414 The Philippine Journal of Science 1914 
of these plants. As most birds frequent land which already 
has vegetation rather than bare ground, the parang species 
are more likely to be found growing in previously vegetated 
areas, in spite of the fact that the bare ground seems entirely 
suitable. Once the seeds actually effect ecesis, which may often 
be difficult in the dense grass, it does not take long for them 
to dominate. Height development in either shrubs or trees 
cuts off light from the grass, to which the grass can respond 
by growing somewhat higher, but soon reaches its limit and 
has to give way. The fact that grass dies down to the ground 
in the unfavorable season, while shrubs and trees retain their 
elevation, makes the struggle all the more one-sided. Generally 
grass can get into a place quicker and obtain a readier start 
and so comes to occupy the ground ; but, barring fires, it cannot 
hold forth forever where conditions are favorable for the devel- 
opment of higher vegetation. 
On the slopes of Taal the opportunities for shrub ecesis are 
rather great for the grass is in general not dense, and over 
large areas decidedly not so. Still most of the invading parang 
species do not obtain a foothold in this ground, but seem to 
prefer to wait until the grass becomes established and then 
drive it out. So shrubs become established in many different 
places and furnish many centers of distribution for further in- 
vasion of the grassland. With the establishment of shrubs, 
larger numbers of birds visit the area and the number of vines 
increases very decidedly. In the room afforded under the shrubs 
when the grass has been driven out, certain herbaceous plants 
find their way and thus the parang association is built up. 
As this association now exists on Taal Island it is largely in 
the distribution stage, that is, mostly as isolated plants with here 
and there little groups. In the northeastern part of the island, 
where devastation was least severe, the vegetation obtained an 
earlier start and succession is rapidly replacing both the grass 
and the parang with species of the Bambusa-Parkia association, 
so that at present a large part of the ridges and most of the 
valleys are vegetated with woody plants to the exclusion of the 
grass. On some of the edges of the ridges even trees from 5 
to 6 meters in height have had time to develop. Establishment 
of tree covering is going on very much faster with the island 
uninhabited, as fire — the greatest accident that normally oc- 
curs — is kept at a minimum, thus giving the shrubs a chance. 
Greater detail of the parang association follows under the 
separate consocies recognized. 
