fulltext - DiVA

Lost and Living Lakes In the Upper Ume ValleyBy GUNNAR WASSENA traveller on his way from the Bothnian coastto the mountains of Lappland, althqugh roadboundto-day, has still to take his route along oneof the many waterways used since the Neolithicage by primitive hunters and fishermen, reindeernomads, settlers, priests, early botanists, touristsand log-floaters. These parallel and little-branchingwatercourses cut the forested land, the Swedishcounterpart of the Taiga, into large strips elongatedin the NW -SE direction. We select the U meriver (cf. RunBERG & BYLUND 1959) for our journeythat then will follow "the Blue Road" of touristicparlance, nowadays stretching along a series oflongish reservoirs, each of which obeys the WaterFlow Control Board's officers in its reversed annualrhythm of water-level fluctuation, and has at itsdownstream end a more or less imposing dam andusually a hydroelectric power plant.Had we selected the parallel left-hand tributary,the almost equivalent Vindel river, we would havetravelled along a still-but not for long we fear-free-living river. It has an almost incredibly largebut quite natural fluctuation in flow and level.The peak flow at the end of the thaw period usuallyin early June may be over a hundred times as largeas the minimum flow in late winter. The amplitudein level in natural rivers is accordingly often of themagnitude of four or five metres and locally more.The present author has had the opportunity tostudy the upper course of the Ume river before andduring its succumbing to the hydroelectric enterprise,a yet not fully completed process. The studyhas been concentrated to the shore vegetation ofthe large lakes.The river valleys are of Pre-glacial origin butdeepened through the work of the inland ice. Theyare crossed at intervals by resistant thresholdsof bedrock or natural dams consisting of deposits ofglacial drift, and thus most of the extremely elongatedlakes or lake chains of Lappland were formed(HOGBOM 1906). Situated between the water divideand the last remnants of the inland ice, they arein fact only bottom furrows left from the enormous,short-lived but sediment-rich ice-dammed lakes ofthe melting period. It is these sediments that onceattracted agriculture to some of the remote mountainvalleys, settlements that to-day are againabandoned to a regrettable extent, only partly dueto the inundation of fertile land brought about inlocal areas by the reservoir development. In theUme river valley this is the case on what is now thebottom of Lake Gardiken, to be described below.But on our way upstream we have to pass otherreservoir lakes, including the large Lake Storuman,about sixty km in length. The geological boundaryknown as the Caledonian border (discussed in"Lappland east of the mountains") is crossed here,and further upstream we are within the schistdominatedarea of the Scandes.LAKE GARDIKEN.-Originally a chain of sixseparate lakes, the present Gardiken Reservoir is aresult of their coalescence. The woods around LakeGardiken, at 377 m before it was raised 18 m by thedamming, are typical of the pre-alpine subregionof the conifer forest region. Du RIETZ (1942b)characterized these woods as having "an upwardincreasing under-storey of birch (Betula pubescenssens. lat.) below an over-sto.rey of pine (Pin ussilvestris) . or spruce (Picea abies), the trees of whichgrow with decreasing density at higher altitudes.On further ascent, this mountain conifer forestActa Phytogeogr. Suec. 50