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PRE SL I A 1960 32 : 225-253 Emil Had a c: The History of the Flora of Spitsbergen and Bear Island and the Age of some Arctic Plant Species Preface Since DARWIN's eminent work, the problem of the Origin of Species has not lost its attraction and interest. In the last years the discussion on this problem has revived very vigorously. As we are not able to give a definition of the Species acceptable for the majority of scientists, as well as an universal method for distinguishing a species from a variety or a genus, it is difficult to find a solid platform for the solution of this question. In this situation we must try to find at least some material to elucidate some ways which led to the origin of one or another wellknown species and hope, that our little contribution will throw some light on the ge­ neral problem. There are several methods, which can help us: the physiology, the ecology, the cytotaxonomy, etc. One of them, used already by Darwin him self, is the plant geography. During the last twenty years, the present author has studied the flora and vegetation of the European Arctic and Subarctic regions, and the mountain flora of Central Europe. Some of his studies have been already published; in this treatise he will try to summarize some results of his work. The first explorers of the Arctic thought that its flora came to this t erritory from the south in the postglacial. Another explanation of its occurrence was in this time unthinkable. The facts, accumulated by several authors, e. g. by BLYT'l', A. HANSEN, NoRDHAGEN, LYNGE, TH. SORENSEN, EILIF DAHL, A. and D. LovE, FERNALD, Huvr:EN, ToLMACEV, TrcHOMIROV etc., have shown, that at least some of the artic species survived the glaciation or glaciations on spot. If we now compare the recent distribution of arctic species with the extent of the ice and icefree land and with probable land connections during the Ice Age, we shall be able to find out their ways of migration and in some cases, may be, their approximate age. The Or i gin of the Flora of Bear I s land We shall begin with the Bear Island, because it is very small and relatively isolated, and therefore it will be ralatively easy to say something on the origin and age of its flora. Some years ago (cf. HADAC 194lb), I published a study on the origin of the flora of thio island, but it was written in the Norwegian language in a journal for the popularisation of science, and therefore little known outside of Scandi­ navia. I shall therefore recapitulate here the results of my study. 225 Bear Island (Bjornoya) is situated at 74°20'- 31' N. Lat. and 18°46'- 19°17' E. Long., about 400 km to the North of Scandinavia, 230 km to the South of Spits bergen, and still longer from N ovaya Zemlya and Greenland. Its rocks are of dolomite, limestone and sandstone. The climate of Bear I sland is relatively rough and windy . The year's mean t emperature js - 3,8° C ( + 4,2° C in July, - 11 ,2° C in February). Let us see the relations of the Flora of Bear I sland to the neighbouring lands. In a list of vascular plants, published by 0. H ANSSEN and JENS HOLMBOE , are 53 of 55 species in common with Spitsbergen, but several species are wantirig in Scandinavia, i. e. Alopecurus alpinus, Cerastium R egelii, Dupontia Fisheri, Draba oblongata and Cochlearia groenlandica. The only two species of Bear Island, common with Scandinavia and lacking in Spitsbergen, are Hippuris· vulgaris and Rhododendron lapponicum. Hippuris vulgaris has its northern limit in Greenland at 76°30'- 76°46' N. Lat. Its absence from Spitsbergen may be caused by climatic conditions. It spreads mostly by means of birds and may be a relatively recent immigrant to the island. Rhododendron lapponicum has in Scandinavia a bicentric, continental distri­ bution and has, as supposed by NoRDHAGEN (1933), survived the last glaciation in Scandinavia. Its total distribution is shown on map 1. Rhododendron. lapponicum belongs to the "amphiatlantic" element. Its presence on Bear· Island, with oceanic actual climate, suggests its relic character. The list of mosses of Bear I sland was published more than 80 years ago by BERGGREN. Most of them have a wide distribution and were found in Spits­ bergen and in Scandinavia as well. But two of them are wanting in Scandinavia .. It is Orthotrichum Breutelii (0. Pylaisei), living in Spits bergen and Greenland, and Hypnum ( Drepanocladus) brevifol-ium LINDB., known i Spitsbergen,. Greenland and Alaska. The lichens were studied by the best student of arctic lichens, Bernt LYNGE. From 185 species of lichens 6 are endemic and some have a very interesting