The average annual rainfall for Sweden increases, on the whole, from north to south, reaching a maximum towards the south west. Thus the average in the north of Norrland is 16.5 in., and in the south is 22.5 inches. At Boras, midway between the south end of Lake Vetter and the Kattegat, the average is 35 inches. The minimum at Karesuando is 12.3 inches. The period of maximum is generally the latter half of the summer, and the minimum in February and March. The proportion of total pre cipitation which falls as snow ranges from 36% in Lappland to 9% in Skane. Snow lies 47 days on an average on the plains of Skane, while in the north it lies from 14o to 190 days. The Swedish glaciers cover some 135 sq. miles. They occur in the north ern highlands about Kebnekaise, Sarjektjakko and Sulitalma. The most southerly is on the slopes of Helagsfjall in Lat. 62° 54' N.
The extensive range of latitude and altitude produces many local vegetation differences. Four main regions can be distinguished tending to grade into one another near their adjacent fringes. In descending order of altitude, and largely of latitude also, are: (r) alpine regions, (2) zone of birch woods, (3) conif erous forest region, (4) the beech wood patches. The alpine region occupies only the upper flanks of the spinal mountain range, at an altitude above 1,600 ft. in the north and above 3,000 ft. in the south. It is treeless, though shrub-like willows and birch exist together with numerous berry-bearing plants. These are intermingled with extensive tracts of heather. In the bleaker wind-swept spots reindeer "moss" occurs with an occasional arctic poppy or a saxifrage. The birch forests are much more extensive in the north and form patches of woodland 1 o to 20 m. wide; southwards the strip narrows to individual trees Rowans, aspens and wild cherries occur and there is consider able undergrowth. At the higher elevations the birch becomes stunted and the lighter woodland is marked by considerable growths of wild strawberry and raspberry. The coniferous forests are the most extensive and cover nearly all of the country north-east of Lake Vener. The important tree on the drier and higher ground is the Scots pine (Pinus sylvestris) but enormous numbers of spruce (Abies excelsa) are also found. The conifers extend from sea-level to 2,500 or 3,00o ft. and though the pine and spruce predominate yet there is a sprinkling of lowland birches, rowans and aspens, in the north, while large numbers of such deciduous trees as oaks, ash, lime, maple and elm are found in the south. These latter trees seldom extend beyond 1,600 f t.
altitude and the oak ceases about 61° N. (inland) and 63° N. (coastal). The undergrowth is usually slight but in the thinner soil areas the bilberry (spruce) and whortleberry (pine) flourish. Much of the coniferous forest has been depleted by forest fires and lumbering, particularly along the lower courses of the larger streams. The beech forests with occasional oak are re stricted to Skane, southern Oland and the shores of the Kattegat. They are tending to be reduced by extended land cultivation. The flowering plants are largely immigrants since the last glacial epoch and the number of species shows a decrease northwards.
The effects of the great latitudinal range of Sweden are also shown in the case of fauna. Only a few animals such as the hare, ermine and the weasel are common to the entire coun try, but the squirrel, fox and various shrews have a wide range over the lower lands. Formerly bounties were paid for the ex termination of the larger animals which have been greatly reduced in number. The bear is now protected. This and the wolf, the glutton or wolverine, and the lynx are becoming restricted to the more solitary depths of the northern forests. The wild reindeer, now protected, is rare, though large domesticated herds form practically the sole source of livelihood to the Lapps. The elk, also carefully preserved, haunts lonely forests over a considerable range ; the roe-deer is confined to the south. In the midland plains the common fox is still abundant and the badger exists in large numbers. The latter and the otter, together with the pine-marten of the coniferous forests, are hunted for their skins. The common porpoise, is the only whale occurring in the Baltic; it, and the common grey seal are held to be responsible for much damage to fisheries. Bird life is very abundant in summer; several types such as the teal, snipe, golden plover and wagtail are common to the whole country. The arctic fox and the lemming are moun tain animals: the former is normally confined to the highlands of the north, but it also joins in the chase when the lemmings make their non-periodical migrations to the lowlands during which their vast moving hordes are the prey of bird, wild and domesticated animals and man alike.