SOME VEGETATION TYPES AT HIGH ALTITUDES. 53 



The foregoing types of forest form a natural succession 

 which may be traced from Zernez along Val Cluoza and 

 Valletta to Piz Quater Vals. The types forming the succession 

 have undergone little or no modification, so that they give a 

 fair sample of the original forest flora of the district. This 

 natural sequence of forest is all the more interesting in that 

 it is practically a pure coniferous one. Of the broad-leaved 

 species which occur sporadically in it, birch {Betula pubescens) 

 ascends highest, in the intermediate zones rowan {Sorbiis 

 aucuparia) is to be found, and in the lowest forest zone, 

 aspen {Fopulus tremula) appears. A comparison of the above 

 with forest zones in Scotland ^ shows considerable variation. 

 In the first instance the individual species differ, while there 

 are also fewer types in Scotland. As regards altitudinal 

 distribution the Scottish forest zones have a more restricted 

 range, and do not form any definite succession such as occurs 

 in Val Cluoza and Valletta. 



The forest succession in the Alps- is completed by the 

 silver fir {Abies pecthiata) and beech {Fagus silvatica) associa- 

 tions, the former following the mixed coniferous associations as 

 a descent is made to lower altitudes. Such a succession shows 

 clearly that different conditions of locality demand different 

 species, and points to the importance of suiting the species 

 to the locality in artificial cultivation. 



Grazing Associations. 

 It is to be expected that where a natural succession of forest 

 meets the agricultural land of the valleys, it will undergo 

 modification. A very good example occurs in Valle di Livigno, 

 a continuation of the Spoltal into the north of Italy. Valle 

 di Livigno is a broad glaciated valley with a flat bottom, which 

 is worked as meadow land. The only crops raised are grass 

 and hay as fodder for cattle. The following plants constitute 

 the meadow land association : — Trisetum flavescens^ Agrostis 

 vulgaris, Phleum alpi/ium, Polygomon bistorta, Crepis grandiflora, 

 Campanula Sc/iei/chzeria, Rumex arifolius, Trifoliurn pratense, 

 T. alpinum, Euphrasia minima, Nardus stricta, Atithoxanthum 



1 See " Primitive Woodland and Plantation types in Scotland," G, P. 

 Gordon, Transactions of the Royal Scottish Arboricultural Society, vol. 

 xxiv., part ii., 1911, p. 174. 



- See Fremdldndliche Wald und Parkbdume Jar Europa, Prof. Ileinrich 

 Mayr. . 



