (thomson, 1984). However, the particular preference as regards habitat of different lichens changes rather much and is reflected in the quantity of the species in different parts of South West Greenland. Thus, a gradual decline in quantity from the oceanic areas to the more or less continental areas is observed as regards many terricolous macrolichens (K. hansen, 1971). This applies to species such as Alectoria nigricans, A. ochroleuca, Bryocaulon divergens, Cetraria delisei, C. islandica, C. muricata, Cladonia borealis, C. cenotea, C. gracilis, C. macroceras, C. mitis, C. rangiferina, C. stellaris, C. stygia, C. uncialis, Dactylina arctica, Nephromopsis cucullata, N. nivalis, Peltigera aphthosa, P. canina, P. extenuata, P. leucophlebia, P. malacea, P. ponojensis, P. rufescens, P. scabrosa, Solorina crocea, Stereocaulon alpinum, S. arenarium, S. glareosum, S. paschale and Thamnolia vermicularis var. subuliformis. Most of these lichens occur in different types of dwarf shrub heaths and fell-fields with scattered dwarf shrubs. Some also grow in Sa-lix glauca thickets and a few in snow patches, for example, Solorina crocea. Present and future global warming influence the terricolous lichens in different ways. Two different climatic scenarios and their influence upon the lichens are discussed in the following. Under the first scenario with melting inland ice, thawing permafrost and precipitation increasing, the water supply is not a problem in many, in particular coastal, areas in Greenland. However, the thawing permafrost results in unstable soil conditions, which influence both higher plants and lichens in a negative way. The warmer climate also results in increased competition with higher plants, which are favoured by higher contents of nutrients in the soil. These conditions will presumably result in reduction of some lichen populations in, for example, the dwarf shrub heaths. As regards the mountain flora, the lowest plant zones with more or less dense Salix thickets and scattered lichens such as Cladonia cenotea, C. fimbriata and Peltigera extenuata will presumably expand to higher levels on the mountains at Sisimiut, and the plant mosaics of the heaths and fell-fields occurring at greater altitudes will change in a warmer climatic scenario. Epiphytic lichens probably will be more common in the Salix thickets. This is in need of long term studies of the vertical distribution of lichens on the mountains (e.s. hansen, 1978). Many biotopes will probably dry up during continuing global warming. Under this second, more inland climatic scenario, a great part of the above-mentioned terricolous macrolichens presumably will be threatened and rare, unless they are able to disperse to more moist habitats. The steppeand desert-like areas in North East Greenland and continental areas in West Greenland, for example, the Kangerlussuaq area, already now demonstrate this clearly with fewer and often fragmented macrolichens (alstrup et al., 2000; e.s. hansen, 2000). In the same way, many terricolous microlichens such as Lepraria subalbicans, Massalongia carnosa and Psoroma tenue var. boreale are threatened and risk desiccation in a future scenario characterized by warm summers. With respect to the group of saxicolous macro-and microlichens belonging to the CO-category, the abundance of many species is almost the same in coastal and inland areas. This applies to fairly sturdy and common species such as Arctoparmelia centrifuga, A. incurva, Brodoa oro-arctica, Lecanora polytropa, Lecidea lapicida var. lapicida, L. lapicida var. pantherina, Lecidea tesselata, Melanelia hepatizon, Orphniospora moriopsis, Parmelia omphalodes, P. saxatilis, Pseudephebe minuscula, P. pubescens, Rhizocarpon geographicum, Umbilicaria hyperborea and U. proboscidea. Widely distributed, nitrophilous, CO-lichens such as Candelariella vitellina, Physcia caesia, P. dubia, Polycauliona candelaria and Rusavskia elegans probably will expand under warmer and drier climatic conditions. This also applies to widely distributed lichens growing on wood such as Amandinea punctata and Rinodina turfacea.
The COO-category represented in the Sisimiut area consists of 44 lichens. They occur most frequently in coastal areas and more rarely in inland, more or less continental areas. In the same way these species occur in smaller quantity in inland areas than in coastal areas. Generally, the lichens occurring in moist heaths, bogs and snow patches thrive rather well at present, but in a future scenario with a warmer and drier climate a part of these lichens will be threatened. This applies to species such as Alectoria sarmentosa, Arctocetraria andrejevii, Cladonia bellidiflora, C. crispata, C. ecmocyna, C. sulphurina, C. trassii, Lecidoma demissum, Nephroma arcticum, Pertusaria oculata, Protoparmelia pezizoides and Trapeliopsis granulosa. The saxicolous seashore lichens belonging to the COO-category, Acarospora molybdina, Amandinea cacuminum, Caloplaca alcarum, Candelariella arctica, Lecanora contractula, L. straminea, Physcia tenella var. marina and Verrucaria ceuthocarpa, all have their main distribution in the arctic region and are adapted to a cool climate (thomson, 1997; e.s. hansen, 1995a). Under warmer climatic conditions, these lichens will probably extend their distribution area northwards concurrently with melting of the ice along the coasts of North Greenland. There is a risk of reduction of the southernmost populations of the arctic sea shore lichens under future warmer climatic conditions. It is important to follow their development along the arctic coasts. The saxicolous lichens growing on iron-containing rocks, such as Amygdalaria panaeola, Miriquidica atrofulva, Porpidia flavicunda, P. melinodes and Tremolecia atrata, is another group of COO-lichens, which it is of great interest to monitor (e.s. hansen, 1999). These lichens have a distinct preference for moist rock faces more or less coated by limonite and are supposed to be threatened in a warm and dry climate.
Only eight species are recorded as CCO-lichens. Lobarina scrobiculata is restricted to south-facing rocks and large boulders in Salix thickets, where it occurs together with, for example, Nephroma parile. Lecanora argopholis and L. atromarginata also prefer rather dry rock habitats. Baeomyces placophyllus and Physconia muscigena are best developed in inland heaths. These species will probably expand their distribution area under warmer and dry climatic conditions. They both belong to a very characteristic community of soil crust, which is well-developed and rich in CCO-lichens in the Kangerlussuaq area situated west of Sisimiut close to the inland ice (e.s. hansen, 2001). The soil crust community is best developed on neutral to slightly basic soil, for example, loess. Under a warm and dry climatic scenario the soil crust lichens and other lichens with a more or less continental distribution will presumably expand to bare, nutritious soil in the Sisimiut area. Generally, the Greenland lichen diversity is, however, supposed to be reduced, if global warming continues with the present high and in the future possibly higher carbon dioxide contents in the atmosphere.