REPRINTED FROM THE SURTSEY PROGRESS REPORT VI, 1972

Studies on Colonization in Surtsey 1970

By HÖRÐUR KRISTINSSON

Surtsey was visited in the summer of 1970 for The other species, gelida, was found study of lichen colonization. Samples were col- here and there growing together with T. coarc tata. lected in different habitats, much in the same way The specimens were rather small and not fertile, but as in 1968 (Kristinsson 1970). Communities of some were sorediate. were detected around the crater Surtur II. Three species, coarctata (Sm. & Sow.) DISTRIBUTION IN ICELAND Choisy, Placopsis gelida (L.) Lind. and Stereo- Two of the lichen species here recorded for caulon vesuvianum Pers. were identi fied in the Surtsey, Stereocaulon vesuvianum and Placopsis samples brought back from this ex cursion. These gelida, are very common throughout Iceland. S. were the first lichens ever found on the island. A vesuvianum is especially abundant in postglacial second trip had been planned later in the summer to lava fields, frequently associated with Rhacomi- provide some more in formation on the distribution trium lanuginosum. P. gelida usually occurs in the and the structure of this community, but had to be lava fields too, but is also frequent on any kind of delayed until 1971. basalt rock or palagonite tuff. It is pro bably rare or lacking in some of the more con tinental valleys of Northern and Northeastern Iceland. But even there HABITATS it is frequent in the mountains, This agrees with its The lichens were found in two different worldwide dis tribution, which is considered rather places in the vicinity of Surtur II. Both oceanic. habitats were infl uenced by warm steam. For T. coarctata no records are found in the One of them was a level lava block north- literature from Iceland. Deichmann Brandt (1903) east of the crater, periodically kept moist mentioned Trapelia ornata (under the name by steam coming out of a crack. At this Lecanora coarctata var. ornata) from Viðvík, place only tiny pieces (single phyllo cladia) Northern Iceland, a species closely related to T. of a Stereocaulon were de tected by a lens. coarctata. This, howeve r, does not permit the A depressed, dark s pot in the center of the conclusion, that T. coarctata should be lack ing or phyllocladia indicates that they belong to even rare in Iceland, because the informa tion on Stereocaulon vesuvianum, which is one of crustose rock lichens in Iceland is very poor, and the major pioneer lichen species rapidly dates mainly from the last century. T. coarctata colonizing all new lava fields throughout prefers damp localities and pro bably a relatively Iceland . oceanic climate (Hertel 1969, 1970) and should The second habitat was much richer in lichen therefore be expected to occur along the southern vegetation, a north-facing steep slope of lava rock coast of Iceland. on the outside of the crater Surtur II. Here a community with an extension of several meters was ACKNOWLEDGEMENTS formed by only two lichen species and kept damp The excursion to Surtsey 1970 was sponsored by by warm steam. One of them, the Surtsey Research Society. I would like to was present in such quantities, as to turn the rocks express my thanks to Dr. H. Hertel, Berlin, for the pale yellowish brown, not always easily reco- identification of Trapelia coarctata. gnizable against the almost concolored mineral References: residues found here and there on the rocks around Deichmann Branth, I. S. 1903: Lichenes Islandiae. Bot. Tids skr. 25, the crater. T. coarctata is a crustose lichen, already 197-220. found with a great number of spore-producing Hertel, H. 1969: Die Flechtengattung Trapelia Choisy. Herzogia 1, apothecia in Surtsey. It ap peared to be closely 111-130. associated with water tracks on the rock surface, as Hertel, H. 1970: Trapeliaceae - eine neue Flechtenfamilie. if it were distributed mainly by rainwater from the Dtsch. Bot. Ges. Neue Folge Nr. 4, 171-185. Kristinsson, H. 1970: Report on Lichenological Work on Surtsey top to the base of the crater. and in Iceland. Surtsey Res. Progr. Rep. 5, 52.