14
Light
It was difficult on these -few occasions to take
meaningful measurement of light intensity
because of the great range of values with time
and position. However, the relative develop-
ment of the shrub and ground layers were good
indicators of the light penetrating during the
growing season. Structural adaptations of the
plants to light were discussed and recorded.
It was evident that most of the woodland plants
displayed as much leaf surface as possible
through the leaf mosaics. This can be exem-
plified by the large surface area of bracken
spread to fill all available space, like the
dense mosaics of the beech leaves. Similarly,
the bluebells with their narrow leaves radiat-
ing in all directions, with little overlap,
formed almost a complete circle to maximise
their exposed leaf surface. Such effective
modifications make use of all available light
penetrating the canopy and help to minimise
competition.
Soil
The soil profiles were examined at each site
with a clean cut vertical section dug to a
depth of 30—45 cm. The areas were reported to
be gleyed brown earth over clay. However, the
soil profiles showed local variations on this.
(a) Under the coniferous woodland a dark mor
type sandy humus layer some 10 cm thick was
over a lighter stony, sandy layer more than 45
cm deep. There was no evidence of gleying and
the area was freely drained. Apparent lack of
earthworms and the limited amount of humus