distribution: L ecanora heteroplaca ZAHLBR. was found outside of Bear Island in Novaya Zemlya only, L ecanora Nordenslcjoldii VAIN. was found on the East Siberian coast at Pitlekai. only, and the same known distribution has Lecanora torrida VAIN. All these facts indicate that the flora of Bear Island has a relatively high age .. It is not probable that it came to the island after the last Ice age, except some few recent immigrants. The migration of plants in the Arctic is relatively slow and the migration to such long distances is very rare. Plants in the Arctic mi­ grate, as it seems, not as single individuals, but with their plant communit­ ies, step by step. The migration of such plants, as Cardamine pratensis ssp. angustifolia , Deschampsia alpina and Saxifraga cernua on long distances is improbable. They produce no seeds and their bulbils or leaflets are not likely to be transported more than some few kilometers. The geologists deny the possibility of a land connection of Bear Island with Spitsbergen, Scandinavia or Novaya Zemlya after the last Ice age. But if such plants came during or befqre the last glaciation to the island, we must find out some possibility of their persistance in some refuges. The study of HORN and ORVIN ( 1928) shows that during the last glaciation Bear Island was glaciated partially only. There were several places in the. 226 . outhern as w ll as in th northern part of the i land, which wer icefr e at least during the last glaciation (se fig. 1.). If the flora of thi island has per isted on spot through h last Jc ag , w should find the majority of pecics, and first of all the rare and endemi Rpecie in t hese refuges. Let us see, if this supposition is right: the mo. t rare sp cies of va cular flora is Rhododendron lapponiwm: it grows in a refnge, not uti;;ide it . On the other side, Hippuris, supposed to be a r cent immigrant, wa found n t he place, which was covered by ice during the Ice age. Orthotrichum Breutelii as well as Hypnum brevifolium were found in refuges. In all D2 % of all lichen species were found in refuges and more , . .... ..... _ than 50% only th re. All five endemic ) lichen species were found in refuges and :... ..... .. _.r• .. .. ..··· not outside. ,,······· ·~ It is evident, that the theory of the ;, T ·~ - survival of the florn of Bear Island ~f ~,,, - - ... ) during the last Ice age is well founded. c.;·~ .. y I ' _.\, There are geological indices of a land C ff ...... connection between Spitsbergen and { /// I ~ / /' Bear Island during the last interglacial. I , I We can thus suppose that the present v_\ flora of Bear Island came from Spits­ fi' I bergen during the last interglacial or N <... ..... , ~\\ '_I ~ \ before and has endured on the island ·1 ~ ( till now. L .... "7 I \ \ \ ·, •.. , \ J I J "It As there are not known any endemic i \ I I - 1' species of vascular plants from Bear \'~ ' I /, Island, we can suppose that during the 1 last glaciation the vascular speci s of Bear Island have not specifically chang­ 0 , l 3 4 Jim\ . ed. It is of course not impossible that an accurate study will show some dif­ ferences, but they need not be great, Fig. 1. Bear I sland during the last Ice age b ecause prof . H OL rnoE was a keen (After HOlrn and Onvrn). observer and it is not probable that. he had overlooked greater differences. The History of the Flora of Spit s bergen If the persistance of the flora on the small Bear Island is probable, more probable it is in Spitsbergen itself. Spitsbergen is a large archipelago, where several refuges, not glaciated during at least the last le age, are probable. Prof. LYNGE had e.g. suggested several refuges on the northern coast of Vestspitsbergen, but I think there were more of them in the interior of Vestspitsbergen, e. g. in Icefjord. It is not necessary to discuss further this aspect of the problem. In short we can state that the flora of Spitsb ergen as well as the flora of the whole Arctic is very old and has persisted on spot over several Ice ages. Now, let us analyse the composition of the vascular flora of Spitsbergen, to see if this supposition is right. 227 Spitsbergian vascular plants can be arranged in several groups with similar total distribution; we can presume that plants with similar distribution had similar history. 1. Circumpolar alpine -arctic group I (23 species, i. e. 15, 9% of the total flora) Lycopodium selago L . var. appressum (DEsv.) SIMMONS Equisetum variegatum ALL. ex SCHLEICH. 0?1stopteris Dickieana SIM. W oodsia glabella R . BR. Trisetum spicatum (L.) RICHT. (see map 2.) Eriophorum Scheuchzeri HOPPE Oarex bipartita ALL.

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