Chapter V — 77 — Types of Areas 



siderable measure (e.g., western Transcaucasia, as compared with other 

 parts of the Caucasus adjacent thereto). 



In many cases relic species do not extend beyond their limited 

 habitats, since outside the boundaries they do not find favorable condi- 

 tions for growth. For example, the relic species, Wulfenia carinihiaca, 

 growing in isolated locahties in the Carinthian Alps and on the Balkan 

 Peninsula, does not extend beyond these localities. However, within 

 the latter it is represented by millions of individuals, and it can by no 

 means be considered a plant that is becoming extinct. It has been 

 estabhshed that the confinement of this species to limited areas is due 

 to its need of a humid climate {see Gilli, 1934, and literature cited by 

 him). 



Lastly, a relic species, which has inhabited a certain region un- 

 interruptedly for a prolonged period, may have contracted and later 

 again expanded its area, depending on climatic changes during geo- 

 logical ages. Thus, a Tertiary relic, inhabiting a certain territory from 

 the Tertiary period to the present day, may have curtailed and again 

 expanded its area corresponding to the great changes in climate — from 

 Tertiary to glacial, from glacial to inter- and post-glacial — provided, of 

 course, that this territory was located in that part of the globe where 

 these changes affected habitat conditions. 



The isolation of the stations of a species and the resultant discon- 

 tinuity of its area are often regarded as definitely distinguishing the 

 species as a rehc. In many cases this holds true, but it is not an in- 

 variable rule, as a relic species may not have a discontinuous area and 

 not every discontinuous area is relic, since the existence of isolated 

 portions of an area may be due to biological and not historical causes. 



A relic species may have an extensive area of distribution, embrac- 

 ing several natural regions of vegetation, or its area may be restricted 

 to some one region, in which case the species may be regarded as an 

 endemic rehc. In case a species occupies an area relic throughout its 

 entire extent, it may be called an absolute relic; if, however, only an 

 isolated part of the area of a species is relic, the species is known as a 

 local relic. 



Not only separate species (single relics) or groups of species (relic 

 groups or colonies) may be relic, but also entire floras. All the phyto- 

 coenoses composing the vegetation of a given region may be relic; on 

 the other hand, there are relic phytocoenoses (associations, formations) 

 belonging to floras that are not relic. Consequently, it is necessary to 

 distinguish between relic floras (Refugialfloren or Primarfloren — 

 SCHWARZ, 1938), most of the species composing which are relic, and 

 floras destroyed as a result of climatic changes and restored due to the 

 mass migration of species from surrounding floras — migration floras 

 (Invasionsfloren — Schwarz, 1938). 



A center of concentration of relic species is known as a relic center, 

 which in some cases may coincide with the ancient center of develop- 

 ment of the flora to which the given species belong. 



If relic species find it possible to achieve a secondary distribution 

 by the gradual occupation of habitats ecologically suited to them, such 

 species may be called migrant relics (Wanderrelikte — Schroter, 1934). 

 In such case, the more recently adopted habitats should be regarded, 



