ECOLOGY OF WOODLAND PLANTS. 339 
as to practically exterminate the shrubs, and the increased light 
thus admitted favoured the development of Bracken, until at 
the present time its distribution is limited, as shown in fig. 2. 
Similar changes have taken plaee over extensive areas in the 
adjoining Woodsome Woods. 
Another interesting illustration of the effect of trees on the 
distribution of plants is found in the Woods at Honley. 
Twenty years ago the thickly planted Pines produced such a 
dense shade that the ground beneath was practically devoid of 
Birks Woop. 
Map showing the distribution of Pteris aquilina, Linn. 
vegetation, the deep shade favouring the accumulation of consider- 
able humus. Since then, thinning has taken place in a portion of 
the wood to the west, thus exposing the remaining pines to the 
prevailing winds. This, together with the ravages made by the 
pine-bark beetle and some felling of the pines, has gradually 
admitted light, thus favouring the development of Bracken. 
It has made inroads from the adjacent wood, slowly pushing its 
way, until at the present time it forms a dense sheet in the 
