Page:Encyclopædia Britannica, Ninth Edition, v. 21.djvu/92

Rh 76 11 U S S I A [FLORA. country are highways for sledges. The Volga remains frozen for a period varying^ between 150 days in the north and 90 days at Astrakhan, the Don for 100 to 110 days, and the Dnieper for 83 to 122 days. On the Diiua ice prevents navigation for 125 days, and even the Vistula at Warsaw remains frozen for 77 days. The lowest temperatures are experienced in January, in which month the average is as low as 20 to 5 Fahr. throughout Russia ; in the west only does it rise above 22. On the whole, February and March continue to be cold, and their average temperatures rise above zero only on the Black Sea coast. Even at Kieff and Lugaft the average of March is below 30, while in central Russia it is 25 to 22, and as low as 20 and 16 at Samara and Orenburg. Isotherms. All Russia is comprised between the isotherms of 32 and 54. On the whole, they are more remote from one another than even on the plains of North America, those of 46 to 32 being distributed over 20 degrees of latitude. They arc, on the whole, inclined towards the south in eastern Russia ; thus the isotherm of 89 runs from St Petersburg to Orenburg, and that of 35 from Tornei to Uralsk. The inflexion is still greater for the winter isotherms. Closely following one another, they run almost north and south ; thus Odessa and Kb'nigsberg are situated on the same winter isotherm of 28 ; so also" St Petersburg, Orel, and the mouth of the Ural river (about 20) ; Mezen and Ufa (9). The summer isotherms cross the above nearly at right angles, so that Kiel!' and Ufa, Warsaw and Tobolsk, Riga and the upper Kama have the same average summer temperatures of 64, 62J, and 61. Winds, Moisture, Rainfall. The investigation of the cyclones and anticyclones in Russia cannot as yet be regarded as completed. It appears, however, that in January the cyclones mostly cross north-west Russia (north of 55 and west of 40 E. long.), following directions which vary between north-east and south-east. In July they are displaced towards the north, and cross the Gulf of Bothnia, while another series of cyclones crosses middle Russia, between 50 and 55 N. lat. The laws of the anticyclones are not yet estab- lished. The winds closely depend on the routes followed by both. Generally, however, it may be said that alike in January and in July west and south-west winds prevail in western Russia, while- eastern ones are most common in south-eastern Russia ; northern winds are most common on the Black Sea coast. The strength of the wind is greater, on the whole, than in the continental parts of western Europe, and it attains its maximum in winter. Terrible gales blow from October to March, especially on the southern steppes and on the tundras. Gales with snow (burans, myatclx), lasting from two to three days, or northerly gales without snow, are especially dangerous to man and beast. The average relative moisture reaches 80 to 85 per cent, in the north, and only 70 to 81 per cent, in southern and eastern Russia. In the steppes it is only 60 per cent, during summer, and still less (57) at Astrakhan. The average amount of cloud reaches 73 to 75 per cent, on the White Sea and in Lithuania, 68 to 64 in central Russia, and only 59 to 53 in the south and south-east The amount of rainfall is shown in the subjoined table (III.): * North Latitude. Height above Sea in Feet. Average Temperatures. Average Full Range of Ther- mometer. First Frosts. Last Frosts. Number of Days per Year. Average Rainfall in Inches. Year. January. July. Minimum. Maximum. Bright. Cloudy. Year. November to March. Archangel Petrozavodsk. . Helsingfors St Petersburg.. Bogoslovsk Dorpat 64 34 61 47 60 10 59 57 59 45 56 22 57 46 56 49 55 47 55 45 54 41 52 14 51 45 51 44 50 27 48 42 48 27 46 29 46 21 44 37 42 9 41 42 30 160 40 20 630? 220 360 890 260 520 390 360 360 690 590 100 200 270 -70 130

