342 . , R I K A R D S T E R N E R 



parts of southeastern Sweden. They should be able to throw a certain amount 

 of light on the composition of that type of forest. 



One of the most characteristic plant-communities of the South Swedish high- 

 land is the meadoius or forest-meadows rich m Arnica niontayia. In this respect 

 the South Swedish highland suggests comparison with the mountain tracts of 

 Central Europe that are poor in lime and rich in precipitation (see, for instance, 

 Drude 1902, pp. 137, 140, 217, 241). These Arnica-communities are common 

 in the western parts of the highlands. Further east they appear less abundantly, 

 and they are extremely rare on the coast along the Straits of Kalmar. 



Their flora, which is poor in species, consists, as a rule, of species that are 

 ubiquitous m the forest tracts of Middle Europe, or of West European species; 

 but in the east of Smaland they may sometimes be richer in species, and in such 

 cases may contain one or other continental species, of which examples are pro- 

 vided in the analyses 9 and 10, Table 5, Appendix II. 



The Distribution of the species. 



hrom what has already been said it will be seen that the continental species 

 that are to be treated here are extremely dependent on the topography in regard 

 to their natural possibilities of occurrence. The natural region of distribution of 

 the species ought to be located in districts with broken terrain where slopes and 

 rocky escarpments facing south and shore belts are occupied by more or less 

 thin forest associations. Thus it is the requirements of the plants for light which 

 should chiefly determine their natural distribution. 



Another ecological character that appears in this way seems to be high re- 

 quirements with regard to the nature of the soil. The species appear in their 

 entire distribution area only on spots with more or less mould-like humus and 

 soil rich in electrolites. Thus their natural distribution would to some extent be 

 detern)ined by the precipitation conditions and the nutritive (lime) content of the 

 weathered material in the soil. 



In contrast to what is the case witli the steppe species, the actual distribution 

 of the species in our days is also chiefly determined by these factors. The 

 bringing of new areas into existence by means of cultivation is not of such 

 salient influence with regard to them as with regard to the steppe species. 



Species closely akin to the steppe species. P'or a number of species certain charac- 

 teristics appear again which are found in the distribution of the steppe species. 

 Naturally these features show closer resemblance the more a species approa- 

 ches the steppe species in its mode of occurrence. A transition between the 

 two groups of species is formed by the previously treated Crepis praemorsa 

 and Ra7mnculus polyanthemos, which are marked by an abundant distribution in 



