562 SCIENCE PROGRESS 



Himalaya. In this region most of the area below an altitude 

 of 8,000 ft. is cultivated provided the slope is not too great. 

 Most of the uncultivated areas present a gradient of about 

 35°, and the climatic conditions, especially rainfall, are 

 apparently the predominant factors in determining the char- 

 acter of the vegetation. Five climax formations are recognised : 



I. The Caragana-Lonicera- Artemisia Formation. This is 

 found in the region with an average precipitation of under 

 ten inches, most of which falls as snow during the resting 

 season. Trees, grasses, and shallow-rooted plants are absent 

 and the deciduous vegetation is usually very xerophytic and 

 characterised by the presence of Artemisia mariiima, A. sacro- 

 rum, Caragana Gerardiana, C. pygmcea, and Lonicera spp. 

 Where there is a good supply of subsoil water, however, this 

 arid region produces a vegetation dominated by Myricaria 

 germanica, Salix hastata and S. scleropJiylla. 



II. The Betula-Rhododendron Formation, which occurs 

 between altitudes of 9,000 and 13,500 ft., where the precipi- 

 tation is from ten to eighty inches per annum, of which 

 from one-quarter to three-quarters falls during the period of 

 vegetative activity. The conditions are appreciably more 

 humid than in the arid zone, and the vegetation is either 

 shrubby, consisting of species of Rhododendron and Lonicera, 

 or low trees such as Betula utilis and Abies IVebbiana may 

 preponderate. 



III. The Pinus-Cedrus Formation occurs in the drier 

 regions between 6,500 and 12,000 ft., where the annual pre- 

 cipitation is from ten to forty inches and fairly evenly dis- 

 tributed. The vegetation is considerably affected by aspect, 

 and the prevailing trees are either conifers, e.g. Cedrus deodara, 

 Cnpressus torulosa, and Finns excelsa, or hardwoods such as 

 jEsculus indica, Acer ccesium, Corylus colurna. 



IV. The Shorea-Anogeissus-Pinus Formation. This oc- 

 cupies the moist valleys below 6,500 ft. with a similar pre- 

 cipitation to V, but drier and characterised b}^ the presence 

 of Pinus longifolia, Anogeisstis latifolia, and other trees. 



V. The Quercus-Abies Formation is found between 5,000 

 and 1 1 ,500 ft., with a precipitation of from fifty to eighty inches. 

 This is a mesophytic type of vegetation, characterised by the 

 presence of evergreen oaks {Quercus semecarpi folia, Q. incana) 

 Abies Pindrow, and deciduous types. In this moister zone 

 of vegetation a marked edaphic effect is found where limestone 

 soil occurs, the drier conditions resulting in the replacement 

 of the Quercus-Abies formation by the more xerophytic Pinus- 

 Cedrus formation. 



An important contribution to the study of plant distribu- 

 tion in Europe has been made by Sterner (Geografiska Annaler, 