1440 327 36-4 39-0 38-4 29-4 39-5 37-3 32-8 37-2 39-0 43-8 44-9 37-9 41-0 44-2 44-4 45-6 49-0 49-0 537 58 -4 54-5 7-6 11-8 19-5 15-0 -3'8 17-6 9-4 2-2 7-0 12-1 22-1 23-8 47 137 21-0 13-4 17-0 24-8 19-2 35-2 39-0 33-0 60-6 62-1 61-5 64-0 62-5 63-1 66'3 63-5 67-3 60-0 65-6 65-4 70-9 67-2 66-3 74-6 73-0 72-3 77-9 73-8 73-3 757 -33 -24 -17 -20 -47 -14 -27 -33 -25 -22 -10 - 2 -28 -19 -13 -18 - 3 -14 + 10 4-25 + 10 84 86 80 83 87 85 88 87 89 88 85 86 96 91 89 95 89 97 93 93 96 147 135 112 135 150 124 140 142 129 144 110 123 147 139 122 146 108 135 105 88 100 26 Sept. is'b'ct. 20 Sept. 7 Oct. 21 'bet. 1 Oct. 7 Oct. 17 Oct. 18 Oct. 19 Oct. 11 Oct. 10 Nov. 27 Oct. 12 Jan. 18 Nov. 20 May 23 199 16-2 4-3 8 May 14 May 3 May 14 May 27 April 26 April 27 April 7 April 17 April 35 43 40 40 35 23 40 34 148 94 145 138 142 175 154 132 19-6 18'3 15-8 24-9 19-4 14-1 18-0 23-0 22-8 17-1 19-9 20-1 7-3 5-3 3-1 7-3 5'2 1-6 5'4 7-3 6-7 5-8 5-6 6-0 Kostroma Ekaterinburg. . Kazafi Moscow Vilna Warsaw Orenburg Kursk Kieff Tsaritsyn Lugaft. . . 11 April 31 Mar. 5 April 1 Mar. 15 Mar. 64 67 69 124 112 114 14-3 15-6 5-7 15-4 64-9 19-3 4'3 5-4 1-5 7'2 23-4 4-3 Odessa Astrakhan Sebastopol Poti Tiflis The flora of Russia, which represents an intermediate link between those of Germany and Siberia, is strikingly uniform over a very large area. Though not poor at any given place, it appears BO if the space occupied by Russia bo taken into account, only 3300 species of phanerogams and ferns being known. Four great regions may be distinguished : the Arctic, the Forest, the Steppe, and the Circum-Meditcrranean. The Arctic Region comprises the tundras of the Arctic littoral beyond the northern limit of forests, which last closely follows the coast-line, with bends towards the north in the river valleys (70 N. lat. in Finland, on the Arctic Circle about Archangel, 68 N. lat. on the Urals, 71 on West Siberia). The shortness of the summer, the deficiency of drainage, and the thickness of the layer of soil which is frozen through in winter are the elements which go to the making of the characteristic features of the tundras. Their flora is far nearer those of northern Siberia and North America than that of central Europe. Mosses and lichens cover them, as also the birch, the dwarf willow, and a variety of shrubs ; but where the soil is drier, and humus has been able to accumulate, a variety of herbaceous flowering plants, some of which are familiar also in western Euro{>e, make their appearance. Only from 275 to 280 phanerogams are found within this region. The Forest Region of the Russian botanists occupies the greater part of the country, from the Arctic tundras to the Steppes, and it maintains over this immense surface a remarkable uniformity of character. M. Beketoff subdivides it into two portions the forest region proper, and the "Ante-Steppe" (predslcpie). The northern limit of the Ante-Steppe would be represented by a line drawn from the South Pruth through Zhitomir, Kursk, TamboflT, and Stavropol-on- Volga to the sources of the Ural. But the forest region proper itself presents a certain variety of aspect in its northern and southern parts, and must in turn be again sub- divided into two parts the coniferous region and that of the oak forests, these being separated bv a line drawn through Pskoff, Kostroma, Kazan, and Ufa. Of course, the oak occurs farther north than this, and conifer forests extend farther south, advancing even to the border-region of the Steppes ; but this line must still be considered as important. To the north of it AVC have dense forests, covering very large areas, and interrupted oftcner by marshes than by meadows or cultivated fields. Vast and impene- trable forests, unpassable marshes and thickets, frequent lakes, swampy meadows, with cleared and dry spaces here and there occu- pied by villages, are the leading features of the region. Fishing and. hunting are the important sources of livelihood. The characteristics of what may be described as the oak region, which comprises all central Russia, are totally different. The surface is undulatory ; marshy meadow lands no longer exist on the flat watersheds, and only a few shelter themselves in the much deeper and broader river valleys. Forests are still numerous where not destroyed by man, but their character has changed. Conifers are rare, and the Scotch pine, which covers the sandy plains, has taken the place of the Abies ; birch, oak, and other deciduous trees . Memoir* of the Central Physical Observatory; Repertorium /Or Mtteorologie and Meteorological Sbornit, published by the same body ; Ves- tclovsky, Climate of Russia (Russian) ; Wild, Temperatur-Verhaltnisse des Ruts. R., 1881 ; Woycikoff, The Climates of the Olobe, 1884 (Knss.), containing the best general information about the climate of Russia; Klossovsky, Thunderstorms in Russia, 1885 (Russ.) ; Memoirs and Jzrettia of the Geographical Society ; many papers in the Memoirs and Bulletin of the Academy of Sciences, in the Trudy of the Scientific Societies at the Universities, in the Moscow Bulletin, &c. ; Wnyfikfiff and Leist in Appendix to Russian translation of Elise Reclus's Geogr. I'nir.; Woyeikoff, in Russkiy Kalcndar and in Man. Russ. Geogr. Soc., 1885.