106 S. Kurz — A Sketch of the Vegetation of the Nicobar Islands. [No. 3, 



group are forest-clad from the bottom to the top, the forests on the north- 

 ern group are restricted to the plutonic rocks and to the slopes and 

 dells of the older alluvium, while the hilly plateaux and ridges are covered 

 with park-like grass-heaths. 



Botanically, we have to consider the following rocks and soils as influ- 

 ential : — 



1. Plutonic and metamorphic rocks, which crop out only in a few 

 localities and are very subordinate. 



2. Calcareous sandstones, which cover by far the greater part of the 

 southern group. 



3. Raised coral-reefs much broken up and intermingled with calca- 

 reous sand and vegetable mould. 



4. Calcareous sea-sand, or blown sand, consisting of minute rounded 

 fragments of shells and corals. 



5. Polycistina-clay, which covers the greater part of the area on the 

 northern group. It is very light and siliceous, and remarkable for the 

 absence of alkalies. Locally it is ferruginous and of a red colour, and in this 

 case usually accompanied by fossil sea-weeds. 



6. Marine silty clay at the debouchures of rivers, more especially in 

 sheltered bays and shoals. 



Dr. Rink and Dr. Hochstetter have already been struck by the close 

 coincidence of the vegetation with the underlying rocks on these islands ; 

 and although a close examination of this relation revealed to me many im- 

 portant exceptions, we must be guided in all phytogeographical matters not 

 only by the consideration of climatic influence but as much also by that of 

 the influence of soil. 



As the climate is a tropical moist one, identical with that of most 

 Malay islands, and the elevation of the hills too small to affect vegetation, 

 the influence of the soil naturally becomes more conspicuous and marked. 

 Owing to the uniformly damp climate deciduous forests have ceased at this 

 latitude, although deciduous trees are not unfrequently interspersed, especi- 

 ally in sunny localities. Evergreen trees thus form the bulk of the forests, 

 and even the beach-forests, sunny forests growing on calcareous sand, are 

 studded with evergreens, so that the deciduous trees become quite subordi- 

 nate. I have distinguished the following kinds of vegetative combinations 

 on these islands : — 1. Mangrove Foeests. 2. Beach Foeests. 3. Teopi- 

 cal Foeests. 4. Geass-heaths. 5. Mabine Vegetation". 



Cultivation is little represented, being restricted to small patches of 

 cleared land usually at some distance inland from the villages. 

 1. Mangeove Foeests. 



The mangrove-forests of all tropical Asia are so uniform, not only in 

 external aspect but also in their botanical character, that it is hardly 



