. The continental element in the flora of south Sweden. Plants. THE CONTINENTAL FLORA OF SOUTH SWEDEN 259 exactitude naturally involves j^reat difficulties. Values of a certain usability may be obtained by calculating the number of days during which the mean temperature exceeds o° Centigrade. On the basis of the mean-temperatures for pentades published by Hamberg (igo8) I have computed the values given in Table 4, which may be left to speak for itself. b. Atmospheric precipitations and Cloudiness. Precipitations exercise a great influence on the distribution of plant species, above all by thei
. The continental element in the flora of south Sweden. Plants. THE CONTINENTAL FLORA OF SOUTH SWEDEN 259 exactitude naturally involves j^reat difficulties. Values of a certain usability may be obtained by calculating the number of days during which the mean temperature exceeds o° Centigrade. On the basis of the mean-temperatures for pentades published by Hamberg (igo8) I have computed the values given in Table 4, which may be left to speak for itself. b. Atmospheric precipitations and Cloudiness. Precipitations exercise a great influence on the distribution of plant species, above all by their effect on the quality of soil, the heat of the soil and its physical and ehe- mical structure. When we try to find a rela- tion between the distribution of atmospheric precipitations and of species, the meteoro- logical data can give us a safer basis of discussion than in the matter of the distribution of temperature. Fig. 3 shows, according to Hamberg (1911), the distribution of rainfall in South Sweden during the sum- mer half-year (May—October). Among the general features the following might be speci- ally emphasized: The importance of topo- graphy to the distribution of rainfall is conspicuous in the considerable outward bulge to the east of the isohyetals over the South Swedish highland, over Tiveden and Kolmarden. The western slope of the South Swedish highland has the largest rainfall within this region, and the south-eastern coast regions — situated as they are in »rain shadow* — have the smallest amount. The large flattish districts, especially the Malar and Ostgota plain, show small amounts of rainfall. The consequence of the small coast rainfall, however, is, as far as plants are concerned, counterbalanced by a smaller saturation-deficit of the air, which de- presses the intensity of transpiration. The precipitations during the winter half year (November—April) are naturally. Fig. 3. The average rainfall in South .Sweden tluring the mer half-year (May—O
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplants, bookyear1922
