237 



CHAPTER III. PRINCIPAL TYPES OF INDIAN 

 FORESTS. 



218. For the purposes of a brief 



and general description the forests of India may be divided 

 broadly into the following types : 



(1) Arid-country Forests. 



(2) Deciduous Forests. 



(3) Evergreen Forests. 



(4) Hill Forests. 



(5) Tidal or Littoral Forests. 



It must be remembered that as each type of forest often passes 

 very gradually into a different type, the boundary line between 

 the various types cannot always be clearly denned; moreover 

 differences in the soil, local conditions affecting the amount of 

 moisture available, and other factors may entirely alter the 

 type of forest over small areas, which cannot be taken into con- 

 sideration in a broad and general account. The approximate 

 distribution, however, of these types is shown in Plate XXII 

 areas bearing no forest not being separately shown. In each of 

 these main types also numerous sub -types of course exist which 

 it is impossible to note in detail here. The principal factor Factors 

 responsible for the distribution of types 1 to 3 is the amount of responsible 

 available moisture as measured approximately by the annual Distribution, 

 rainfall, which is clearly shown by a comparison of Plates XXI 

 and XXII ; type 4 owes its existence mainly to low temperature 

 caused by the elevation above sea-level, while type 5 is due 

 mainly to the large quantities of salts dissolved in the sea-water 

 and to the action of the tides. 



219. The principal tract of country (i) Arid- 



which, with reference to its rainfall, may be called arid, the country 

 annual rainfall being less than 20 inches, occurs in the North- Forests - 

 Western corner of India, including Sindh, the southern portion 



of the Panjab, and a large part of Rajputana. A large 

 portion of this area is occupied by desert, the principal 

 woodlands being the so-called rakhs of the Panjab in the north 

 and the belts of the riverside forest along the Indus and its main 

 tributaries. The rakhs occupy the high ground between the 

 rivers and are poor, scanty woods of small trees and shrubs, the 

 most characteristic species being Prosopis spicigera and species 

 of Salvadora and Capparis. Owing to the great depth of the 

 subterranean water the species occurriDg in these rakhs are 

 often characterised by possessing roots of immense length and a 

 taproot of Prosopis measuring 86 feet in length has been exhibit- 



