EFFECT OF SETTLEMENT UPON INDIGENOUS VEGETATION. 213 
the heath, and had failed. No wonder that, as soon as the land 
was enclosed, it became thickly clothed with vigorously growing 
young firs. Yet the heath was so extremely barren, and so exten- 
sive, that no one would ever have imagined that cattle would 
have so closely and effectually searched it for food.”* 
(b) Alteration of drainage caused by the introduction of a new fauna. 
It has already been shown in Division I. how alterations in 
surface drainage may affect the plants of a country. It now 
remains to be seen how drainage is altered by stock. 
A very good description of how the damage is done is given by 
Mr. R. B. Smyth in the following passages :—“ Quite extensive 
tracts of forest lands have lately deteriorated by the decay of belts 
‘of trees. Numerous theories have been started to account for the 
destruction of the timber on these once flourishing areas. Many 
suppose that insects have attacked the tender buds, and destroyed 
them, or the roots, and prevented their growth. Others suggest 
that the extraordinary increase of the smaller marsupialia, now 
that their natural enemy, the dingo is, in inhabited parts, almost 
extinct, has caused the mischief. But after examining many 
tracts where the trees have decayed both in the Jevel country and 
in the high lands, I am inclined to think that, in most cases, the 
trees are killed by the changes effected on the surface by cattle 
and sheep which have been introduced by the settler. The tracks 
made by these animals carry off the rain water, and, when there 
is a slight incline, these tracks deepen into gullies, and drain the 
land so effectually as completely to destroy the conditions which 
in the natural state of the ground were favourable to the growth 
of the gums. In the camping places of the cattle, you see many 
trees destroyed. The grass is beaten down and the soil broken 
“and the long roots of the trees exposed to the intense heat of the 
sun, and the frosts of winter. When the roots are protected by 
litter or earth, the trees quickly recover and spread their branches 
with a luxuriance not observable even in the natural forests.” + 
* Origin of Species, 6th Edit., p. 56. 
+ Goldfields and Mineral Districts of Victoria, p. 28. 
