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Woods on the Isle of JungfrunBy IVAR OTTOSSONThe Isle of Jungfrun is situated in the northernpart of Kalmar sund, south-eastern Sweden, 20 kmfrom the mainland and 9 km from (Hand. Theisland is small, 1060 m long and 840 m wide, andcomprises an area of 0.66 km 2 • It consists of graniteand has a very characteristic cupola form whichrises 86.5 m above sea level. The island is uninhabitedand has been a National Park since 1926(Bla Jungfruns nationalpark).On his journey to Oland and Gotland in 1741LINNJEUS also visited Jungfrun and gave the firstscientific description of the island (LINNJEUS 1745,pp. 128-132). Not until the beginning of this centurywas its flora studied again (J. ERIKSON 1904,1905, 1915). During the last five decades Du RIETZhas devoted much of his time to studies of the vegetationof the island (e.g. 1915, 1921 b, 1925a, 1934,1961a; Du RIETZ & CuitRY-LINDAHL 1950). He hasespecially investigated the lichens.The topography of Jungfrun shows clearly theeffect of the inland ice. The northern half is mainlyformed by rocky ground and ravines. In the middleof the island there is a steep slope and in thesouthern half the ground is covered with an enormousnumber of boulders in general some dm to afew m in diameter. Some bare granite areas alsooccur in this part.The contrast is striking between the woods ofdeciduous trees on the boulderlands, the woods ofconifers on the rocky slopes, ·and the birchwood onthe top-plateau. The scarcity of soil in most placesand the strong exposure to winds have to a verylarge extent affected the trees which generally arerather low and have poorly developed crowns.In the dense almost virgin woods of deciduoustrees, which cover the boulderlands, the oaks arevery abundant. Quercus robur is the predominantspecies, but Q. petraea is also frequent in someplaces, and besides the hybrid between these twospecies occurs. The largest oaks have a trunk diameterof about one meter and the tallest are about15 meters. Many oaks do not reach more than about10-30 cm in diameter. Mter that the stems begint? die back but often sprout from the base. Nearthe shore on the south part of the island the oaks(Q. robur), due to the wind, form dense shrubs .about1-2 m high. Some old specimens grow with thetrunk decumbent on the stony ground. Mixed withthe oaks, Acer platanoides and Tilia cordata arerather common, while Fraxinus excelsior has a morelimited distribution below the steep slope in themiddle of the island, where about 25 specimensgrow among big boulders. The trees of Tilia haveoften several trunks and are more or less procumbent.As is common in this species, they generallyreproduce vegetatively. In some places Populustremula forms stands. The trees of this species donot reach more than at most 30-40 cm in diameterbefore they begin to die. Sorbus aucuparia is spreadin the whole oakwood. and often grows as smalltrees with multiple stems. This species also occursin other parts of the island. S. intermedia is ratherrare, and only a few specimens are found of S. rupicola,Malus silvestris, Corylus avellana, Hedera helix,and Taxus baccata. In one place rather many treeformedspecimens of J uniperus communis grow. Sometrees of Betula. pubescens also occur in the oakwood,but this species is mainly found in depressionson the rocky grounds. From the top-plateau,here about 70 m above sea level, the deciduouswoods on the southern part of J ungfrun look likea green carpet in summer, but in the beginning ofActa Phytogeogr. Suec. 50