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eral appearance of the forest. In its other ecological characteristics the 
Dipterocarpus-Shorea resembles the Anisoptera-Strombosia formation. 
Summary.—1. Over 30 per cent of the Dipterocarpus-Shorea forma- 
tion is composed of members of the Dipterocarpacee. 
2. Corresponding with the greater rainfall, less saturation deficit and 
less heat, this formation, in contrast with those lower down the moun- 
tain side, is less xerophytic. This is shown by the almost complete 
absence of deciduous trees and by the greater leaf display among the 
evergreens during the dry season. 
3. The formation, as a whole, has a more regular profile. 
4. In other ecological respects the formation resembles the Anisoplera- 
Strombosia formation. 
5. For the first time a topographical situation is encountered where 
exposure brings about a tendency to dwarf the trees—a tendency which 
finds its best expression on the exposed ridges higher up the mountain. 
' 
LV. SHOREA-PLECTRONIA FORMATION. 
In striking contrast with the formation in which over 30 per cent 
of the larger tree species are members of the Dipterocarpacew is the 
one immediately above it in which this family is represented by only 
16 per cent of the total number of trees over 4 meters in height. 
Again, an under story vegetation is represented by a number of species. 
Among the larger of these, the genus Shorea stands first and the rubiace- 
ous Plectronia viridis is typical of a number of about the same height 
and having the same ecological characteristic—that is, an ability to 
withstand a considerable amount of shade, and therefore this has been 
called the Shorea-Plectronia formation. In extent it lies approximately 
between the 450 and 900 meter contour lines. Its upper limits are 
marked by a rather sudden restriction of the Dipterocarpacee. 
Description of Table XIX. 
Plots in Shorea-Plectronia formation.—A, a plot on a level bench of a side 
ridge leading from the main ridge to the Lamao river. It comprises an area of 
675 square meters. B, a plot starting at an.altitude of 675 meters and running 
through a vertical distance of 30 meters. The slope is about 25° and the area 
1,440 square meters. It is on the same ridge as A. Plots C, D, E, F, and G, 
each extending through a vertical distance of 30 meters, represent portions of a 
narrow side ridge leading directly to the river at right angles to the one on 
which are A and B. C, is on a slope of 42° and has an area of approximately 
252 square meters; D, on a gradient of 40° and with an area of 336 square 
meters; E, one of 44°, and it represents an area of 360 square meters; F, is a 
still steeper slope of 45° on a narrow ridge between two ravines. It has an 
approximate area of 250 meters. A canyon to the right of it has a depth of 18 
meters with perpendicular sides. G, is on a very steep and unstable slope 
(over 45°); it has an estimated area of 300 square meters and ends at the 
junetion of two canyons. The first line tabulates trees over 4 meters in height ; 
the second, those under 4 meters; H, is the total of trees over, and I of those 
under 4 meters; J, represents the percentage in all plots of trees over 4 meters. 
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