EFFECT OF SETTLEMENT UPON INDIGENOUS VEGETATION. 189 
district springing up in soil from a considerable depth when it 
was exposed to sun and air.* It may be in this manner that pines 
and wattles succeed other trees in Australia when the land is 
cleared. But I think it will be manifest that that is not the case 
in Danish or Sumatran forests. } 
In the beginning of 1887 a road was cleared through virgin 
brush-land over the side of Mount Kembla. The prevailing trees 
were palms, gums, giant-nettles, Omolanthus, Eleocarpus, Diplo- 
glottis, and Pennantia, with very rarely plants of Commersonia, 
Panazx elegans, and Asterotriche. In October of the same year, I 
walked up the road, and on each side, cutting off the road from the 
brush, was a dense hedge composed of nothing but Commersonia 
Fraseri, Asterotriche floccosa, and Panax elegans. At present - 
(1892) the majority of the smaller plants have been killed off in 
the struggle for existence, but there is a row of fair-sized trees of 
these three species—the first predominating—on each side, to the 
exclusion of all other trees. Here we see the mere fact of an 
opening in the forest gave these plants an advantage over others 
which they made the most of. 
(b.) Indirect injury to vegetation caused by alteration.of surface. 
In clearing land and during the progress of settlement, the 
surface of the ground is injured in many ways; in the formation 
of paths and roads; and in ploughing the ground. When the 
surface is broken on a slope, no matter how gentle, the protection 
afforded by the grasses and herbaceous plants to the soil is removed 
and the surface drainage is altered. Small runlets of water begin 
to travel along the line of disturbance and to cut channels which 
become deeper and deeper. The amount of earth cut away of 
course depends greatly on the slope, the nature of the soil and the 
amount of rainfall, being greatest in light soils and on steep slopes. 
In a light sandy soil I have seen on a very slight slope, channels 
nine feet deep and twelve or fourteen feet wide cut ina single wet 
winter. If the channel cut passes through forest land, the roots 
* Vide Wallace in “Island Life,” p. 513, et. seq. 
