5© TRANSACTIONS OF ROVAL SCOTTISH ARBORICULTURAL SOCIKTY. 



association gives place to a forest of erect varieties of mountain 

 pine. Here again the difference is an increase in the depth of 

 soil, combined with greater stability. 



PiNUS MONTANA (eRECT FORM) ASSOCIATION. 



Following immediately on the last association, and forming 

 with it the upper forest zone of the whole district, is the mountain 

 pine (erect form) association. In general appearance it differs 

 greatly from the last association, since it forms high-forest with 

 an undergrowth. The individual trees have a height of over 

 30 feet, and, although the density of stocking is low, the quality 

 of the stems is fairly good. A slight admixture of rowan {Sorbin 

 ■aucuparid) is obtained in these forests. Species of juniper 

 {Jimiperiis communis and J. nana) for the most part form the 

 undergrowth, while Erica carnea, Calluna vulgaris, Vaccinium 

 myrtillus, V. vitis idcea, Dryas octopetala, Globularia cordifolia. 

 Daphne fuezereum, D. striata, Pirola secunda, Arctostaphylos iiva 

 iirsi, Rhododendron hirsutum, Luzula silvatica, Poa alpina, Oxalis 

 acetosella complete the association, which is a practically closed 

 one. This formation appears to be specially suited to the 

 zone it occupies, constituting as it does the intermediate 

 stage between the dwarf forest above and the high-forests 

 of larch, Cembran pine, Scots pine and spruce at lower levels. 



As regards general distribution the upper forest zone extends 

 over large areas. Its outer margin assumes a very ragged 

 appearance, particularly in the small valleys near the head of 

 Val Cluoza, where the cold winds from the mountains limit its 

 distribution in exposed places. The various forms of Finns 

 montana occupying this zone have been fully described by 

 Dr S. E. Brunies.i 



Larch {Larix europcBa) and Cembran pine {Pinus Cembra) 

 Association. 



At a lower level the zone of larch and Cembran pine is 

 entered upon. This is the highest belt of mixed coniferous 

 forest in the district. It may, in parts, consist of practically 

 pure larch forest, while elsewhere Pinus Cembra may 

 predominate. Towards the upper limit of the formation, the 

 canopy is even more open than that of the mountain pine 



^ Die Flora des Ofengebietes, Separatabdruck aus dem Jahresbericht der 

 Naturforschenden Gesellschaft. Graubiindens : Band xlviii, 1905-06, pp. 

 205-211. 



