12] VEGETATIONAL TYPES OF TEMPERATE LANDS 343 



and eastern Europe are sometimes described as a further type, and 

 the drier, park-like woodland on limestone hills of central Europe 

 as yet another. Deciduous ' parklands ' also occur in the northern 

 prairies of North America, and though dominated by groups of Aspen 

 and other Poplars {Popuhis spp.) in a manner reminiscent of serai 

 stages, appear in Alberta and Saskatchewan to constitute ' a forest 

 type in its own right ' (H.M. Raup in Htt.). Also characteristic, if 

 limited, are the deciduous forests of the Pacific coastal regions of 

 the northern United States, and the very luxuriant ones of the 

 western Caucasus where various kinds of Oaks, Beeches, Maples, 

 Horse-chestnuts {Aescuhis spp.). Cherries, and Cherry-laurel {Pruniis 

 laurocerasus) are ccmmonly mixed with Conifers and a wealth of 

 shrubs and climbers. On the other hand, the open Birch forests of 

 northernmost Scandinavia, etc., in spite of their broad-leafed 

 deciduous nature, belong to the next group. 



Northern Coniferous Forests 



These are also known as ' boreal forests ', ' subarctic forests ', or 

 ' taiga ', although it seems preferable to reserve the last term for 

 their open, park-like northern tracts {see pp. 346-8). 



The main dominants of these forests, instead of having broad 

 leaves which they shed in winter, typically solve the problem of 

 perennation through that unfavourable period by having narrow or 

 small, needle-like or sometimes scale-like leaves. Besides their size 

 and shape, these leaves usually have other xeromorphic characteristics 

 that help to reduce transpiration to very modest rates. Consequently 

 they can be retained in winter, most such trees being evergreen and 

 having the advantages over deciduous types of being able to photo- 

 synthesize whenever conditions allow, and meanwhile of saving the 

 wastage involved in complete annual leaf- fall. However, it is as 

 though at their northernmost extremity such trees were unable to 

 support winter transpiration, for the Larches {Larix spp.) among 

 these needle-leafed types are regularly deciduous, losing their leaves 

 every autumn, and in places persisting farther north than the ever- 

 green trees. Thus it is the Dahurian Larch {Larix dahurica) that 

 alone forms the farthest north ' forest ' in the world (at about 

 72° 50' N. and 105° E. in Siberia). 



Although the main dominants of these hardiest of forests are 

 needle-leafed Spruces, Pines, Firs, and other Conifers, they often 

 have associated broad-leafed deciduous Birches, Poplars, and the 



