225 



injurious at high elevations and may there be sufficient to 

 prevent the existence of trees. Winds, by distributing pollen, 

 aid in the fertilisation of flowers and production of seeds, and 

 also help in the distribution of seeds. Grasses are thus parti- 

 cularly favoured in windy localities and so are conifers among 

 trees. The fact that the light, large-winged seed of the 

 Blue Pine is distributed further by the wind than is the seed of 

 the Deodar is one of the causes which handicap the latter 

 in its struggle for existence with the former. Finally the 

 presence of poisonous substances in the air may make it p r => sence O f 

 impossible for some plants to survive in certain* localities, Poisonous 

 e.g. in smoky towns, near Iron Works, or Chemical Factories. Substances. 



203. The Forester in India knows (6) Existence 



from experience that, if he wishes to create forests oi some of of other 

 his valuable species, he must in the first place establish on P lant9 - 

 the area a growth ^of . other plants under the shelter of^any 1 " 5 

 of which his valuable species can be successfully introduced, Species on 

 whereas in the open their existence, at all events when young, ther P ^t3 

 would be impossible. This question of dependence on other Existence 

 plants may often decide which species shall survive in a given 

 locality. On hot dry aspects, for instance, shelter during 

 youth is essential for Deodar, which in such situations usually 

 establishes itself naturally under the shade of species of Indi- 

 gofera, Desmodium, and others. The seedlings of the Blue 

 Pine on the other hand grow readily in the open and, in this 

 respect, this species is favoured in its struggle for existence 

 with the Deodar. The Sal also usually establishes itself best 

 in open grassy areas if it is preceded by a growth of shrubs 

 of inferior species, such as Mallotus philippinensis, and others, 

 under the shade of which the young Sal are able to exist, a 

 phenomenon which may be often seen on the edges of grassy 

 blanks where the Sal forest is gradually extending and en- 

 croaching on the grassland. A very interesting case on record 

 in this connection is that of the Bhinga Forest of the 

 Bahraich Division of Oudh. In 1875 this was practically 

 a ruined Sal forest, very open with no Sal regeneration ; closure 

 to grazing and the encouragement of a growth of Mallotus 

 philippinensis and other shrubs has gradually resulted in the 

 establishment of a growth of young Sal. An even more 

 remarkable case is afforded by the Spruce and Silver Fir 

 forests of the North-Western Himalayas. Here the natural 

 reproduction of these species is usually conspicuous by its 

 absence, and if a clearing is made, instead of good fir re- 

 generation taking place, the ground is at once occupied by 



